| 摘要 |
A catalyst for the preparation of enol-acetates from ketene and an enolizable organic compound (see Group IV(b)) comprises an equimolecular mixture of monofluorophosphoric acid and difluorophosphoric acid which may be prepared by reaction between phosphorus pentoxide and hydrogen fluoride. This catalyst, or difluorophosphoric acid alone, may be neutralized with sodium acetate after the enolacetate preparation is complete.ALSO:Enol-acetates are prepared by reaction between ketene and an enolisable carbonyl compound at a temperature of 20-110 DEG C. in the presence of difluorophosphoric acid or a mixture of equimolecular proportions of difluorophosphoric acid and monofluorophosphoric acid as catalyst (see Group III). The process may be carried out continuously or discontinuously and the catalyst is preferably used in a concentration of 0.01 to 2.0% calculated on the total weight of the reactants. The catalyst is preferably neutralised (see Group III) before isolating the desired reaction product, acetic acid being formed during the neutralisation. In examples the following compounds are prepared: (1)-(5) isopropenyl acetate from acetone; (6) a -acetoxystyrene from acetophenone; (7) n-but-1-enyl acetate from n-butyraldehyde; (8) the enol acetate of ethyl acetoacetate; (9) the mono- and (10) the mono- and di-enol acetates of acetylacetone. Acetic anhydride is formed as a by-product. |
