THE SYSTEM PYRIDINE-HYDROGEN CHLORIDE AS AN
ACID MEDIUM
BY
HYMAN MITCHNER
A THESIS.SUBMITTED IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
in the Department
of
CHEMISTRY
We accept this thesis as conforming to
the standard required from candidates
for the degree of MASTER OF SCIENCE
Members of the Department of Chemistry
THE UNIVERSITY OF BRITISH COLUMBIA
APRIL, 1953
ABSTRACT
P y r i d i n e s a l t s were i n v e s t i g a t e d as a c i d s i n t h e
p y r i d i n e system.
The mono and t h e d i h y d r o c h l o r i d e
were found t o be t h e best
salts
d i s s o l v i n g reagents f o r t h e
a
metals and t h e s u l p h i d e s
used.
Pyridine
hydrochloride
was most e f f e c t i v e i n t h e molten s t a t e , whereas p y r i d i n e
dihydrochloride
was found t o be q u i t e r e a c t i v e a t room
temperature when d i s s o l v e d i n a c h l o r o f o r m s o l u t i o n .
S i d e r e a c t i o n s were i n v e s t i g a t e d and were found t o occur
only w i t h Mg, A l , and Zn w i t h molten p y r i d i n i u m
The
complex s a l t s ,
(C H N.H)HgCl
5
B
4
(C H N.H) [MnCl 3c H N
5
e
8
B
5
B
and
were i s o l a t e d and i n v e s t i g a t e d .
chloride.
1
I
AKNOWLEDG-EMENT
Sincere appreciation i s expressed to Dr. K. Starke
for his'encouragement and help i n making this work
possible.
TABLE OF CONTENTS
PAGE
INTRODUCTION
1.
Water as an unique s o l v e n t
1
2.
H i s t o r i c a l approach t o r e a c t i o n s i n nonaqueous
systems
a. . Confusion
and misconcepts i n t h e a c i d -
has e t h e o r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
b.
Bronsted
1
theory o f a c i d s and bases.. «,...© 4-
3.
Disadvantages o f water as a s o l v e n t . . . . . . . . . . .
5
4.
Alms o f i n v e s t i g a t i o n
5
......
EXPERIMENTAL
1.
P u r i t y o f reagents
2.
Preparation of pyridinium
3.
7
salts
a.
Pyridinium n i t r a t e
7
b.
Pyridinium t r l c h l o r o a c e t a t e
7
Co
Pyridinium thiocyanate
8
d.
Pyridinium oxalate
8
e.
Pyridinium fluoride.......................
9
f.
Pyridinium chloride
9
g.
Pyridine dihydrochloride.................
11
h
Other s a l t s o f p y r i d i n e . . . . . . . . .
11
0
Methods o f u s i n g C H N.HC1 and C H N.2HC1
5
a.
B
B
B
Molten C H N.HC1 and molten C H N.2HC1... 12
5
5
B
6
-11
b.
Room temperature systems
1.
C. H N.HCl i n pyridine,,....
6
lie
......
B
Saturated
14
chloroform solutions of
C H N.HC1 and C H N.2HC1............
B
c.
B
B
B
15
The r e a c t i o n o f metals i n molten C H N.HCl
e
and
e
the r e a c t i o n o f metals w i t h a s a t u r -
ated c h l o r o f o r m s o l u t i o n of C H N.2HC1
6
B
at room temperature.....
16
S o l u b i l i t y of C H N.HC1 and C H N.2HC1 i n . 5
B
B
B
-
c h l o r o f o r m a t 23°C
17
Absorbency - wavelength, i n v e s t i g a t i o n o f the. ,
c h l o r o f o r m s o l u t i o n s o f G H N HC1 and
B
B
0
C H N.2HC1
B
17
5
Side
reactions
a.
Materials
i.
ii.
iii.
Preparation
of 4-pyridyl-pyridinium
dichloride
20
P u r i f i c a t i o n of synthetic quinoline.
20
Preparation
of quinoline hydrochlo-
ride
b.
Product o f s i d e
1.
ii.
ill.
21
reactions
Isolation...............
22
Examination f o r b i p y r i d y l s .
23
Decomposition product o f 4 - p y r i d y l pyridinium
d i c h l o r i d e i n NaOH..........
24
-iii*
iv.
C H N.HC1
F u r t h e r r e a c t i o n s o f Zn +
5
B
r e a c t i o n product..................•«
c.
Reaction
of quinoline hydrochloride
metals
i.
with
• . ,.
S i d e r e a c t i o n product o f q u i n o l i n e ,
'hydrochloride
ii.
Reaction
plus zinc
of quinoline
25
hydrochloride
25
product w i t h a c e t i c . anhydride
7.
24
Reactions with p o s s i b l e a n a l y t i c a l a p p l i c a t i o n
a.
M a t e r i a l s - p r e p a r a t i o n . o f . Mn.(OAc ) . . . . . .
b.
Reaction
3
i.
ii.
of C H N.2HC1
B
B
i n CHC1
iv.
v.
vi.
w i t h MnS
Nature o f sample of, MnS
26
Reaction
of. manganese, s a l t s , . metal. •.
and Mn0
with a saturated
8
chloro-
form s o l u t i o n o f C H N . 2 H C 1 . . . . .
27
Heating o f a f r e s h sample o f MnS.....
27
B
iii.
3
26
B
..... 27
E f f e c t o f o x i d i z i n g agents
C H N.2HC1
B
B
i n CHC1
S
on Mh(OAc) .".....
I s o l a t i o n o f t h e substance
8
28
confer—
r i n g . t h e green c o l o u r t o t h e
G5H5N.2HCI i n GHCI3.................
28
vii.
A n a l y s i s p f the green c r y s t a l s . . . . . .
29
viii.
L i m i t o f v i s i b l e colour...,..,,......,.
29
Colourometric
29
ix.
x.
analysis..,,.,....,...
V a r i a t i o n of colour with
t i m e . 3 3
4
-ivc.
R e a c t i o n o f C H N.2HCl i n CHC1
B
i.
ii.
III
e
I s o l a t i o n o f the•mercury
3
w i t h HgS.
salt.......
33
A n a l y s i s o f t h e mercury s a l t . . . . . . . .
33
DISCUSSION
lo
P y r i d i n e s a l t s as r e c t i o n media
a.
Type o f r e a c t i o n most d e s i r a b l e .
37
b.
Examination of t h e p y r i d i n e s a l t s prepared
2.
37
Methods o f u s i n g C H N.HC1 and C H N.2HC1
B
B
a.
Molten s t a t e
b.
Room temperature
B
38
systems
3.
The n a t u r e o f C H N.2HC1 i n CHC1
4.
Side r e a c t i o n s
B
B
B
39
Al
3
a.
P o s s i b i l i t y of formation of b i p y r i d y l s . . .
42
b.
Ring cleavage............................
43
c.
L i m i t a t i o n s due t o s i d e r e a c t i o n s
45
5. . R e a c t i o n s w i t h p o s s i b l e a n a l y t i c a l a p p l i c a t i o n
a.
T r i v a l e n t manganese
i.
F o r m u l a t i o n o f t h e compound
(C H N.H) CMnCl 3C H N...............
5
ii.
B
s
B
B
5
E x p l a n a t i o n o f r e a c t i o n s o f manganese
sstXts© •»••••«*««»••«•««••»•
iii.
46
• • • « o « •
©• *
D e t e r m i n a t i o n o f t r i v a l e n t manganese
by c o l o u r o m e t r i c a n a l y s i s o f t h e
green complex...
48
-V-
b.
The m e r c u r y - p y r i d i n e
.1.
F o r m u l a t i o n o f t h e compound
(C H N»H)gHgCl^••.••••.«•«..««*»•«..
50
A p p l i c a t i o n of s o l u b i l i t y
51
B
ii.
6.
XV
complex
B
Conclusions
..
BIBLIOGRAPHY. «....-.
•
...
51
. . . . . . . . . . . . . . . 0 . . . . . . . . 0 . . . . .
TABLES . .
Table I
o f HgS....
.•«
..........
R e a c t i v i t y o f s u l p h i d e s i n molten C H N.HCl
5
e
and molten C H N.2HC1.......*.....*...••.....
B
Table I I
52
B
13
R e a c t i v i t y o f s u l p h i d e s i n C H N.HCi i n
B
pyridine.
B
•
14-
Table I I I R e a c t i o n o f s u l p h i d e s i n s a t u r a t e d c h l o r o f o r m
s o l u t i o n s of C H N.HC1 and C H N.2HC1
B
Table IV
B
5
15
B
The r e a c t i o n o f metals I n molten C H N.HCl
B
e
and t h e r e a c t i o n o f metals w i t h a s a t u r a t e d
c h l o r o f o r m s o l u t i o n of C H N.2HC1 a t room
5
temperature
Table V
6
•
16
R e a c t i o n of manganese s a l t s , metal and Mn0
8
with a saturated chloroform s o l u t i o n of
CH N.2HC1...................................
B
B
0
27
-vi-
FIGURES
Figure I
Absorbency-wavelength
plot f o r a saturated
c h l o r o f o r m s o l u t i o n o f C H N . 2 H C 1 and a
6
B
d i l u t e d c h l o r o f o r m s o l u t i o n o f C H N . H C 1 . . . f'lQ
B
B
i
Figure II
Absorbency wavelength.plot
for a diluted •
T
c h l o r o f o r m s o l u t i o n of C H N . 2 H C 1
5
Figure III
..
B
S p e c t r a l - T r a n s m i t t a n c e curve o f green
19
tri-
v a l e n t manganese complex l a a s a t u r a t e d
chloroform s o l u t i o n of C H N . 2 H C 1 . .
B
F i g u r e IV
31
B
C o n c e n t r a t i o n - T r a n s m i t t a n c e curve of green
t r i v a l e n t manganese complex i n 10 c c . of a
saturated chloroform s o l u t i o n of C 5 H 5 N . 2 H C I .
T r i v a l e n t manganese o b t a i n e d by r e d u c t i o n
Figure V
C o n c e n t r a t i o n - T r a n s m i t t a n c e curve of green
t r i v a l e n t manganese complex i n 10 c c . o f a
saturated chloroform s o l u t i o n of C H N.2HC1.
B
5
T r i v a l e n t manganese o b t a i n e d by o x i d a t i o n
of d i v a l e n t > manganese, o »».»»•«.»..... •«...
s
F i g u r e VI
34
V a r i a t i o n o f c o l o u r of green t r i v a l e n t manganese complex w i t h time.
.35
-1-
I - INTRODUCTION
1.
Water as aaunique solvent.
Of a l l our known solvents, the one most used i s
water.
As a solvent, water i s considered to be unique.
Its physical properties, such as i t s capacity as a gene r a l solvent f o r s a l t s and i t s power of e l e c t r o l y t i c
dissociation,
i t s low molecular elevation constant, i t s
high b o i l i n g point, and i t s heat of fusion, heat of
v o l a t i l i z a t i o n , c r i t i c a l , temperature,
s p e c i f i c heat,
association constant, and d i e l e c t r i c constant with values
so much higher than the corresponding values f o r other
substances, a l l tend to remove i t f a r from other s o l vents and to place i t i n a class by i t s e l f .
