| 摘要 |
1,250,265. Process for the manufacture of unsaturated esters of carboxylic acids. KNAPSACK A.G. 7 Nov., 1969 [13 Nov., 1968], No. 54658/69. Heading C2C. A process for the manufacture of unsaturated esters of carboxylic acids by reacting an olefinic compound having from 2 to 20 carbon atoms and an aliphatic or aromatic carboxylic acid having from 2 to 20 carbon atoms with molecular oxygen or air in the gas phase, if desired in the presence of one or more inert gases, at temperatures between 100‹ and 250‹ C., preferably between 150‹ and 220‹ C., under pressures between 1 and 21 atmospheres absolute, preferably between 5 and 11 atmospheres absolute, in contact with a catalyst consisting of metallic palladium, a carrier and optionally a further activator metal, comprises supplying the alkali metalfree catalyst, in a first step and during operation, with one or more alkali metal carboxylates or compounds yielding alkali metal carboxylates under the reaction conditions, the said alkali metal carboxylates or compounds being supplied in the quantity necessary to effect catalyst activation, and, following establishment of an optimum catalyst activity, supplying the alkali metal carboxylate-saturated catalyst, in a second step, with a further quantity of alkali metal compound, the said further quantity of alkali metal compound being normally just sufficient to replace the loss of alkali metal carboxylates occasioned by evaporation from the hot catalyst. Using this process vinyl acetate, vinyl propionate, vinyl isobutyrate and allyl acetate are prepared in the Examples. |
