U.S. patent application number 09/725642 was filed with the patent office on 2002-07-25 for process for the selective esterification of tertiary alcohol by an acid anhydride using a reusable solid catalyst.
This patent application is currently assigned to COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH. Invention is credited to Choudhary, Vasant Ramchandra, Jana, Suman Kumar, Mantri, Kshudiram.
Application Number | 20020099238 09/725642 |
Document ID | / |
Family ID | 24915391 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020099238 |
Kind Code |
A1 |
Choudhary, Vasant Ramchandra ;
et al. |
July 25, 2002 |
PROCESS FOR THE SELECTIVE ESTERIFICATION OF TERTIARY ALCOHOL BY AN
ACID ANHYDRIDE USING A REUSABLE SOLID CATALYST
Abstract
This invention provides an environmentally clean process for the
selective esterfication of a tertiary alcohol (I) by an acid
anhydride (II) to produce corresponding tertiary ester (III) and
carboxylic acid (V), using a reusable solid catalyst (IV)
comprising one or more halides of indium, gallium, zinc and iron.
The process comprises: (i) contacting a mixture of (I) and (II) in
the absence or presence of a non aqueous solvent with the fine
particles of (IV) in a stirred hatch reactor provided with a reflux
water condenser at atmospheric pressure at the reaction conditions,
such that the mole ratio of (II) to (I) is in the range from about
0.1 to about 10.0; the weight ratio of (IV) to (I+II) is in the
range from about 0.005 to about 0.5; the reaction temperate is
below about 80.degree. C.; and the reaction period is in the range
from about 0.1 to about 50 h; (ii) removing the solid catalyst (IV)
from the reaction mixture by filtration; and (iii) reusing the
separated solid catalyst for subsequent batch of the process.
Inventors: |
Choudhary, Vasant Ramchandra;
(Pune, IN) ; Mantri, Kshudiram; (Pune, IN)
; Jana, Suman Kumar; (Pune, IN) |
Correspondence
Address: |
Ladas & Parry
26 West 61st Street
New York
NY
10023
US
|
Assignee: |
COUNCIL OF SCIENTIFIC &
INDUSTRIAL RESEARCH
|
Family ID: |
24915391 |
Appl. No.: |
09/725642 |
Filed: |
November 29, 2000 |
Current U.S.
Class: |
560/231 ;
560/250 |
Current CPC
Class: |
C07C 67/08 20130101;
C07C 67/08 20130101; C07C 67/08 20130101; C07C 67/08 20130101; C07C
67/08 20130101; C07C 69/003 20130101; C07C 69/14 20130101; C07C
69/157 20130101; C07C 69/78 20130101 |
Class at
Publication: |
560/231 ;
560/250 |
International
Class: |
C07C 067/035 |
Claims
We claim:
1. A process for the selective esterification of a tertiary
alcohol(I) represented by a formula: 8by reacting an acid anhydride
(II) represented by a formula: (R.sub.3CO).sub.2O to produce an
organic tertiary ester(III) represented by a formula: 9wherein, C,
H and O are the carbon, hydrogen and oxygen atoms, respectively; n
is an integer value greater than or equal to 1.0; R.sub.3 is H
(hydrogen) or a chemical group other than hydrogen selected from
the group consisting of halogen NH.sub.2, NO.sub.2, OH, SO.sub.3H;
and R.sub.1, R.sub.2, and R.sub.4 are organic chemical groups, each
comprising both carbon and hydrogen atoms selected from the group
consisting of COOH, C.sub.nH.sub.2n+1, C.sub.6H.sub.5 (phenyl),
substituted phenyl, OC.sub.nII.sub.2n+1, C.sub.nH.sub.2n-1,
OC.sub.nH.sub.2nC.sub.6H.sub.5, C.sub.nH.sub.2n--C.sub.6H.sub.5 and
the like, wherein n is an integer having a value equal to or
greater than 1.0, using a reusable solid catalyst(IV), represented
by a formula: MZ.sub.y(c)/S wherein, M is a chemical element
selected from Ga (gallium), In (indium), Zn (zinc), Fe (iron) or a
mixture of two or more thereof; Z is a halogen selected from Cl
(chlorine), Br (bromine), I (iodine) or a mixture thereof; y is an
integer having a value of 2 or 3, depending upon the valence
requirement of M; S is a porous solid support on which % is
deposited; and c is a loading of MZ.sub.y on the support, S,
expressed as the mmols of MZ.sub.y deposited per gram of the
support, S, in the range from about 0.01 mmol g.sup.-1 to about
10.0 mmol g.sup.-1; said process comprising: i) contacting a
mixture of (I) and (II) in the absence or presence of a non aqueous
solvent with the file particles of (IV) in a stirred batch reactor
provided with a reflux water condenser at atmospheric pressure at
the reaction conditions, such that the male ratio of (II) to (I) is
in the range from about 0.1 to about 10.0, the weight ratio of (IV)
to (I+II) is in the range from about 0.005 to about 0.5; the
reaction temperature is below about 80.degree. C.; and the reaction
period is in the range from about 0.1 h to about 50 h; ii) removing
the solid catalyst(IV) from the reaction mixture by filtration; and
iii) reusing the separated solid catalyst for subsequent batch of
the process.
