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Thesis/Dissertation Collections
10-1-2000
Rhodium trichloride catalyzed hydroboration of
1-octene: Unexpected results
Anthony Sampognaro
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Sampognaro, Anthony, "Rhodium trichloride catalyzed hydroboration of 1-octene: Unexpected results" (2000). Thesis. Rochester
Institute of Technology. Accessed from
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RHODIUM TRICHLORIDE CATALYZED
HYDROBORATION OF 1-0CTENE:
UNEXPECTED RESULTS
Anthony 1. Sampognaro
October 2000
A thesis submitted in partial fullfillment of the requirements for the
degree of Master of Science in Chemistry.
Approved: __T~.c=..:. . .~Mo~rr~ill
Thesis Advisor
Department Head
_
Table
Table
of
of
Contents
Contents
List
of Figures
List
of
1
ii
Tables
iv
Permission for Use
v
Acknowledgements
vi
Foreword
vi i
Abstract
viii
Introduction
1
Experimental
15
Results
22
Discussion
50
Conclusions
57
Future Research Directions
59
Appendix A: Physical Data
of
Selected Compounds
M
List
Figure 1: Mechanism
Figure 2:
Mannig
of Hydroboration
of
Figures
7
& Oxidation.
& Noth Mechanism for Wilkinson's Catalyst Mediated
Hydroboration
5
Figure 3: Mechanism for RhCl3-Aliquat 336 Ion Pair Mediated Hydroboration
Octene
with
Catecholborane
of 1-
8
Figure 4: 1-Octanol
Consumption, Experiment
Figure 5: 2-Octanol
Production, Experiment Ha
27
Figure 6: 3-Octanol
Production, Experiment Ha
28
Figure 7: 4-Octanol Production, Experiment Ha
29
Figure 8: Octane
30
Ha
Production, Experiment Ha
Figure 9: 1-Octanol
Consumption, Experiment lib
26
33
Figure 10: 2-Octanol Production, Experiment Hb
34
Production, Experiment Hb
35
Figure 12: 4-Octanol Production, Experiment Hb
36
Figure 13: Octane Production, Experiment Hb
37
Figure 14: 1-Octene Consumption, Experiment Ilia
40
Figure 15: f)-2-Octene Production, Experiment IHa
41
Figure 16: (Z>2-Octene Production, Experiment Ilia
42
Figure 17: 3-Octene Production, Experiment nia
43
Figure 18: 1-Octene Consumption, Experiment IHb
46
Figure 11: 3-Octanol
n
List
of
Figures (continued)
(^-2-Octene
Production, Experiment Mb
47
Figure 20: (ZJ-2-Octene
Production, Experiment IHb
48
Figure 19:
Figure 21 : 3-Octene
49
Production, Experiment Hlb
Figure 22: Initial Proposal
of the
Lifetime
of
56
RhCh
Figure 23 : Revised Scheme for the Proposed Lifetime
m
of
RhCL
57
List
Table 1: Theoretical Ratios
of
Tables
Octanol Isomers Produced for
Isomer Upon Hydroboration and Oxidation
of
a
Given Octene
13
Table 2: Product
Ratios, Experiment Ila
25
Table 3: Product
Ratios, Experiment Hb
32
Table 4: Product
Ratios, Experiment Ilia
39
Table 5a: Product
Ratios, Experiment IHb (Nitrogen Filled Glovebag)
45
Table 5b: Product
Ratios, Experiment IHb (Sealed
45
Table 6: Comparison
of Expected and
and
Purged
Actual Percentages
of
with
Nitrogen)
Octanol Products
Formed in Experiment Ila
Table 7: Comparison
of
Expected
and
54
Actual Percentages
Formed in Experiment Hb
of
Octanol Products
55
iv
Acknowledgements
like to thank Dr. Terence Morrill for his unending support and advocacy
throughout my academic career at RIT. Without his tremendous assistance, the
completion of this thesis would not have been possible.
I
would
Many thanks
while
I
ran
reactions,
also
to my wife,
Marna,
who put
and who also endured countless
up with many long hours at RIT
hours of listening to me talk to
myself and pace around our apartment.
Additionally, I wish to
comments on
my
thank Dr. James Kallmerten
work.
vi
of
Syracuse
University for
his
Foreword
Who is John Gait?
vn
Abstract
Previous
studies of the rhodium
octene showed a reversal of
regiochemistry
complex mechanism was proposed
analytical
technique
has
revealed
to
the
the expected 2-octanol and 1 -octanol
products
normal
has been
attributed
hydroboration
Initial kinetic
and
trichloride
to the
(RhCl3)
compared
explain
this
presence of
products.
oxidation, instead
of
to the
of
hydroboration
of 1-
uncatalyzed reaction, and a
phenomenon.
4-octanol
The
isomerization
catalyzed
and
Recent
advances
3-octanol.
in
in addition
to
existence of these unexpected
1-octene to
the previously
internal
isomers
prior
to
proposed mechanism.
indicated that the RI1CI3 catalyzed isomerization of 1-octene occurs
too slowly to account for the high levels of isomerized octanols found when a full
hydroboration and oxidation is performed. Further research indicates that two distinct
studies
species are responsible
for the isomerization
believed to isomerize 1-octene
via
the
71-allyl
process.
Rhodium trichloride itself is
mechanism, and
RhHCh,
a proposed
resulting from reaction with borane (BH3), which isomerizes 1-octene via a Rh-H
insertion into the double bond followed by P-hydride elimination. Additionally, previous
species
research
indicated the
Aliquat 336 (trioctylmethylammonium chloride) was
to occur, while current studies have shown that while Aliquat
presence of
necessary for the reaction
336 is not necessary to produce
amounts of the octanol
isomers
octanol
products, its
produced.
Vlll
presence
influences the
relative
Introduction
The hydroboration reaction, discovered
tool used
by organic
its versatility
chemists to
and power earned
olefins can react with
borane
oxidation
to
an alcohol
converted
to
ketones,
instead
of oxidation.
oxidation
in any
may be
The
functionalize
(BH3)
aldehydes,
The
an end
an
extremely
useful synthetic
Recognition
molecules of interest.
of
Brown the 1979 Nobel Prize in Chemistry. Brown found that
to produce
(1). Upon treatment
BH3
a
trialkylborane product,
with various
and carboxylic
acids,
production of an alcohol
in itself,
or
it
reagents,
an olefin via
important
then
undergoes
organoboranes can also
as well as alkylation of
from
can provide an
which
site
the
be
organoborane
hydroboration
and
for further functionalization
formation.1
NaOH
^
(RCH2CH2)3B
^
3 RCH.CH.OH
(1)
H,0,
mechanism of the oxidative
four-centered
reaction
The
intermediate,
repulsions, but
reactive,
hydroboration
also
substituted carbon.
from
and can undergo
reaction
by boron,
This behavior
'
minor electronic effects.
two
(Figure
a concerted mechanism with no
olefin undergoes electrophilic attack
predominantly to the less
quite
and
C. Brown, is
synthetic strategy.
