Vol. 21 (1984)
Thesis
Examination of Chemical Reaction through Continuous
Measurement of Specific Dielectric Constant
Addition of Bromine to Double bond
Isao
OGURA,
YAMAGUCHI*
Masahiro SAKATA, Katsuichi NAKAMURA, Masao
and Matsuji TAKEBAYASHI**
(Received July 18, 1984)
The change of values of dielectric constant was observed through the addition reaction
of bromine to an unsaturated linkage. A state of the addition can't be observed throughly
for the benefit of a large reaction velocity except the cases containing some water or
halide in the reaction solution.
The existence of a little water had scarcely an effect on
the addition, but the existence of pretty much water or halide brought the results that were
seemed to be went by way of the production of the molecular compounds or another halides.
KEYWORDS
Dielectric constant CDK), halogen, unsaturated linkage, bromine, 1-hexene, l-octene,
addition
The description on addition of halogen to unsaturated linkage under the various conditions
has been collected in "Organic Synthesis"!).
About the mechanism on addition of bromine to a
double bond, the theory 2) that the addition to a trans position was accomplished through an ion
formation, has been estabilshed now.
As a part of the research on reaction mechanism by the
continuous measurement of dielectric constant (DK), the authors carried out the addition reaction
of bromine to I-hexene in acetic acid solution under the various conditions, then from the results
the reaction states were inspected.
Experimental
1.
Apparatus The same apparatus used in previous paper3) was utilized and DK values were
measured by it at 18 MHz (room temp. ca. 25·C).
2.
Reaction In a 200 ml four necked round-bottomed flask, fitted with a reflux condenser, a
mechanical stirrer with a mercury seal, a burette and a silicon gum stopper having two glass pipes
connected with the U-tube through a silicon tube, 109 of I-hexene CO.12M) and 15g of acetic acid
are placed.
The solution containing 19.2g CO.12M) bromine in 20g of acetic acid was added on
the placed mixteure.
The addition was devided into 29 times for each one minute interval from
* Wakayama Medical College
** Faculty of Science and Technology
(Department of Chemistry)
-11-
OGURA etc: Examination of Chemical Reaction through Continuous Measurement of Specific
Dielectric Constant
Addition of Bromine to Double bond
DK
70
50
30
10
o
7
35
21
49
(min)
Fig. 1 DK Curve depend on Difference of Amount of Acetic Acid
Bromine Solution dropped into I-Hexene Solution
a. I-Hexene dissolved into 100ml Acetic A:>id
b. I-Hexene
/I
75
/I
c. L-Hexene
/I
15
/I
DK
.,.............,. b
70
,t-\"
.
;1
50
d
a
c
-.--------.----~----------__r__'----------~-
o
7
21
35
49
(min)
Fig. 2 DK Curve depend on Difference of Amount of Water and Acetic Acid
a.
b.
c.
d.
1-Hexene+H 2 0+CH aCOOH
109
0.5ml
15g
10
1.0
15
10
50
10
3.0
50
-
12-
Brz+CHaCOOH
18g
20g
18
20
18
20
18
20
Vol. 21 (1984)
burette. Moreover, the experiments that was added some water and various bromides to the placed
mixture were enforced (d. Fig. 2, 3, 4 and 5).
Results and Consideration
1.
Addition of bromine to I-hexene
Fr('lm the decolorization of bromine and the obtained DK
curve it was recognized that the addition of bromine to the double bond progressed very quickly.
Therefore, it seemed that the reaction mixture consisted of 1-hexene, 1, 2-dibromohexane and
acetic acid and the curve ascended slightly according to the increase of 1, 2-dibromohexane. On a
sudden descent of the curve appeared at just before the end of dropping, it was supposed that
bromine gave no influence onto the measured DK values before the surplus came out, and when
the addition ended, the bromine's DK (3.09) was shown; then, after the end of dropping, as the
value was fixed the DK curve progressed nearly in a straight line.