Furthermore,
because of i t s abundance, i t i s one of the most studied
substances known.
...
.
•
2. . H i s t o r i c a l approach to reactions i n nonaqueous systems.
a.
Confusion and misconcepts i n the acid-base
theory.
Following the discovery of the v o l t a i c c e l l by
Volta early i n the 19th century, considerable work was
done to d i f f e r e n t i a t e between those substances which
conduct an e l e c t r i c current i n aqueous solutions and
those which do not.
Electrochemists of the middle 19th
century such as H i t t o r f and Kohlrausch studied the
-2-
behavlour of the so-called electrolytes such as hydrogen
chloride and ammonia i n t h e i r l i q u i d states.
l a t t e r two
i t was
substances were found to be nonconductors,
promptly assumed that they did not break up
ions and
into
that only i n water did they possess character-
i s t i c chemical and
only i n water was
The
When these
electrochemical properties,
and hence
i t possible to effect i o n i c
reactions.
c r i t e r i o n for the pure substance to be able to.act
as an acid per se was
thus related to i t s a b i l i t y to
conduct e l e c t r i c i t y .
The r o l e of water as an i o n i z i n g medium In electrol y t i c d i s s o c i a t i o n intrigued many investigators.
Arrhenius (1884) attempted to completely explain
electro-
l y t i c d i s s o c i a t i o n by placing the emphasis on the r o l e
37
of water.
Werner
, the originator of the complex
compound theory, also t r i e d to explain what happened when
a nonelectrolyte
solution.
dissolved i n water to give a conducting
He introduced the terms "anhydro base" and
"aquo base", as well as "anhydro acid" and
"aquo acid".
"Anhydro bases (such as ammonia) are compounds which
combine with the hydrogen ions of water i n aqueous solution, and thereby cause a s h i f t i n d i s s o c i a t i o n e q u i l i brium of water u n t i l t h e i r corresponding c h a r a c t e r i s t i c
hydroxyl ion concentration has been reached."
"Aquo
bases (such as potassium hydroxide) are addition compounds
of water, which i n t u r n d i s s o c i a t e i n aqueous s o l u t i o n
t o g i v e hydroxy! i o n s . "
Anhydro a c i d s
(such as H C l )
are "compounds which i n aqueous s o l u t i o n so combine
hydroxyl
with
i o n s o f water as to cause a s h i f t i n d i s s o c i a -
t i o n e q u i l i b r i u m o f the s o l v e n t water u n t i l t h e c o r r e s ponding c h a r a c t e r i s t i c hydrogen i o n c o n c e n t r a t i o n has
been reached."
I t was not l o n g , however, b e f o r e
of the Arrhenius
the l i m i t a t i o n s
concept were r e c o g n i z e d .
Work on non-
36
aqueeus
s o l u t i o n s by Walden
i n Europe and contemporary
is
a c t i v i t y i n t h e U n i t e d S t a t e s by Cady, F r a n k l i n
Kraus made a r e v i s i o n o f a c i d and base theory
, and
necessary.
I t was shown t h a t numerous s o l v e n t s y i e l d e d conducting
s o l u t i o n s and that a l l substances e x h i b i t ^ s o l v e n t prope r t y t o a g r e a t e r or l e s s e r degree.
Some compounds
regarded as s a l t s i n t h e aquo system were found t o behave
as a c i d s or bases i n nonaqueous
systems and t h e r e f o r e ,
c e r t a i n changes w i t h r e s p e c t to t h e d e f i n i t i o n s o f
c l a s s e s o f compounds i n terms o f the s o l v e n t
were o b v i o u s l y
employed,
necessary.
Ammonium s a l t s behave as ammono-acids i n l i q u i d
ammonia as the s o l v e n t
, whereas a c e t a t e s behave as
9
aceto-bases i n g l a c i a l a c e t i c a c i d .
In general,
"onium"
s a l t s e x h i b i t a c i d c h a r a c t e r i s t i c s i f the corresponding
anhydro base i s the s o l v e n t .
b.
Br^nsted theory of a c i d s and bases.
One
of the most u s e f u l t h e o r i e s proposed to
c o o r d i n a t e these more advanced i n v e s t i g a t i o n s was
proposed by Brpnsted
.
one
The phenomenon of a c i d i t y
was
simply c o n s i d e r e d as a matter of c o m p e t i t i o n between the
s o l v e n t and the a c i d anion as bases f o r the
A^=±B +
H
proton:
+
Thus an a c i d would be any molecule or i o n which acted as
a p r o t o n donor, a base, any molecule or i o n which acted
as a p r o t o n a c c e p t o r .
be due
ion.
A c i d i t y i n b a s i c s o l v e n t s would
to the formation of the corresponding
"onlum"
I n ammonia t h e r e i s formed the ammoniated hydrogen
i o n or ammonium i o n as the bearer of a c i d i t y :
NH . + H
+
3
NH
+
4
S i m i l a r l y i n a n i l i n e t h e r e i s formed the a n l l i n i u m i o n
( C H N H « H } and i n p y r i d i n e the p y r i d i n i u m i o n
+
6
6
S
(C H N.H ).*
+
B
5
The n a t u r a l experimental
e x t e n s i o n was
to i n v e s t i -
gate the s o l i d and fused s t a t e s of the "onium" s a l t s i n
which the "onium" i o n must e x i s t , to see i f the s a l t s of
the s o l v e n t e x h i b i t e d t h e r e i n the p r o p e r t i e s of a c i d s .
I n v e s t i g a t i o n s c a r r i e d out w i t h fused p y r i d i n i u m chlorfede
* The Brc^nsted theory, of course, i s l i m i t e d
because i t takes i n t o c o n s i d e r a t i o n o n l y p r o t o n i c substances, but where a p p l i c a b l e i t i s extremely u s e f u l .
As the s o l v e n t s c o n s i d e r e d i n the i n v e s t i g a t i o n h e r e i n
are p r o t o n i c , the Brj^nsted theory i s used.
i
demonstrates c o n c l u s i v e l y t h a t an e x t e n s i o n t o the
molten s t a t e of the "onium" r e a c t i o n s u & s
fied.
perfectly
Furthermore, a l l o t h e r "onium" s a l t s
justi-
Investigated,
have been found to behave i n a s i m i l a r manner .
Disadvantages of water as a
solvent.
The h i g h d i s s o c i a t i n g power of water can prevent
the f o r m a t i o n of n e u t r a l molecules o r complex i o n s
which
might form i n nonaqueous r e a c t i o n s , but d i s s o c i a t e i n
the presence of water.
even be f o l l o w e d
U n d e s i r a b l e d i s s o c i a t i o n may
by a r e a c t i o n w i t h t h e s o l v e n t
as a
r e s u l t of water i t s e l f b e i n g always d i s s o c i a t e d .
Thus,
i n order to o b t a i n an o v e r a l l p i c t u r e of r e a c t i o n s i n
nonaqueous s o l v e n t s
was
not formed was
a s e r i e s of r e a c t i o n s
i n which water
c a r r i e d out.
Alms of i n v e s t i g a t i o n .
a.
I t was proposed t o i n v e s t i g a t e the a c i d s a l t s
o f p y r i d i n e as r e a c t i o n media f o r metals and common
sulphides.
b. I t was proposed to i n v e s t i g a t e f u r t h e r those
s a l t s which showed, i n the molten s t a t e , good r e a c t i v i t y
f o r the metals and s u l p h i d e s
ing a solvent
used, w i t h the aim o f
system which c o u l d be used a t room
obtain-
temper-
ature.
c. I t was proposed to i n v e s t i g a t e any s i d e
reactions
which might l i m i t the a p p l i c a b i l i t y o f t h e r e a c t i o n media
used.
d.
I t was proposed to i n v e s t i g a t e any
t h a t might suggest p o s s i b l e a n a l y t i c a l
reactions
applications.
I I - EXPERIMENTAL
1.
P u r i t y of reagenta.
The reagents used I n a l l p r e p a r a t i o n s were of
"Reagent Grade" q u a l i t y *
The p y r i d i n e was
f u r t h e r pur-
i f i e d by r e f l u x l n g f o r two hours over sodium hydroxide
p e l l e t s t o remove any water t h a t might have been absorbed
from the a i r .
The p y r i d i n e was
then d i s t i l l e d and the
f r a c t i o n coming over between 115-ll6°C. c o l l e c t e d .
2.
P r e p a r a t i o n of p y r i d i n i u m s a l t s .
1*33
a.
Pyridinium n i t r a t e
(C H N.HN0 )
5
B
3
S l i g h t l y more than an e q u i v a l e n t amount of
t r a t e d n i t r i c a c i d was
added to 100 gm.
concen-
of p y r i d i n e and
' the r e s u l t a n t mixture evaporated on a steam b a t h
till
viscous.
Upon c o o l i n g , a c r y s t a l l i n e product was
which was
t r e a t e d w i t h e t h e r , f i l t e r e d by s u c t i o n and
washed a g a i n w i t h e t h e r .
obtained
The p y r i d i n i u m n i t r a t e was
then
r e c r y s t a l l l z e d from a b s o l u t e a l c o h o l and white needles
o f l a r g e s i z e were o b t a i n e d ,
was
quantitative.
m.p.
115-116°C.
The
yield
No m e l t i n g p o i n t has been p r e v i o u s l y
reported.
b.
Pyridinium trichloroacetate
(C H N.GCl C00H)
6
e
a
To prepare p y r i d i n i u m t r i c h l o r o a c e t a t e , e q u i v a l e n t
amounts of p y r i d i n e and t r i c h l o r o a c e t i c a c i d were used.
P a r t i c u l a r care was
taken to keep the t r i c h l o r o a c e t i c
—8**
acid free from moisture.
i n an i c e bath.
The reaction was carried out
The pyridine was added slowly with s t i r -
r i n g to the cooled t r i c h l o r o a c e t i c acid.
A vigorous
reaction ensued with the production of a yellow-brown
semi-solid.
After the reaction was complete, the product
was heated on a steam bath t i l l l i q u i d and cooled again
i n the i c e bath, where i t formed a yellow slush. The
cold residue was treated with absolute ether, f i l t e r e d
and washed twice with a d d i t i o n a l amounts of absolute ether.
The buff coloured residue was r e c r y s t a l l i z e d
from-absolute
alcohol and gave white, planar (mica-like) c r y s t a l s which
decomposed on heating at 111-112 C.
Reitzenstein
report-
ed a melting point at 112°C.
13
c.
Pyridinium thiocyanate (C H N.HSCN)
e
6
Pyridinium thiocyanate was prepared by the addi t i o n of alcoholic solutions of equivalent amounts of
pyridine hydrochloride and ammonium thiocyanate.
On
addition of the two alcoholic solutions, NE^Cl precipi t a t e d out.