RCH^CTL,
steric
build
by H.
more rounds of
with
arises
The
1)
takes
formal
place
through
carbocation
the boron
mainly from
bonding
avoidance of
resultant monoalkylborane
hydroboration, yielding
a
a
is
trialkylborane.
still
Figure 1. Mechanism
of
Hydroboration & Oxidation
1. Hydroboration
c
=
c-
C
C
J
R3B
H
-B
(twice more)
B
2. Oxidation
a)
YLp2
b)
HOO
c)
NaOH
+
+
HOO
[RgBOOH]"
R3B
HO
R
V
O
O
[OH]
HOO
D
B
(RO),B
B
(twice more)
R
R
R
R
R
hydrolysis
d)
Mono- and
olefins are
(RO)3B
+
^O / NaOH
dialkylboranes
are more
hydroborated (2),
monochloroborane
(BH2C1)
*-
difficult to
isolate, but may be
or when a reagent with
is
substitued
for borane
3ROH
+
Na3B03
produced when
hindered
less hydrogens to donate to olefins,
(3)."
such as
CH3
BH
1
CH3
CH3 CH
*-
C
(2)
BH,
CH,
BH2C1
RCH^C^
Once the
peroxide yields
acid will yield
alkylborane
forms,
addition of
ethanol, methanol,
excess of borane
product of the
a
primary
is usually
or water
typically with
acid
added
2 RCH2CH2OH
sodium
corresponding
steric
olefins, nearly
alcohols upon
if a terminal
alkene
1
.
2.
BH3
is hydroborated
terminal olefin
1-Hexene undergoing this treatment
are
oxidation)
sides of
the two
isomeric
generally produced,
the
hydrogen
and
to ensure complete reaction, necessitating the
and oxidation of a simple
equal portions of
difference between the two
and
oxidation with meta-chloroperbenzoic
which represents a net anti-Markovnikov addition of water across a
of non-terminal
hydroxide
(3)
to decompose any remaining borane before
hydroboration
alcohol.
0xidatl0n>
Alternatively,
the corresponding carboxylic
An
predominantly
oxidation,
the corresponding alcohol.
oxidized.
The
(RCE^CH^BCl
>
yields
is
94% 1-hexanol,
double bond
organoboranes
provided
oxidation.
there is
(4).3
In the
(and
no significant
olefin.
THF
EtOH, NaOH, H, O
(4)
,
case
~50%
I.BH3
2.
THF
EtOH, NaOH,
H,02
^\^^/
-50%
OH
Borane
commercially
(BH3)
itself is
not
and
stable,
available as a complex with
forms
a
relatively
unreactive
tetrahydrofuran, dimethyl
dimer. However, it is
sulfide, phosphines,
and
amines.1
A commonly
tertiary
solution of a
borane
must
be
borane-tetrahydrofuran
decompose
will
glassware and
blanketing
reason
borohydride
use of
(NaBH4)
Wilkinson's
in both the hydrogenation
Wilkinson's
catalyst,
original
a rhodium
temperature,
and
air; therefore
gas
with
of alkenes
generated
used
in
very
the
selective.
2-one,
rather
The
catalyzed method
than at the
was
reported
demonstrated that this
keto oxygen,
of
oven
dried
It
used,
reaction
the
use of
while
(PPh^RhCl]
studied since
in 1985 that Wilkinson's
with catecholborane at room
for hydroboration
method of
preferentially hydroborated
more susceptible
by
chloride,
catalyst.5
without
situ
M
(BF3 Et20).
to hydroborate olefins
required
.0
necessary.
are often
has been extensively
Mannig and Noth
to the high temperatures
Furthermore, it
BH3 THF
1
reactions
beyond using
syringes, and introduced to the
etherate
a
Any complex
hydroboration
[tris(triphenylphosphine)rhodium
hydroboration
1968.
all
is
agent
N2, Ar, etc.) is usually
(e.g.
complexes such as
boron trifluoride
species, may be
compared
inert
bottles
catalyst
discovery in
(I)
tetrahydrofuan.
Alternatively, borane may be
and
hydrborating
although no special apparatus
that the solutions of borane
sealed
plentiful
(BH3 THF) in
moisture or
a reaction under an
vessel under airtight conditions.
The
to
dry conditions,
because they may be handled in
sodium
commercially
complex
upon exposure
carried out under
is for this
used and
at
with catecholborane
hydroboration
was
the double bond of 5-hexen-
the reverse occurs in the
uncatalyzed reaction
Mannig
norbornene-2-one.
2. The
catalyst
catalyst
After the
of a
and
then
adds
B-Rh bond.
results were obtained
Noth's
is self-activating
(RhL2Cl),
formation
(6). Similar
to the
proposed mechanism
the dissociation
via
hydroborating
Following the
loss
ligand
reassociation of one of the
from the
undergo eventual oxidation
to the corresponding
reaction
Mannig &
species
groups
5other substrates, such as
for this
of one of
of another
regenerated via elimination
Figure 2.
using
process
shown
its three ligands. The
in Figure
active
(cathecolborane in this case),
ligand,
the
olefin
lost previously, the
complex,
is
leaving the
with
bonds to the
activated catalyst
hydroborated
olefin
the
rhodium.
is
to
alcohol.
Noth Mechanism for Wilkinson's Catalyst
Mediated
Hydroboration5
B
o
-H
H
oxidative
addition
o
reductive
elimination
olefin
insertion
into Rh-H bond
ssociation
-O
B-O-
uncatalyzed
>-
"O
B-H
+
*-'
A
hydroboration
336 ion
in
student
our
laboratory, Lu Yang
reaction of
Aliquat 336 is
pair catalyst.
(CgHi7)3NCH3+
[
[(CgHi7)3NCH3]+
Cf
],
and
the
to
catalyzed
uncatalyzed reaction.
Blum
its ion
a
a normal
reaction,
This
(RIT MS
presense of
trade
pair with
[RhCl4(H20)n]". Lu
reversed when compared
2-octanol for the
1-octene in the
catalyzed
Yang
the
the
(III)
rhodium
rhodium
chloride
tetrachloride
anion
found that the regiochemistry
(uncatalyzed) hydroboration;
and
studied
the expected 1 -octanol
research was conducted
the
hydrate
for trioctylmethylammonium
name used
that the RhCl3-Aliquat 336 ion
and coworkers
Chemistry 1996),
partly
as
she
the
of
is
the
Aliquat
chloride
expected
to
be
reaction was
found predominantly
predominant product
as an extension of
pair can promote
/
the
for
findings
the hydrogenation
of
of
7t-
results.7
systems
in both
this study
as a phase
transfer
most rhodium catalysts
Therefore, Lu Yang's
Mannig & Noth),
a
function
catalyst
have been
to
used
allow
for
a
homogeneous reaction,
heterogeneously with
hydrogenation)
reaction.
anti-Markovnikov products
of the use of the
in
pair
Lu Yang's
(e.g. the
RhCl3-Aliquat 336 ion
a
in the
in
past,
these two labs (Blum and
homogeneous (not
objective was
ratio of
pair
whereas
was used
water and an organic solvent.
studies were a combination of the work of
using the RhCl3-Aliquat 336 ion
hydroboration (not
Markovnikov to
The Aliquat 336
alkyl and aromatic compounds with novel
to
examine
1 -octanol to
instead
of
heterogeneous)
the ratio of
2-octanol)
Wilkinson's
produced as
catalyst when
1
-
octene
is hydroborated
with catecholborane and
described in Lu Yang's thesis for the
catecholborane
Among her
is
reaction of
The
presence of Aliquat
as a
high
ratio of
336 is necessary to
2-octanol to 1
achieve
2-octanol. This
The
and
use of
ratios
2-octanol,
THF
(-4%
as a
more
1
Higher temperature
when used as
-octanol
favors the
rather
process
production of
kind
than
high
a
overall yield as well
is competing
-octanol.
of
to proceed, the
are stable
although a
ratio of
with a
higher
to the
1
-octanol
reaction conditions.
a minor effect on product
overall yield
2-octanol to 1
kinetic
production of
more
time dependence.
CH2C12, has only
increase the
favors the
1
both
allowed
controls,
produced),
conditions
a thermodynamic process
thermodynamic
suggests some
solvent,
slowly.
very
-octanol.
