| abstract |
Cpds. of gen. formula (I): (where R is Cl or Br) are prepd. by reacting a cpd. (II): with elemental bromine in a ratio of 1:1 to 1:2.3 in inert organic solvent, opt. using catalysing initiating agents such as light or dibenzylperoxide at room temp. to max. 100 degrees C to form a cpd. (III): (where R1 is H or Br) and heating (III) opt. in the presence of organic solvent at 100-200 degrees C. Prefd. solvents for the bromination reaction are halogenated hydrocarbons. Solvents for reaction of (III) are halogenated hydrocarbons, or solvents which react with Br themselves such as paraffin oil, tetrahydronaphthaline, xylene, carboxylic acids or -anhydrides, used in equal quantities as (III). (I) are inters. for medicaments, esp. for psychopharmaca and anticonvulsives. The process is simpler than known processes, giving a high yield and purity. Isolation and purification of (III) which has skin-toxicity, is not necessary. |