This was f i l t e r e d and the product
recovered
by evaporating the f i l t r a t e - t o a small volume.
The
c r y s t a l s thus obtained were f i l t e r e d and washed with ether.
They were easily r e c r y s t a l l i z e d from ethanol to y i e l d
white planar crystals of melting point 98°C.
No melting
point has been previously reported.
3 8 > 3
d.
X
Pyridinium oxalate ( ( C H N ) C H 0 )
5
5
s
2
s
4
Pyridinium oxalate was prepared by the addition of
p y r i d i n e to an acetone s o l u t i o n of a x a l i c a c i d .
white p r e c i p i t a t e was
o b t a i n e d which was
A bulky
filtered,
washed
w i t h acetone and r e c r y s t a l l i z e d from a b s o l u t e a l c o h o l t o
3
g i v e white c r y s t a l s of m.p.
152-153°C.
i
Pfeiffer
r e p o r t e d a. m e l t i n g p o i n t a t 153'vC.
e.
Pyridinium f l u o r i d e
P y r i d i n i u m f l u o r i d e was
not prepared.
An- attempt
to prepare i t along the l i n e o f p y r i d i n i u m n i t r a t e
not s u c c e s s f u l .
E q u i v a l e n t amounts of p y r i d i n e
hydrogen f l u o r i d e
No product was
obtained.
to prepare the h y d r o f l u o r i d e was
to aqueous HF,
and
( i n the form of 48$ HF) were mixed
i n a s t a i n l e s s s t e e l beaker and the r e s u l t i n g
evaporated.
was
solution
A second
attempt
made by adding p y r i d i n e
but t h i s time a c e t i c anhydride was
to r e a c g w i t h the water.
added
The e n t i r e mixture was e x t r a c t e d
w i t h ether to remove the a c e t i c a c i d and to l e a v e behind
the p y r i d i n i u m f l u o r i d e , which, i f i t behaved as o t h e r
p y r i d i n e s a l t s , would be i n s o l u b l e i n e t h e r .
was
obtained.
No
product
The f i n a l method t r i e d I n c l u d e d the above
two procedures, but an excess of h y d r o f l u o r i c a c i d
was
used to the extent of s i x moles of HF t o one mole of
pyridine.
No p y r i d i n i u m f l u o r i d e c o u l d be
isolated.
S3 $3
f.
Pyridinium chloride
mm
(C H N.HCl)
B
e
P y r i d i n i u m c h l o r i d e i s h y g r o s c o p i c and i t was
found best to prepare i t Just b e f o r e use.
were found to work q u i t e r e a d i l y !
Three methods
-10i.
Using a Kipp generator,
by r e a c t i n g concentrated
chloride.
HCl gas .was evolved
s u l p h u r i c a c i d w i t h ammonium
The gas was d r i e d by p a s s i n g i t through two
gas washing b o t t l e s c o n t a i n i n g concentrated
sulphuric
a c i d and was then i n t r o d u c e d i n t o ,a s o l u t i o n o f p y r i d i n e
i n dry ether.
P y r i d i n i u m c h l o r i d e p r e c i p i t a t e d almost
immediately as a white s a l t * .
I t was f i l t e r e d i n a
Buchner f u n n e l and s t o r e d i n a vacuum d e s l c a a t o r over
anhydrous magnesium .perchlorate.
Ii.
Concentrated
h y d r o c h l o r i c a c i d was added
to a s l i g h t excess o f p y r i d i n e and t h e r e s u l t i n g aqueous
s o l u t i o n of p y r i d i n i u m c h l o r i d e was d i s t i l l e d .
The d i s -
t i l l a t e coming over i n t h e range 218-218.5°C was c o l l e c t ed as C H N.HC1.
B
6
The s o l i d i f i e d s a l t was then d i s s o l v e d
i n a b s o l u t e . a l c o h o l and c r y s t a l l i z e d by c o o l i n g .
s a l t remaining
The
i n t h e mother l i q u o r c o u l d be p r e c i p i t -
a t e d w i t h dry e t h e r .
iii.
Anhydrous ether was s a t u r a t e d w i t h dry
HCl and p l a c e d i n a separatory f u n n e l .
The s o l u t i o n was
s l o w l y added to f r e s h l y d i s t i l l e d p y r i d i n e u n t i l the p r e c i p i t a t i o n o f t h e p y r i d i n i u m c h l o r i d e was almost complete,
whereupon t h i s s o l u t i o n was t r e a t e d as i n ( i i ) .
The
* P y r i d i n e should be present i n excess t o prevent
the p o s s i b l e f o r m a t i o n of C H N.2HC1.
6
5
-11melting p o i n t of p y r i d i n i u m c h l o r i d e prepared by any of
these three methods was found to be l 4 3 - l 4 4 ° C .
This
value was i d e n t i c a l to that reported by A u d r i e t h and
a
Long o
16
g.
P y r i d i n e d l h v d r o c h l o r i d e (C H N..2HC1)
B
B
Dried HCI gas from a Kipp generator was passed
through f r e s h l y d i s t i l l e d p y r i d i n e contained i n a threeneck f l a s k f i t t e d w i t h both a s t i r r e r and a r e f l u x
condenser.
The p y r i d i n e h y d r o c h l o r i d e formed f i r s t and
the s o l u t i o n , was then kefit at a temperature s u f f i c i e n t
to maintain a homogeneous s o l u t i o n .
HCI was passed
through continuously and, a f t e r the formation.of the
C H N.HC1 was completed, the temperature,of the f l a s k
B
B
was lowered.so that i t was maintained Just above that
p o i n t at which c r y s t a l s s t a r t e d to form.
This was cont-
inued t i l l the temperature of the s o l u t i o n i n the f l a s k
f e l l to about 4 8 ° C .
ified,
On c o o l i n g a c r y s t a l l i n e mass s o l i d -
46-47°C. and decomposition p o i n t 55°C.
m.p.
These
16
values agreed c l o s e l y to those of K a u f l e r and Kunz
m.p,
46.7°C. and decomposition p o i n t 55°C.
By d i r e c t
weighing i t was observed that the p y r i d i n e had taken on
two moles of HCI per mole of p y r i d i n e .
The c r y s t a l s can
be r e p r e c i p i t a t e d from anhydrous ether and a l c o h o l as
an o i l and white n e e d l e - l i k e c r y s t a l s .
h.
Other "Se4-d- s a l t s of p y r i d i n e
i.
H Fe(CN)
s
and H4Fe(CN) ; *
8
6
6
9 , 3 6
-1213
ii.
C H40
4
iii.
iv.
e
(furoic
G H 0 + 2C H N
H P0 3 3
8
6
3
v.
4
e
B
acid)
(phthalic
acid)
3 9
4
H Mo0
s
vi.
HCr0
vii.
H S0
s
S3
4
16 > 3 5 * 3 9
6
1»S3
4
30
viii.
HI
ix.
HBr
31
Methods o f u s i n g C H N..HC1 and C H N.2HC1.
6
a.
S
B
6
Molten C H M.HCl and molten
B
B
C H N.2HC1
B
5
A s e r i e s of t e s t tube r e a c t i o n s we>$^ c a r r i e d out
u s i n g the reagents mentioned.
The r e a c t i v i t y o f these
r e a g e n t s on metal s u l p h i d e s wf|®$. i n v e s t i g a t e d w i t h t h e
e v o l u t i o n o f H S as the c r i t e r i o n o f r e a c t i o n .
S
Lead
a c e t a t e paper was used t o check the e v o l u t i o n o f the
H S gas.
a
TABLE I
Reactivity of sulphides i n molten C H N.HC1 and molten
K
K
C H N. 2HCl
B
Sulphide
e
0
C H N.HCl at 175°C
C H Ni.2HCl at 53°C.
Colour of Reactivity
solution
Colour of
solution
B
B
e
B
Reactivity
MnS
1
2
ZnS
1
1
PeS
orange
CdS
yellow
1
1
1
1
CoS
blue-green
1
blue-green
1
NiS
blue
1
blue
1
SnS
1
i
4
4
PbS
1
3
Sb S3
1
1
Bi S
a
2
3
As S
3
3
4
SnS
8
s
s
8
CuS
I t . yellow
1
I t . yellow
2
Ag S
2
2
HgS
1
1
8
1 - quite reactive: 2 - reactive:
reactive: 4 - unreactive.
3 * slightly
b.
Room temperature systems
i.
C K H K I . H C X
I n p y r i d i n e (6N i n G H N . H C 1 )
B
5
TABLE I I
R e a c t i v i t y of s u l p h i d e s i n C H N . H C 1 i n p y r i d i n e
B
Sulphide
B
Colour of
solution
Reactivity
MnS
3
ZnS
3
FeS
yellow
CdS
3
.
GoS
blue-green
N1S
...
2
4
3
SnS
SnS
2
4
8
3
PbS
Sb S
a
4
Bi S
3
3
As S
3
4
8
a
3
CuS
3
Ag S
s
4
HgS
4
1 - quite reactive: 2 - reactive:
reactive:
4 ~ unreactive*
3 - slightly
-15-
11o
Saturated chloroform solutions of
C H N.HC1 and C H N.2HC1
8
S
B
B
TABLE III
Reaction of sulrjhides i n saturated chloroform solutions of
CHN..HC1 and C H N.2HC1
5
Sulphide
B
5
C H N.HC1 i n CHC1
C H N.2HC1 i n CHCl ,
Colour of Reactivity
solution
Colour of Reactivity
solution
B
6
S
MnS
3
ZnS •
1
FeS
B
yellow
2
B
B
dark green*
1
1
yellow
1
CdS
a
1
1
CoS
blue-green
2
blue-green
2
NiS
blue
2
blue
1
SnS
3
1
4
4
3
1
2
1
BigSg
4
3
As S
4
3
SnS
a
PbS
Sb S
a
s
CuS
a
3
I t . yellow
3
I t . yellow
2
Ag S
3
3
HgS
2
1
s
1 «• quite reactive:: 2 - reactive: 3 - slightly
reactive: 4 - unreactive.
* A freshly prepared sample of MnS gave a colourless solution. An old sample gave a dark green solution.
TABLE IV
c.
3 > 3 » 36.
The reaction of metals i n molten
and the
0 HKN..HC1
k
reaction of metals with a saturated chloroform solution
of
Metal
Al
C H/ N.2HC1
B
B
at room temperature
Molten CH«N«HC1
C H N,2HC1 In CHCl
Colour of
solution
Colour of
solution
brown
Reactivity
K
B
2
Bi
4
3
Mn
1
• 1
Qd
yellow
1
yellow
1
Co
blue-green
2
blue-green
2
Cr
pink
2
pink
2
Cu
yellow
1
yellow
1
Mg
brown
1
1
4
4
Ni
blue
2
blue
3
Pb
2
3
Sb
3
3
Sn
2
2
1
1
Zn
brown
1 - quite reactive: 2 - reactive:
reactive: 4 - unreactive.