2. A process as claim in claim 1 wherein the catalyst support, S,
is cationic clay on mesoporous zeolite-like crystalline
material.
3. A process as claim in claim 1 wherein, M in the solid
catalyst(IV) is In (indium) or Ga (gallium) or a mixture
thereof.
4. A process s claim in claim 1 wherein, Z in the solid
catalyst(IV) is Cl (chlorine).
5. A process as claim in claim 1 wherein tho catalyst loading C, is
in the range from about 0.02 mmol g.sup.-1 to about 2.5 mmol
g.sup.-1.
6. A process as claim in claim 1 wherein, each of the chemical
groups R.sub.1, R.sub.2, and R.sub.4 is selected from methyl,
ethyl, propyl butyl and phenyl groups.
7. A process as claim in claim 1 wherein, R.sub.3 is H
(hydrogen).
8. A process as claim in claim 1 wherein, the mole ratio of acid
anhydride(II) to tertiary alcohol(I) is in the range from 0.5 to
2.0.
9. A process as claim in claim 1 wherein, the weight ratio of solid
catalyst (IV) to the reactants, acid anhydride(II) and tertiary
alcohol (I) is in the range tow 0.01 to 0.2.
10. A process as claim in claim 1 wherein, the reaction temperature
is in the range from 10.degree. C. to 50.degree. C.
11. A process as claim in claim 1 wherein, the reaction period is
in the range from 0.2 h to 10 h.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a process for the selective
esterfication to a tertiary alcohol by an acid anhydride to
corresponding tertiary ester using a solid catalyst. This process
particularly relates to a process for the esterfication of a
tertiary alcohol by an acid anhydride to corresponding tertiary
ester with very high soloctivity at a high conversion using a
reusable solid catalyst.
[0002] The process of this invention can be used for the
preparation of tertiary esters, which are speciality chemicals
and/or chemical intermediates, used in the chemical industries for
the production of perfumes and other fine chemicals.
BACKGROUND OF THE INVENTION
[0003] Process for the esterfication of normal alcohols by
carboxylic acids using homogeneous acid catalyst, such as
concentrated sulfuric acid, are well known in the prior af
[Encyclopedia of Chemical Technology, Editor: Mary Howe-Grant
4.sup.th Edition, John Wiley and Sons.vol 9. pp. 755-809]. However,
such prior art processes cannot be commercially used for the
esterfication of tertiary alcohols because of the high rate of
dehydration of tertiary alcohol to corresponding iso-olefin. For
example, tertiary butanol is dehydrated to isobutylene in the
presence of the acid catalyst. Moreover, the homogeneous acid
catalyzed alcohol esterfication process have following
limitations:
[0004] 1) The separation and recovery of the dissolved acid
catalysts from the liquid reaction mixture is difficult.
[0005] 2) The disposal of the used acid catalysts creates
environmental pollution.
[0006] 3) The homogeneous acid catalysts also pose several other
problems such as high toxicity, corrosion, spent acid disposal,
etc.
[0007] The prior art information on the esterfication of tertiary
alcohols is scarce. To the applicants' knowledge, there is no
patent literature disclosing a process for the esterfication of
tertiary alcohol with carboxylic acid or acid anhydride. However, a
few research papers disclosed the esterfication of tertiary butyl
alcohol with an acid halide, as follows:
[0008] Nagasawa el. al., have reported the esterfication of
tert-butanol by an acid bromide or acid chloride, having formula
RCOCl(or Br), wherein R is an organic group, to a tertiary ester
having formula RCOOC(CH.sub.3).sub.3, using activated basic
alumnina catalyst with catalyst to tert-butanol and acid bromide or
chloride wt/wt ratio of above about 2.0 at room temperature for
9-15 .mu. [Ref. Nagasawa, K. et. al., Chemistry Letters, year 1994,
pp. 209-212; and Nagasawa, K. et. al., Synthetic Communications,
vol. 20(13), year 1990, pp 2033-2040]. However, this process has
number of limitations, as given below.
