Antibacterial sulphonamide intermediate 2.6-di:chloro:pyrazine prodn. - by chlorination of mono:chloro-pyrazine in di:methyl-formamide in the presence of a high-boiling paraffin hydrocarbon mixt. to eliminating e

摘要

In a new process for the prodn. of 2,6-dichloropyrazine (I) by chlorination of a soln. of monochloropyrazine (II) in dimethylformamide with gaseous chlorine, a mixt. of high-boiling paraffin hydrocarbons is added to the reaction soln. before the chlorination. Pref. paraffin hydrocarbon mixts. are those of b.pt. more than 300 deg.C. The hydrocarbon mixt. is pref. used in an amt. of 0.5-10 g per gramme (II), the amt. of (II) being 1 g per 0.5-10 g dimethylformamide, provided that the amt. of paraffin hydrocarbon mixt. is at least equal to the amt. of dimethylformamide. Reaction temp. is pref. 10-120 deg.C. (I) is useful as an intermediate, e.g. for the antibacterial sulphonamide 2-sulphanilamido-6-chloropyrazine. Addn. of high-boiling paraffin hydrocarbons to the reaction mixt. eliminates the risk of explosion without reducing reaction rate, so that the process is suitable for use on an industrial scale.