The longer the time the hydroboration step is
-octanol
pair with
with catecholborane at room temperature at an
uncatalyzed reaction proceeds
The
1
mechanism
are:
appreciable rate.
vs.
The
RhCl3 / Aliquat 336 ion
RhCl3 is necessary to hydroborate 1-octene
forms
oxidized.
in Figure 3.
shown
findings
subsequently
is
obtained.
-octanol,
suggesting
process, where the
2-octanol,
while the
kinetic
process
Figure 3. Mechanism for RhCl3-Aliquat 336 Ion Pair Mediated
Catecholborane6
Hydorboration
of
1-Octene
with
o
B-H
Q+C1-
+
Q+
/B\
O
2.
RhCl3
+
O
Q+C1-
Q+RhCl4
^
"cix
3.
^/R
+
CI
RhCl4-
cix
/C1
Rh
C1
\
CI
^ ^R
/C1
\\
^\
-
^-o7
cix
EtOH
,ci
NaOH
.Rh
cr
.R
OH
CK
H202
H
R
/Bx.
O
O
Q+
=
5+
(C8H17)NV
-C1
Rh
I
CI
^R
xci
Preliminary findings of the current research
Initial
stages of
Yang's thesis for the
catalyzed
can
purpose of
hydroboration
be found in
familiarization. This
by other students.
performed
previously
the current research involved repeating
The
and oxidation of
experiments
analyses of reaction products
la
and
reaction performed was
1-octene
with
BH3 THF,
chromatograph with a
flame ionization detector (FID). These
revealed
octanol.
the
The
ratio of
analytical methods used
4-, 3-,
and 2- octanols
C
of one
another,
A for
0.5
physical
data),
Carefully selected
secondary
hydroborating
results suggested
were
4-, 3-,
and
from
for
1 -octanol
or a
RhCh / Aliquat 336
exact conditions of which
capillary
analyses
by GC/MS
addition
thesis. Previous
column gas
indicated
product ratios
of experiments
to 2-octanol
each other.
elute
in
order
section
versus
(7)
and
2-octanols.
(8).
not
boiling
la
and
lb
1 -octanol.
and
conditions
other
(See Appendix
three octanols.
to
Assuming
or no
occuring whereby
involving RhCl3
these compounds arc
system used
used.)
resolution needed
one another
from the
BH3 THF) has little
Futhermore,
have the
points of
very closely to
for the GC/MS
for
a complex process was
reactions
The
enjoys a wide separation
or similar reactions
and
analysis
consequently
(cathecholborane
that the
the products of this
(TCD)
previously apparently did
(See Experimental
being produced
unresolved
while
agents
the
3-octanol, in
conditions were used
alcohols
been
these products was discovered to be predominantly 4-octanol and 3-
to distinguish
within
while
of 4-octanol and
the presence
Moreover,
5% 1 -octanol,
and
also
experiment were conducted on either a packed column gas
thermal conductivity detector
95% 2-octanol
the
the
based from Lu
the time
at
section of this
chromatograph with a
of
had
experiment
lb in the Experimental
for this
an experiment
resolve all
that the
effect, these
choice of
intial
all possible octanol
all previous reports of
as a catalyst are
likely
three
isomers
2-octanol in
to have been
Previous
results:
I.BH3THF, RhCl3,
Aliquat336,
95%
"OH
THF
3
2. EtOH,
(7)
NaOH, H,0,
5%
Results
as reported
by
GC/MS:
I.BH3THF, RhCl3,
Aliquat336, THF
-
2.
EtOH, NaOH, F^O,
OH
(8)
OH
OH
Further investigation into the
complexes of rhodium
internal
olefins
trichloride
that
would
include
3- and
uncomplexed rhodium
literature
isomerize
by uncomplexed rhodium
resultant products would
indicating
chemical
revealed previous research
olefins.
trichloride
prior
If 1-octene
we are unaware of
isomerizes double bonds.
10
be isomerized to
to hydroboration and oxidation, the
4-octanol (9). However,
trichloride
could
showing that
any
studies
liydroborale
liydroborutc
&
.X;
oxidize
h\drohnr;ile
6c
oxidize
oxidize
(degenerate product)
OH
'Note:
cisltrans
isomerism
of
is ignored for simplicity
alkenes
(9)
Horner
and
coworkers, seeking to
various phosphine
ligands
expand on
Wilkinson's
complexed with rhodium
original
research,
trichloride to hydrogenate
olefins.8
Secondarily,
and substituted
pentene
using
found that
degree
of
a
brief study
various ratios of triphenylphosphine
lowering
the
isomerization
was performed of
[(Ph)3P]
ratio of triphenylphosphine relative
of
1 -pentene
over a
fixed
experimented with
period of
the isomerization
trichloride.
and rhodium
to
simple a-olefins
rhodium
trichloride
time. One hypothesis
these data is that triphenylphosphine inhibits the isomerization
of
1 -pentene
by
of
It
1
-
was
increased the
supported
by
rhodium
trichloride.
A
pair of
Wilkinson's
isomerization
studies were also performed
found that the
catalyst.9
mole ratio of
isomerization
It
1:1
with
was
the rhodium,
of a-olefins.
catalyst complex
presence of
in
key role
these later
oxygen,
when
and van
bubbled
into solution at a
dramatically increasing the
papers also confirm
Peppen using
extent of the
that triphenylphosphine
process, and that the solvent used with this particular catalyst
key to determining whether or not
ethanol), the
plays a
Furthermore,
indeed inhibits the isomerization
of
by Augustine
isomerization
does
not
occurs.
dissociate,
11
In
ethanol
and extensive
(or benzene
with even
isomerization is
is
traces
observed
when a
hydrogenation
of
1-heptene is
dissociate, producing free triphenylphosphine,
heptene,
deuterium
study it. The
these discrepancies
integrity of the
prior
to hydroboration.
Wilkinson's
because, due
upon,
van
catalyst
The
catalyst.
in
was named as
Thus,
to earlier
the conflicting
Peppen regarding isomerization taking
To
triphenylphosphine
rather
before
use
in
order
to
susceptible
This
to the
on commercial
reduce
to the
was more
suppliers;
different
degree
the
it back to Wilkinson's
of
double
using
of oxidation of
the
appear scrambled
results of
being
acted
Augustine
and
is bubbled into solution,
solutions are available.
from the
Additional
prepared
the catalyst may be treated
catalyst
was
oxidized species,
mixture; the catalyst may be
or
It
air oxidation,
than one substrate
confirm
place when oxygen
reaction
10
results of various research groups
These findings
several
to
attempted
with
in the
hydrogen
oxidized species (i.e.
Rh+
species
Clearly,
could
this problem,
maybe added
Rh3+
reduce a
combat
than relying
highly
apparently causing the deuterium to
research groups.
that
the culprit for the isomerization
to isomerization to internal alkenes, there
above.
various groups
Evans group in 1 992.
by the
mechanistic studies were attributable
oxidized catalyst was
unknown
discussed
lab,
species,
hydroboration
catalyst mediated
amoung the
catalyst was
of 1-
place.
Wilkinson's
of the
does
catalyst complex
in turn inhibits the isomerization
was proposed
Wilkinson's
the
contamination with a rhodium-peroxo species.
likely a rhodium (III)
bonds
which
labeling resulted in conflicting results
resulting in up to 40%
most
the mechanism
elucidate
reason
found that the
benzene,
allowing the hydrogenation to take
while still
Attempts to
via
In
attempted.