[0009] 1) It produces in stoichiometric quantities gaseous HCl or
HBr as a by-product, which is highly corrosive and also
environmentally unacceptable.
[0010] 2) The acid chloride or bromide, which is used as an
esterification agent, is also corrosive in nature and hence
difficult to handle.
[0011] 3) This process requires a very largo amount of catalyst per
unit mass of the tertiary ester produced; the wt/wt ratio of
catalyst to reactants is above about 2.0.
[0012] Hence, the process of Nagasawa et. al., is not suitable for
the commercial esterification of tertiary alcohols for producing
tertiary esters.
[0013] The prior art alcohol esterfication processes, described
above, are not suitable for the esterification of tertiary alcohol
to corresponding tertiary ester and hence there is a need for the
development of an environmentally and highly efficient process for
the selective esterification of tertiary alcohol by using an
esterification agent, which leads to the formation of noncorrosive
and environmentally acceptable by-product, and also using a
reusable catalyst having high activity and selectivity for the
esterification at close to room temperature. This invention is made
to develop a novel process for the esterification of tertiary
alcohol, meeting the above mentioned goals or conditions.
SUMMARY OF THE INVENTION
[0014] Accordingly, the main object of this invention is to provide
a novel liquid phase process, which is environmentally clean
process, for the esterification of ti alcohol to tertiary ester
with high conversion and selectivity using a highly efficient solid
catalyst, which is easily separable and which can he reused, at
close to the room temperature
[0015] This invention provides a process for the selective
esterification of a tertiary alcohol(I) represented by a formula:
1
[0016] by its reaction pith an organic acid anhydride (II)
represented by a formula:
(R.sub.4CO).sub.2 (II)
[0017] to produce an organic tertiary ester(1II) represented by a
formula: 2
[0018] wherein, n is an integer having value greater than or equal
to 1.0; R3 is II (hydrogen) or a chemical group selected from the
group consisting of halogen, NH.sub.2, NO.sub.2, OH, SO.sub.3H,
(preferably hydrogen); and R.sub.1, R.sub.2, and R.sub.4 are
organic chemical groups, each comprising both carbon and hydrogen
atoms selected from the group consisting of COOH,
C.sub.nH.sub.2n+1, C.sub.6H.sub.5 (phenyl), substituted phenyl,
OC.sub.nII.sub.2n+1, C.sub.0II.sub.2-1 ,
OC.sub.nH.sub.2nC.sub.6H.sub.5, C.sub.nH.sub.2n--C.sub.6H.sub.5and
the like, wherein n is an integer having a value equal to or
greater than 1.0 (preferably selected from methyl, ethyl, propyl,
butyl and phenyl groups) using a reusable solid catalyst (IV),
represented by a formula:
MZ.sub.v(u)/S
[0019] wherein, M is a chemical element selected from Ga (gallium),
In (indium), Zn (zinc), Fo (iron) or a mixture of two or more
thereof (preferably selected from Ga, In and mixture thereof); Z is
a halogen selected from Cl (chlorine), Br (bromine), I (iodine) or
a mixture thereof (preferably Cl); y is an integer having a value
of 2 or 3, depending upon the valence requirement of M; S is a
porous solid support on which MZ.sub.y is deposited; and c is a
loading of MZ.sub.y on the support, S, expressed as the mmols of
MZ.sub.y deposited per gram of the support, S, in the range from
about 0.01 mmol g.sup.-1 to about 10.0 mmol g.sup.1 (preferably
from 0.02 mmol g.sup.-1 to 2.5 mmol g.sup.-1 ) said process
comprising:
[0020] i) contacting a 1mixture of (I) and (II) in the absence or
presence of a non aqueous solvent with the fine particles of (IV)
in a stirred batch reactor provided with a reflux water condenser
at atmospheric pressure at the reaction conditions, such that the
mole ratio of (II) to (I) is in the range from about 0.1 to about
10.0 (preferably from 0.5 to 2.0); the weight ratio of (IV) to
(I+II) is in the range from about 0.005 to about 0.5 (preferably
from 0.01 to 0.2); the reaction temperature is below about 80 C.
(preferably between 10.degree. C. and 50.degree. C.); and the
reaction period is in the range from about 0.1 h to about 50 h
(preferably from 0.2 h to 10.0 h);
[0021] ii) removing the solid catalyst (IV) from the reaction
mixture by filtration; and
[0022] iii) reusing the separated solid catalyst for subsequent
batch of the process.
