| 摘要 |
A mixture of ortho- [salicylaldehyde] and para-hydroxybenzaldehydes is prepared by a modified Reimer-Tiemann reaction.
<??>An alkali metal (e. g. sodium or potassium) hydroxide powder is dispersed in an inert anhydrous organic liquid, e. g. an aromatic hydrocarbon (e. g. benzene or toluene), aliphatic alcohol or alkyl ester. An alkali metal phenolate is prepared from alkali metal and phenol. This dispersion and phenolate are placed in a reactor, and chloroform is added dropwise to the stirred mixture. It is important that the reaction is under anhydrous or substantially anhydrous conditions.
<??>For recovery of the products, ethyl acetate or methylisobutyl ketone is added, and hydrochloric acid, and the mixture of hydroxybenzaldehydes is extracted from the aqueous acid layer.
<??>The ratio of reactants can be phenol:alkali:chloroform = 1.0:10.0:10.0 to 1.0:2.0:0.3.
<??>A surfactant preferably nonionic, can be added to the reaction mixture, to improve the yields especially of the para isomer, in amount of 0.1 to 5 mol% of surfactant of the alkali phenolate.
<??>The examples show good conversions of phenol of 65 to 95.7%, and ratios of ortho to para of 7.8:1 to 4.5:1 with surfactant and of 0.77:1 without surfactant. |