).
back to
the isomerization
provide an origin of all of
knowledge, however,
of
1-octene
by rhodium
the 4-octanol
and
no studies of how rhodium
trichloride to
3-octanol in
our reaction.
trichloride alone
12
2-, 3-,
and
4-octenes
To the best
isomerizes
olefins
of our
have been
to
conducted.
If our hypothesis that
the amounts
over
the
of octanols produced over
time
same
periods.
therefore
octanols should
thrichloride
rhodium
time should
isomerizes double bonds is correct,
alone
correlate
to the amounts
Applying simple rules of which octenes
yield consistent
data,
as summarized
of octenes produced
yield which ratios of
in Table 1
.
Table 1
Theoretical Ratios
of
Octanol Isomers Produced for
Hydroboration
Octene Isomer
% 1-Octanol
and
% 2-Octanol
a
Given Octene Isomer Upon
Oxidation
% 4-Octanol
% 3-Octanol
1-Octene
5
95
0
0
2-Octene
0
50
50
0
3 -Octene
0
0
50
50
4-Octene
0
0
0
100
*Note:
Therefore, if a
found to
upon
sample of
contain
A late
Harvard
and
hours
of
isomerization
in
and
by rhodium
trichloride is
20% 4-octene, then the
result
be approximately 2.5% 1-octanol, 57.5% 2-octanol,
25% 4-octanol.
discovery in
of
after n
and oxidation should
University.12
development
1-octene taken
octenes.
50% 1-octene, 20% 2-octene, 10% 3-octene,
hydroboration
15% 3-octanol,
The
isomerism is ignored for
cis/trans
The
our
literature
review
main research
situ generated
is
a series of
conducted
homogeneous
catalyst precusors are all of the general
by the
investigations
for
[Rh(diene)L]A\
13
Osborn lab
Osborn group involved the
rhodium complexes
formula
by the
use
in hydrogenation.
where
L
is
typically
a
at
tertiary phosphine
hypochlorate
used are
and
have the form
additional product
catalyst, but
given
to
a
occur
hydrogen
very
is
with n
of
situ catalyst
[RhH2LS^]+,
or
effective olefin
3. Some
catalyst.
which
The
(10),
as opposed
small number of other catalytic systems
to the
gas
in the
is
to a
were
solution of
hydrgenation. These
reaction.
a poor
by
An
hydrogenation
mechanism of
hydride insertion into the double bond, followed
on an adjacent carbon
A that
counterions
hydrogen
solvent used
[RhHLS3,],
isomerization
the
capable of olefin
S is the
form
of
addition of
is formed
where
a monohydride of the
by metal
2
=
tetrafluoroborate. Upon
these catalyst precursors, an in
catalysts
ligand,
or phosphite
this
process
p-elimination
7i-allyl mechanism which operates
is
of a
in
a
(11).
(3-Hydride Elimination
H*
CH,
M-H*
+
M
CH2=CHCH2CH3
CH
CH,CH,
(10)
H*
CH2
M
MH
CH
+
CH3*CH=CHCH3
CH2CH3
7E-AUyl Mechanism
H*
CHCH,
M
+ CH,=CHCH,*CH
2 ^A13
*
MI
CH
CH,
14
M +
CH3*CH=CH3
(11)
The important
336
catalyzed
literature
catalyst.
hydroboration
precedent
trichloride
questions
and
and oxidation of
for the isomerization
in Lu Yang's thesis
was used
However,
following
discovery of 3-octanol
4-octanol in the
of a-olefins
research
in
is
a
a co-catalyst
adjuvant
kinetic process,
and
as well as
Do the
is
role
what
isomers
allowed
isomers
to hydroborate
Aliquat
336,
and
extent of
co-
as a
Therefore,
the
on
by rhodium
isomerization
time, eventually reaching
with rhodium
trichloride
both the total
alone
extent of
trichloride
as well as
an
(with
no
isomerization,
produced?
the
produced correlate with
ratios of octanols produced
if the
and oxidize?
does Aliquat 336 play in this
place without
varies with
is the time dependence
specific ratios of
ratios of
reaction
What
the
unclear.
of a
Rhodium
Aliquat 336
process of a-olefins
that both the total
When 1-octene is isomerized
ligands),
is
species.
Aliquat
raised:
the ratios of specific isomers produced
equilibrium.
by rhodium (III)
conjunction with
Previous literature indicates the isomerization
complexes
trichloride-
1-octene in THF has led to the scrutiny
the necessity of Aliquat 336 as
have been
rhodium
reaction?
if so, how do the
15
Will the hydroboration
results compare
to
when
reaction
it is
take
used?
Experimental
All
reagents and solvents were aquired
exception of
obtained
the 4-octanol standards, which
from Fluka,
Chromatography / Mass Spectroscopy (GC/MS)
Packard 6890 Gas Chromatograph. Two
equal power
other with
Siloxane)
and
were used
for
columns, one
dimensions
column"
m
columns were used
to resolve all necessary compounds. Both
Phenyl Methyl
octanol
were obtained
and
with
the
THF solvent,
from J.T. Baker.
Gas
the
from the Aldrich Chemical Co.,
"60
each
of
60.0
m x
with
0.25
urn x
in the
of
30.0
urn.
m x
These
column"
m
respectively, as
column;
isomers, depending
one
on
Conditions for the 30
Octanol
for
the
they
course of the
columns are
dimensions
250.00
was carried out on a
are otherwise
separation of octene
isomers,
Hewlet
analyses, both
Hewlet Packard HP-5 (5%
250.00
will
be
urn x
refered
identical. Two
and
the
0.25
other
for
urn, and
to as the "30
programs
separation of
experiment conducted.
m column are:
separation:
Initial Temperature: 60 C
Initial Time: 1.00
Rate: 5
min
C / min
Final temperature: 100 C
Inlet temperature: 250 C
Split
ratio:
Total flow
Octene
30:1
rate:
33.4
mL
/
min
separation:
Initial Temperature: 30
All
other conditions
C (isothermal)
identical to Octanol
16
separation conditions
Conditions for the 60
Octanol
m column are:
separation :
Initial Temperature: 60
Initial Time: 10.00
Rate: 50
C
min
C/min
Final Temperature:
100
C
Split Ratio: 100:1
Total flow
This
Octene
rate:
102.9
method separates
mL/min
both
octenes and octanols.
separation:
Initial Temperature: 60 C (isothermal method)
Split Ratio: 100:1
Total flow
rate:
102.8
mL/min
17
la & lb. Hydroboration & Oxidation
of 1-Octene
Trichloride, Without(Ia)
and
to
Octanol Isomers
With(Ib) Aliquat
with
Rhodium
336
LRhCl3,BH3THF,THF
Aliquat 336 (lb only)
2.
To
10
a
three neck flask blanketed under nitrogen
mL anhydrous
THF. One
(Experiment lb only)
was
minutes, after
1.6
which
BH3 THF followed,
room
The
black
mL anhydrous
via
was
hours,
organic
low
layer
by
then
after which
was again
mL
to
to
filtered
the
Portionwise
and
it
The
RhCl3 xH20, followed by
was cooled
NaOH,
and
in
and
an
addition of
10
mL
over
yield a pungent yellow oil.
18
1
Quenching
addition of
warming to
20
mL
room
.0
M
with
15
30% H202.
temperature,
remainder was extracted with
was separated and washed with
then dried
THF
to stir for approximately five
ice bath.
dropwise
discarded. The
layer
or one mL of
reaction was allowed to stir at
stir overnight while
organic
separated,
pressure evaporation
3 M
allowed
precipitate was
whereupon
was added.
was allowed
and evolution of heat.
