Method for preparing 2-quinoxalinol

Abstract

The invention discloses a method for preparing 2-quinoxalinol, which comprises the following steps: preparing 2-quinoxalinol-4-oxide by the cyclization of chloro-m-nitroacetoacetanilide serving as a raw material in the presence of a hydroxide; and preparing 2-quinoxalinol by reducing the 2-quinoxalinol-4-oxide with phosphorous acid or trimethyl phosphate serving as a reducer. In the invention, the phosphorous acid or trimethyl phosphate is used as a reducer to reduce 2-quinoxalinol-4-oxide with high selectivity to prepare 2-quinoxalinol, so the byproducts are reduced, and product yield and purity are high; the conditions of the reduction reaction are mild, and the possibility of explosion generated by low-pressure catalytic hydrogenation with hydrogen serving as a reducer is lowered; because the phosphorous acid or trimethyl phosphate commodity serving as the reducer is cheap and readily available, the production cost of the 2-quinoxalinol is reduced; and as the reaction raw materials and the products produced in the reaction process are nontoxic, the method contributes to environmental protection.

Description

Preparation method of 2-quinoxalinol Technical field The invention belongs to the field of compound preparation. In particular, it relates to a preparation method of 2-quinoxalinol. Background technique 2-quinoxalinol compounds, such as 2-hydroxy-6-chloroquinoxaline, are well-known intermediates for the production of medicinal chemicals and agrochemicals. They are generally processed by 2-quinoxalinol-4-oxide. Selective reduction to prepare. US Patent US4620003 discloses a method for reducing 2-quinoxalinol-4-oxide to 2-quinoxalinol compound. This method uses hydrazine as a reducing agent in the presence of Raney nickel catalyst and alkali metal hydroxide, alkaline earth metal hydroxide or ammonium hydroxide, and reacts with 2-quinoxalinol-4-oxide to obtain 2- Quinoxalinol compounds. US Patent No. 4,636,562 discloses a method for preparing 2-chloro-6-haloquinoxaline compounds from the corresponding 4-halo-2-nitroaniline. In this method, hydrogen is used as a reducing agen...

AI Technical Summary

Problems solved by technology

The price of the reducing agent used in the above method is relatively high, and the production cost of the product is large.

Using hydrogen as a reducing agent, an explosion may occur through low-pressure catalytic hydrogenation, which poses a great safety hazard, and there is also the possibility of over-reduction, resulting in a large amount of over-reduction by-products

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