Preparation of 2,4-dichloroquinazoline

Abstract

The invention relates to a method for preparing 2,4-dichloroquinazoline. The method comprises the following steps that: (1) ortho-aminobenzoic acid reacts with potassium cyanate to generate 2,4-quinazoline diones; and (2) the 2,4-quinazoline diones and a chlorinating agent undergo a chlorination reaction to generate the 2,4-dichloroquinazoline. Particularly, in step (1), the mass ratio of the ortho-aminobenzoic acid to the potassium cyanate is 1:1-3, the reaction uses water as a solvent, and is performed at a temperature of between 20 and 100 DEG C with pH of between 9 and 12; and in step (2), the chlorination reaction uses fatty amine as a solvent. The method uses non-toxic solvent and accessible raw materials, has high reaction yield, and is applicable to industrial production.

Description

technical field

[0001] The invention relates to a preparation method of 2,4-dichloroquinazoline. Background technique

[0002] 2,4-Dichloroquinazoline is an important organic intermediate, which is mainly used in the fields of medicine, pesticide, dyestuff and organic synthesis. In recent years, with the application and popularization of downstream products of 2,4-dichloroquinazoline, the demand has increased, and its market prospect is very broad.

[0003] In the prior art, the synthesis of 2,4-dichloroquinazoline mainly contains the following two synthetic routes:

[0004] Route 1: aniline / phenoxycarbonyl isocyanate method, the reaction equation is as follows:

[0005]

[0006] In the US 04 / 02885 patent, the synthetic route is described, and the total yield of the synthetic route is about 58%.

[0007] Route 2: anthranilic acid / potassium cyanate method, the equation is as follows:

[0008]

[0009] Anthranilic acid reacts with potassium cyanate in acetic acid sys...

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