| 摘要 |
In the manufacture of laevulinic acid esters furfuryl alcohol is heated with another primary or a secondary alcohol under substantially anhydrous conditions with agitation in the presence of hydrogen chloride or hydrogen bromide as catalyst and the furfuryl alcohol is gradually added to the other alcohol at a rate such that at no time does the amount of unreacted furfuryl alcohol present in the reaction mixture exceed 2 per cent by volume of the other alcohol. Alcohol starting materials specified are methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, isopentanol, n-hexanol, n-octanol, n-nonyl alcohol, n-decanol, an alkoxy-ethanol, e.g. b -methoxy- or b -ethoxy-ethanol, a cycloaliphatic alcohol, e.g. cyclohexanol and tetrahydrofurfuryl alcohol. The furfuryl alcohol may be added to the other alcohol while the latter is maintained at the boil, under atmospheric or reduced pressure. The process may be carried out by continuously withdrawing part of the reaction mixture during the reaction and adding furfuryl alcohol, fresh amounts of the alcohol to be esterified and hydrogen bromide or chloride to replace the constituents withdrawn. In examples methyl, ethyl, n-butyl, isobutyl, cyclohexyl, b -methoxy- and b -ethoxyethyl, tetrahydrofurfuryl, n-propyl, isopropyl, n-amyl, isoamyl, n-hexyl, n-octyl and n-nonyl laevulinates are obtained by gradually adding furfuryl alcohol to the appropriate alcohol boiling under reflux and containing hydrogen chloride (1-4, 6-9); (3) is repeated at a temperature below the boiling point of the alcohol; n-decyl laevulinate is prepared in a similar process (5) and n-butyl laevulinate is prepared by a similar process to (3) but using hydrogen bromide (9) and n-butyl laevulinate is obtained in a continuous process in which n-butanol containing hydrogen chloride is boiled under reflux whilst n-butanol containing hydrogen chloride and furfuryl alcohol are added and reaction mixture is withdrawn at the same rate. n-Butyl laevulinate is isolated by distillation (10). The esters may be converted to laevulinic acid by hydrolysis with water or salts by hydrolysis with metal compounds of alkaline reaction. |
