Preparation of Monodeuteriomethyl Bromide

Abstract

THE exchange of deuterium and hydrogen has prevented the attainment of a high degree of isotopic purity in the preparation of compounds of the type CH₂DX, where X is a halogen atom or hydroxyl group. CH₂DOD has been prepared by the action of diazomethane on heavy water. Halford et al. ¹ acidified the D₂O with SO₃. No exact indication of the isotopic purity of the product was obtained². Langseth and Bak³ claimed that about 10 per cent CH₃OH was present in CH₂DOD prepared by the same method due to water unavoidably present in the CH₂N₂. Beersmans and Jungers⁴ repeatedly bubbled gaseous CH₂N₂ through D₂O until reaction was complete. The product was a mixture of all the different isotopic forms. Without acidification the reaction may proceed by a free radical mechanism⁵ leading to exchange. The methyl bromide prepared by esterification with HBr (in which no exchange occurs) contained 51 per cent CH₂DBr and CHD₂Br⁶.