A solution of 10.0 g. (0.051 mole) of 3-(2-piperidinoethoxy)pyrrolidine and 10.4 g. (0.07 mole) of 1-(2-chloroethyl)piperidine in 200 ml. dry benzene was stirred with 28 g. (0.2 mole) of potassium carbonate at reflux for 15 hr. After cooling, the reaction mixture was filtered and concentrated. The residual oil was molecularly distilled to give a slightly impure product which when treated with three equivalents of oxalic acid dihydrate gave 9.3 g. of the trioxalate salt, m.p. 155°-162° C. (32% yield). The salt was recrystallized from methanol to give 5.8 g. of white crystalline salt, m.p. 177°-179° C.
