Preparation method of hydroxyl pyridine compound

Abstract

The invention discloses a preparation method of a hydroxyl pyridine compound, which comprises the following steps of: taking hydrochloride or sulfate or nitrate of alkyl guanidine (shown in the formula II) as a reaction raw material; neutralizing with sodium hydroxide or potassium hydroxide; and then, taking toluene or xylene or chlorobenzene as a reaction solvent, and taking methanol or ethanol as a cosolvent for refluxing, dehydrating and dealcoholizing with alpha-alkyl acetoacetic ester (shown in the formula III) to react to obtain the hydroxyl pyridine compound (shown in the formula I). In the invention, by adding the methanol or ethanol as the cosolvent in the hydroxyl pyridine synthesis reaction, the solubility of the alkyl guanidine can be well increased, the decomposition of the reactants (alpha-alkyl acetoacetic ester and alkyl guanidine) is effectively controlled, the formation rate of the target product namely the hydroxyl pyridine compound shown in the general formula (I) is greatly increased, and the yield and content of the hydroxyl pyridine compound product shown in the general formula (I) are obviously improved, wherein the product yield is greater than 94%, and the product content is greater than 97%.

Description

Technical field: The invention relates to a preparation method of hydroxypyrimidine compounds. Background technique: Hydroxypyrimidines are the intermediates of very important bactericides and pesticides, and the general structural formula is as follows (formula I): Formula I: general structural formula of hydroxypyrimidine For example: the compound 2-ethylamino-5-n-butyl-6-methyl-4-hydroxy-pyrimidine (ie R 1 is CH 3 , R 2 is H, R 3 is n-C 4 h 9 , compound) is the key intermediate of the fungicide ethirimol (ethirimol) or ethirimol sulfonate (bupirimate) (GB1,182,584, GB1,400,710, J.R.Finney et al Proc.Br.Insectic.Fungic.Conf. 8th.1975,2,667); compound 2,2-dimethylamino-5-n-butyl-6-methyl-4-hydroxyl-pyrimidine (ie R 1 is CH 3 , R 2 is CH 3 , R 3 is n-C 4 h 9 , compound) is the fungicide dimethirimol (dimethirimol, GB1,182,584); compound 2,2-dimethylamino-5-methyl-6-methyl-4-hydroxy-pyrimidine (ie R 1 , R 2 , R 3 are all CH 3 The compound) is the key int...

AI Technical Summary

Problems solved by technology

The main reason that causes yield is not high is because the solubility of alkylguanidine (formula II) in organic solvent toluene, xylene or chlorobenzene is not large, causes it to react with α-alkyl acetoacetate alkyl ester (formula III) Speed ​​is very slow, and α-methyl acetoacetate alkyl ester (formula III) easily decomposes under alkaline conditions: