Catalyst for synthesizing 2-cyano pyrazine from 2-methy/pyrazine and synthesizing method

A technology of methylpyrazine and cyanopyrazine is applied in the synthesis field of catalyst and 2-cyanopyrazine, and can solve the problems of difficulty in separation and purification, difficulty in preparing raw material cyanoethylenediamine, high price of pyrazinamide, and the like, Achieve the effect of high conversion rate of raw materials, easy separation, simple and reliable operation

Inactive Publication Date: 2005-02-16
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] Among the above five routes, the raw material cyanoethylenediamine of the first route is difficult to prepare, and its use to prepare 2-cyanopyrazine has only been seen in early reports
The second route raw material pyrazine carboxylic acid is prepared by oxidizing benzopyrazine to 2,3-dicarboxylic acid through decarboxylation, and its separation and purification are difficult (Hall, Spoerri.J.Am.chem.Soc.1940 , 62, 664)
The third synthetic route raw material pyrazinamide is expensive
(5) Sb-V-Mn system Sb, V, Mn supported on α-Al 2 o 3 Above is used as catalyst, although there is only 75% selectivity in the conversion ratio greater than 90%, the total yield is less than 70% (Fomi, LucioAmmoxidation of 2-methylpyrazine over oxide catalysts.Appl.Catal.1986,20(1-2) , 219-30)

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0018] Combined for 1h, filtered, dried, roasted at 500°C for 2h, cooled naturally and stored for later use.

[0019] 40 grams of the catalyst prepared above are loaded into the reactor, the ammonia gas flow rate is 400 ml / min, the air flow rate is 1000 ml / min, the preheater temperature is controlled at 130°C, the reactor temperature is 380°C, and the 2-methylpyrazine The flow rate is 0.1 ml / min. The liquid received in the receiver was extracted with chloroform and adjusted to neutral pH with sulfuric acid. The reaction solution was analyzed by gas chromatography, and the calculated raw material conversion rate was 97.8%, the product selectivity was 89.0%, and the yield was 87.0%. Chloroform was removed by distillation, and the 90°C / 3.6Pa fraction was collected by rectification under reduced pressure. The yield was 65% based on the input of raw material 2-methylpyrazine, and the purity by gas chromatography was 99.1%.

example 2

[0021] Dissolve 10 grams of ammonium molybdate and 21 grams of alum pentoxide in 60 milliliters of distilled water, and slowly add 9 grams of 85% phosphoric acid under stirring. To this solution was added flake α-Al 2 o 3 Carrier 80g, fully mixed for 30 minutes, filtered, dried, calcined at 500°C for 2h, cooled naturally and stored for later use.

[0022]40 grams of the catalyst prepared above are loaded into the reactor, the ammonia flow rate is 200 ml / min, the air flow rate is 1000 ml / min, the preheater temperature is controlled at 230°C, the reactor temperature is 400°C, and the 2-methylpyrazine The flow rate is 0.1 ml / min. The liquid received in the receiver was extracted with chloroform and adjusted to neutral pH with sulfuric acid. Gas chromatographic analysis of the reaction solution showed that the conversion rate of raw materials was 98.1%, the product selectivity was 87.0%, and the yield was 85.3%. Chloroform was removed by distillation, and the 90°C / 3.6Pa fracti...

example 3

[0024] Add 11 grams of ammonium metavanadate, 2 grams of ammonium molybdate and 23 grams of 85% phosphoric acid into 100 milliliters of distilled water, stir and dissolve to form a solution, then add 60 grams of carborundum carrier and mix thoroughly for 1 hour, filter, dry, and roast at 500 ° C for 2 hours, and naturally Store after cooling down.

[0025] 40 grams of the catalyst prepared above are loaded into the reactor, the ammonia flow rate is 150 ml / min, the air flow rate is 1500 ml / min, the preheater temperature is controlled at 200°C, the reactor temperature is 420°C, and the 2-methylpyrazine The flow rate is 0.5 ml / min. The liquid received in the receiver was extracted with chloroform and adjusted to neutral pH with sulfuric acid. The reaction solution was analyzed by gas chromatography, and the calculated raw material conversion rate was 90.8%, the product selectivity was 77.8%, and the yield was 70.7%. Chloroform was removed by distillation, and the 90°C / 3.6Pa fra...

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Abstract

The catalyst is VMoOP system carried catalyst prepared via soaking process. The catalyst features the carrier alumina, silica gel and silicon carbide and active component V / P / Mo in the molecular ratio of 1 to 1-6 to 0.01-1. When the catalyst is used in synthesizing 2-cyanopyrazine and the user amount of catalyst is 40 g, the introduced amount of 2-methylpyrazine 0.05-2 ml / min, that of ammonia is 100-200 ml / min and that of air is 1000-2000 ml / min; the material feeding molar proportion among 2-methylpyrazine, ammonia and air is 1 to 8-20 to 10-90. The present invention has the advantages of high catalyst activity, long service life, no need of activation period, simple synthesis process, high material conversion rate and high product quality.

Description

technical field [0001] The invention relates to a catalyst used for synthesizing 2-cyanopyrazine from 2-methylpyrazine through gas-phase catalytic ammoxidation and a synthesis method of 2-cyanopyrazine. It belongs to the preparation technology of 2-cyanopyrazine. Background technique [0002] 2-cyanopyrazine is an important organic chemical raw material and pharmaceutical intermediate. It is widely used in spices, medicine and other fields. Especially in the pharmaceutical industry, the anti-tuberculosis drug pyrazinamide can be prepared after hydrolysis of 2-cyanopyrazine, which is a new route for the preparation of pyrazinamide proposed abroad in the 1980s. Previously, pyrazinamide was obtained by oxidation of benzopyrazine to pyrazine 2,3-dicarboxylic acid through potassium permanganate, alcoholysis and decarboxylation to obtain ethyl pyrazinecarboxylate, and finally ammonia solution. This method has a long process route and requires huge ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D241/24
Inventor 冯亚青张尚湖
Owner TIANJIN UNIV
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