(25°C;)
Reactivity
1
Hg
a
3 - slightly
-1T-.
After driving o f f the chloroform, the only changes observed i n the reactions carried out with the C H N.2HC1
B
B
i n CHG1 on metals, were that the solutions of A l , Zn,
3
and Mg turned brown.
This was the same colour as was
observed with the molten C H N.HC1 on the same metals.
5
B
S o l u b i l i t y of C^H N.HC1 and C H N.2HCl In chloroform at
B
fi
E
23° C.
The s o l u b i l i t i e s of pyridinium chloride and pyridine
dihydrochloride were measured by saturating a chloroform
solution of known volume with these reagents and prec i p i t a t i n g the pyridine content as 2C H N.CuCl , using
5
excess CuCl
8
i n a water solution.
B
s
The chloroform was
driven o f f by heating on a steam bath.
The values
determined were:
C H N.HC1
B
- 123 gm. per 100 cc. of chloroform
B
C H N.2HC1 - 108 gm. per 100 cc. of chloroform
B
B
Abserbencv - wavelength investigation of the chloroform
solutions of C H M.HC1 and C H M.2HC1.
5
E
B
5
o
The wavelength region \ = 3300 - 5300 A was investigated on a Beckmann Spectrophotometer.
was taken as the dependent variable.
solution was used as the standard.
The absorbency
A pure chloroform
Figure I represents
a saturated solution of C H N.2HCl i n CHC1 and a d i l u t e d
B
e
chloroform solution of C H N.HCl,
B
B
3
Figure II represents
a d i l u t i o n of the saturated chloroform solution of
C H N.2HC1.
B
B
I
L—-„ i
3 * 0 0
,_J
C_.
i
_Ji
L..
I
HObO'
Ll.
L
I
i
j
.. HS0O
WAVELENGTH
X
1
j'oOO
L_
•
!
^°
V
FIG.UR€ I o '
ABSORBENCY-WAVELENGTH PLOT FOR A SATURATED CHLOROFORM SOLUTION OF Cc;H^N«2HCl
• AND A DILUTED CHLOFORM SOLUTION OF C5H5N0HCI0
• •
1
FIS.URE II,
ABSORBSNCY-WAVELENGEH "PLOT FOR A DILUTED CHLOROFORM SOLUTION OF C^H^N 2HClo
0
Side
reactions.
a.
Materials
i.
Preparation
17/
of 4-pyrldyl-pyrldinlum
dichloride
One h u d r e d a n d f i f t y
slowly
a d d e d t o 50 gm.
was k e p t
grams o f t h i o n y l c h l o r i d e were
of pure p y r i d i n e .
c o o l i n an i c e b a t h .
The m i x t u r e
The r e s u l t a n t
yellow
s o l u t i o n was r e f l u x e d f o r f i v e h o u r s , whereupon i t g r a d ually
was
distilled
raised
The
assumed a d a r k brown c o l o u r .
u n d e r vacuum;
The brown s o l u t i o n
t h e t e m p e r a t u r e was
t o 1 0 0 ° C . a n d was m a i n t a i n e d t h e r e
d a r k brown r e s i d u e
r e d up w i t h
i n the d i s t i l l i n g
50 c c . o f a b s o l u t e
f o r one h o u r .
f l a s k was
There remained a b u f f
w h i c h was
dissolved i n dilute hydrochloric
filtered.
lization
just
The f i l t r a t e
commenced.
added t o t h e c o o l e d
was
coloured
granular
by
residue
acid, boiled
evaporated t i l l
At t h i s point
mixture.
stir-
a l c o h o l and f i l t e r e d
suction.
and
slowly
alcohol
There r e s u l t e d a
crystalwas
faintly
y e l l o w i s h mass o f c r y s t a l s o f 4 - p y r i d y l * p y r i d i n i u m
d i c h l o r i d e w h i c h were f i l t e r e d
a n d washed w i t h
alcohol.
38
ii.
Purification of synthetic
quinoline
One h u n d r e d c c . o f q u i n o l i n e were d i s s o l v e d i n
1200 m l . o f d i l u t e h y d r o c h l o r i c
a c i d and h e a t e d t o 6 0 ° C ,
w h e r e u p o n a s o l u t i o n o f 140 gm.
of ZnCl
dilute hydrochloric
a c i d was
added.
8
i n 24o m l . o f
-212C H N
9
+ ZnCl
7
A white p r e c i p i t a t e
+ 2HC1 — —*
8
C(0 H N) ZnCu3H
9
7
8
o f t h e q u i n o l i n e c h l o r o z i n c a t e soon
began t o form and t h e w e l l s t i r r e d m i x t u r e
in
an i c e bath.
with
The
was c o o l e d
The c r y s t a l s were s e p a r a t e d
by f i l t e r i n g
s u c t i o n and washing w i t h d i l u t e h y d r o c h l o r i c
acid.
w h i t e c r y s t a l l i n e p r e c i p i t a t e was t r a n s f e r r e d t o a
b e a k e r a n d 10% NaOH s o l u t i o n a d d e d t i l l
of
a
Zn(OH)
with
dissolved.
8
the precipitate
The s o l u t i o n was t h e n
extracted ,
s i x 100 m l . p o r t i o n s o f e t h e r a n d t h e c o m b i n e d
e x t r a c t s were d r i e d w i t h
sulphate.
ether
20 gm. o f a n h y d r o u s magnesium
The e t h e r was d i s t i l l e d
off.
The w a t e r
con-
d e n s e r was r e p l a c e d b y a n a i r c o n d e n s e r a n d t h e f r a c t i o n
b o i l i n g b e t w e e n 2 3 7 - 2 3 8 ° C . was c o l l e c t e d .
in
vacuo gave a c l e a r
iii.
colourless d i s t i l l a t e
Redistillation
of quinoline.
Preparation of quinoline hydrochloride
(0. H N,HC1)
9
7
Fifty
in
cc. of thep u r i f i e d
100 c c . o f e t h e r
tion to precipitate
is
difficultly
q u i n o l i n e were d i s s o l v e d
and d r y HCI p a s s e d t h r o u g h t h e s o l u the quinoline hydrochloride
s o l u b l e i n warm e t h e r
which
and s o l u b l e i n h o t
10
ether
bath
.
The p r e c i p i t a t e
and f i l t e r e d ,
washed t w i c e w i t h
using
cold
i n e t h e r was c o o l e d
suction.
ether
i n an i c e
T h e p r e c i p i t a t e was
a n d d r i e d I n a vacuum d e s - ,
l o c a t o r , m.p. 1 3 4 ° C .
The same v a l u e
p o i n t was o b t a i n e d b y E r k s t e i n 1 0 .
;
f o r the melting
-22b.
Product o f s i d e r e a c t i o n s
i.
The
Isolation
r e a c t i o n s o f Zn, Mg, and A l w i t h molten
pyridinium
c h l o r i d e r e s u l t i n a brown s o l u t i o n .
The
r e a c t i o n w i t h Zn has been s t u d i e d as t y p i f y i n g those
r e s u l t i n g i n side reactions.
Pyridine plus
p y r i d i n e d i h y d r o c h l o r i d e p l u s Zn, p y r i d i n e
plus ZnCl
8
ZnCl ,
8
hydrochloride
d i d not r e s u l t i n a s o l u t i o n o f brown c o l o u r .
The brown c o l o u r was t y p i c a l only o f the r e a c t i o n o f t h e
metal w i t h p y r i d i n e
hydrochloride.
T h l r t y ^ f i v e grams o f C H N.HCl were r e a c t e d
B
e
an excess o f z i n c dust a t 175°C
the s o l u t i o n turned
with
As z i n c dust was added,
8
l i g h t - y e l l o w , but r a p i d l y
brown on t h e a d d i t i o n o f more Zn.
turned
On c o o l i n g , t h e mix-
t u r e was t r e a t e d w i t h 600 ml. o f 6N. NaOH.
A brown o i l
separated
The o i l had
a very
on t h e s u r f a c e o f t h e s o l u t i o n
strong odour o f p y r i d i n e .
0
I t was separated
the a l k a l i n e s o l u t i o n by a separatory
funnel.
from
The
brown o i l was washed w i t h f i v e 50 ml. p o r t i o n s of 6N
NaOH by shaking i n t h e separatory
f u n n e l and drawing
o f f t h e NaOH.
The p y r i d i n e i n t h e brown o i l was removed
by
the s o l u t i o n on a steam b a t h t i l l a
evaporating
t a r r y brown sbstance remained.
T h i s product d i d not
c r y s t a l l i z e from any o f t h e common organic
solvents.
I t was found t h a t t h e presence o f p y r i d i n e w i t h
the r e s i d u e I n t e r f e r r e d w i t h t h e i s o l a t i o n o f t h e r e a c t i o n
-23product
a n d i t was n e c e s s a r y
further purification
an
t o remove i t c o m p l e t e l y
c o u l d b e made,
Repreclpitation i n
amorphous f o r m c o u l d b e a c c o m p l i s h e d
residue
before
i f the the tarry
from which t h e p y r i d i n e had been c o m p l e t e l y
evap-
o r a t e d was t r e a t e d a s f o l l o w s :
1,
the
a
s o l u t i o n e v a p o r a t e d on a steam b a t h t i l l
sticky
2,
its
The r e s i d u e was d i s s o l v e d i n c h l o r o f o r m a n d
i t became
mass,
The r e s i d u e was t a k e n up w i t h
about
s i x times
volume o f carbon t e t r a c h l o r i d e , a t which p o i n t
some
buff?-coloured p r e c i p i t a t e appeared.
3,
Low b o i l i n g p e t r o l e u m
ether
(30-60°C,)
was
added t o complete t h e p r e c i p i t a t i o n .
The
maximum amount o f b u f f . c o l o u r e d r e s i d u e
ed was a b o u t 6% o f t h e s t a r t i n g w e i g h t
chloride.
The powder o b t a i n e d
obtain-
of the pyridinium
by t h e d e s c r i b e d
method
d i d n o t m e l t up t o 3 5 0 ° C ,
I t was f o u n d t o b e s o l u b l e
in
and c h l o r o f o r m
aqueous a c i d s , e t h a n o l ,
coloured
giving a red
s o l u t i o n i n each, b u t i n s o l u b l e i n benzene,
water and e t h e r ,
iia
The
and
Examination f o r b i p y r i d y l s
sodium h y d r o x i d e
the buff
coloured
for bipyridyls
evaporation
s o l u t i o n , t h e brown o i l ,
r e s i d u e were e x t r a c t e d w i t h
ether
( a l l o f which a r e s o l u b l e i n e t h e r ) .
of the ether,
no b i p y r i d y l s were
On
obtained.
-24-:
Iii.
Decomposition product of 4 - p y r l d y l -
p y r l d i n l u m d l c h l o r i d e i n NaOH
4 - P y r i d y l - p y r i d i n l u m d l c h l o r i d e was
s o l u t i o n of sodium hydroxide.
appeared and,
added to a
An i n t e n s e y e l l o w
6N
colour
on the a d d i t i o n of more 4 - p y r i d y l - p y r i d i n i u m
d l c h l o r i d e , a red-brown p r e c i p i t a t e formed,,
cinnamon odour was
noticeable.
