Amino Acid Feed Additive – Glycine Synthesis Process

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[Alias] glycine; amino acetic acid; amino acetic acid [chemical name] amino acetic acid; amino acetic acid [English name] glycine [molecular formula] C2H5NO2 [structural formula] H2N-CH2-COOH [CAS number] 56-40-6 [traits] For white single-lacular or hexagonal crystal or white crystalline powder, glycine is a polar amino acid that does not charge, odorless, and has a special sweet taste. Soluble in water, insoluble in ethanol and ether. Melting point 232 ~ 236 ¡ã C (decomposition). The relative density is 1.1607, and the hydrochloric acid can be formed with hydrochloric acid. [Method] The method of chemically synthetic glycine mainly has three kinds of chloroacetic acid ammonia, Sterrekfa and Hydance. At prnt, there is still use of chloroacetic acid ammonia solutions that have been eliminated abroad in China, and foreign countries use improved Strakerfa and Haicin Technology route. Due to the difference in raw materials and processes, the ammonia solution of chloroacetic acid has the characteristics of high production cost, and the quality of product quality. Most of the glycine produced is industrial grade, the purity is generally 95%, which seriously constitutes downstream applications, and most foreign manufacturers. Glycine by acrylonitrile by-product hydrocyanic acid and hydroxyacetonitrile, the method is low, and the product quality is good, and general purity can reach more than 99%. 1. Aminoethonate of chloroacetic acid is based on chloroacetic acid as a raw material, reacts with ammonia in the prnce of catalyst Urotrine. The reaction temperature was 50 to 60 ¡ã C, atmospheric pressure, after the reaction was carried out in ethanol solution, the reaction time was 14 to 15 hours. It is a traditional glycine synthetic process, simple process, not high, environmental pollution pressure is small; but there are many shortcomings, one is to separate by-products such as ammonium chloride, leading to poor product quality, can not meet the pharmaceutical and food industry The need, if the refiltrative cost is high; the second is that the Urotrotine as a catalyst cannot be recovered, causing a lot of resources; the third is long, and it is not easy to operate. At prnt, this method is the main industrialization method in my country. In order to overcome the shortcomings, improve the quality and yield of glycine, do tic and foreign chemical workers have conducted in-depth rarch on this method of synthesis technology, and the hotspots of the study focused on the choice and use of new catalysts. In addition, a large number of work is also made in the intensive process control, optimization reaction conditions. CLCH2COH + 2NH3 ¡ú H2NCH2COOH + N4CL 2. Streck method The traditional Streck method is reactive with acetal aldehyde, sodium cyanide, sodium chloride, adding acetic acid, precipitated to obtain methylethoacetitrile, and add methylene acetonitrile Ethanol decomposition was added to the prnce of sulfuric acid to give amino acetonitrile sulfate, and the sulfate was decomposed with hydratrium hydroxide to give a glycinate salt, then sulfuric acid precipitated, filtered, filtrate, cooled to give glycine crystallization. The method is easy to refine, the product quality is good, but the use of highly toxic chemical raw materials, the operating conditions are high, the desalination operation is complex after the reaction, the process route is long, currently many foreign companies have a tedSterreckfa, but most is a technical route for improvement. 3 Direct HYDANTION Process The development of the Hydance process originated from alternatives to hydrocyanic acids to eliminate geographically limitations of glycine production. Hydrogefonitrile is a addition product of hydrocyanic acid and formaldehyde, which is 183 ¡ã C which is easily decomposed to hydrocyanoate and formaldehyde at high temperatures. Therefore, from the production and chemical perspective, glycine is produced by hydroxyacetonitrile to produce glycine, which does not only solve the defects of hydrocyanate, and maintain the advantage of improving the STRECKER process. The process is currently the most concerned technology in foreign countries. One of the routes.

[NEXTPAGE] 4 Improved STRECKER and HYDANTION processes in order to increase the quality of glycine, reduce Production costs and reduced environmental pollution, developed STRECKER processes in replacing sodium cyanide or hydrocherine acid, reaction with hydrocherine acid, formaldehyde, ammonia and carbon dioxide, reaction liquid in e reactor . Glycine is precipitated at low temperatures, and the mother liquor circulates, by changing the concentration of the by-products in the reaction system, the balance is moved to the target product direction, thereby achieving the purpose of improving the reaction rate. Although the process has many advantages such as short flow, high yield and no pollution, but due to the volatility of hydrocyanic acid, the device can only be transported long distance transport, the device can only be placed near the raw material device, glycine Development of production. 5 Biological Process Biological Method Preparation is currently in the technical development stage, and some Japan companies are active in this field and apply for many pate. It uses glyaminozoitrile as a raw material, under the action of microbicase, the glycinelonitrile solution is hydrolyzed, which is converted into glycine, and the system contains at least one organic matter inhibiting the microbicase when the system is generated when the ammonia is produced. 6 Glycine refined by chloroacetic acid ammonia solution between 90% and 95%, the impurity content is 4% to 10%, with a deeper color, such as not refined treatment, can not meet food and Medical grade glycine requireme. Currently, the method of purifying glycine in industrial is to recrystallize using activated carbon suction. First, the crude glycine is dissolved in hot water, and the powder-like activated carbon suction is added, and then the activated carbon suction is added, and then heat it, when the activated carbon is separated, when the concentrated volume is one-half of the original volume, cool to room temperature, then add 3 to 4 ti Volume ethanol or methanol causes glycine junction, in order to achieve the required quality indicator, this refining needs to be repeated 2 to 3 ti . Usually the purified yield is 60% to 70%, consu a large amount of ethanol and activated carbon, and the production cost is higher. To this end, there is a literature report a modified crude glycine refining process with strong alkaline anionic resin and weak alkaline anion as an adsorbent, simplifying the refining process, and improves the purified yield.[Process] Taking chloroacetic acid ammonia solution as an example.

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