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

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

1993-08-23

1995-01-10

Ivy, C. Warren

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

546290, 546303, C07D21361

Patent

active

053808622

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.

REFERENCES:
patent: 3244722 (1966-04-01), Johnston
Abramovitch, R. A., The Journal of Chem Soc, Sect B, Physical Organic Chem Part I, pp. 492-496, 1968.
Umeno, M., Chem Abstracts, vol. III, No. 15, 134004y, p. 746, 1989.
E. Spinner, J. Chem Soc, Perkin Trans., pp. 991-995, 1966.
Min-Jen Shiao, Synthetic Comm., 20(19), pp. 2917-2977, 1990.
Kikugawa, K. et al., "Studies on the Vilsmeier Haack Reactions . . . ", J. Org Chem, vol. 37, No. 2, 284-288, 1972.
Fieser, L., Reagents for Organic Synthesis, 286-288, 1967.
Henderson, Organic Chemistry, p. 10, 1970.

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