| 摘要 |
Carboxylic esters are obtained by interaction of an ether and not appreciably more than a molecularly equivalent quantity of carbon monoxide in the presence of a boron-halogen-containing compound or other halides including those of Ti, Sb, Al, Be, Zr, Hf, Th, Cb, S, Si, P, Ta, Cr, V, and Mo. Carbon monoxide may be passed into a dialkyl ether-boron trifluoride addition compound, a carboxylic ester-boron fluoride addition compound being formed. The ester may be freed by reaction with dialkyl ether and distillation, the original compound being reformed. Metal halides act similarly to replace the ester in the addition compound. Dihydroxyfluoboric acid, hydrofluoboric acid, and other acids made by reacting hydrofluoric acid with boric acid and borates may be used in place of or in addition to boron fluoride. Boron fluoride-water addition compounds are also suitable. Promoters such as metals or metal oxides may be present. Temperatures up to about 350, e.g. 150-240 DEG C., and pressures up to 1000 atm. or more, e.g. 350-750 atm., may be used. Carbon monoxide from commercial sources or mixed with inert gases may be employed although compounds such as sulphur derivatives and carbonyls are preferably removed. Ethers specified are methyl, ethyl, propyl, butyl, diallyl, b - and g -chlorethers, cyclohexyl, methyl-ethyl, ethyl-propyl, methyl-propyl, methyl-allyl, and anisol. In examples (1) dimethyl ether and boron fluoride are reacted to form an addition compound and carbon monoxide added until pressure is 900 atm. Temperature is kept at 150-190 DEG C. for 2 hrs. The product is distilled while dimethyl ether is added to give methyl acetate; (2) the same addition compound + 10 per cent dihydroxyfluoboric acid is used, CO pressure being 800 atm.; (3) a silver lined autoclave charged with (C2H5)2O.BF3 and BF3.H2O under an initial CO pressure of 575 atm. is heated to 170 DEG C. pressure being increased to 800 atm. The product is fractionated while (C2H5)2O is added. |