These results were shown in
Fig. 1. In this figure, the fairly fall of DK curve of c compared with a and b seemed to be brought
from the dilution of the reaction solution.
2.
Existence of water
For the confirmation of influence on the addition by the existence of
some water, the reactions containing some water in 1-hexene solution were enforced and the
obtained results showed in Fig. 2.
When a small amount of water was added to the solution, the
curve (Fig. 2-a) descended slightly at the begining of the dropping, and suddenly fell just before
the quickly ascension at near the end of that. From this fact it was surmised that as follows; the
existence of a little water scarcely exerted the influence upon the addition reaction, accordingly
the curve descended gradually by remaining of a small amount of bromine or by the formation of
DK
70
50
._.·\YUI'I.f,_ _
b
,...-.'_'_.IV.I.
a
,'.l-
/ ; ......
30
I
rJ
I
I
",
I
I
II
'I
".
\.1..
10
.
,+__ ,
•
~t·.,.·····'··· ~,...........-t-\
.-,'
.
~
I
"
\.
'. \....',./..... ...,\-l'1Il'I,"'I"---r,....\..
\.,
.,o
7
'-,-
c
35
21
49
(min)
Fig. 3 DK Curve depend on Difference of Acetic Acid and Sodium Acetate
1-Hexene+CH aCOOH+H 2 0+CH sCOONa
a. 109
15g
l.Oml
0.2g
b. 10
15
1.0
0.6
c. 1(}
50
-13 -
Br2+CH~COOH
l8g
18
18
20g
20
20
OGURA etc: Examination of Chemical Reaction through Continuous Measurement of Specific
Dielectric Constant
Addition of Bromine to Double bond
hydrobromide (DK 3.8).
The curve fairly descended as above, but after that the curve ascended
suddenly by the molecular compound from water with accumulated bromine.
Afterward, the
molecular compound decomposed gradually to the other compounds, but the curve descent was
only a little degrees through the bromine remained yet in a pretty amount.
A conjecture, the
molecular compound had generally a large DK value, expressed in previous paper a ).
When double
amount of water than the experiment above mentioned was added to the solution (Fig. 2-b) the
curve ascended quickly after sudden descent, afterward it descended gradually and then at about
the end, it ascended suddenly alike with the former. This fact was presumed as follows; the first
descent of the curve was caused from the decrease of water amount by the reaction of dropped
bromine with water eXlstlllg in msch amount, but according to an increase of bromine amount
the molecular compound was formed, consequently, the first ascent came out. When the compound
reached to a certain amount, the curve descended slowly according to the progress of the decomposition of the molecular compound and the addition of bromine to double bond, but after that for
the formation of the molecular compound had priority to the addition, the curve ascended suddenly
as same as the former.
The difference of d, obtained by the use of 3 times of water compared
with b, against b seemed to due to use of acetic acid in a large amount.
3.
Existence of sodium acetate It was considered that the DK showed a small value (Fig. 3-b)
for a decrease of mole fractions of the water according to the increase of bromine, but the addition
progressed somewhat according to an increase of bromine, consequently the curve ascended alike
as before.
When a small amount of sodium acetate was used (a), the curve ascended a little for
DK
70
.
50
Ir·.
. ...•.•
'-/ ..',I'
.
.- :-'-'-1.,
,l-\.\\
-I.
.it
'<.
...
I.. I'"
'I
\
,.1""
'_0-
,--
"<:,:.
.:~
•
•
1,\
a
•• \'
f·" -,.",.,.
'.
v....'__\'\'..~\ 'or
\..
• _ _....,••,••
I
b
'\,
"',.
..J,•
•',\-."U.,(,--, ,~u.J.T~'L~;r-\
_"'1
..............;;n,a.•• ,,'II.I~ I, •
-."
If
~
o
d
c
:~~
._""..
l
10
, . -..... ·n'MI..
.\.........
