synthesis method of chromium 2-picolinate_industrial additives

background technology of synthesis method of chromium 2-picolinate

the synthesis process route of chromium 2-picolinate in the prior art:

1. patent cn1408708a uses 2-vinylpyridine as raw material and uses potassium permanganate oxidation method to synthesize 2-pyridinecarboxylic acid and then complex it with chromium trichloride. the 2-picolinic acid obtained by this method has low purity and requires multiple crystallizations to obtain qualified 2-picolinic acid. moreover, this process also produces a large amount of by-product manganese dioxide that needs to be treated. potassium permanganate is also more expensive.

2. patent cn1772737a uses 2-methylpyridine as raw material, oxidizes it with sulfuric acid to 2-picolinic acid, and then complexes it with chromium trichloride to obtain the product. since this process uses sulfuric acid for oxidation, a large amount of waste acid is produced, which brings great difficulties to environmental protection treatment.

3. use 2-methylpyridine as raw material, oxidize it with potassium permanganate to obtain 2-pyridinedimethoxypyridinecarboxylic acid, and then perform complexation to obtain the product. this process also produces a large amount of manganese dioxide as a by-product that needs to be disposed of. potassium permanganate is also more expensive. the single-pass yield of the product is also low and there are many side reactions.

synthesis method of chromium 2-picolinate contents of the invention

the object of the present invention is to provide a synthesis method of chromium 2-picolinate with simple synthetic route, safe and reliable process, strong operability and high reaction yield.

the technical solution of the present invention is:

a synthesis method of chromium 2-picolinate, which is characterized by: first hydrolyzing 2-cyanopyridine to obtain a sodium salt solution of 2-picolinic acid, and then adding chromium trichloride solution for complexation to obtain 2-picolinic acid chromium products.

the synthesis method of chromium 2-picolinate includes the following steps:

(1) synthesis of aqueous solution of 2-pyridinecarboxylic acid: add 2-cyanopyridine and deionized water into the flask in a ratio of 1:2, and start stirring.

raise the temperature to 50~70°c, add 2-cyanopyridine:30% sodium hydroxide with a molar ratio of 1:1.0-1.5 to the flask. after the addition is completed, continue to heat up at 60 ~80°c insulation reaction for 6~10 hours, then, cool to 30~50°c, add 30% hydrochloric acid, adjust the ph value of the reaction solution at 3.5~5.5, and wait until the temperature of the reaction solution drops to 45~50°c. use;

(2) complexation reaction:

add the prepared 20% chromium trichloride aqueous solution dropwise into the above flask. the dripping amount is 2-cyanopyridine: chromium trichloride molar ratio is 1: 1.02-1.22. after the addition is completed, stir the complexation reaction for 1 hour, then cool to 20°c, discharge and drain, the filter cake is washed 4 times with 2-cyanopyridine: an ion-free water mass ratio of 5-10 of ion-free water, and then pumped consider and dry to obtain chromium 2-picolinate. reaction equation:

compared with the traditional method of oxidatively synthesizing chromium 2-picolinate using 2-methylpyridine as raw material, the present invention has a simple synthesis route, safe and reliable process, strong operability, high reaction yield and good product quality. .

the present invention will be further described below in conjunction with examples.

synthesis method of chromium 2-picolinate synthesis method

(1) synthesis of aqueous solution of 2-pyridinecarboxylic acid:

in a 200ml three-necked flask, add 40g of deionized water, then add 20g of 2-cyanopyridine, start stirring, raise the temperature to 70°c, and add 26g of 30°c sodium hydroxide into the flask. after the addition, continue to raise the temperature and keep the reaction at 70°c for 6 hours. then, cool to 30°c, add 30% hydrochloric acid, adjust the ph value of the reaction solution to 5.5, and maintain the temperature of the reaction solution at 50°c for later use. ;

(2) complexation reaction formylbenzeneboronic acid:

add the prepared 20% chromium trichloride aqueous solution dropwise into the above 200ml three-necked flask. the dropwise amount is 51.8g. after the addition, stir the complexation reaction for 1 hour, and then cool to 20 °c. , discharge and drain, the filter cake is washed 4 times with 100g of ion-free water, and then filtered and dried to obtain about 26.53g of chromium 2-picolinate, with a yield of 99.0%. the quality index exceeds the national standard, and the content is greater than 99. 5%.