15
50 mg
Aliquat 336 (Experiment la only)
1-octene
foaming
followed
ether,
was added
then added, and the reaction
oxidation reaction was
after which a
The
with
mL of
mL of
temperature for five
95% EtOH
mL
EtOH, NaOH, H202
MgSOzi. The
30
mL
40
brine.
solvents were removed
Ila & lib.
Study of the Extent of Hydroboration &
Isomers
with
Oxidation of 1-Octene to Octanol
Rhodium Trichloride, Without (Ila) and With (lib) Aliquat 336
1.
RhCl3, BH3 THF, THF, Aliquat 336
2. EtOH, NaOH, H20,
In
a nitrogen purged
THF, followed by
allowed
addition of
in
an
ice bath,
for five hours,
with
and
0.48
after which
The
samples were allowed
1.8
it
Aliquat 336
layer
mL
1
or
of
0.7
to sit
mL
in
3 M NaOH
organic
layer
was again separated and
dried
dissolved in 20
mL anhydrous
3.6
mL
1-octene
ice bath,
The
mL anhydrous
THF. The
mL sample was
was added.
an
overnight at room
The
were
whereupon
1.0 M BH3 THF
was again cooled
mL anhydrous ether.
organic
GC/MS
mL
RhCl3
the 1-octene was added, a 1
after
EtOH, followed by addition
The
1
to stir for approximately five minutes,
1-12, 24, & 48 hours
cooled
atmosphere, 100 mg
reaction was
taken.
Each
and careful addition of
and
then
0.9
analysis.
19
MgS04,
whereupon
0.7
mL
mL
to
sit
95%
30% H202.
were each extracted
was separated and washed with
over
sample was
sample was allowed
and quenched with
temperature,
At 0.5,
were added.
it
1
.4
mL
brine.
was submitted
for
Ilia & IHb.
of the Isomerization of 1-Octene Over Time
Without (Ilia) and With (Mb) Aliquat 336
Study
Rhodium Trichloride
with
l.RhCl3,THF,
Aliquat 336 (lib only)
2.
To
a nitrogen purged
mL anhydrous
THF,
five minutes, 3.2
octene, 1
by 0.7
mL
mL
1-octene
3 M NaOH
temperature overnight,
organic
layer
separated,
three
and either
mL samples were
and
EtOH, NaOH, H202
1
neck
mL
was added.
mL
whereupon
At
then dried
over
or
they were
100 mg
RhCl3 xH20, followed by 20
treated
with
1
.4
mL
after which
0.7
after
mL
samples were allowed
each extracted with
it
brine. The
1.8
20
the
addition of 1-
95% EtOH followed
to
sit at room
mL anhydrous ether.
organic
was submitted
After stirring for
THF
mL anhydrous
0.5, 1-12, 24, & 48 hours
30% H202. The
MgS04,
1
samples were
was separated and washed with
and
was added
Aliquat 336
taken. The
0.9
flask
layer
was again
for GC/MS
analysis.
The
IVa & IVb.
Study of the Effect of Rhodium Metal Over Time to Isomerize 1-Octene
Isomers Without (IVa) and With (IVb) Aliquat 336
1
to
Octene
Rh, BH3 THF, THF
.
Aliquat 336 (IVb only)
-*-
2.
(The
catalytic
In
by 0.7
mL
1-octene
3 M NaOH
temperature overnight,
organic
layer
separated,
neck
mL
and
taken. The
0.9
mL
whereupon
flask, 49
Aliquat 336
were added.
mL samples were
mL
three
THF, followed by 1
minutes, 3.2
black to isomerize 1-octene
of rhodium
a nitrogen purged
anhydrous
octene, 1
activity
EtOH, NaOH, H202
At
then dried
over
or
1
black
mL anhydrous
treated
samples were
30% H202. The
they were
MgS04,
of rhodium
studied.)
with
brine. The
mL
after which
the
after
0.7
mL
samples were allowed
each extracted with
1.4
was suspened
it
1.8
21
mL
addition of 1-
95% EtOH followed
to sit
at room
mL anhydrous ether.
organic
was submitted
in 20
THF. After stirring for five
0.5, 1-12, 24, & 48 hours
was separated and washed with
and
mg
was
layer
was again
for GC/MS
analysis.
The
Va & Vb. Control Experiments: Va. 1-Octanol
Vb. 2-Octanol
subjected to reaction conditions;
subjected to reaction conditions
0H
1.
RhCl3, BH3 THF, THF, Aliquat 336
or
2.
EtOH, NaOH, H202
OH
To
10
a
three
neck
mL anhydrous
stir
THF. One
under nitrogen was added
mL of
for approximately five minutes,
added.
Portionwise
heat. The
cooled
and
flask blanketed
in
reaction was allowed
an
ice bath.
dropwise
while
The
addition of
room
20
30
1
with
.0
M
mL
1
mL
40
.6
mL of
95% EtOH
1 -octanol
was
reaction was
black
mL anhydrous
and evaporated under reduced pressure
22
1
or
with
xH20, followed
mL of
.6
foaming
followed
by
15
a yellow oil.
was
it
was
3 M NaOH,
stir overnight
and
organic
separated,
to
and evolution of
mL
filtered
the
2-octanol
after which
then allowed to
was again
by
reaction was allowed
hours,
whereupon
layer
to
the
precipitate was
ether,
organic
RhCl3
and
temperature for five
after which a
brine. The
then added,
BH3 THF followed,
room
15
was
30% H202. The
remainder was extracted with
MgS04,
mL
temperature,
separated and washed with
over
mL
after which
to stir at
Quenching
addition of
warming to
10
Aliquat 336
50 mg
discarded.
layer
was
and then
dried
Results
la & lb. Hydroboration & Oxidation of 1-Octene to Octanol Isomers
without (la) and with (lb) Aliquat 336
The
GC/MS
is 84.5%,
crude yield of this reaction
gave
with no
further
with
Rhodium Trichloride,
purification.
Analysis
by
following relative product ratios:
the
14.422% 1 -octanol
14.169% 2-octanol
35.115% 3-octanol
36.316% 4-octanol
Small (<1%
)
of unreacted
Analysis
crude
yield,
1-octene
by packed column
with
93.4% 2-octanol
was
GC
and
found,
with
as well as
-3%
2-ethyl-l-hexanol.
thermal conductivity detector
6.6% 1-octanol.
23
indicated
an
82%
Ha.
& Oxidation of I -Octene to Octanol Isomers Over Time
Study of the Hydroboration
with
Rhodium Trichloride, Without Aliquat 336
Table 2
levels
was at
summarizes
the results
of this
experiment,
of products produced or reactant consumed.
34 hours
octene and
after
the addition
BH3 THF). One
2-octanols) decreases
over
produced remains at about
reduction
can see
time,
1%
as
or
product, is formed. The
1-octene have been treated
of
as
1-octene
(i.e., 34 hours
the amount
results
outliers,
Figures 4-8 graphically illustrate the
The last
that the amount
below,
and
of
of the
sample of
elapsed
taken
included
24
as
at
(up
to
addition of 1-
amount of
25%)
12 hours
data
taken
(1- and
octanol products
3-octanol increases. The
samples
and are not
reaction was
between the
"expected"
while a sizeable amount
for the
this
points
of
after
4-octanol
octane, the
the
addition of
in Figures 4-8.
