反应详情

This invention resides in an improvement in the process for preparing 3-(4-pyridinyl)-2-cyclohexen-1-oxime by heating ethyl 5-oxo-2-[(4-pyridinyl)carbonyl]hexanoate under aqueous acidic conditions to produce 1-(4-pyridinyl)-hexan-1,5-dione, reacting said hexan-1,5-dione with a basic condensing agent to produce said 3-(4-pyridinyl)-2-cyclohexen-1-one, and converting said cyclohexen-1-one to its oxime, said improvement being a one pot sequence consisting of first heating ethyl 5-oxo-2-[(4-pyridinyl)carbonyl]hexanoate with excess aqueous sulfuric acid, neutralizing the excess acid, shaking the resulting mixture well with isopropyl alcohol to extract the 3-(4-pyridinyl)-2-cyclohexen-1-one, draining off the heavier warm (40° to 50° C.) aqueous layer, adding hydroxylamine hydrochloride to the isopropyl alcohol solution of 3-(4-pyridinyl)-2-cyclohexen-1-one, stirring the mixture at reflux, basifying the mixture and evaporating it to dryness, and isolating the 3-(4-pyridinyl)-2-cyclohexen-1-one oxime from the residue. In a preferred embodiment three mole-equivalents of sulfuric acid were used per mole of ethyl 5-oxo-2-[(4-pyridinyl)carbonyl]hexanoate, the excess sulfuric acid was neutralized with aqueous sodium hydroxide solution and the reaction mixture was basified after oxime formation with concentrated ammonium hydroxide.

1. customto produce
2. extractionto extract the 3-(4-pyridinyl)-2-cyclohexen-1-one
3. temperatureheavier warm (40° to 50° C.) aqueous layer
4. additionadding hydroxylamine hydrochloride to the isopropyl alcohol solution of 3-(4-pyridinyl)-2-cyclohexen-1-one
5. temperatureat reflux
6. customevaporating it to dryness