Patent GB-880788-A (GB)
Title: A process for the production of aliphatic and cycloaliphatic monocarboxylic acid alkyl esters
IPC: C07C51/10
Filed: 1958-04-01
Abstract: Alkyl esters of aliphatic or cycloaliphatic monocarboxylic acids and minor amounts of the corresponding free acids are prepared by reacting an aliphatic or cycloaliphatic olefinic hydrocarbon containing at least 6 carbon atoms with carbon monoxide under elevated pressure in the presence of a catalyst comprising a mixture of hydroxy and alkoxy fluoroboric acids, the alkoxy groups of which contain 1-3 carbon atoms, the mol ratio of combined water plus alcohol to boron trifluoride in the catalyst mixture being not less than 1 : 1 and not greater than 2 : 1 and treating the resulting reaction product with a C1-3 alkanol to form the alkyl ester and render the catalyst separable.  The amount of alcohol used is preferably stoichiometrically equivalent to the amount of olefine which has reacted with the carbon monoxide.  The regenerated catalyst which separates may be re-used though make-up water corresponding to that lost in by-product carboxylic acid formation may be required. The carbonylation step is suitably effected at between -20 DEG C. and 100 DEG C at pressures ranging from 20 to 300 atmospheres.  A low-boiling hydrocarbon diluent may be present.  The esters may be recovered by distillation and the by-product carboxylic acids may be removed by extracting the crude ester or the distillation residue with aqueous caustic soda or potash or by contacting the esters with an ion exchange resin.  In Examples: (1) undec-1-ene is sprayed into an autoclave containing a stirred mixture of H(BF3OH) and H(BF3OCH3) under 100 atmospheres CO pressure at 10 DEG C.-20 DEG  C. and the product is diluted with n-hexane and treated with methanol; the catalyst is separated for re-use and the products worked up to provide the methyl esters of resulting C12 acids and minor amounts of free C12 acids and of free C23 acids and methyl esters thereof; the corresponding ethyl and propyl esters are obtained using the ethoxy or propoxy fluorboric acid catalysts and ethanol or propanol as the alcohol in the second stage; in similar manner, (2) tetradecene-1 yields methyl esters of C15 acids and minor amounts of free C15 acids and C29 acid methyl esters; (3) octene-1 yields methyl esters of C9 and C17 acids and the free acids; (4) isononene yields methyl esters of C10 and C19 acids and the free acids.  (5) Di-isobutene is similarly reacted using a catalytic mixture of (H3O)(BF3OH) and (CH3OH2)(BF3OCH3) yielding methyl esters of C2 acids and the free acids; in like manner, (6) 2-ethyl-hexene-1 yields methyl a -methyl a -ethyl caproic acid and the free acid; (7) octahydronaphthalene yields methyl decahydronaphthalene-9-carboxylate and the free acid. (8) an isodocosene, obtained by dimerising n-undec-1-ene with the aid of an aluminium alkyl, is treated as in (1) yielding the methyl ester of a -methyl a -nonyl tridecane-1-carboxylic acid and the free acid and (9) a 2-tridecyl-heptadec-1-ene similarly obtained by dimerising n-pentandec-1-ene, is reacted in like manner yielding methyl a -methyl-a -tridecyl-heptadecan-1-oate and the free acid. Other olefinic hydrocarbons are specified including n-hexene, cyclohexene, camphene and the dimer of n-hexadec-1-ene. Specification 516,477, U.S.A.  Specification 1,979,717, Belgium Specification 537,933 and German Specification 942,987 are referred to.