Sulphobenzoic anhydride → 4-(2-Acetyl-9-thioxanthenylidene)-1-methyl-piperidine

Participants

Reaction Steps

140 grams of the ethylene glycal ketal of 2-acetyl-9-(1-methyl-4-piperidyl)-9-thioxanthenol (MP 206-208 degrees Centigrade) were heated for two hours under reflux with a mixture of 1500 milliliters of propionic acid and 100 grams of 2-sulfobenzoic acid anhydride. Thereafter the mixture was evaporated in vacuum, the residue dissolved in water and made alkaline. The base which separated out was extracted with ether, the ether phase dried over anhydrous potassium carbonate and evaporated until beginning crystallization. The crystals were sucked off and dried. --50 grams of 4-(2-acetyl-9-thioxanthenylidene)-1-methyl-piperidine were obtained melting at 125-127 degrees Centigrade.

Provenance & Evidence