Preparation of 4,5-diamino-1-(substituted)-pyrazole and acid addition salts thereof

A technology for acid addition salts and pyrazoles, which is applied in the fields of preparing 4, preparing 5-amino-1-pyrazoles, sulfuric acid addition salts, and azo compounds, can solve problems such as inability to obtain separated products, and achieves safe operation. Effect

Inactive Publication Date: 2008-10-15
EASTMAN CHEM CO
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  • Abstract
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Problems solved by technology

[0012] The generation of large amounts of impurities after hydrogenation limits the recrystallization of the desired product and usually does not give the isolated product

Method used

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  • Preparation of 4,5-diamino-1-(substituted)-pyrazole and acid addition salts thereof
  • Preparation of 4,5-diamino-1-(substituted)-pyrazole and acid addition salts thereof
  • Preparation of 4,5-diamino-1-(substituted)-pyrazole and acid addition salts thereof

Examples

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Embodiment

[0044] The method provided by the present invention is further illustrated by the following examples. All percentages in the examples are % by weight unless otherwise stated.

[0045] 5-Amino-4-carboxy-1-(2’-hydroxyethyl)-pyrazole hydrochloride

[0046] Ethanol (80ml) and 2-hydroxyethylhydrazine (245.04g, 90% analytical grade) were mixed in a stirred round bottom flask. A solution of ethyl (ethoxymethylene)cyanoacetate (470.4 g) in ethanol (300 mL) was added causing the reaction mixture to exotherm to 75-80 °C. The mixture was maintained at 75-80°C for 3 hours and then cooled to room temperature. A 50% aqueous sodium hydroxide solution (282.2 g) was diluted with water (94 mL) and added to the reaction mixture. The resulting mixture was heated to 75-80°C for 3 hours. Water (300 mL) was added and the solution was cooled to 10-15°C. The hydrochloric acid addition salt of 5-amino-4-carboxy-1-(2'-hydroxyethyl)-pyrazole was obtained by precipitation by addition of aqueous hydr...

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Abstract

Disclosed is an improved process for the preparation of 4,5-diamino- 1-(substituted)pyrazoles and acid addition salts thereof by coupling the corresponding 5-amino-1-(substituted)pyrazole with an aromatic diazonium compound to produce an intermediate azo compound and contacting the intermediate azo compound with hydrogen in the presence of a hydrogenation catalyst to produce 4,5-diamino-1-(substituted)pyrazoles. Also disclosed is a decarboxylation process for the preparation of a 5-amino-1-(substituted)pyrazole by heating a solution comprising a 5-amino-4-carboxy-1-(substituted)pyrazole, an inorganic acid and an inert solvent.

Description

field of invention [0001] The present invention relates to an improved process for the preparation of 4,5-diamino-1-(substituted)pyrazoles and their acid addition salts, such as sulfuric acid addition salts. More specifically, the present invention relates to a method for preparing 4,5-diamino-1-(substituted)pyrazoles and acid addition salts thereof, comprising combining corresponding 5-amino-1-(substituted)pyrazoles with aromatic Coupling of the diazo compound yields an azo compound intermediate which is contacted with hydrogen in the presence of a hydrogenation catalyst to yield 4,5-diamino-1-(substituted)pyrazoles. The present invention also relates to the azo compounds prepared as intermediates in the improved process. Another particular embodiment of the present invention relates to a process for the preparation of 5-amino-1-(substituted)pyrazoles, comprising heating the Solutions in solvents of alkanols or mixtures thereof. Background of the invention [0002] 1-Sub...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D231/38
CPCC07D231/38
Inventor K·S·钱伯林C·E·凯利
Owner EASTMAN CHEM CO
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