Patent GB-647174-A (GB)
Title: Improvements relating to the production of alkyl esters of fatty acids
IPC: C11C3/04
Filed: 1948-07-23
Abstract: Alkyl esters of fatty acids are prepared from fatty material having an acid value of at least 1, by contacting such materials with a primary or secondary monohydric alcohol of 1 to 8 carbon atoms, in proportion of at least 2 moles of alcohol per fatty acid equivalent and in presence of an alkaline catalyst, adding acid to split the soaps formed during the transesterification and to neutralize the alkaline catalyst and provide slightly acid conditions, and esterifying the free fatty acids thus produced by the alcohol remaining in the reaction mass.  In the case of methanol, the ratio to fatty acid equivalents should be at least 4 moles to 1, while for other alcohols at least 8 moles to 1 should be employed, but less alcohol is required if water is continuously removed.  Oils and fats having acid numbers up to 100 or more can be treated, but in the case of relatively hard oils such as hydrogenated oils and fats it is preferred not to treat materials having acid values above 70.  Oils specified are corn oil, peanut oil, soybean oil, coconut oil, palm oil, cotton-seed oil, olive oil, rice bran oil, tallow and all types of fish oils.  Alcohols specified are methanol, butanol, ethanol, propanol, amyl alcohol, fusel oil, hexyl alcohol, heptyl alcohol octyl alcohol, isopropanol, isobutanol, secondary butanol, and 2-ethyl butanol. Esterification catalysts specified are metallic sodium and potassium and their hydroxides, methylates, amides, and hydrides. Acid catalysts specified are sulphuric, phosphoric, hydrochloric, organic sulphonic, trichloracetic and alkyl sulphuric acids and aluminium trichloride.  According to an example, hydrogenated fish oil is refluxed for 1 hour with methanol in which 1 per cent of sodium based on the weight of the oil has been dissolved; 5 per cent sulphuric acid is then added and refluxed for 4 hours, the mass neutralized with calcium carbonate, and the methanol distilled off.  The ester layer is then separated from the glycerine layer and purified by distillation under vacuum.  Other examples relate to hydrogenated soybean oil, melted tallow, and rice bran foots.  U.S.A. Specification 2,383,601 is referred to.ALSO:Glycerine is produced as a by-product in the preparation of alkyl esters of fatty acids from fatty material having an acid value of at least 1 by contacting such materials with primary or secondary monohydric alcohols containing from 1 to 8 carbon atoms in proportion of at least 2 moles of alcohol per fatty acid equivalent in presence of an alkaline catalyst, adding sufficient acid to split the soaps formed during the transesterification and to neutralize the alkaline catalyst, and esterifying the free fatty acids so produced by the alcohol which remains in the reaction mass.  In the case of methanol, the ratio of fatty acid equivalents should be at least 4 moles to 1, while for other alcohols at least 8 moles to 1 should be employed, but less alcohol is required if water is continuously removed during the process.  Oils and fats having acid numbers up to 100 or more can be treated, but in the case of relatively hard oils such as hydrogenated oils and fats it is preferred not to treat materials having acid values above 70.  Oils specified are corn oil, peanut oil, soybean oil, coconut oil, palm oil, cottonseed oil, olive oil, rice bran oil, tallow, and all types of fish oil.  Alcohols specified are methanol, butanol, ethanol, propanol, amyl alcohol, fusel oil, hexyl alcohol, heptyl alcohol, octyl alcohol, isopropanol, isobutanol, secondary butanol, and 2-ethyl butanol. Esterification catalysts specified are metallic sodium and potassium and their hydroxides, methylates, amides, and hydrides. Acid catalysts specified are sulphuric, phosphoric, hydrochloric, organic sulphonic, trichloracetic, and alkyl sulphuric acids and aluminium trichloride.  According to an example, hydrogenated fish oil is refluxed for 1 hour with methanol in which 1 per cent of sodium based on the weight of the oil has been dissolved; 5 per cent sulphuric acid is then added and refluxed for 4 hours, the mass neutralized with calcium carbonate, and the methanol distilled off.  The ester layer is then separated from the glycerine layer and purified by distillation under vacuum.  Other examples relate to hydrogenated soybean oil, melted tallow, and rice bran foots.  U.S.A. Specification 2,383,601 is referred to.