[0023] The main finding of is invention is that, by the process of
this invention, a tertiary alcohol can be esterified by an acid
anhydride to a corresponding tertiary ester with very high
conversion and high selectivity or without producing appreciable
amounts of tertiary alcohol dehydration products, such as
iso-olefin and water, at room temperature and even when the
catalyst to reactants weight ratio is very much less than 1.0.
[0024] Other important finding of this invention is that the solid
catalyst used in the process of this invention can be separated
from the reaction mature easily, simply by filtration, and it can
be reused repeatedly in the process and hence, it does not create
environmental problems.
[0025] Another important finding of this invention is that the
catalyst for this process of this invention is highly efficient or
highly active and selective and hence, the esterification reaction
can be completed in a short period.
[0026] Yet, another important finding of this invention is that the
by-product of the process of this invention, a carboxylic acid, is
not corrosive and also does not cause environmental pollution or
problems. Being a valuable by-product, it can be sold in the market
or converted back to in acid anhydride and recycled in the
process.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Accordingly, this invention provides a process for the
selective esterification of a tertiary alcohol (1) represented by a
formula: 3
[0028] by its reaction with an organic acid anhydride (II)
represented by a formula:
(R.sub.4CO).sub.2O (II)
[0029] to produce an organic tertiary ester (m) represented by a
formula: 4
[0030] wherein n is an integer having value greater than or equal
to 1.0; R .sub.1 is H or a chemical group selected from the group
consisting of halogen, NE.sub.2, N.sub.2, OH, SO.sub.3; and
R.sub.1, R.sub.2, and R.sub.4 are organic chemical groups, each
comprising both carbon and hydrogen atoms and selected from the
group consisting of COOH, C.sub.nH.sub.2n+1C.sub.6H.sub.5(phenyl),
substituted phenyl, OC.sub.nH.sub.2n+1, C.sub.nH.sub.2n-1,
OC.sub.nII.sub.2nC.sub.6II.sub.5,
C.sub.nII.sub.2n--C.sub.6II.sub.5, wherein n is an integer having a
value equal to or greater than 1.0, using a reusable solid catalyst
(IV), represented by a formula:
MZ.sub.y(c)/S (IV)
[0031] wherein, M is a chemical element selected from G (gallium),
In (indium), Zu (zinc), Fe (iron) or a mixture of two or more
thereof; Z is a halogen selected from Cl (chlorine), Br (bromine),
I (iodine) or a mixture thereof, y is an integer having a value of
2 or 3, depending upon the valence requirement of M, S is a porous
solid support on which MZ.sub.yis deposited; and c is a loading of
MZ.sub.y on the support, S, expressed as the mmols of MZ.sub.y
deposited per gram of the support, S, in the range of about 0.01
mmol g.sup.-1 to about 10.0 mmol g.sup.-1, said process
comprising:
[0032] i) contacting a mixture of (I) and (II) in the absence or
presence of a non aqueous solvent with the fine particles of (IV)
in a stirred batch reactor provided with a reflux water condenser
at atmospheric pressure at the reaction conditions, such that the
mole ratio of (II) to (I) is in the range from about 0.1 to about
10.0; the weight ratio of (IV) to I+II) is in the range from about
0.005 to about 0.5; the reaction temperature is below about
80.degree. C.; and the reaction period is in the range from about
0.1 h to about 50 h;
[0033] ii) removing the solid catalyst (IV) from the reaction
mixture by filtration, and
[0034] iii) reusing the separated solid catalyst for subsequent
batch of the process.
[0035] In the process of this invention, the preferred porous
catalyst support, S, in solid catalyst (IV) is cationic clay or a
mesoporous zeolite-like crystalline material; the preferred M in
said solid catalyst (M is In (indium), or Ga (gallium) or a mixture
thereof; the preferred Z in said solid catalyst (IV) is Cl
(chlorine); the preferred catalyst loading, c, is in the range from
about 0.02 mmol g.sup.-1 to about 2.5 mmol g.sup.-1; each of the
preferred chemical groups R.sub.1, R.sub.2, and R.sub.4 is selected
from methyl, ethyl, propyl, butyl and phenyl groups, the preferred
R.sub.3 chemical group is H (hydrogen); the preferred mole ratio of
acid anhydride (II) to tertiary alcohol (I) is in the range from
O.1 to 2.0; the preferred weight ratio of solid catalyst (IV) to
the reactants, acid anhydride (II) and tertiary alcohol (I) is in
the range from 0.01 to 0.2; the preferred reaction temperature is
in the range from 10.degree. C. to 50.degree. C.; and the preferred
reaction period is in the range from 0.2 h to 10.0 h.
