GB883482A - A novel acetylenic dihalogen compound and a process for the manufacture thereof - Google Patents

Abstract

Lithium amide is prepared by adding lithium wire to liquid ammonia, using powdered hydrated ferric nitrate and a blast of air to catalyse the initial reaction.ALSO:The invention comprises 1-bromo-9-chloro-nonadiyne-(2,5) and its production by condensing 1-bromo-6-chloro-hexyne-2 in a Grignard reaction with propargyl alcohol or a hydroxyblocked propargyl alcohol, to produce 1-hydroxy-9-chloro-nonadiyne-(2,5) or a hydroxy-blocked derivative, splitting off the blocking group if present, and reacting the hydroxy compound with a brominating agent, e.g. PBr3, HBr or SOBr2. The first step may be effected by reacting propargyl alcohol with somewhat more than twice its molar proportion of a Grignard reagent (the extra mole serving to block the hydroxy group), or by reacting 2-propargyloxy-tetrahydropyran with somewhat more than one molar proportion of a Grignard reagent, in an inert solvent containing sufficient tetrahydrofaran to render the resulting magnesium compound soluble, and reacting this compound with 1-bromo-6-chloro-hexyne-2 in the same solvent in the presence of a cuprous salt. The blocking group, if present, e.g. the tetrahydropyran radical, may be removed by acid-catalysed alcoholysis, e.g. with methanol and p-toluenesulphonic acid. 1-Bromo-6-chloro-hexyne-2 can be obtained by reacting a hydroxy-protected propargyl alcohol, e.g. 2-propargyloxy-tetrahydropyran, with 1-bromo-3-chloro-propane in an argano-lithium reaction to form the hydroxy-protected 1-hydroxy-6-chloro-hexyne-2 the protecting group is split off, e.g. the tetrahydropyran radical by acid-catalysed alcoholysis, e.g. with methanol and p-toluenesulphonic acid, to give 1-hydroxy-6-chloro-hexyne-2, which is brominated, e.g. with PBr3, HBr or SOBr2.