Preparation of isomer-free 2,5-dichloro-pyridine

US5380862A · kind A · utility

Assignee

• Rutgerswerke Aktiengesellschaft · DE

Inventors

• Stefan Sendelbach · Neckarsulm, DE
• Wolfgang Weiss · Ottobrunn, DE
• Winfried Orth
• Hans W. Kleffner · Battenberg, DE
• Albrecht Laufer · Hannover, DE

Key dates

• Filing date: Aug 23, 1993
• Grant date: Jan 10, 1995
• Expiry date: Aug 23, 2013

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D213/61
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for the preparation of isomer-free 2,5-dichloropyridine comprising alkoxylating 2-chloro-pyridine or 2-bromo-pyridine in the presence of a base at elevated temperatures, chlorinating with gaseous chlorine the alkoxylated product at ambient temperatures in an aqueous suspension in the presence of an auxiliary base, a small amount of a catalyst and optionally a small amount of an emulsifier, treating the isomer reaction mixture with a Vielsmeyer-Haack reagent, subjecting 2,5- and 2,3-dichloropyridine mixture to water vapor distillation and crystallizing the crystalline product from an alcohol-water mixture.