Treatment of β-propiolactone with dialkylamino (dimethyl) arsines at 80° in benzene gave dimethylarsenic 3-dialkylaminopropionates, formed by alkyl–oxygen bond fission. The addition reactions of dialkylamino (dimethyl) arsines with 1, 1, 1-trichloro-2, 3-epoxypropane took place with normal fission of the epoxide ring to give 2-dialkylamino-1- trichloromethylethoxy (dimethyl) arsines. Although 1-chloro-2, 3-epoxypropane was less ...