Synthesis method of chromium 2-pyridylformate

Abstract

The invention discloses a synthesis method of chromium 2-pyridylformate, which comprises the following steps: by using 2-methylpyridine, potassium permanganate and chromium chloride alcoholic solution as raw materials, adding a phase-transfer catalyst to synthesize the chromium 2-pyridylformate, wherein the phase-transfer catalyst is a quaternary ammonium salt or quaternary phosphonium salt in onium salt phase-transfer catalysts, preferably ammonium tetrabutylbromide, ammonium tetrabutylchloride or phosphonium methyltriphenylbromide. The method disclosed by the invention uses the phase-transfer catalyst to enable the sufficient reaction of 2-methylpyridine in an inorganic reaction environment, thereby enhancing the reaction yield (up to higher than 71%); the methanol or ethanol is used as the solvent to enhance the yield of the reaction step; and the solvent is recyclable, thereby saving the raw material cost, promoting the effective performance of the complex reaction, enabling the product to precipitate sufficiently, enhancing the maximum product yield by nearly 40%, and ensuring the yield and quality of the product.

Description

technical field [0001] The invention relates to a method for synthesizing chromium 2-picolinate. Background technique [0002] Chromium 2-picolinate, also known as chromium 2-pyridinecarboxylate, its English name is chromium picolinate, its structural formula is as follows: [0003] [0004] Molecular formula is C 18 h 12 N 3 o 6 Cr, is purple-red crystalline fine powder, stable at room temperature, slightly soluble in water, insoluble in ethanol, of which chromium is trivalent chromium. [0005] In the periodic table of elements, chromium belongs to the VIB group of the first transition system. It is a silver-white metal with an atomic weight of 51.996 and an atomic number of 24. It is hard and brittle. Its more common oxidation state is 0, + 2, + 3 and + 6. With the increase of the valence state, the oxidation property is enhanced. Divalent chromium is unstable in the air and can be oxidized to trivalent chromium. Hexavalent chromium is mainly combined with oxyg...

AI Technical Summary

Problems solved by technology

Chinese Patent Publication No. CN1408708A, published on April 9, 2003, the invention created the name "Feed Additive Chromium 2-Pyridinecarboxylate Synthesis Process", which uses 2-vinylpyridine as raw material to synthesize 2-pyridine by oxidation of potassium permanganate Formic acid is complexed with chromium trichloride to obtain chromium 2-picolinate. The 2-picolinic acid obtained by oxidation of this method needs to be recrystallized many times, which leads to low yield of reaction and poor quality of the final product obtained.

[0009] Chinese Patent Publication No. CN1772737A, date of publication: May 17, 2006, invention name "a kind of synthesis method of chromium 2-picolinate", discloses 2-picoline as raw material, chromic anhydride, sodium dichromate Synthesize 2-picolinic acid with concentrated sulfuric acid as an oxidant, and then complex with trivalent inorganic chromium to obtain chromium 2-picolinic acid. The chromic anhydride and sodium dichromate used in this method are strong oxidants with high toxicity and strong carcinogenicity. Moreover, the participation of concentrated sulfuric acid in the reaction makes the reaction difficult to control and cannot be scaled up industrially, and the large amount of waste liquid produced is also difficult to handle, causing great harm to the environment.

[0010] Chinese Patent Publication No. CN101602716A, date of publication December 16, 2009, invention name "synthesis method of chromium 2-picolinate", discloses a method for synthesizing chromium 2-picolinate with 2-cyanopyridine as raw material, In this invention, 2-cyanopyridine is hydrolyzed with alkali, then neutralized with acid to form 2-picolinic acid, and then complexed with trivalent inorganic chromium to obtain chromium 2-picolinic acid. The synthesis route is simple, but the hydrolysis time is long and the energy consumption is high. , although the yield of the reaction complexation reaction is high, the overall reaction yield is low, and 2-cyanopyridine is expensive, so it is not suitable for large-scale production

[0011] Chinese Patent Publication No. CN101318929A, date of publication December 10, 2008, invention name "synthesis process of chromium pyridine carboxylate", discloses that 2-cyanopyridine is used as raw material, and trivalent inorganic Chromium reaction to obtain chromium 2-picolinate, the method is simple, but the reaction time is long, and it needs to be carried out in a high-pressure reactor, there is a certain danger in the reaction, and the energy consumption is relatively high, which is not conducive to large-scale production

"Continuous Synthesis of Chromium 2-Pyridinecarboxylate" (Chu Wenyi et al., "Chemical Engineer", Issue 01, 2004) discloses the use of picoline and chromium chloride hexahydrate as raw materials and potassium permanganate as raw materials. Oxidant, added in 5 batches, the ratio of 2-picoline to potassium permanganate is 1:2.5, the volume ratio of 2-picoline to water is 1:22, the oxidation temperature is 80-82 ° C, 2-methylpyridine The molar ratio of pyridine to chromium chloride hexahydrate is 1:3.5, the complexation temperature is 40-45°C, and water is used as solvent for the complexation, and the yield is 82.7%. Although the yield of this method is high, the chromium trichloride The consumption is greater than the theoretical amount, so unreacted inorganic trivalent chromium will remain in the mother liquor to bring difficulties to environmental protection, and the chromium 2-picolinate that this method obtains is of low quality, and needs to be purified to reach the standard

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