A mixture containing of 23 g of 1-ethyl-3-hydroxypyrrolidine, 51.2 g of
ethylbenzilate and 1.50 ml of benzene is subjected to azeotropic distillation to
remove traces of water and then 250 mg of metallic sodium added to the
residual solution. The mixture heated under reflux for about 8 hours while
slowly drawing off the benzene-alcohol azeotrope formed. The reaction
mixture is cooled, treated with 1 ml of acetic acid and washed with water. The
benzene is removed by distillation and the residue distilled in vacuo to obtain
the desired 1-ethyl-3-pyrrolidinyl benzilate as a viscous oil; yield 44 g,
68.1%; b.p. 164-170°C at 0.2 mm.
If desired, this same product can be prepared by adding 8 g of 1-ethyl-3-
hydroxypyrrolidine in about 40 ml of dry methylene dichloride to 18.4 g of
diphenylchloroacetyl chloride in about 40 ml of boiling methylene dichloride
and refluxing the mixture for 1 hour. The solvent is evaporated and the
residue heated on a steam bath with 200 ml of water for 5 min and then allowed to stand at room temperature for 2 days. The mixture is treated with
potassium carbonate, extracted with benzene and the benzene distilled from
the extract to obtain crude l-ethyl-3-pyrrolidinyl benzilate. Distillation in vacuo
yields the pure l-ethyl-3-pyrrolidinyl benzilate; yield 8 g (31%); b.p. 197°C at
2 mm.
22 g of 1-ethyl-3-pyrrolidinyl benzilate prepared by either of the above
methods is mixed with 32 g of ethyl bromide in 100 ml of isopropanol and
refluxed for 1 hour to give 23 g of 1,1-diethyl-3-pyrrolidinium bromide
benzilate, m.p.196-197°C.