Table 2
Product Ratios Produced for Experiment Ila:
Study of the Hydroboration
& Oxidation of 1-Octene to Octanol Isomers Over Time
Rhodium Trichloride, Without Aliquat 336
time
(hours)
with
1-octanol
2-octanol
3-octanol
4-octanol
octane
% Present
% Present
% Present
% Present
'!<> Present
0.5
78.459
5.359
1.274
0.217
10.162
1
72.458
8.305
4.808
0.268
9.461
2
64.163
5.689
3.394
0.424
16.999
3
59.958
6.827
5.861
0.418
16.454
4
59.378
7.669
6.821
0.467
14.313
5
54.164
13.397
13.998
0.489
10.057
6
54.180
12.662
14.292
0.530
8.650
7
44.613
13.205
16.251
0.655
12.983
8
39.973
16.047
19.938
0.585
13.048
9
36.431
17.451
21.517
0.887
10.246
10
33.862
19.149
24.987
0.771
13.385
11
29.964
18.219
23.073
1.124
12.168
102
5.670
21.921
31.974
0.999
25.308
7.064
6.850
7.321
0.130
54.576
12"
Note: Values
Data treated
shown are not absolute
yields, but
as outliers
25
relative percentages of products produced.
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Results:
Experiment lib:
Table 3
of the Extent of Hydroboration & Oxidation of 1-Octene
Isomers with Rhodium Trichloride, With Aliquat 336
Study
summarizes
experiment as
the
results of this experiment.
in la. Data from hours 1 1
during the
experimental process.
produced,
or reactant consumed.
and
The
same products are produced
12 have been treated
as outliers
Figures 9-13 illustrate graphically the
31
to Octanol
in this
due to mishandling
amounts of products
Table 3
Product Ratios Produced for Experiment lib:
Study of the Hydroboration & Oxidation of 1-Octene to Octanol Isomers
Rhodium Trichloride, Without Aliquat 336
time
with
1-Octanol
2-Octanol
3-Octanol
4-Octanol
Octane
% Present
% Present
% Present
% Present
"o Present
0.5
52.992
15.140
15.093
0.648
1
50.261
11.780
12.770
0.723
14.955
2
58.813
8.383
6.624
0.397
11.748
(hours)
3
50.200
9.130
8.702
0.375
11.634
4
52.128
7.492
6.758
0.202
10.550
5
46.947
12.124
13.096
0.357
10.697
6
43.059
11.052
12.576
0.472
13.515
7
30.378
16.474
20.185
0.524
13.854
8
22.385
17.301
22.869
0.370
14.243
'
9
23.360
15.777
21.887
4.083
11.943
10
33.391
14.514
16.893
0.431
7.909
34
35.843
9.645
11.045
0.963
11.118
6.570
1.290
0.454
0.196
59.238
53.176
11.127
10.557
0.262
8.136
11*
12*
Treated
as outliers
32
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Results
Experiment Ilia:
Study of the Isomerization of 1-Octene
Trichloride Without Aliquat 336
Table 4
results of this experiment:
shows
the
(Z)-2-octene, 3-octene,
and
4-octene. The
the isomers
with
produced
conformation of
(E). Figures 14-17 illustrate graphically the
production of
material.
38
Rhodium
the
from 1-octene
3- and
isomers,
4-octenes is
are (E)- and
assumed
or consumption of
to be
starting
Table 4:
Results
of
Experiment Ilia:
Study of the Isomerization
of 1-Octene
with
Rhodium
Trichloride, Without Aliquat 336
time, h
% 1-octene
% 4-octene
% 3-octene
% Present
% Present
% Present
% Present
/it Present
0.000
0.000
% (E)-2-octene % (Z)-2-octene
0
100.000
0.000
0.000
0.5
99.118
0.000
0.489
0.231
0.162
1
98.874
0.000
0.415
0.399
0.312
2
98.226
0.000
0.527
0.613
0.634
3
97.448
0.000
0.603
0.896
1.053
4
96.571
0.000
0.613
1.277
1.538
5
95.611
0.000
0.657
1.639
2.093
6
94.569
0.000
0.812
1.997
2.622
7
93.473
0.000
0.893
2.365
3.269
8
92.665
0.000
0.898
2.709
3.729
9
91.644
0.000
0.955
3.050
4.351
10
90.128
0.000
1.059
3.637
5.177
11
89.261
0.000
1.036
3.913
5.790
12
87.808
0.000
1.105
4.482
6.604
24
73.439
0.249
1.739
9.502
15.071
51.75
47.083
0.333
3.215
20.016
29.353
39
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Results
Experiment IHb.
Study of the Isomerization
Trichloride,
Tables 5a
and
5b list the
graphically illustrate the
reaction was conducted
neck
flask
of 1-Octene
With Aliquat 336
results
for both
production of octene
in
a nitrogen
runs of
isomers,
filled glovebag,
which was sealed with rubber
septa,
and
44
with
Rhodium
this experiment,
or
and
the depletion
the
and
of
Figures 15-18
starting
other was performed
periodically
material.
in
a
purged with nitrogen.
three
One
Tables 5a & 5b.
Results
of Experiment
IHb:
Study of the Isomerization of 1-Octene with
Rhodium Trichloride, With Aliquat 336
Table 5a. Reaction Performed in Nitrogen-Filled
Glovebag
time, h
% 1-octene
% 4-octene
% 3-octene
% (E)-2-octene
% (Z)-2-octene
0.000
0.000
0
100.000
0.000
0.000
0.5
99.070
0.000
0.394
0.535
0.000
1
98.506
0.000
0.378
0.892
0.224
3
96.394
0.000
0.356
2.281
0.970
4
96.195
0.000
0.426
2.741
0.638
5
95.298
0.000
0.322
3.549
0S31
6
94.443
0.000
0.379
4.216
0.963
7
93.820
0.000
0.392
4.724
1.064
8
93.278
0.000
0.493
5.103
1 127
1.297
9
92.300
0.000
0.322
6.080
11
91.200
0.000
0.771
6.579
1.450
12
90.819
0.000
0.423
7.247
1.511
24
87.502
0.000
0.377
9.897
2.224
51.75
82.254
0.000
0.351
14.279
3 116
Table 5b. Reaction Performed in Sealed Three Neck Flask Purged
time, h
% 1-octene
%
with
Nitrogen
% 4-octene
% 3-octene
% (E)-2-octene
% (Z)-2-octene
0.000
0.000
0.000
0.421
0.411
octane
0
100.000
0.000
0.000
0.5
98.412
0.121
0.173
0.461
1
97.608
0.116
0.142
0.341
1.297
0.449
0.426
2.820
0.780
2
95.690
0.136
0.147
3
95.066
0.185
0.170
0.316
3.346
0.916
4
91.770
ND
ND
0.286
5.540
2.314
1.316
7.030
1.821
7.177
1 715
5
87.444
ND
ND
6
88.854
0.134
0.352
1.769
7
82.790
0.127
ND
6.206
8.994
1.882
ND
16.309
2 57s
8
80.943
0.060
0.110
9
85.348
0.222
ND
2.964
9.183
2.284
10
84.463
0.091
0.158
0.395
12.231
2.663
81.547
0.092
0.168
0.310
10.521
3.624
85.146
0.098
0.205
0.327
11.148
3.075
11
12
45
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Results
Experiment IVa & IVb
of Rhodium Metal to Isomerize
1-Octene to Octene Isomers Without (IVa) and With
Study of the activity
In both cases, these
isomers.
(E)- and
Only at
experiments showed
extended periods
(Z)-2-octene
present.
