Potassium Hydroxide → HCID 21519695, compound

Participants

Reaction Steps

The whole amount of the 3-methyl-4(benzo[b]thien-2-yl)-1-piperidinecarboxylic acid ethyl ester obtained as crude product according to the following section (a) is dissolved in 100 ml of ethylene glycol. There is then added 30 g of solid potassium hydroxide, and the resulting cloudy solution is heated, with vigorous stirring, for 15 hours at 160°. The reaction solution is subsequently cooled to 20°, and extracted 3 times with 150 ml of toluene each time. The combined toluene solutions are washed 5 times with 250 ml of water each time, and subsequently extracted twice with 200 ml of 2N hydrochloric acid each time. The acid solutions are combined; the pH-value is adjusted to 12 by the addition of 10% sodium hydroxide solution, and extraction is performed with 500 ml of chloroform. The chloroform solution is dried with sodium sulphate, filtered, and concentrated by evaporation to obtain crude 3-methyl-4-(benzo[b]thien-2-yl)-piperidine. The crude base is distilled in a bulb tube (molecular distillation) under high vacuum (0.20 Torr at a bath temperature of 170°-190°). From the distillate there is prepared the hydrochloride with hydrogen chloride in ethyl acetate; the hydrochloride is recrystallised from acetone and then melts at 253°-255°.

Provenance & Evidence