Hydrochloric Acid → 5-(3-Dimethylaminopropyl)-5H-dibenzo[a,d]cycloheptene hydrochloride

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Reaction Steps

The Grignard solution prepared in Step A. is cooled to room temperature and stirred while a solution of 5.05 g. (0.0221 mole) of 5-chloro-5H-dibenzo[a,d]cycloheptene in 25 ml. of dry tetrahydrofuran is added dropwise, external cooling being applied as required to maintain the temperature close to room temperature. When the addition is complete, the mixture is heated to refluxing for 15 minutes. The bulk of the tetrahydrofuran then is distilled under reduced pressure, keeping the water-bath temperature at 50°-60°C. The syrupy mixture is dissolved in 75 ml. of benzene and water, 15 ml., is added dropwise with stirring. The benzene layer is decanted from the gelatinous precipitate which then is re-extracted with three 20 ml. portions of boiling benzene. The combined benzene extracts are washed with water and extracted with three 15 ml. portions of 3N hydrochloric acid. The acid extract is made basic with sodium hydroxide and the yellow oily base that separates is extracted into hexane. After washing the combined extracts with water, the hexane is evaporated and the product obtained as a yellow oil in a yield of 4.61 g. The base is converted to the hydrochloride by dissolving it in a mixture of 15 ml. of absolute alcohol and 15 ml. of absolute ether and adding 1.8 ml. of a 10.28 N solution of dry hydrogen chloride in absolute alcohol. The solution then is diluted to incipient crystallization by the addition of 25 ml. of absolute ether. The yield of 5-(3-dimethylaminopropyl)-5H-dibenzo[a,d]cycloheptene hydrochloride, m.p. 186°-190°C. is 4.17 g. Recrystallization from mixtures of absolute alcohol and absolute ether gives the product, m.p. 191°-193°C.

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