[0036] In the process of this invention, tertiary alcohol (I) and
acid anhydride (II) are the reactants, and a non-aqueous solvent is
essential if both the reactants are solid or if one of the
reactants is solid and it is not soluble completely in the liquid
reactants, the role of solvent is to dissolve the reactants(s).
Examples of non-aqueous solvent are benzene, toluene, n-hexane,
nitromethane, ethylene dichloride, nitrobenzene, acetonitrile,
etc.
[0037] A large number of chemical groups are known to be present in
different organic compounds. Examples of common chemical groups are
H, halogen, NH.sub.2, NO.sub.2, OH, SO.sub.3H, COOH,
C.sub.nH.sub.2n+1, C.sub.6H.sub.5 (phenyl), substituted phenyl,
OC.sub.NH.sub.2n+1, OC.sub.nH.sub.2nC.sub.6H.sub.5.
C.sub.nH.sub.2n--C.sub.6II.sub.5 and the like, wherein a is an
integer having a value equal to or greater than 1.0.
[0038] An acid anhydride, derived from dicarboxylic organic acid,
such as malcic anhydride, phthalic anhydride and the like may also
be used as an esterification agent in the process of this invention
for the esterification of tertiary alcohol
[0039] The main product of the process of this invention is a
tertiary ester (III). The by-product of the process of this
invention is a carboxylic acid (V), represented by a formula.
R.sub.4COOH (V)
[0040] wherein, R.sub.4 is a chemical group present in the acid
anhydride (II) used in said process. The side products, which are
formed by the dehydration of the tertiary alcohol (1), are water
and an iso-olefin (VI) represented by a formula: 5
[0041] wherein, R.sub.1, R.sub.2and R.sub.3 are chemical groups and
n is an integer, same as that present in the tertiary alcohol (I).
The formation of the side products, water and iso-olefin, in the
process of this invention is very small relative to the formation
teritiray ester (III) and carboxylic acid.
[0042] In the process of this invention, the main product,
by-product and side products are formed according to the following
reactions 6 7
[0043] The process of this invention can be carried out in a
stirred batch reactor fitted with a reflux condenser.
[0044] In the process of this invention, the mole of reflux
condenser fitted with the reactor is to condense reactants and
solvent, if used, and to return them back to reaction mixture. The
role of stirring is to provide to a thorough mixing of the
reactants and the catalysts in the reaction mixture, and thereby to
provide a very efficient contact between the catalyst and the
reactants.
[0045] The catalyst (IV), is in solid form, heterogeneous with
respect to the reaction mixture, and hence it can be removed from
the reaction mixture simply by filtration and the separated
catalyst can be reused in said process for subsequent batches. The
role of said catalyst (IV) in the process of this invention to
activate both the reactants, tertiary alcohol (I) ad acid anhydride
(II) and thereby drastically reduce the activation energy of the
esterification reaction between the reactants.
[0046] The rule of porous support, S, in said catalyst (IV) of this
invention is to immobilise the active catalyst component MZ.sub.y,
defined above. The catalyst support, S, may also show activity for
the conversion of tertiary alcohol (I) but it shows less
selectivity for the formation of tertiary ester (I) in the absence
of active catalyst component, MZ.sub.y. The presence of MZ.sub.y is
essential for both high activity and high selectivity of the
catalyst (IV) in the process of this invention. The catalyst
support, S, for said catalyst (IV) of this invention is selected
from various cationic clays and mesoporous zeolite-like materials
and it may be acidic, non acidic or basic in nature. Example of the
cationic clays are montmorillonite K-10, commonly called as Mont
X-10, montmorillonite KSF, commonly called as Mont KSF, kaolin,
kaolinites, serpentinites, nontronites, verculite and other clays
in smectite group [Ref. Vaccari A, Catalysts Today, vol. 41, year,
1998, pp. 53-71]. Examples of mesoporous zeolite-like crystalline
material are MCM41 type mesoporous materials, such as Si-MCM41.
Al-Si- MCM-41, Ga.Al-Si-MCM41, etc. These cationic clays and
mesoporous materials are well known in the prior art. The most
preferred catalyst support, S, for said catalyst (IV) of this
invention is Mont K-10 [Montmorillonite K-10]. Mesoporous materials
have pore diameter above about 1.0 min and below about 20.0 nm.
