Über die Isomerenverteilung bei der nichtkatalytischen Chlorierung einiger Mono- und Dimethylnaphthaline

Abstract

The non-catalyzed nuclear chlorination of methylnaphthalenes (MN) proceeds under mild conditions and yields more homogeneous products. It could be shown that the constitution of the reaction products depends on the position of the methyl group, the ratio of mono-/dichloro-/trichloro derivatives mainly on the reaction temperature. In the temperature range from 0°C to 30°C 1-MN yields predominantely 4-Cl-1-MN and a little 2-Cl-1-MN and 2,4-dichloro-1-MN; 2-MN yields predominantely 1-Cl-2-MN and traces of 3-Cl-2-MN and 1,3-dichloro-2-MN. When chlorinating the dimethyl-naphthalenes (DMN), 2,6-DMN gives 1-Cl- and 1,5-dichloro-2,6-DMN and traces of 1,7-di-Cl-2,6-DMN; 2,7-DMN gives 1-Cl-2,7-DMN, 3-Cl-2,7-DMN, 1,6-di-Cl- and 3,6-di-Cl-2,7-DMN. 2,7-DMN gives also 1,3,6-tri-Cl-2,7-DMN. The chlorination of 1,5-DMN leads to 4-Cl- and 2-Cl-1,5-DMN and three isomeric di-Cl-derivatives, two of which could be identified as 4,8-di-Cl- and 2,4-di-Cl-1,5-DMN. 2,3-DMN yields only 1-Cl-2,3-DMN and 1,4-di-Cl-2,3-DMN.