An
aldehydic
The p r e c i p i t a t e d i s s o l v e d
i n a c e t i c a c i d to gfeve a red-brown c o l o u r , very much l i k e
y
that
o f - t h e b u f f c o l o u r e d r e a c t i o n product from p y r i d i n e
hydrochloride
and
zinc.
However, t h i s new
product formed
a d e r i v a t i v e with 2-4-dinitrophenylhydrazine,
whereas
the p y r i d i n i u m c h l o r i d e r e a c t i o n product w i t h z i n c d i d
not
form any p r e c i p i t a t e w i t h t h i s l a t t e r r e a g e n t .
iv.
F u r t h e r r e a c t i o n s o f Zn + C H N.HC1
B
6
r e a c t i o n product
A s o l u t i o n of the r e a c t i o n product i n 6N a c e t i c
a c i d gave the f o l l o w i n g r e a c t i o n s :
Decolourized
2.
Became c o l o u r l e s s when allowed
t r e a t i n g w i t h 30$
3.
Br
8
a 2% KMn0
1.
0
solution.
to stand a f t e r
H 0 .
8
8
Gave a yellow-brown p r e c i p i t a t e w i t h
i n aqueous
4
4
20%
KBr.
Gave a dark brown p r e c i p i t a t e w i t h 20$
I
3
i n aqueous KI.
On i s o l a t i o n of the bromine d e r i v a t i v e as a brown
powder, no m e l t i n g p o i n t c o u l d be determined.
Analysis
showed 5 . 2 9 $ n i t r o g e n .
c.
Reaction
i.
of quinoline hydrochloride
Side r e a c t i o n product
hydrochloride
plus
of quinoline
was f o u n d t o r e a c t
metals.above hydrogen i n t h e E l e c t r o m o t i v e
t o g i v e a dark orange t o r e d s o l u t i o n .
quinoline hydrochloride
metals
zinc
Quinoline hydrochloride
all
with
with
Series
The r e a c t i o n o f
and z i n c r e s u l t e d i n a dark r e d
s o l u t i o n w h i c h , when p o u r e d i n t o w a t e r , f o r m e d a d a r k
red residue.
T h i s r e s i d u e was powdered I n a m o r g a r a n d
p e s t l e a n d washed w i t h
concentrated
i t a t e d with
with
chloroform.
On s t a n d i n g ,
turn tarry,
uniform
The r e s i d u e was a g a i n
some o f t h e s u b s t a n c e a p p e a r e d t o
s u b s t a n c e was o b t a i n e d ,
y i e l d was 60% o f t h e w e i g h t
an
apparently
m.p.
126°C.
o f t h e q u i n o l i n e hydro-
reacted.
ii.
product
The
washed
t o d r y i n a vacuum d e s i c -
b u t on p o w d e r i n g t h e r e s i d u e ,
dark' r e d
chloride
I t was d i s s o l v e d i n
h y d r o c h l o r i c a c i d s o l u t i o n and r e p r e c i p -
c o l d w a t e r and a l l o w e d
cator.
The
c o l d water.
Reaction
with
of quinoline
hydrochloride
a c e t i c anhydride
r e d product
obtained
quinoline hydrochloride
from t h e r e a c t i o n o f
and z i n c was t r e a t e d w i t h a n
e x c e s s o f a c e t i c a n h y d r i d e a n d r e f l u x e d f o r two h o u r s .
W a t e r was a d d e d t o decompose t h e e x c e s s a c e t i c a n h y d r i d e
and
t h e s o l u t i o n was n e u t r a l i z e d w i t h
dilute
ammonium
-26hydroxide.
A yellow-brown c o l l o i d a l p r e c i p i t a t e resulted
which was centrifuged, washed with very d i l u t e ammonia,
f i l t e r e d and dried.
350°C.
This substance did not melt up to
At this point research into these side reaction
products had to be abandoned because of the lack of time.
Reactions with possible a n a l y t i c a l application.
a.
Materials - preparation of Mn(OAc)
3
One hundred cc. of acetic acid were heated to b o i l ing i n an evaporating dish and 6.9 gm.
Mn(0Ac)
8
added.
of anhydrous
After the acetate had been dissolved,
1.6 gm. of KMn0 was added slowly with s t i r r i n g .
4
The
solution turned dark brown and after heating f o r a few
minutes was allowed to cool.
The solution was
concen-
trated and on cooling a crop of manganiacetate
was obtained.
crystals
The f i r s t crop was washed with d i l u t e
acetic acid and r e c r y s t a l l i z e d twice from g l a c i a l acetic
acid.
over
The crystals were dried i n a vacuum desiccator
KOH,
KMn0 + 4Mn(0Ac)
4
+ 8H0Ac —
s
<+
5Mn(0Ac) + KOAc + 4H 0 ..
3
b.
3
Reaction of C H N,2HG1 i n CHC1 with MnS
6
i.
B
3
Mature of sample of MnS
Freshly prepared MnS reacted with the reagent used,
but did not colour the solution.
A sample of MnS
pre-
pared at least one year previously, reacted to give an
intense green solution.
.ii.
TABLE V
R e a c t i o n o f manganese s a l t s ,
m e t a l a n d MnOa w i t h ' a s a t -
c h l o r o f o r m s o l u t i o n o f C H N.2HC1
urated
B
Substance
Reaction
MnC0 3
Very r e a c t i v e
MnS0 4
No v i s i b l e
Mn(N03)
MnCl
B
Colour of solution
No v i s i b l e
3
Mn0 3
Mn(OAc)
Dark
green
Dark
green
reaction
Very r e a c t i v e w i t h
evolution
green
reaction
Some r e a c t i o n
a
Dark
of C l
s
Some r e a c t i o n
a
Mn
Very
The s a l t s ,
manganese m e t a l , a n d MnO
w i t h C H N.HC1
B
reactive
B
s
were a l s o
tested
i n CHC1 3 b u t d i d n o t g i v e t h e g r e e n
colour.
\
i i i . H e a t i n g o f a f r e s h sample o f MnS
A f r e s h sample o f MnS w h i c h d i d n o t g i v e a g r e e n
colour
when t r e a t e d
with the dihydrochloride
reagent
was h e a t e d w i t h a b u n s e n b u r n e r f o r 10 m i n u t e s .
sample w i t h t h e C H N . 2 H C l
i n CHC1 3 r e a g e n t ,
ing
this
the
s o l u t i o n turned l i g h t
ing
f o r a longer time turned t h e reagent
darker
e
B
green.
On t r e a t -
The s a m p l e a f t e r h e a t solution a
green.
iv.
Effect of oxidizing
agents
The C H N . 2 H C 1 i n CHC1 3 r e a g e n t was a l l o w e d t o
B
5
-28react
w i t h manganese m e t a l .
s o l u t i o n were t r e a t e d
K Cr 0 ,
s
s
7
e
S
agents
green colour.
solutions
the
w i t h C H N.HN0 ,
NaOCl, a n d H 0 .
oxidizing
S
caused
5
They a l s o
The a d d i t i o n
v.
and M n C l
s
t o appear i n
o r MnS0 .
Heating
4
effect.
B
(4.a. ) r e a c t e d
o f any o f t h e s e
i n t h e reagent d i d not
C H N.2HC1 i n C H C 1
The M n ( 0 A c )
(cone),
3
caused t h e colour
o f manganese m e t a l
have any apparent
HN0
3
the formation of the f a m i l i a r
o f the reagent
solution
Samples o f t h e r e s u l t i n g
B
3
3
on M n ( 0 A c )
3
c r y s t a l s p r e p a r e d as d e s c r i b e d
w i t h t h e reagent t o g i v e a dark
in
green
colour.
vi.
the
I s o l a t i o n o f t h e substance
green colour
C H N.2HC1
B
excess
was
o f Mn0 .
s o l u t i o n was r e a c t e d
3
w i t h an
resulted
3
1
o f d r y ether a dark green c r y s t a l l i n e
precipitate resulted
vacuum d e s i c c a t o r .
I t was f o u n d t h a t
w h i c h was f i l t e r e d
The m e l t i n g p o i n t
the solutions
had t o c o n t a i n
to whitish
B
i n t o an excess o f a l c o h o l i c HCl solution ' and
on t h e a d d i t i o n
crystals
B
The d a r k g r e e n s o l u t i o n w h i c h
2
poured
t o t h e C H N.2HC1 i n CHC1
i n CHCl^
B
conferring
used
and d r i e d
was
100-101°C.
f o ri s o l a t i n g the
an excess o f HCl or l i g h t
crystals resulted.
ina
green
The c r y s t a l s a p p e a r e d t o
* The a l c o h o l i c H C l s o l u t i o n was p r e p a r e d b y bubb l i n g d r i e d H C l gas from a Kipp g e n e r a t o r t h r o u g h absolute alcohol.
-29be
a
quite hygroscopic
loss of colour.
utions
and d i s s o l v e d i n moist a i r
I t was f o u n d t h a t
the original
sol-
o f t h e g r e e n s u b s t a n c e i n C H N.2HC1 i n CHC1
B
also lost
their
colour
S
on s t a n d i n g .
s o l u b l e i n w a t e r , a n d on f i r s t
a pink
appeared
colour
vii.
The
Analysis
dissolving
momentarily.
of the green c r y s t a l s
s o l u b l e c h l o r i n e content
s Method
3
The g r e e n c r y s t -
a l s were v e r y
Fajan
with
was a n a l y z e d
a n d t h e manganese c o n t e n t
by
was d e t e r m -
33
i n e d g r a v i m e t r i c a l l y a s MnNH4P0 .H 0
4
was
.
s
The r e m a i n d e r
assumed t o b e p y r i d i n e .
%
*
Atomic Weight
Ratio
Mn
11.5
55
=
.21
1
CI
37.6
35.5
=
1.06
5
50.9
79
=
.64
3
C H K
5
5
vili.
Solid
pyridine.
reagent
was
just
4
KMn0
This
the
KMn0
Limit
of v i s i b l e
colour
(.0.2 gm. ) was d i s s o l v e d i n 10 c c . o f
4
s o l u t i o n was a d d e d d r o p w l s e t o 2 c c . o f
o f C H N.2HC1 i n C H C 1 .
B
B
The g r e e n
8
colour
v i s i b l e a f t e r t h e a d d i t i o n o f 0.02 c c . o f t h e
5
s o l u t i o n o r 5 X 10"
ix.
gm. o f manganese,
Colourometric
analysis
A Coleman S p e c t r o p h o t o m e t e r was u s e d f o r t h e
colourometric
of a saturated
work.
As a r e f e r e n c e
standard,
10 c c .
s o l u t i o n of p y r i d i n e dihydrochloride i n
-30
chloroform was used
The spectrophotometer was
0
adjusted
so that for this,reference solution concentration C = 0 ,
and transmittance T = 0 .
was
KMn0
4
dissolved i n pyridine
added to a similar solution of reagent u n t i l a medium
green colour was obtained.
