4,4-二甲基-3-氧戊腈合成的研究

对以丙酮为原料、先依次制得片呐醇、片呐酮、α 氯代片呐酮、最后由α 氯代片呐酮与NaCN反应制得 4,4 二甲基 3 氧 戊腈最后两步的反应条件进行了研究。片呐酮的α 卤代反应 ,氯代反应的产率比溴代反应的高 ,而且氯代产物与氰化钠反应的产率也比溴代产物的高。氯代反应在无水甲醇中进行 ,温度维持在 0～ 1 5℃。溶剂与片呐酮的质量比为 2 5∶1 0。氯气的通入量不应超过计算量 ,通入速度以维持反应体系温度不超过 0～ 1 5℃为宜 ,以防止反应温度过高而生成二氯化物。反应完成后 ,溶剂甲醇在减压下蒸出 ,并可以在下一次氯代反应中使用。将氰化钠的水溶液分批加入到α 氯代片呐酮的甲醇溶液中 ,然后在 0～ 1 0℃下酸化反应体系 ,制得 4,4 二甲基 3 氧 戊腈。

Study of the Synthetic Conditions of 4,4-Dimethyl-3-oxopentanenitrile

The synthetic conditions of 4,4 dimethyl 3 oxopentanenitrile prepared sequentially from acetone through pinacol,pinacolone and α chloropinacolone were investigated.For the halogenation reaction of pinacolone,the yield of chlorination was higher than that of bromination.The yield of reaction of chloropinacolone with sodium cyanide was higher than that of bromopinacolone.The chlorination was carried out in solvent,anhydrous methanol,at 0～15 ℃.The mass ratio of solvent to pinacolone was 2.5∶1.0.The amount of chlorine gas as chlorination agent shouldn't exceed the calculated amount.The flow rate of chlorine gas should be appropriate so as to prevent the temperature of the reaction mixture going up excessively and to avoid the formation of dichloride.The solvent methanol was distilled under vacuum after reaction and used again in next batch of chlorination.For synthesis of 4,4 dimethyl 3 oxopentanenitrile,an aqueous solution of sodium cyanide was added gradually into the solution of chloropinacolone in methanol and the reaction mixture was acidified under cooling.