Abstract: Described is a process for easily preparing an .alpha.-bromo,.omega.-chloroalkane which is high in purity represented by the formula: Br(CH.sub.2).sub.n Cl in which n stands for an integer of 4 to 12. The process comprises reacting in an organic solvent an .alpha.,.omega.-dichloroalkane with an .alpha..omega.-dibromoalkane. As the organic solvent, an aprotic nitrogen-containing or sulfur-containing organic solvent having a dielectric constant at 20.degree. C. of 20 or larger, for example, N,N-dimethylformamide, N,N-dimethylacetamide or N,N-dimethylimidazolidinone is preferred.

Abstract: A process for the preparation of phosphonium salts by the use of chlorides, which is useful in the course of synthesis of olefin compounds by the Wittig reaction, and which comprises reacting a phosphine compound of the general formulaR.sup.1.sub.3 Pwherein R.sup.1 is a phenyl group or a straight-chain alkyl group having 2 to 8 carbon atoms, with a primary or secondary chloride of the general formula ##STR1## wherein R.sup.2 and R.sup.3 are hydrocarbon radicals, in a solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide and N,N-1,3-dimethyl-2-imidazolidinone, and in the presence of an alkali metal salt of the general formula MBr or MI.