A Specttfal-Transmittance
curve was made (Wavelength i n millimicrons vs % Transmittance) to determine the portion where T was
i a l l y constant
essent-
(Figure I I I ) . This region, at 665 m i l l i -
microns was used i n a l l subseuent work.
A solution of KMn0
4
i n pyridine was added drop-
wise to a saturated chloroform solution of pyridine
dihydrochloride and the percent transmlttanee was
record-
ed as was, the volume of solution containing K M n 0 .
4
The
concentration of KMn0 was determined, accurately by
4
t i t r a t i o n against a standard solution of A s 0 .
s
3
The
volume of an average drop was measured, and hence the
concentration of manganese i n grams per dribp was known.
A l l the manganese was
complex and KMn0
4
assumed to exist as the green
solution was added t i l l the percent
transmittance dropped to a small value (Figure IV).
Another run of the percent transmittance and concentration i n grams of manganese was
obtained by adding
a known amount of manganese metal dissolved i n a known
volume of saturated solution of C H N.2HC1 i n chloroform
5
B
to 10 cc. of a saturated chloroform solution of
C H N.2HC1 i n which excess C H N.HN0
B
6
5
B
3
was dissolved.
-33-
This reagent produced the green colour on the a d d i t i o n
of the manganese metal (Figure V).
x.
KMn0
4
V a r i a t i o n of colour w i t h time
i n p y r i d i n e was added t o the p y r i d i n e
d i h y d r o c h l o r i d e reagent i n chloroform t o conform t o
6
55 X 10"* gm. of manganese i n 10 cc. of reference s o l u t i o n and the v a r i a t i o n of percent transmittance was
s t u d i e d w i t h respect t o time (Figure V I ) .
c.
Reaction of C H N.2HC1 i n CHCl
B
i.
B
a
w i t h HgS
I s o l a t i o n of mercury s a l t
A s o l u t i o n of C H N.2HC1 i n C H C 1 was allowed t o
B
r e a c t w i t h excess HgS.
3
B
A vigorous r e a c t i o n ensued,
and the r e s u l t i n g s o l u t i o n was b o i l e d t o remove H S,
3
which i f present, was found t o r e p r e c i p i t a t e the HgS
on attempting t o I s o l a t e the mercuric s a l t .
The b o i l e d
s o l u t i o n was poured i n t o excess ethanol from which a
white c r y s t a l l i n e p r e c i p i t a t e was obtained, which,
a f t e r f i l t r a t i o n and a f t e r d r y i n g i n a vacuum d e s i c c a t o r
had a melting point of 123°C.
ii.
A n a l y s i s of the mercury
salt
The c r y s t a l l i n e mercuric compound was s o l u b l e i n
water.
The c h l o r i n e content was determined by F a j a n s
1
88
Method
. Mercury, i f l e f t i n s o l u t i o n , l e d t o erroneous
r e s u l t s due t o the formation of the s o l u b l e but nonionized HgCl .
8
Na C0
s
3
I t was removed by p r e p i t a t i o n w i t h
and f i l t r a t i o n of the s o l u t i o n .
The amount of
FIGURE VI.
VARIATION OF COLOUR OF GREEN TRIVALENT MANGANESE COMPLEX WITH TIME.
-36-.
mercury was determined g r a v i m e t r i c a l l y as
LCuCNHsCHaCHgNHg ) H H g I i
s
4
and the remainder was assumed
to be p y r i d i n e .
io
*
Atomic Weight
=
Hg
39.6
CI
28.0
35.5
=
CgHgN.H
32 4
80
=
e
iii.
i n C H NoHCl.
e
B
201
Ratio
197
1
.788
4
0
e
40§
2
A compound was made by d i s s o l v i n g H g C l
A p r e c i p i t a t e was a l s o obtained fuom
ethanol which had a melting point of 123°C.
A mixed
melting point w i t h the f i r s t mercuric s a l t a l s o was
123°C.
8
-37
I I I •* DISCUSSION
Pyridine
salts
a.
as r e c t l o n media.
Type o f r e a c t i o n most
I t was d e c i d e d
to
t h e most s u i t a b l e r e a c t i o n s
i n v e s t i g a t e w o u l d b e t h o s e o f m e t a l s and s u l p h i d e s .
Sulphides
were c h o s e n b e c a u s e a c i d r e a c t i o n s w i t h
would produce H S
2
thus
serve,
criterion
which i s given
not only
completion,
to a i d the r e a c t i o n i n going to
f o r a reaction occurring.
to avoid
them
o f f as a gas and would
b u t a l s o t o a c t as an e a s i l y
was d e c i d e
be
that
desirable
observed
Furthermore, i t
those r e a c t i o n s i n which water
might
f o r m e d a s t h e p r e s e n c e o f w a t e r m i g h t make i t d i f 2
ficult
t o study the r e a c t i o n products
b.
Examination of the p y r i d i n e s a l t s
Pyridinium
it
.
t r i c h l o r o a c e t a t e could
decomposed on m e l t i n g .
idinium nitrate
Pyridinium
prepared
n o t be u s e d as
oxalate
and p y r -
o f t e n p r o d u c e w a t e r a s one o f t h e i r
r e a c t i o n p r o d u c t s a n d were t h e r e f o r e d i s c a r d e d .
of
the other
thiocyanate
and
their
idinium
ium
s a l t s used as a c i d s ,
Many
such as p y r i d i n i u m
were t o o weak t o d i s s o l v e many o f t h e m e t a l s
salts.
I t was n o t p o s s i b l e t o p r e p a r e
f l u o r i d e with
t h e equipment a v a i l a b l e .
pyrPyridin-
f l u o r i d e m i g h t b e a g o o d medium, b u t w o u l d h a v e t h e
disadvatage of being
hard to handle.
I t should
be pos-
-38-
s i b l e to prepare p y r i d i n i u m
i d i n e w i t h l i q u i d HF
f l u o r i d e by r e a c t i n g
i n a stainless steel
pyr-
container.in
the r a t i o o f one mole of p y r i d i n e to about s i x of HF,
lowed by evaporation
HF,
of any
T h i s excess of HF
excess of the low
fol-
boiling
i s necessary as amines form com-
pounds of the type B.4HF, where B i s a primary, second6
ary, or t e r t i a r y amine,
B e r l i n e r and
Hann
propose the
structure:
ii:
B H-.F-H-.F:
ii
I t was
found that the p y r i d i n e s a l t s most
a b l e f o r i n v e s t i g a t i o n as s o l v e n t
and
s u l p h i d e s were p y r i d i n i u m
dihydrochloride.
metals and
These two
s a l t s i n general,
n u c l e u s and
c h l o r i d e and
s a l t s r e a c t e d w i t h many
obtain
the advantages of p y r i d i n e
the e x i s t e n c e
Furthermore, t h e r e was
Methods of u s i n g C H M . H C 1 and
K
no
of water as a s i d e prod-
the r e a c t i o n should be r e l a t i v e l y
B
pyridine
of many r e a d i l y i s o l a t e d
p o s s i b i l i t y of the formation
a.
pyridine
t h a t i s , the s t a b i l i t y of the
crystalline derivatives.
u c t and
systems f o r metals
s u l p h i d e s , were r e a s o n a b l y easy t o
i n a pure s t a t e , and had
suit-
simple.
C H N.2HC1.
K
K
Molten s t a t e
R e a c t i o n s w i t h molten p y r i d i n i u m
c h l o r i d e have been
c a r r i e d out w i t h a number of metals, metal oxides,
and
-39S 9 8 6 ' 2 8
metal chlorides
.
Ho*ever, a l t h o u g h p y r i d i n i u m
c h l o r i d e melts a t t h e r e l a t i v e l y low temperature o f
l 4 4 ° C . , r e a c t i o n s w i t h m e t a l s may r e s u l t i n s i d e p r o d u c t s
a s w e r e e v i d e n c e d w i t h A l , Mg, a n d Z n .
ion
With t h e except-
o f t h e s e t h r e e m e t a l s i t was a n e x c e l l e n t
solvent
medium f o r many m e t a l s a n d s u l p h i d e s , ,
P y r i d i n e d i h y d r o c h l o r i d e was a l s o a f a i r l y good
medium f o r t h e s u b s t a n c e s u s e d .
However, b o t h
s a l t s had c e r t a i n disadvantages.
pyridine
They w e r e b o t h q t i i t e
h y g r o s c o p i c a n d , s i n c e t h e p r e s e n c e o f w a t e r was t o b e
a v o i d e d , t h i s was a d e c i d e d d i s a d v a n t a g e .
Furthermore,
a l t h o u g h t h e t e m p e r a t u r e s a t w h i c h t h e two h y d r o c h l o r ide
to
s a l t s m e l t e d w e r e l o w , i t w o u l d b e more c o n v e n i e n t
find
some s y s t e m w h e r e h e a t was n o t n e c e s s a r y t o
p r o d u c e a medium w h i c h w o u l d r e a c t w i t h t h e m e t a l s a n d
sulphides
b.
used.
Room t e m p e r a t u r e
systems
The d i s a d v a n t a g e s m e n t i o n e d
i n the previous section
a c o u l d be overcome b y t h e u s e o f c h l o r o f o r m s o l u t i o n s o f
pyridinfeum c h l o r i d e and p y r i d i n e d i h y d r o c h l o r i d e .
Both
s a l t s were r e l a t i v e l y s o l u b l e i n c h l o r o f o r m and b o t h
still
ary
d i s s o l v e d many m e t a l s a n d s u l p h i d e s .
The s e c o n d -
r e a c t i o n s o f Mg, A l , a n d Z n n o t e d w i t h m o l t e n p y r -
i d i n i u m c h l o r i d e were n o t e v i n c e d w i t h e i t h e r
solvent.
The r e a c t i o n s w i t h t h e d i h y d r o c h l o r i d e s o l u t i o n w e r e
more v i g o r o u s t h a n t h e c h l o r o f o r m s o l u t i o n o f t h e mono-
-40-
hydrochloride
and
a p p e a r e d t o be
only s l i g h t l y
r e a c t i v e than molten p y r i d i n i u m c h l o r i d e .
o f the a d d i t i o n a l mole of HCl
ivity
of the
s o l v e n t and
other r e a c t i o n mixtures.
may
be
e x p r e s s e d i n two
e
5
-—*
8
w h e r e Me
I s an^ e x a m p l e o f any
sulphide
reacts.
It
m i g h t be
reactions i n
6
of a double s a l t
2C H N.HC1 + MeCl
with
w i t h any
2C H N + MeCl
-
6
5
The
occur
react-
of
general
steps:
2 C H N . H C 1 + MeS
i f the formation
presence
r e s u l t e d In reactions
the
and,
The
thus i n f l u e n c e d the
some s a l t s o f manganese t h a t d i d n o t
6
less
8
+
HS
8
i s possible
(C H N.H) MeCl
e
B
8
4
d i v a l e n t element whose
expected that only those
sulphides
r e a c t i n g w i t h aqueous h y d r o c h l o r i c a c i d w o u l d d i s s o l v e
in
the systems s t u d i e d .
