Di:chloro-alkane prepn. by selective chlorination of alkane - in sulphuric acid medium using chloro-amine and reducing metal salt

摘要

beta,beta'-dichloroalkanes are selectively prepd. by chlorination of alkanes of formula CnH2n+2 (where n = 5-10) on the two carbon atoms in the alpha-position to the terminal gps., by reaction of the alkanes with protonated amino radicals of formula RR'N+ degree H (where R and R', identical or different, are methyl, ethyl, propyl, isobutyl, t-butyl). The chlorination reaction is achieved by placing the alkane in sulphuric acid medium in the presence of a chloroamine and a reducing salt, then stirring the mixt. vigorously at 5,000-30,000 rpm at -15 to +60 degrees C, for 5-20 mn. The mixt. is then poured onto ice and the dichlorinated deriv. is extracted by a polar solvent. This process uses a much smaller amt. of reducing metal salt than a previous method. It also uses only sulphuric acid, whereas the previous method required acetic or trifluoroacetic acid as co-acid.