[0047] By the process of this invention, tert-butanol can be
esterified by acetic anhydride to tert-butyl acetate with a
complete (100%) conversion of tert-butanol and above 95%
selectivity for tert-butyl acetate at room temperature
(26-30.degree. C.) using a very small amount of said solid catalyst
(IV), InCl.sub.3 (1 1 mmol g.sup.-1) Mont K-10, with a catalyst to
reactants weight ratio of 0.03, for a short reaction period, 1.0
h.
[0048] The present invention will now be described with respect to
the following non-limitative examples illustrating the process of
this invention for the esterification of tertiary alcohols by
different acid anhydrides to corresponding tertiary esters using
said solid catalyst(M) with different compositions. These examples
are provided for illustrative purposes only and are not to be
construed as limitation on the process of this invention.
Definition of Terms Used in the Examples
[0049] Conversion of tertiary alcohol (%) is defined as mole % of
the tertiary alcohol converted to all products viz., tertiary ester
and iso-olefin. The conversion of tertiary alcohol selectivity for
tertiary ester and selectivity for iso-olefin are estimated as
follows:
[0050] Conversion of tertiary alcohol
(%)=[(X.sub.tA(i)-X.sub.tA(f))/X.sub- .tA(i)) ].times.100
[0051] Srlivity for tertiary ester
(%)=[X.sub.tF/(X.sub.tA(i)-X.sub.tA(f)) ].times.100
[0052] Selectivity for
iso-olefin=[X.sub.IO/(X.sub.tA(i)-X.sub.tA(f))].tim-
es.100=100-[selectivity for tertiary ester (%)]
[0053] wherein.
[0054] X.sub.tA(i)=moles of tertiary alcohol in the reaction
mixture before the reaction
[0055] X.sub.tA(f)=moles of tertiary alcohol in the reaction
mixture after the reaction.
[0056] X.sub.tE=moles of tertiary ester in the reaction mixture
after the reaction.
[0057] X.sub.I)-moles of iso-olefin formed in the reaction.
EXAMPLES 1-14
[0058] These examples illustrate the process of this invention for
the esterification of tertiary alcohol (I) by an acid anhydride
(II) to a tertiary ester (III) using a reusable solid catalyst
(IV).
[0059] The process of this invention was carried out in a
magnetically stirred glass reactor of capacity 50 cm.sup.3 fitted
with a reflux water condenser, the outlet of which was connected to
a constant pressure (atmospheric pressure) gas collector, by
contacting a reaction mixture containing tertiary alcohol (I) and
acid anhydride (II) with the fine particles of said solid catalyst
(IV) at reaction conditions given in Tables 1-3. The reaction
temperature was measured by a mercury thermometer dipped in the
reaction mixture and it was controlled by putting the glass reactor
in a constant temperature water bath After the reaction, the
temperature of the reaction mixture was brought to room temperature
and then the catalyst form the reaction mixture was separated by
filtration. After the removal of the solid catalyst, the reaction
mixture was subjected in the analysis of products and unconverted
reactants. The iso-olefin formed in The reaction was measured
quantitatively by collecting iso-olefin gas evolved, if any, during
the reaction at atmospheric pressure and also by analyzing the
reaction mixture for the iso olefin by gas chromatographic
analysis. The unconverted tertiary alcohol (I) and acid anhydride
(U), tertiary ester (III) and carboxylic acid (V) in the reaction
mixture were analyzed by gas chromatography or high pressure liquid
chromatography.
[0060] Results of the esterfication of tertiary alcohol (I) by the
process of this invention at different process conditions and using
different tertiary alcohols, acid anhydrides and fresh catalysts or
used catalysts are presented in Table 1-3. Before reusing the
InCl.sub.3 (0.02 mmol g Mont K-10 catalyst in Example-13 and the
GaCl.sub.3 (0.5 mmol g.sup.-1)/Mont K-10 catalyst in Example-14,
both the used catalysts were washed with tert-butanol to remove any
material absorbed in the previous reaction.
[0061] The catalysts given in Tables 1-3 were prepared as
follows:
[0062] The INCl.sub.3 (1.1 mmol g.sup.-1)/Mont K 10 catalyst was
prepared by depositing 2.43 g anhydrous InCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h
[0063] The ZnBr.sub.2 (1.1 mmol g.sup.-1)/Mont K-10 catalyst was
prepared by depositing: 2.48 g anhydrous ZnBr.sub.2 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0064] The FeCl.sub.3 (1.1 mmol g-.sup.-1)/Mont K-10 catalyst was
prepared by depositing 1.78 g anhydrous FeCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0065] The GaCl.sub.3 (4.6 mmol g.sup.-1)/Mont K-10 catalyst was
prepared by depositing 8.1 g anhydrous GaCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0066] The InCl.sub.3 (2.3 mmol g.sup.-1 Si-MCM-41 catalyst was
prepared by depositing 5.09 g, anhydrous InCl.sub.3 (Aldrich) from
it acetonitrile on 10 g Si-MCM41 by incipient wetness technique
followed by drying at 120.degree. C. for 8 h.