No
(
>12
hours)
other octene
(IVb) Aliquat 336
virtually
of
isomerization
isomers
50
no conversion at all
were small
were observed.
to any
(~1
%)
octene
amounts of
Discussion
The
results of
experiments
these experiments clearly show that the
ITJa & IHb do
& Hb. Tables 6
and
amounts of octene
7 indicate the
other process
1-octene
at a
present
in
conclusion
faster rate, in
be
order
proposed
chains
temperatures (100-200
which would result
In
in
conjunction with the
order
to
account
that accounts
in
literature1
,
in 1 -octanol,
assumption
bond is
fixed,
which
is
and
made
addition of
BH3 THF
rhodium
boride
Figure 22
to any hydroboration
immediately forms. Currently,
(RhB),
is that there is
results
some
isomers
of octanol
of octanol
of octene isomers
the
upon
isomers,
a
that must
migration of
migration occurs at
be
boron
high
in any hydrocarbon chain,
opposite of the observed
once
hydroboration takes place, the
upon oxidation
reasonable
to
the
assume
position of
the
that the hydroxyl
formed.
not migrate once
mechanism of
that
therefore
hydroxyl group is fixed. Furthermore, it is
Initially the
is the
from the
to isomerize
C), and then always to the primary carbon(s)
enrichment
produced
expected amounts of
for these higher levels
for the higher levels
Ila
experiments
.
RhCL
to produce the higher amounts
For this reason, the
group itself does
is
of or
has been described in the
position of the carbon-boron
resultant
Ilia & Illb. These
to give the high amounts of octanol isomers. Although the
down hydrocarbon
phenomenon.
experiments
in
isomers to be
the rules established in Table 1
on
order
and oxidation.
must
amounts of octanols produced
that may be made given these confluent
occuring instead
hydroboration
hypothesis
based
for the
expected amounts of octanol
isomers found in
octanols were calculated
The only
not account
amounts of octenes produced in
the
was proposed.
reaction
identity of this
which could
be formed
It has been
performed,
precipitate
is
a
fine black
not
by the following
51
observed that upon
precipitate
known, but
process:
a
likely candidate
RhCl3
Rhodium boride is known to have
Given that
rhodium
is
still
isomerize double bonds in
then account for
octanol
a
higher
in the +3
+
oxidation
state, it is
especially for
scheme
1-octene,
of
3HC1
+
could
illustrated in Figure 22 may
and therefore
due to the hypothetical
reduction reactions.
to hypothesize that it
reasonable
to RhCl3. The
isomerization
isomers, if the isomerization
RhB
->
catalytic properties,
a similar manner
rate of
BH3
presence of
higher
amounts of
RhB is faster than that
ofRhCl3.
Ongoing
22 is
valid,
formed the
Experiment la
same as
that the
unidentified
isomers
isomerized;
catalysts
discovered
and
than
it
would
by RhCl3
compound
by the
be THF. Partial
BH3 THF
shown
that the
in Figure
scheme
performed an experiment which
except
substance
has
a new scheme must
Figure 23 is
itself via the
fits the
order of addition of
of
1-octene. This
1-octene
no catalytic
be
proposed
was added
activity,
to
are
two
n-allyl
of
reaction
the
the large amounts
and
may
well
which an octene molecule
the active
The S
other
olefin
portion
would generate
the P-hydride
52
to the
by
a proposed
isomerization
earlier.12
BH3 THF
n-allyl mechanism.
by
reagents
modification
Figure 22,
mechanism, and the
formula
Osborn group, discussed
or complete reaction with
pathways
the
is
thereby refuting
explain
a modified version of
general
via
the
that
preceded
first, before any
isomerize double bonds
RhCl3 by the
thesis,
As in Figure 22, there
one
species, RhHCl2. This
this
precipitate
being produced.
provide a viable model.
would
black
in Figure 22. Therefore,
of octene
maybe
addition of
of
Results indicate that the black
mixture.
scheme
Mr. D'Souza has
and needs
was altered such
rate
D'Souza have
revision.13
not
essentially the
(12),
by C.
experiments performed
in
the
this species
in situ catalyst
elimination mechanism at a
faster
RhCl, +BH3
An
degree
of
octanol
in
situ
^
RhHCl,
+
BCI.H
Rhq
+
BCLH
*-
RhHCl,
+
BC13
experiments peformed
isomerization
RI1HCI2
BClfi,
BC1H,
has been
1-octene,
of
by Mr.
D'Souza
RI1CI3. Given that in
is
and
is in fact
being generated,
experiments
there would be still more than
provide more evidence
to Experiment Ilia. The
enough
present when stoichiometric amounts of
catalyst
(12)
performed where a catalytic amount of
of an experiment similar
isomers
+
+
experiment
to the reactants
RhHCl,
RhCl,
Additional
proposal.
-
la & Ila
enough
and
of
is
to
BH3 THF
this thesis three
BH3 THF
indicate
correlate with
isomerizing
borane left
results
the
at a
after reaction with
PJ1CI3
was added
rate
fully
the
than
BH3 THF
to
larger
a much
Theoretically,
faster
equivalents of
this
amounts of
are added.
1-octene
for
are
added,
hydroboratc
1-octene.
The
verification of
commercially
be
BBr3,
available
which
has
a
Consequently, if the
using
gastight
this
higher
boiling point
reaction
is
in Figure 23.
It
that no
RhCl3
and
matter
borane, resulting in
BC1C,
possibly in
in
inert
evolution of
conjunction with
an
accomplished
the borane
.3
C
and
the
12.5
substituting RhBn,
reaction with
hydrogen
and
BC12H
53
dried
solution was added
gas.
prior
would appear
by
a
would
.
GC/MS
the proposed
to conducting
to a THF solution of
residual water was
It
BH3
C, respectively).
atmosphere and anaylyzed
glassware was
the time that
BC1H2
product of
by
would provide ample evidence of
how thoroughly
was presumed at
of the
BC13 (91
BBr3
was still evolved when
1-octene. It
than
carried out
presence of
reaction scheme
experiments, gas
be easily
compound, for RhCl3. The final
syringes, the
was noted
proposal could
causing decomposition
that this
gas
is actually
Table 6
Comparison of Expected and Actual Percentages of Octanol Products Formed in Experiment Ila
Expected
Actual
Expected
Actual
Expected
Actual
Expected
Actual
time, h
1-octanol
0.5
4.956
78.459
94.359
5.359
0.197
1.274
0.244
0.217
1
4.944
72.458
94.286
8.305
0.356
4.808
(J. 207
0.208
2
4.911
64.163
93.938
5.689
0.624
3.394
0.263
0.424
3
4.872
59.958
93.550
6.827
0.974
5.861
0.301
0.418
4
4.829
59.378
93.150
7.669
1.408
6.821
0.307
0.467
5
4.781
54.164
92.697
13.397
1.866
13.998
0.328
0.489
6
4.728
54.180
92.150
12.662
2.309
14.292
0.406
0.530
7
4.674
44.613
91.616
13.205
2.817
16.251
0.447
0.655
8
4.633
39.973
91.250
16.047
3.219
19.938
0.449
0.585
9
4.582
36.431
90.763
17.451
3.701
21.517
0.477
0.887
10
4.506
33.862
90.028
19.149
4.407
24.987
0.530
0.771
11
4.463
29.964
89.649
18.219
4.851
23.073
0.518
1.124
Note: Expected
rules
1-octanol 2-octanol 2-octanol
octanol percentages calculated from
illustrated in Table 1.
