Process for the preparation of polychloropyrimidines

US5719285A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventor

• Guido Steffan · Odenthal, DE

Key dates

• Filing date: Aug 11, 1995
• Grant date: Feb 17, 1998
• Expiry date: Aug 11, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D239/30
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Polychloropyrimidines, in particular 4,6-dichloropyrimidine and 2,4,6-trichloropyrimidine, are obtained in a particularly advantageous manner from polyhydroxypyrimidines or tautomeric keto compounds thereof and excess phosphorus oxychloride in the presence of a tertiary amine if, in this reaction, PA1 a) 0.75 to 1.5 mol of phosphorus trichloride and 0.7 to 1.4 mol of chlorine per equivalent of hydroxyl groups to be replaced by chlorine are added such that an excess of phosphorus trichloride over chlorine is always present and PA1 b) phosphorus oxychloride and the polychloropyrimidine prepared are distilled off successively over a column under reduced pressure, or steps a) and b) are carried out in the reverse sequence, phosphorus trichloride also being distilled off before the phosphorus oxychloride in the case of b) after a) and phosphorus oxychloride which has formed again after step a) has been carried out being distilled off in the case of a) after b), and PA1 c) a strong base is added to the distillation residue which is then present, and the tertiary amine employed is recovered from this mixture by PA1 d) separating off the upper phase and PA1 e) purifying it by distillation,…