[0067] The InCl.sub.3 (1.1 mmol g.sup.-1)/Mont KSF catalyst was
prepared by depositing 2.43 anhydrous InCl.sub.3 (Aldrich) from its
acetonitrile solution on 10 g montmorillonite KSF clay by incipient
wetness technique followed by drying at 120.degree. C. for 8 h.
[0068] The InCl.sub.3 (0.5 mmol g.sup.-1)/Mont K 10 catalyst was
prepared by depositing 1.11 g anhydrous InCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0069] The InCl.sub.3 (0.02 mmol g.sup.-1)/Mont K-1 0 catalyst was
prepared by depositing 0.044 g anhydrous InCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0070] The GaCl.sub.3 (0.5 mmol g.sup.-1)Mont K-10 catalyst was
prepared by depositing 0.9 a anhydrous InCl.sub.3 (Aldrich) from
its acetonitrile solution on 10 g montmorillonite K-10 clay by
incipient wetness technique followed by drying at 120.degree. C.
for 8 h.
[0071] The InCl.sub.3 (0.5 mmol g .sup.1) and GaCl.sub.3 (0.5 mmol
g.sup.-1)/Mont K-10 catalyst was prepared by depositing the mixture
of 1.11 g anhydrous InCl.sub.3 (Aldrich) and 0.9 g anhydrous
GaCl.sub.3 (Aldrich) from their acetonitrile solution on 10 g
montmorillonite K-1 0 clay by incipient wetness technique followed
by drying at 120.degree. C. for 8 h.
[0072] In the incipient wetness technique the volume of
impregnation solution is just sufficient to completely wet solid to
be impregnated and there is no free solution in the impregnation
mixture.
[0073] The Mont K-10 (montmorillonite K-10), Mont KSF
(montmorillonite KSF) and kaolin clays were obtained from Aldrich
Chemicals Co, USA. The Si-MCM-41 mesoporous crystalline material
was prepared by the procedure given by Mukaya et. al., [Ref.
Mokaya, R and Jones, W., Chemical Communication, year 1997, pp.
2185-2186].
1TABLE 1 Results of the esterification of tertiary butanol with
acetic anhydride at different reaction conditions. Example No.
Example 1 Example 2 Example 3 Example 4 Catalyst (IV) InCl.sub.3
(1.1 mmol InCl.sub.3 (1.1 mmol InCl.sub.3 (1.1 mmol ZnBr.sub.2
(1.14 mmol g.sup.-1)/Mont K-10 g.sup.-1)/Mont K-10 g.sup.-1)/Mont
K-10 g.sup.-1)/Mont K-10 Tertiary alcohol: (I) t-Butanol t-Butanol
t-Butanol t-Butanol Acid anhydride (II) Acetic anhydride Acetic
anhydride Acetic anhydride Acetic anhydride Mole ratio of II to I
1.1 1.1 1.1 0.9 Weight ratio of (IV) to (I-II) 0.03 0.03 0.03 0.03
Rection temperature (.degree. C.) 26 10 50 30 Reaction period (h)
1.0 10 0.25 2.0 Main product [tertiary ester (III)] t-Butyl acetate
t-Butyl acetate t-Butyl acetate t-Butyl acetate Other products
Isobutylene and Isobutylene and Isobutylene and Isobutylene and
acetic acid acetic acid acetic acid acetic acid Conversion of tert-
butanol (%) 100 100 100 48.5 Selectivity for t-butyl 96 5 96.5 87.0
96.9 acetate (%) Selectivity for isobutylene (%) 3.5 4.4 13.0
4.1
[0074]
2TABLE 2 Results of the esterification of a tertiary alcohol with
an acid anhydride at different reaction conditions. Example No.