,10'
30
Il.N~"l''fL..'''''~
.'" I.". '-1_.
~.
\
\,
-"'t--
7
21
35
e
49
Fig. 4 DK Curve depend on Difference of Amount of Iodide
1-Hexene+CH aCOOH+H 2 0+KI
a. 109
50g
3. Omt 19
b. 10
50
3.0
2
c. 10
50
3.0
3
d. 10
3.0
50
4
e. 10
50
-
14-
Br 2 +CH aCOOH
18g
20g
18
20
18
20
18
20
18
20
(min)
Vol. 21 (1984)
DK
70
,.
30
,.,.JwI_
b
f.
10
..J •
'"
• J.t-'I'.._ _••_ _....-I......_ ....
•
--.--_.',._.....
.",..
~.,-.",.--
o
7
21
35
(min)
49
Fig. 5 DK Curve depend on Difference of Alkaline Halide
1-Hexene+CH 3COOH+H 20+KI+KBr+NaI
a. 109
50g
3.0ml 19
h. 10
50
3.0
19
c. 10
50
3.0
3g
Br2+CH~COOH
18g
18
18
20g
20
20
DK
70
a
50
l
...
.-
..
30
\ ...
l
...
\
................''''-.'••':"n!!.•":-,._.l'......~"'''''- ...
'e.".
10
7
b
35
21
49
(min)
Fig. 6 Comparison of DK Curve of 1-Hexene and 1-0ctene on Same Reaction
Wt.
a. 1-Hexene 109
h. 1-0ctene 13.5
CH 3 COOH+KI+H 2 0
50g
3g 3g
50
3
3
-15 -
Brz+CHsCOOH
18g
20g
18
20
OGURA etc: Examination of Chemical Reaction through Continuous Measurement of Specific
Dielectric Constant
Addition of Bromine to Double bond
the produce of molecular compound. After that the addition progressed and the curve extended as
the former.
4.
Existence of potassium iodide The results shown in Fig. 4 were obtained by use of comp-
aratively much water, and these results offered the following conjecture; the curves a and b,
indicated the cases containing a little amount of potassium iodide, pointed out the production of
molecular compound from water with dropped bromine, therefore, the curve ascended in the first
stage.
In the cases of c and d, a suspended fine crystaline was recognized through the circula-
tion of the solution in the silicon tube before the dropping, but it disappeared slowly by the
dropping of bromine solution.
Since potassium acetate has a small solubility (for H 2 0 at 41.3'C,
3.238) altered to potassium iodide (at 25'C, 40.4), it was assumed that the curve descended
according to the progress of this alteration.
After that the curve ascended by the production of
molecular compound depend on the existence of much water, but when the molecular compound
amassed to a certain degree, it descended by occurence of the change of the molecular compound.
In the cases of c and d, the solution was colored to redish brown according to the increase
of bromine and at neer the end of the dropping the crystaline separated out again.
From the
state of the curve, it was presumed that the addition progressed scarcely for an influence of
potassium iodide existing in small amount, especially in the case of d,
the reaction was not
nearly progressed.
The results of the cases containing potassium iodide, potassium bromide or sodium iodide
were shown in Fig. 5 indicated the nearly same results as above.
The curve used l-octene instead of 1-hexene was shown in Fig. 6. From the state of the
curve, it seemed that the addition was prior to the production of molecular compound.
Reference
1) Org. Synth., I, 521, II, 171, 270, III, 128, 209, 123, 731, 350, 531, IV, 130, 851, 909
2) D. R. Dalton, V. P. Dutta, D. C. Jones, J. Am. Chem. Soc., 90, 5498 (1968)
3) 1. Ogura, H. Tanaka, M. Yabushita, K. Shimaki, A. Hirai, M. Ozaki, M. Yamaguchi, Ann.
Rept Kinki Univ. Atomic Energy Res. lnst., 19, 9 (1982)
-
16-