However, t h e
stability
of
p y r i d i n e c o m p l e x e s must be
considered
d i f f e r e n c e i n i o n i z i n g and
d i s s o c i a t i n g powers o f
nonaqueous systems.
Mercuric
solve quite r e a d i l y i n the
idinium chloride.
system the
chloroform
However, i n t h e
C H N.HC16
B
dis-
pyr-
stay
s o l u t i o n , the
the
a l l o w HgS
reduced
s a l t s to
chloroform
o f t h e m e r c u r y c o m p l e x , and
8
B
s o l u t i o n of
allow the mercuric
o f t h e i o n i z a t i o n o f t h e H S,
by
the
found to
s u l p h i d e i o n c o n c e n t r a t i o n c a n n o t be
solution.
stability
c h l o r i d e was
the
I n the water - hydrogen c h l o r i d e
below t h a t which w i l l
in
as w e l l as
the
inhibition
t o be
dissolved
The nature o f C H N.2HCl I n CHC1 .
B
e
3
There i s very l i t t l e r e p o r t e d i n the l i t e r a t u r e
concerning t h e nature o f t h e compound C H N.3HC1.
B
B
is;
K a u f l e r and Kunz
, who f i r s t prepared
s t a t e d t h a t HCl polymerized
hydrofluorides (H F , H F ) .
3
8
3
3
t h e substance,
i n t h e same manner as t h e
In t h e i r subseuent work,
they found t h a t the s t a b i l i t y o f the d i h y d r o c h l o r i d e was
e s s e n t i a l l y l i m i t e d by t h e degree o f a l k y l a t i o n
and.that
o n l y t e r t i a r y and quaternery bases formeithe d i h y d r o chlorides.
No t r i h y d r o c h l o r i d e s Mgre r e p o r t e d .
The
d i h y d r o c h l o r i d e s were simply p o s t u l a t e d a s :
x
C y NH][C1 H]
z
8
S i n c e t h i s compound was prepared,
t h e r e has been no
f u r t h e r suggestions as t o why t e r t i a r y bases such as
p y r i d i n e should take on a second molecule
of HCl.
In order t o determine i f t h e r e e x i s t e d any type
o f bonding o f the second HCl molecule
molecule
t o t h e C H N.HCl
B
e
i n c h l o r o f o r m s o l u t i o n , t h e wavelength r e g i o n
X = 3300-5300 A was i n v e s t i g a t e d on a Beckmann S p e c t r o photometer,
The s a t u r a t e d c h l o r o f o r m s o l u t i o n o f p y r -
i d i n e d i h y d r o c h l o r i d e on d i l u t i o n showed t h a t t h e p l a t eau A i n F i g u r e I was t h e same peak ( F i g u r e I I ) as was
g i v e n by t h e monohydrochlorlde s o l u t i o n .
On the b a s i s
of t h e s i m i l a r i t y of the p l o t s , such p o s s i b l e s t r u c t u r e s
as p i bond f o r m a t i o n a r e r u l e d out, and i n t h e c h l o r o f o r m
-4 absolution,
t h e C H N..2HC1 c a n b e c o n s i d e r e d
B
a s C H N.HC1
B
B
B
+ HCI ( t h e p r e s e n c e o f HCI d o e s n o t e f f e c t t h e a b s o r b ency).
This
seemed q u i t e r e a s o n a b l e a s t h e e v o l u t i o n
o f HCI fumes f r o m s u c h c h l o r o f o r m
s o l u t i o n s was v e r y
noticeable.
Side
reactions.
a.
Possibility
o f formation
of b l o v r i d v l s
P y r i d i n e has a s t r u c t u r e analogous t o t h a t o f
benzene.
ring
its
The i n t r o d u c t i o n o f t h e n i t r o g e n
i n \ p l a c e o f a c a r b o n atom r e s u l t s i n a compound
own p a r t i c u l a r r e a c t i o n s ,
structural
a certain
of the pyridinium
by assuming t h a t
of the nitrogen
ously
the natural
ion.
difficult
This i s
electron attract-
atom i n t h e p y r i d i n e r i n g i s enorm-
e n h a n c e d i n a n a c i d s o l u t i o n where t h e p y r i d i n e
exists
as t h e p o s i t i v e charged p y r i d i n i u m
effect
o f t h e p o s i t i v e i o n could be represented
ing
The
c o n t r i b u t i n g most t o t h e s t a b i l i t y
i f i t d i d o c c u r , would b e v e r y
to the inertness
explained
ion
with
t h e p y r i d i n e r i n g c a n be r e p r e s e n t e d a s :
Hydrogenation,
due
yet maintaining
r e l a t i o n s h i p t o t h e "parent" benzene.
resonance structures
of
atom i n t o , t h e
to the designation
i o n VI.
of the E n g l i s h school
The
accord-
as V I I ,
-43*
which indicates that the electron a t t r a c t i o n of the
p o s i t i v e l y charged nirogen
atom w o u l d r e d u c e t h e e l e c t r o n
i n t h e 2 and 4 p o s i t i o n s and t h e r e f o r e
density
would
enhance t h e p o l a r i z a t i o n I n d i c a t e d by t h e I I I , IV, and
V resonance s t a t e s .
M
Since
by
H
+
3
,
TEL
h y d r o g e n a t i o n c o u l d be r e p r e s e n t e d
i ti s obvious that hydrogenation of an already :
p o s i t i v e charged p y r i d i n i u m
t h a t , when i t d i d o c c u r ,
i o n would be d i f f i c u l t and
i t would a t t a c k , n o t t h e 2 and
4 p o s i t i o n s o f low e l e c t r o n d e n s i t y , but would
the p o s i t i o n which i s r e l a t i v e l y unaffected
ernary
as a t t a c k
attack
by t h e quat-
n i t r o g e n atom, t h e 3 p o s i t i o n .
I n p r a c t i c e , no b i p y r i d y l s w e r e f o u n d a n d t h e s i d e
r e a c t i o n s must b e a c c r e d i t e d t o some o t h e r
type of
reaction.
b.
Ring
Cleavage
Ring cleavage reactions with p y r i d i n e a r e p o s s i b l e
as
t h e p y r i d i n e r i n g o f f e r s a n i t r o g e n atom w i t h a n u n -
shared p a i r o f e l e c t r o n s as a p o i n t
not
t h e case w i t h p y r i d i n i u m
of attack.
compounds.
c e r t a i n s p e c i a l d e r i v a t i v e s t h e normal
T h i s [email protected]
However,
pyridinium
with
-44resistance i s lost.
ions which occur
and
A l may
One
be
I t i s suspected
with pyridinium
of t h i s
t h a t the
c h l o r i d e and
side reactZn,
Mg,
type.
sueh s p e c i a l
compound i s 4 - p y r i d y l - p y r i d i n i u m
dichloride:
Ring
opening i n t h i s
compound s h o u l d
f o l l o w the
reaction
for 2,4-dlnitrophenylpyridinium
40)41)43
alkaline
solution
.
chloride i n
4-pyridyl-pyridinium d i -
c h l o r i d e undergoes a s i m i l a r r e a c t i o n w i t h
of a red-brown product
quite similar
the r e a c t i o n of p y r i d i n i u m
evidence
i n favour
o f an
4-pyridyl-pyridinium
pyridinium
inal
open c h a i n
c h l o r i d e Is t h e i r
colour.
s t r u c t u r e s were c o l o u r l e s s , t h e
tems t o a c c o u n t f o r an
light.
an
the
production
to that obtained
chloride plus
d i c h l o r i d e and
suggested a form w i t h
proposed
Zn.
The
in
main
structure with
the
2,4-dlnitrophenylSince
the
coloured
i n c r e a s e i n the
orig-
compounds
conjugated
increased absorption
of
sys-
visible
If ring
plus
cleavage
i n the pyridinium
chloride
Zn r e a c t i o n , i t d o e s so i n t h e fefsence o f any o x y -
g e n a t e d substance,,
ure
occurs
This
as i s found w i t h
discussed.
there
eliminates the enol
t h e two examples o f r i n g
Because o f t h e c o l o u r e d
should
exist
some i n c r e a s e d
reaction
an open c h a i n w i t h
at least
struct-
opening
product
conjugation.-
more, t h e d e c o l o u r a t i o n o f a d i l u t e KMn0
gested
type
Further-
s o l u t i o n sug-
4
one d o u b l e b o n d .
This
seemed s u b s t a n t i a t e d b y t h e l o s s o f c o l o u r o f a s o l u t ion
o f t h e unknown p r o d u c t
and
allowed
oxidized,
It
products
offer
t o stand.
when t r e a t e d w i t h
I f the side ohain
t h i s would account
had been hoped t h a t a study
of quinoline hydrochloride
more, t h e l a r g e i n c r e a s e i n y i e l d
this
and m e t a l s
of the quinoline
FurtherhydroAt
stopped.
The
only
s i d e r e a c t i o n s o b s e r v e d were t h o s e
a t h i g h temperatures w\ifchpyridinium
which
chloride
t h e e l e c t r o p o s i t i v e m e t a l s Zn, Mg, a n d A l .
These r e a c t i o n s produced o n l y
r e a c t i o n products
observed with
was
would
of the reaction.
L i m i t a t i o n s due t o s i d e r e a c t i o n s
extent.
s
of the reaction
c.
only with
slight
postulated
was a n a d d i t i o n a l a d v a n t a g e .
p o i n t however, r e s e a r c h was
occurred
and
side product
3
f o r the l o s s of colour.
some c l u e a s t o t h e n a t u r e
chloride
30$ H 0
a very
small
quantity of
and were assumed t o o c c u r
In the other
to only a
m e d i a no s i d e r e a c t i o n s were
e i t h e r metals or s a l t s .
Since
^matty m e t a l s
-46and
sulphides
a r e s o l u b l e i n some o f t h e s o l v e n t
tems s t u d i e d , t h e y
The
offer
sys-
e x c e l l e n t media f o r s o l u t i o n .
s o l v e n t system o f s p e c i a l note because o f i t s h i g h
r e a c t i v i t y a n d u s e a t r o o m t e m p e r a t u r e was p y r i d i n e
d i h y d r o c h l o r i d e i n chloroform,,
Reactions
with possible
a.
analytical-application,
T r i v a l e n t manganese
i.
Formulation
o f t h e compound
(0 H N.H) EMnCl iC H N
5
s
a
B
e
6
I t was n o t i c e d t h a t C H N . 2 H C 1 i n C H C 1
5
5
similar reactions with different
3
gave d i s - .
s a m p l e s o f MnS.
A
f r e s h l y p r e p a r e d sample d i s s o l v e d t o g i v e a c o l o u r l e s s
s o l u t i o n , whereas an o l d sample r e s u l t e d i n a dark
colour.