Example 5 Example 6 Example 7 Example 8 Example 9 Catalyst (IV)
FeCl.sub.3 (1.1 mmol GaCl.sub.3 (4.6 mmol InCl.sub.3 (2.3 mmol
InCl.sub.3 (1.1 mmol InCl.sub.3 (0.5 mmol g.sup.-1)/Mont K-10
g.sup.-1)/Mont K-10 g.sup.-1)/Si-MCM-41 g.sup.-1)/Mont KSF
g.sup.-1)/Mont K-10 Tertiary alcohol (I) t-Butanol t-Butanol
t-Butanol t-Butanol .alpha., .alpha.-dimerhyl benzyl alcohol Acid
anhydride (II) Acetic anhydride Benzoic anhydride Acetic anhydride
Propionic anhydride Acetic anhydride Mole ratio of II to I 0 91 0.2
0.91 0.9 2.0 Weight ratio of (IV) to (I + II) 0 03 0.03 0.03 0.005
0.01 Reaction Temperature (.degree. C.) 26 48 26 26 40 Reaction
period (h) 2 0 2.0 8.0 20 3.0 Main product [tertiary ester (III)]
t-Butyl acetate t-Butyl benzeate t-Butyl acetate t-Butyl propionate
.alpha., .alpha.-dimerhyl benzyl acetate Other products Isobutylene
and Isobutylene and Isobutylene and Isobutylene and 2-phenyl
propylene acetic acid benzoic acid acetic acid propionic acid and
acetic acid Conversion of tertiary alcohol (%) 65.7 25.6 52.9 100
100 Selectivity for tertiary ester (%) 97.1 65.1 97.6 93.5 91.2
Selectivity for clefin (%) 2 9 34.9 2.4 6.5 8.8
[0075]
3TABLE 3 Results of the esterification of t-butyl alcohol with an
acid anhydride at different reaction conditions. Example No.
Example 10 Example 11 Example 12 Example 13 Example 14 Catalyst
(IV) InCl.sub.3 (0.02 mmol GaCl.sub.3 (0.5 mmol InCl.sub.3 (0.5
mmol InCl.sub.3 (0.02 mmol GaCl.sub.3 (0.5 mmol g.sup.-1)/Mont K-10
g.sup.-1)/Mont K-10 g.sup.-1) and GaCl.sub.3 g.sup.-1)/Mont K-10
g.sup.-1)/Mont K-10 (0.5 mmol g.sup.-1)/ after its use in after its
use in Mont K10 Example 10 Example 11 Tertiary alcohol t-Butanol
t-Butanol t-Butanol t-Butanol t-Butanol Acid anhydride (II) Acetic
anhydride Acetic anhydride Acetic anhydride Acetic anhydride
Butyric anhydride Mole ratio of II to I 1.1 5.0 1.1 1.1 1.2 Weight
ratio of (IV) to (I + II) 0.1 0.05 0.03 0.1 0.05 Reaction
Temperature (.degree. C.) 30 26 26 30 26 Reaction period (h) 2.0
3.0 1.5 2.0 3.0 Main product [tertiary ester (III)] t-Butyl acetate
t-Butyl acetate t-Butyl acetate t-Butyl acetate t-Butyl acetate
Other products Isobutylene and Isobutylene and Isobutylene and
Isobutylene and Isobutylene and acetic acid acetic acid acetic acid
acetic acid butyric acid Conversion of tertiary butanol (%) 100 100
100 100 100 Selectivity for tertiary ester (%) 92.1 90.2 97.0 91.8
90 1 Selectivity for isobutylene (%) 7.9 9.8 3.0 8.2 9.9
Novel Features and Advantages of the Process of this Invention Over
the Prior Art Processes for the Esterfication of Tertiary
Alcohol
[0076] 1) By the process of this invention, a tertiary alcohol can
be esterified by an acid anhydride to a corresponding ester with
very high conversion (upto 100%) and high selectivity for the
tertiary er (above 95 %), without producing appreciable amounts of
tertiary alcohol dehydration products and/or ally environmentally
unacceptable product, using a reusable solid catalyst for a short
reaction period, as short as 1.0 h.
[0077] 2) Unlike the prior art process, thie process of this
invention is environment-friendly process; no toxic/corrosive
product, like gaseous hydrogen halide is formed as a by-product in
the process of this invention. The by-product of the process of
this invention, carboxylic acid, has a commercial value and it can
be converted into an acid anhydride, and thereby, recycled in the
process.
[0078] 3) Unlike the prior an processes, the amount of solid
catalyst used in the process of this invention is very small. The
solid catalyst to reactants weight ratio in the process of this
invention is very much lower than that used in the prior art
processes.
[0079] 4) Unlike the prior art processes, the reaction time require
for completing the esterification reaction in the process of this
invention is much shorter even though the amount of catalyst used
is very much smaller.
* * * * *