GB651853A - Process for the production of esters of organic carboxylic acids - Google Patents

Abstract

In the process for producing esters by heating an olefinic compound, carbon monoxide and a primary alcohol in the presence of specified types of cobalt catalysts (see Group IV (b)), the olefinic compounds specified as starting materials include polymerized dienes and the specified alcohols include polyvinyl alcohol.ALSO:Esters of carboxylic acids are obtained by heating to a temperature within the range of 150 DEG to 500 DEG C. and under a pressure of at least 50 atmospheres a compound containing non-aromatic olefinic unsaturation with carbon monoxide and a primary alcohol in the presence of a cobalt salt of a carboxylic acid soluble in the reaction mixture as catalyst, and in the absence of other substances known to catalyse the reaction. Specified unsaturated compounds are the olefinic hydrocarbons, e.g. ethylene, alkyl-substituted ethylene such as propylene, butene-2, isobutylene, pentene-1, tetramethyl ethylene, diisobutylene, cracked gasoline fractions, cyclohexene, butadiene, isoprene, polymerized dienes, styrene, alpha-methyl styrene, vinyl cyclohexene, pinene, limonene, mixed olefines or olefine fractions obtained by cracking and/or dehydrogenation of petroleum, cyclohexadiene, dicyclopentadiene, unsaturated oxygenated compounds such as allyl alcohol, allyl acetate, allyl ethers, methallyl alcohol, vinyl acetate, furane, methyl methacrylate, methyl acrylate, methallyl propionate, methyl oleate, oleic acid, methyl vinyl ketone, methyl vinyl ether, cyclohexene carboxylic acids and esters thereof, methallyl methacrylate and acrolein and in general the unsaturated hydrocarbons, esters, ethers, carboxylic acids, amides, aldehydes and ketones containing non-benzenoid olefinic unsaturation. Polymerization inhibitors may be employed with the readily polymerizable reactants. As alcohols there may be used the primary, especially aliphatic, monohydric and polyhydric alcohols such as methanol, ethanol, n-propanol, n-butanol, isobutanol, allyl alcohol, lauryl alcohol, myricyl alcohol nitroalkanols, chlorohydrin, methoxyethanol, methoxymethoxy - ethanol, ethylene glycol, glycol monoesters, glycerine, polyvinyl alcohol, triethanolamine, benzyl alcohol, monoethanolamine, hydroxyacetic acid, methyl hydroxyacetate, and cycloaliphatic primary alcohols such as hexahydrobenzyl alcohol, beta-cyclohexyl ethanol, beta- or gamma-cyclohexyl propanol. The catalyst may be employed in combination with inert materials or supports such as charcoal, silica, aluminium, kieselguhr, pumice, or with promoters consisting of thorium oxide or manganese. The reaction may be carried out either batchwise or continuously. The reactants may be employed in equimolar quantities, but best results are obtained when the mole ratio of olefinic compound : CO : alcohol is from 1 : 1 : 1 to 1 : 20 : 1. Any inert liquid may be employed as a reaction medium, e.g. cyclohexane, xylene, benzene, saturated hydrocarbons and esters. Carbon dioxide may be used as a diluent. The preferred temperature range is 175 DEG to 375 DEG C. The reaction vessel may be made of or lined with inert materials such as glass or porcelain or with relatively inert metals such as copper or silver. In examples, the following are heated under carbon monoxide pressure in the presence of cobalt propionate as catalyst: (1) methanol and butene-1 to yield methyl n-valerate; (2) methanol and isobutylene to yield methyl isovalerate; (3) ethanol and ethylene to yield ethyl propionate; (4) methanol and ethylene to yield methyl propionate; (5) methanol and propylene to yield methyl n-butyrate; (6) ethylene glycol and ethylene to yield ethylene glycol monopropionate. U.S.A. Specification 1,979,717 is referred to. The Specification as open to inspection under Sect. 91 is not restricted to the use of a cobalt salt of a carboxylic acid as catalyst, but refers also to the use of any substance containing metallic cobalt, cobalt oxides, cobalt hydrides and cobalt carbonyls, e.g. CO2(CO)8, CO4(CO)12 and COH(CO)4. It also states that any cobalt compound formed during the reaction may be recovered and used as catalyst. Triisobutylene, tetraisobutylene and halogen containing olefinic compounds which do not form halide catalysts are also specified as olefinic starting materials. It is stated that the reaction may be conducted in the liquid or in the vapour phase and that when solid catalysts are employed they may be in the form of a fixed bed or may be passed through the reaction vessel with the reactants, alternatively they may be employed in a finely divided fluidized state or may be suspended in the reaction mixture. In additional examples: (1) methanol and ethylene are heated under carbon monoxide pressure in the presence of metallic cobalt to yield methyl propionate and diethyl ketone; (2) methanol, butadiene and carbon monoxide yield methyl 4-pentenoate which may be hydrolysed to a C5 unsaturated acid or converted to the amide; (3) as in (2) but using cobalt-copper-thoria as catalyst; (4) the methyl ester of a C6 unsaturated acid is obtained from methanol, isoprene and carbon monoxide, using cobalt obtained by reducing cobaltous oxide as catalyst; (5) a distillation residue (obtained by distilling the product resulting from the reaction between methanol, carbon monoxide and propylene in the presence of cobalt carbonyl produced in situ from the reaction of metallic cobalt and carbon monoxide at elevated temperature and pressure) is processed with methanol, propylene and carbon monoxide to yield methyl butyrate and a distillation residue containing cobalt. The distillation residue may be recycled and recovered repeatedly in successive syntheses of methyl butyrate by the same procedure; (6) methanol, methyl 4-pentenoate and carbon monoxide are reacted in the presence of reduced, unsintered cobalt oxide to yield a mixture of methyl esters of 6-carbon dibasic acids which on hydrolysis yield a mixture of dibasic acids containing adipic acid. This subject-matter does not appear in the Specification as accepted.