54
3-octanol 3-octanol 4-octanol 4-octanol
the
results
of Experiment Ma, applying the
Table 7
Comparison of Expected
Expected
and
Actual
Actual Percentages of Octanol Products Formed
Expected
Actual
Expected
Actual
Expected
time, h 1-octanol 1-octanol 2-octanol 2-octanol 3-octanol 3-octanol 4-octanol
in
Experiment lib
Actual
4-octanol
0.5
5.000
52.992
95.000
15.140
0.000
15.093
0.000
0.648
1
4.954
50.261
94.384
11.780
0.465
12.770
0.000
0.723
2
4.925
58.813
94.139
8.383
0.747
6.624
0.000
0.397
3
4.820
50.200
93.199
9.130
1.803
8.702
0.000
0.375
4
4.810
52.128
93.075
7.492
1.903
6.758
0.000
0.202
5
4.765
46.947
92.723
12.124
2.351
13.096
0.000
0.357
6
4.722
43.059
92.310
11.052
2.778
12.576
0.000
0.472
7
4.691
30.378
92.023
16.474
3.090
20.185
0.000
0.524
8
4.664
22.385
91.729
17.301
3.361
22.869
0.000
0.370
9
4.615
23.360
91.374
15.777
3.850
21.887
0.000
4.083
*Note: Expected octanol percentages
rules
calculated from
illustrated in Table 1.
55
the results
of Experiment Mb, applying
the
Figure 22:
Initial Proposal
of
the Scheme
of
the Lifetime
of
RhCb
RhCh
isomerize k 1
BHjTHF
{slow)
RhB (+
3HC1)
BHjTHF
isomerize A:,
(fast)
Hydroborate
Hydroborate
& Oxidize
& Oxidize
Octanol
isomers
56
Figure 23: Revised Scheme for the Proposed Lifetime
1-octene
BH,
-*-
P-hydride
Tt-allyl
elmination
mechanism
mechanism
(slow)
(fast)
isomers
octene
&
isomers
hydroborate
hydroborate
&
oxidize
octanol
isomers
57
RhCh
1-octene
RhCl
octene
of
oxidize
Conclusions
Results
hydroboration/oxidation
of
isomerization
secondary process
of
generated catalyst
arising from the
catalyzed
isomerization
isomerization is
partial or
rhodium metal.
may be
Rhodium
by a proposed
full
reaction of
albeit at
different
1-octene indicate
experiments of
species
RhCl3
RhHCl2,
with
rates and
an
in
situ
BH3. Both RhCl3
by
different
a
and the
mechanisms.
proposed to proceed via the 7i-allyl mechanism, while the
by RhHCl2
catalyzed
situ generated catalyst
be
1-octene
isomerize double bonds,
proposed species
RhCl3
of
isomerization
and
short
may proceed
via a
(3-hydride
lived, decomposing
metal as well as
the black
to
an
The in
elimination mechanism.
inert black
precipitate
precipitate, which
have both been
may
to
shown
be
catalytically inactive.
In light
Yang
shown
as
these
discoveries, it
not
likely to
Figure 23. Therefore,
not reverse
previously thought.
octene
new
in Figure 3 is
mechanism of
RhHCl2 do
of
be
a viable
rhodium
the regiochemistry
Instead, it is
would appear
of
4-octanol
and
2-octanol to 1-octanol.
mixture of
4-, 3-,
produced at
3-octanol,
action of
higher
Lu
octanols, the fact that Lu
reaction
temperatures may be
isomerization to internal olefins
would
increase
Yang
with
ratio of
to the
borane,
1-octene,
1-octene to internal
that forms the unexpected
observed as
attributed
of
Lu
to the proposed
oxidation reaction of
observed
by
situ product with
the isomerization
the high
Yang
58
its in
and/or
and oxidation
and also produces
what
mechanism proposed
when compared
the hydroboration /
the simple
Remembering that
and 2-
hypothesis,
trichloride,
isomers, followed by normal hydroboration
products
that the
that
4-octanol, 3-octanol,
2-octanol is in fact
more
2-octanol
fact that the
increasing temperature,
and
a
was
rate of
resulting in
more
4-, 3-,
oxidation experiment
outcome
is
presence of
mechanism,
albeit
hydroboration
has
it
(i.e., if no isomerization
1-octanol,
-95%
The
which
by Lu
and 2- octanols, or 2-octanol as observed
was
of
in
and
-5%
Aliquat 336
1-octene is
not
were
hydroboration /
to take place), the
doubt increases the complexity
The
exact role of
clear, but based
included, Aliquat 336 has been
a minor effect on product ratios.
1-octene
a classic
expected
2-octanol.
no
unknown ways.
of
Yang. In
on an
discontinued.
59
the
reaction
the RhCl3-Aliquat 336 ion
inspection
shown not
It is therefore
of
to be
of
the
essential
recommended
pair
in the
results of experiments
to the reaction,
that the
use of
in
although
Aliquat 336 be
it
Future Research
Additional
Directions
research of
the
material presented
in this thesis may include
answers
to the
following questions:
What is the
identity of the
This may be
crucial
Carry out the
prove or
precipitate produced
to the full elucidation
experiment with
disprove the
What is the
black
RhBr3
of the mechanisms
proposed
reaction scheme of
reactions?
Literature
involved in
in the Discussion
reactions?
our reaction.
section of
this thesis to
Figure 23.
result of the addition of phosphine
hydroboration
in the hydroboration
ligands
evidence suggests
place.
60
such as
triphenylphosphine to the
that
isomerization
no
will
take
References:
1.
i
Advanced Organic Chemistry, 4
hi
edition;
March, J., Ed. John Wiley & Sons:
New York, 1992.
2.
McMurry, J.
Organic Chemistry,
4th
edition; Brooks/Cole Publishing: New
York,
1996.
3.
Brown, H. C; Ravindran, N.; Kulkarni, S. U. J. Org. Chem. 1979, 44, 2417.
4.
Zweifel, G; Arzoumanian, H. J. Am. Chem. Soc. 1967, 59, 291
5.
Mannig, D.; Noth, H. Angew. Chem. Int. Ed. Engl. 1985, 24, 878.
6.
Yang, Lu. M.S. Thesis, Rochester Institute
7.
Blum, J.; Amer, I.; Zoran, A; Sasson, Y. Tet. Lett. 1983, 24 (38),
Blum, J; Amer, I; Bravdo, T. Tet. Lett. 1987, 28 (12), 1321-2.
8.
Horner, L.; Btithe, H
9.
Augustine, R.;
10.
Evans, D.; Fu, G; Anderson, B. J. Am. Chem. Soc. 1992, 114,
11.
Brown, H. C. Hydroboration; W. A. Benjamin: New York, 1962,
Brown, H. C; Zweifel, G J. Am. Chem. Soc. 1966, 88, 1433.
12.
Schrock, R. R.; Osborn, J. A. J. Am. Chem. Soc, 1976, 98,
van
;
of
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Technology, Rochester, NY, 1998
4139-42.
Sigel, H. Tet. Lett. 1968, 37. 4023-4026.
Peppen, J. J. Chem. Soc. D. 1970, 8, 495-496.
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13.
D'Souza, C. MS Research, Rochester Institute
1999-2000.
61
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Technology, Rochester, NY,
Appendix A: Physical Data
of
Compound
Formula
MW
bp (C)
1 -octanol
C8Hl7OH
130.23
195.1
2-octanol
C8H17OH
130.23
180
3-octanol
C8H17OH
130.23
171
4-octanol
C8H17OH 130.23
176.3
1-octene
C8Hi6
112.22
121.2
(EJ-2-octene
C8Hi6
112.22
125
(Z)-2-octene
C8Hi6
112.22
125.6
fJ-3-octene
C8Hi6
112.22
123.3
(Zj-3-octene
C8H)6
112.22
122.9
(E)-4-octene
C8Hi6
112.22
122.3
(%)-4-octene
C8Hi6
112.22
122.5
octane
C8H]8
114.23
125.6
2-octanone
CgHieO
128.21
172.5
3-octanone
C8Hi60
128.21
167.5
4-octanone
C8H]60
128.21
163
1 -chlorooctane C8Hi7Cl
148.68
181.5
Selected Compounds
Al