Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1999-10-20
2001-04-03
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
Reexamination Certificate
active
06211406
ABSTRACT:
The invention relates to a process for the manufacture of quaternary carboxylic acids. More in particular the invention relates to a process for the manufacture of &agr;,&agr;-branched carboxylic acids from linear olefins having from 2 to 5 carbon atoms by means of a Koch synthesis using carbon monoxide as reagent and a solid acid catalyst.
Processes for the preparation of &agr;,&agr;-branched carboxylic acids from branched olefins by means of a Koch synthesis, using carbon monoxide and water, are known.
International Application WO 96/20154 describes a process for the production of trialkylacetic acids from branched olefins and carbon monoxide in a non-aqueous reaction system using a solid resin catalyst comprising a cationic resin, having sufficient acid groups to provide requisite protons for conversion of branched olefin and carbon monoxide to trialkylacetic acids. In particular, the cationic resin was specified to have an acidity of at least equivalent to that of a 65 wt % sulphuric acid. It can be appreciated that such process can only be performed in two steps, i.e. one step comprising contacting the solid catalyst with olefin/CO feed and a subsequent step contacting the catalyst with water feed, and that stoichiometric amounts of branched olefin and water will not lead to the desired products in an acceptable yield. Moreover, such process cannot produce more than 1 mole of converted olefin per mole active proton on the solid catalyst in one cycle of two steps.
On the other hand, WO 92/18592 describes a process for the manufacture of trialkylacetic acids and particularly of pivalic acid, from branched olefins and particularly isobutene, and Carbon monoxide, using a solid acid catalyst together with minor amounts of a Lewis acid, such as boron trifluoride.
In addition, EP-A-0249976 describes a process for the manufacture of branched carboxylic acids, by catalytic conversion of olefins with carbon monoxide and water in the presence of zeolites as catalysts at temperatures of from 200 to 500° C. and at pressures of 200 to 700 bar. More in particular, zeolites of the pentasil type are used as catalysts. According to the exemplified embodiments only high temperatures (300° C.) and pressures (300-500 bar) are used. It can be appreciated that such reaction conditions will give rise to higher operation costs due to required measures as to safety and environment.
An object of the present invention is providing a further improved, efficient one step manufacturing process for &agr;,&agr;-branched carboxylic acids, which process starts from lower linear olefins containing from 2 to 5 carbon atoms, and which uses a catalyst system under relatively mild conditions on the one hand and which shows economically acceptable conversion and economically acceptable selectivity to &agr;,&agr;-branched carboxylic acids on the other hand.
As a result of extensive research and experimentation there has now been surprisingly found a one step process for manufacture of &agr;,&agr;-branched carboxylic acids from linear olefins by means of reaction with carbon monoxide and an acid catalyst, characterized in that a linear olefin containing from 2 to 5 carbon atoms, or a precursor thereof, is reacted in a batch reactor or a continuous reactor with carbon monoxide and water, in the presence of an acidic catalyst, having sufficient acid groups to provide requisite protons for the formation of Koch acids and in the presence of a polar non-coordinating organic solvent.
More in particular the invention relates to an improved manufacturing process of trialkylacetic acids of the formula
wherein each symbol R represents a radical having 1 to 10 carbon atoms.
More preferably the total number of carbon atoms in the trialkylacetic acids ranges from 5 to 11 and most preferably from 9 to 11 carbon atoms.
With the term “linear olefin or a precursor thereof” as used throughout the present specification is meant that the specified linear olefin itself as well as alcohols, esters or ethers, from which the specific olefin can be easily derived, can be used as starting materials for the present manufacturing process, which makes this process much more flexible than conventional prior art processes.
An important advantage of the present process is that it can be operated as one step or one reactor process showing an economically acceptable combination of conversion degree and selectivity and starting from cheap lower linear olefins which have been found to dimerize before the actual Koch synthesis step.
The catalyst to be used for the process of the present invention can be in general a strong acid catalyst which is known to efficiently catalyze the Koch synthesis, such as homogeneous H
2
O/BF
3
catalyst, H
2
O/BF
3
/H
3
PO
4
catalyst, or concentrated sulfuric acid or sulfonic acid catalysts, such as paratoluene sulfonic acid, methane sulfonic acid, trifluoromethane sulfonic acid, or a heterogeneous acidic solid catalyst. Homogeneous H
2
O/BF
3
/H
3
PO
4
catalyst or methane sulfonic acid catalyst or a heterogeneous acidic catalyst are preferred.
More preferably a solid acidic ion exchanger showing strong acid behaviour is used. It is preferably selected from the group consisting of sulfonated resins and more preferably sulfonated copolymers of styrene and divinylbenzene, copolymers of vinylnaphthalene and divinylbenzene, copolymers of styrene and methacrylic acid resins, phenolic based resins, sulfonated poly(tetrafluoroethylene) and sulfonated siloxane polymers and sulfonated cellulose derivatives.
In either case of the presence of active sulfonic acid groups, the resin is treated to give a sulfonic acid cation-exchange resin capable of providing sufficient protons, i.e. the resin having an acid strength equivalent to at least 65 wt % sulphuric acid and preferably to at least 70 wt % sulphuric acid.
Catalyst solid resins, comprising sulfonic acid groups and derived from copolymers from styrene-divinylbenzene, copolymers from vinylnaphthalene-divinyl benzene or derived from (tetrafluoroethylene)polymers or from siloxane polymers are preferred.
Specific more preferred examples of commercial effective acidic catalysts are AMBERLYST, NAFION or DELOXAN catalysts (AMBERLYST, NAFION and DELOXAN are Trade Marks).
Most preferred are styrene-divinylbenzene copolymer based catalyst such as the AMBERLYST type catalysts. More preferably AMBERLYST 38 catalyst is used. The reaction temperature in the batch reactor is in the range of from 25° C. to 200° C. and preferably from 100 to 150° C.
The pressure in the reactor is in the range of from 1 to 200 bar and preferably from 50 to 100 bar.
As polar non-coordinating organic solvents can be used chemically inert polar organic solvents such as carboxylic acids or derivatives thereof and more in particular esters, or an optionally substituted sulfolane (preferably sulfolane).
According to a more preferred embodiment of the present process, as polar non-coordinating solvent an &agr;,&agr;-branched acid is present in the reactor and preferably a back mixed reactor. Most preferably the carboxylic acid to be produced can be used as solvent.
Normally the back mixed reactor is filled with solvent and catalyst with a catalyst/solvent wt ratio of in the range of from 0.01 to 0.5 w/w solid/liquid and preferably 0.2-0.3 w/w. The other respective reactants are introduced into the reactor and reaction mixture is heated to the desired 5-30 mmol/reaction temperature.
Alternatively for a fixed bed reactor with liquid recycling can be operated with a catalyst/solvent ratio up to 0.95 w/w (solid/liquid) and preferably in the range of from 0.4 to 0.8.
The feed of starting olefin is for batch processes in the range of from 0.3 to 2 mmol/g catalyst and preferably from 0.6 to 1.5 mmol/g catalyst and for continuous processes in the range from 0.1 to 10 mmol feed/gr cat/hr., while the water/olefin molar ratio or the molar ratio of the respective precursors therefor, is in the range of from 0.1 to 2 mole/mole and preferably about 0.5 and the CO/olefin molar ratio is in the range of from 0.5 to 1000 mole/mole
Lange Jean-Paul
Otten Vincent
Stil Hans Arie
Calve John N
Killos Paul J.
Shell Oil Company
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