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Process for preparing 4,6-dichloropyrimidine

A kind of technology of dichloropyrimidine and dihydroxypyrimidine, applied in preparation 4, can solve problems such as producing phosphoric acid by-products

Inactive Publication Date: 2004-09-15
SYNGENTA LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem with these methods is that when used on a large scale, considerable amounts of phosphoric acid by-products are produced which must be disposed of in some way

Method used

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  • Process for preparing 4,6-dichloropyrimidine
  • Process for preparing 4,6-dichloropyrimidine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 4,6-Dihydroxypyrimidine (0.94g) was suspended in dichloromethane, xylidine (1.12g) was added and phosgene (5g) was compressed into the mixture. The resulting mixture was heated at reflux for 24 hours, then cooled and poured into water. High pressure liquid chromatography (HPLC) analysis of the resulting organic layer showed a 4,6-dihydroxypyrimidine:4,6-dichloropyrimidine ratio of 39:58.

Embodiment 2

[0023] 4,6-Dihydroxypyrimidine (20.5 g) was dispersed in dichloromethane (400 ml) with stirring. To the stirred mixture was added xylidine (40.4 g) and the system was sealed (except for the vent tube connected to the scrubber), phosgene (56 g) was introduced from a cylinder and condensed with a cryofinger, and Collected in a constant pressure dropping funnel. Once collected, the phosgene liquid was added to the reaction mixture over 15 minutes. The mixture was heated and stirred at reflux (ca. 29° C.) for 17 hours, then the mixture was cooled to room temperature and excess phosgene was removed by purging with nitrogen.

[0024] With cooling, water (400ml) was slowly added to the stirred reaction mass to maintain the temperature at ambient. The organic layer was separated and the aqueous solution was extracted with dichloromethane (2 x 100ml). The combined extracts were dried over anhydrous sodium sulfate and concentrated by rotary evaporator to give 4,6-dichloropyrimidine a...

Embodiment 3

[0026] 4,6-Dihydroxypyrimidine (2.0 g) was dispersed in acetonitrile (40 ml) with stirring, xylidine (2.1 g) was added thereto, and the mixture was heated to 50°C. To the mixture was added phosgene (14.6 g) (bubbling through the mixture) over a period of 1 hour. The mixture was maintained at 50°C for 4.5 hours, cooled to room temperature, and excess phosgene was removed by purging with nitrogen. Analysis (HPLC) of the resulting reaction mass indicated that it contained 4,6-dichloropyrimidine (81% yield).

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Abstract

A process for preparing 4,6-dichloropyrimidine from 4,6-dihydroxypyrimidine in the presence of a tertiary amine base characterised in that phosgene is added to a mixture of 4,6-dihydroxypyrimidine and a tertiary amine of formula R<1>R<2>R<3> N (wherein R<1>, R<2>, R<3> are, independently C1-10 alkyl, phenyl, a 3-7 membered carbon nitrogen heteroaryl group or phenyl(C1-4)alkyl) in a chlorinated solvent, wherein the molar ratio of 4,6-dihydroxy-pyrimidine:base:phosgene is in the range 1:(0.8 to 2.5):(2.5 to 3.6).

Description

[0001] This application is a divisional application of the invention patent application No. PCT / GB95 / 00676 filed on March 27, 1995. The original application entered the Chinese national phase on October 25, 1996, and obtained the Chinese patent application number 95192763.9. field of invention [0002] The present invention relates to the conversion of 4,6-dihydroxypyrimidine (1) to 4,6-dichloropyrimidine (2) using phosgene in the presence of a suitable base. 4,6-Dichloropyrimidine can be used as a chemical intermediate in the pesticide industry, and it is especially useful in the preparation of ICIA 5504. Background technique [0003] It is known, for example, that phosphoryl chloride can convert 4,6-dihydroxypyrimidine to 4,6-dichloropyrimidine in the presence of xylidine (Journal Chemical Society (1943) 574-5 cited above (1951) 2214). The problem with these methods is that, when used on a large scale, considerable amounts of phosp...

Claims

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Application Information

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IPC IPC(8): C07D239/30
CPCC07D239/30
Inventor M·C·包顿S·M·布朗J·D·琼斯
Owner SYNGENTA LTD
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