F r e s h l y p r e p a r e d MnS, when h e a t e d o n e x p o s u r e
to a i r , and again
treated with thechloroform
a l s o gave t h e g r e e n c o l o u r .
MnCl
s
and
chloroform
ultant
All
green
Manganous s a l t s
solution
such as
MnS0 d i d n o t g i v e t h e g r e a t c o l o u r i n t h e
4
reagent,
b u t i t a p p e a r e d on t r e a t i n g t h e res'*
s o l u t i o n s of these
s a l t s w i t h an o x i d i z i n g agent.
t h e f o r e g o i n g e v i d e n c e seemed t o i n d i c a t e t h a t t h e
g r e e n c o l o u r was d u e t o t h e e x i s t e n c e o f a n o x i d a t i o n
s t a t e e# g r e a t e r t h a n +2,
MnO
the
a
reacted very v i g o r o u s l y w i t h t h e reagent and
e v o l u t i o n o f c h l o r i n e was n o t i c e a b l e ,
that theoxidation state of ther e s u l t i n g
compound was l e s s t h a n +4.
suggesting
manganese
The p r e s e n c e o f manganese
i n the t r i v a l e n t
s t a t e seemed <#ite e v i d e n t .
a t i o n was o b t a i n e d
when a c o l o u r l e s s s o l u t i o n r e s u l t e d
on r e a c t i n g M n ( 0 A c )
i n chloroform
Confirm-
with the pyridine
3
dihydrochloride
whereas Mn(0Ac) , r e s u l t e d i n a g r e e n
sol-
3
u t i o n on i d e n t i c a l t r e a t m e n t .
Analysis of the isolated
compound s u g g e s t e d t h e f o r m u l a t i o n
o f t h e complex
(C H N.H) CMnCl 3c H N.
6
e
6
8
6
6
Calculated
Theoretical
CI
37.6$
37.6$
Mn
11.5$
11.6$
T h i s p a r t i c u l a r s t r u c t u r e was s u g g e s t e d a s t h e c o m p l e x e s
of trivalent'manganese a r e confined
t o the unusual
type
M C M n i l , o f t e n w i t h a molecule o f water which presumably
a
B
c o m p l e t e s t h e c o o r d i n a t i o n number o f 6 ; t h e t y p e
M [MnX 3
3
6
87
i s n o t known t o o c c u r
.
The compound i s o l a t e d i n t h i s
case had a molecule o f p y r i d i n e t o complete t h e c o o r d i n a t i o n number o f 6 i n s t e a d o f a m o l e c u l e o f w a t e r .
ii.
Explanation
o f r e a c t i o n s o f manganese
salts
1.
I t h a s b e e n shown t h a t when MnS was
heated o x i d a t i o n takes place
I n s u c h a manner t h a t mang-
a n e s e ^ i n an o x i d a t i o n s t a t e o f g r e a t e r
t h a n +2 a s t h e
h e a t e d MnS r e a c t e d
w i t h t h e C H N.2HC1 i n CHC13 t o g i v e
the green coloured
trivalent
B
B
manganese c o m p l e x .
-482.
Pure c r y s t a l l i n e
slowly darkens i n a i r through
MnC0 , i s p i n k . - I t
3
oxidation.
I t evolves
C0
l e a v i n g MnO w h i c h i s r e a d i l y
oxidized i na i r t o higher
S0
oxidation
and Mn 0
states,
e.g, M n O
s
a
s
,
4
Since the
s a m p l e u s e d was n o t a f r e s h one, t h e p r e s e n c e
and
Mn 0
3
account
4
t o be expected
ion.
o f Mn 0
3
3
f o r t h egreen c o l o u r a t i o n .
3.
is
S
The c o l o u r w i t h manganous
due t o t h e p r e s e n c e
nitrate
of the nitrate
I t h a s b e e n shown t h a t o x i d i z i n g a g e n t s
such as
HN0 c a u s e t h e f o r m a t i o n o f t h e g r e e n complex f r o m s t a b l e
3
divalent
manganese
salts.
4. M n O l , MnS0 , Mn(0Ac)
4
3
a green
than
8
d i d not give
c o l o u r a s a n o x i d a t i o n s t a t e o f manganese
greater
+2 was n o t f o r m e d .
iii.
by
Determination
of trivalent
manganese.
colourometric a n a l y s i s o f t h e green
complex
L a m b e r t - B e e r Law ( 1 ^ = I Q I O " * ^ ) i s t h e o n l y -
The
0 1
r a t i o n a l means f o r t r a n s l a t i n g p h o t o m e t e r r e a d i n g s t o
expressions
sample.
of the corresponding
A simple
form f o r t h i s
concentration of the
expression i s :
. C = -K l o g T
where C i s t h e c o n c e n t r a t i o n , K i s a p r o p o r t i o n a l i t y
constant
and T i s t h e t r a n s m i t t a n c e
( T = It/lo)-»
^
t h e L a m b e r t - B e B r Law i s o b e y e d , t h e C o n c e n t r a t i o n Transmittance
l o g paper,
graph o f t h i s
i sa straight
relationship
line
plotted
on semi-
intersecting the point
-490=0,
of
law
T = 100$.
the green
I t was
trivalent
i n order
t h e p o i n t C = 0,
g r a p h and
s o l u t i o n t o be
percent
T o f one
will
by
Such a
c o n t r a t i o n of
measuring only
L a m b e r t - B e e r Law
r e q u i r e d that the
ment be made w i t h m o n o c h r o m a t i c l i g h t
length corresponding
any
the
constant.
The
c u r v e where T was
r e f e r e n c e s e l e c t e d must be
C = 0 when T = 100$
u t i o n must b e
and
the nature
665
Figure
a t a wave-
of the
essentially
such
the
flat
that
sample
such t h a t i t s T responds o n l y to
With these l i m i t a t i o n s
c h o s e n was
and
T measure-
to a r e g i o n of the constituent's
Spectral-Transmlttance
C.
intersect-
transmittance.
The
in
line
Concentration-
allow the
determined
this
s o l u t i o n o f known
T = 100$.
then represents a v a l i d
Transmlttance
other
show t h a t s o l u t i o n s
t h e n draw a s t r a i g h t
i n g t h i s p o i n t and
line
to
manganese complex o b e y e d
to determine the
c o n c e n t r a t i o n and
straight
necessary
sol-
changes
p o r t i o n best
millimicrons (Figure I I I ) .
IV,
o b t a i n e d by
t h e r e d u c t i o n o f KMnO*,
showed t h a t t h e L a m b e r t - B e e r Law
was
o f 8 X 10*
10
gm.
o f manganese p e r
gm.
of t r i v a l e n t
obeyed i n the
region
c c . o f s o l u t i o n down
_e
t o 3 X 10
volume o f s o l u t i o n .
o b t a i n e d by
forming
manganese i n t h e
same
Figure V i s a similar plot,
the t r i v a l e n t
o f a manganous s o l u t i o n .
complex by
but
oxidation
Concentrations of t r i v a l e n t
-4
manganese g r e a t e r t h a n 8 X 10
gm. i n 10 c c . o f s o l u t i o n
-50can be d e t e r m i n e d
noted,
by s u i t a b l e d i l u t i o n .
however, t h a t t h e c o l o u r r e p r e s e n t s n o t o n l y any
manganese o r i g i n a l l y
but
I t must b e
present
i n the trivalent
state,
any manganese o f h i g h e r v a l e n c e w h i c h may b e
to the t r i v a l e n t
state,
and d i v a l e n t
reduced
manganese w h i c h
may become o x i d i z e d .
F i g u r e VI r e p r e s e n t s t h e v a r i a t i o n o f c o l o u r o f a
6
55 X 10"
reagent
gm. t r i v a l e n t
manganese complex p e r 10 c c . o f
s o l u t i o n w i t h time.
The p l o t
t i m e may b e a v e r y i m p o r t a n t
ometric
a n a l y s i s based
f a c t o r a n d t h a t any c o l o u r -
on t h e u s e o f t h e green
manganese complex w i l l
time.
The m e r c u r v - p y r l d i n e
i.
Formulation
complex
o f t h e compound
Analysis of the i s o l a t e d mercuric
gested that the formula
The
B
o f t h e compound was
a
sug-
(C H N.H) HgCl4.
B
Hg
39.6$
39.9$
Cl
28.0$
28.2$
mixed m e l t i n g p o i n t o f t h i s
5
compound
Theoretical
B
a
compound p r e p a r e d
from
c h l o r i d e i n c h l o r o f o r m w i t h HgS a n d t h e
compound i s o l a t e d
i n a s i m i l a r manner f r o m
C H N.HC1 was 1 2 3 ° C .
5
(C H N.H) HgCl4
Calculated
pyridinium
trivalent
have t o take i n t o c o n s i d e r a t i o n
the fading of the colour with
b.
shows t h a t t h e
B
This value agreed
HgCl
a
with that of
13
Grossmann a n d H u n s e l e r
plus
f o r t h e a b o v e compound.
-51iio
The
o f HgS
one a p p l i c a t i o n o f t h e s o l u b i l i t y
the reagent
itself
Application of solubility
s o l u t i o n C H N.HC1
B
immediately
B
i n CHC1
3
was i n r a d i o c h e m i c a l
o f HgS i n
that
suggested
separations.
HgS i s a n e x c e l l e n t e a r r l e r f o r many r a d i o a c t i v e i s o t o p e s ,
and
t h e ready s o l u b i l i t y
used here,
6„
may s i m p l i f y
o f HgS i n t h e r e a g e n t
separation
solution
techniques.
Conclusions.
It
i s evident
t h a t r e a c t i o n s i n media such as
molten pyridinium c h l o r i d e or p y r i d i n e d i h d r o c h l o r i d e
in
chloroform
reactions
aredifferent
carried
i n many r e s p e c t s t o s i m i l a r
out i n water.
The s t r o n g b o n d i n g o f
t h e h y d r o g e n atom t o t h e n i t r o g e n atom o f t h e p y r i d i n e
ring
a l l o w s many s a l t s t o b e h e a t e d
without
temperatures
decomposing.
The
hydrochlorides
t o be s t r o n g
reagents.
o f p y r i d i n e h a v e b e e n shown -
enough a s a c i d s t o a c t a s good
dissolving
They h a v e t h e f u r t h e r a d v a n t a g e o f f o r m i n g
complexes which a r e s t a b l e .
c a n be i s o l a t e d
erature.
to high
A l s o many o f t h e s e
complexes
a s c r y s t a l l i n e d e r i v a t i v e s a t room temp-
Thus, t h e s e h y d r o c h l o r i d e s
of pyridine
m e d i a i n w h i c h t h e sometimes d i s a d v a n t a g e o u s
o f w a t e r may b e c i r c u m v e n t e d .
offer
ionization
The f o r m a t i o n — o f
Many
complexes w h i c h would d i s s o c i a t e i n water c a n o c c u r and
oaa b e i s o l a t e d .
-52-
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