_3003 Synthesis of glycine

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Studies on the synthesis of glycine

CN as the raw material, the reaction in HCN escape, and thus require high equipment and waste treatment, the other is used in industrial production of chloroacetic amination. The method of equipment and waste treatment requirements low, but low yield (50 ~ 6O), reaction cycle is long (60 ~ 70h), so that the _ production costs, the two methods have advantages and disadvantages. In this study, to improve yield and shorten the response cycle,[link widoczny dla zalogowanych], using a reasonable process to reduce waste for the purpose of amination of chloroacetic acid was greater improvement. Our approach is first made TCA TCA ammonium, and high concentrations of catalyst in the presence of hexamine, possession of controlled reaction pH, ammonium and ammonia dropping TCA, the reaction carried out rapidly and more completely. This method increased the yield of 76 (in total TCA), shorten the cycle just 5h, by-product NHCI recovery,[link widoczny dla zalogowanych], solvent recycling, which essentially no waste (see the reaction and process Ying chart.) Reaction: CICH: COOH + NH3 a CICH2COONH. CICH2COONH. + NH3NH2cHiCOOH + NH. CI process prince Yu: A l TCA TCA + ammonia ammonia ammonium jI {Received 1991-11 the date of receipt of a banner Zl modify a friends-199Z 05-05 �� optional subjects? Yan 1, Taiwan, Zhejiang Agricultural University into Methods: 0.471kg acid (purity> 98%) in the slow stirring of dry 0.42L ammonia solution (concentration> 25%), the heat can be dissolved with water cooling. The acidity of ammonium chloroacetate should pH6.5 ~ 7.5, standby. In the 2L three-neck flask, to 0.175kg urotropine (purity> 99) water soluble 0.125L. Into a paste. Installed between mixer, dropping funnel fitted on both sides, start stirring and heating to an internal temperature of about 6012, maintaining an internal temperature of 65 ~ 70'C. At the same time dropping ammonium chloroacetate solution and ammonia water (concentration> 25) 0.38L,[link widoczny dla zalogowanych], respond immediately. Maintain the reaction solution pH7 ~ 8. The temperature does not exceed 70 After the reaction, pour hot in the intense stirring I. 70L industrial methanol (concentration of 8O), water bath cooling. A large number of white solid precipitates; filtration, in the 9O ~ 100 ~ C and dried 2h, the crude product 0.422kg; its yield was 89.6 (in TCA dollars), a purity of 85.5, the melting point of 180 ; C (decomposition). Leaching down the methanol solution recycling. After the crude product can also be drained, dried and directly without using industrial methanol (concentration of 8O) recrystallization purification. The crude products were dissolved in 0.45L 0.422kg water, heated to boiling to the whole solution, and then stirring I. Methanol 70L (add a little slow, so as not to block too solid precipitation). At this time a large number of fine crystallization. Cooling to 20 Methanol washed with 0.13L I ~ 2 times, pumping out too refined products,[link widoczny dla zalogowanych], and dried 90 ~ i00 �� 2h, was pure white crystalline powder solid 0.354kg. The yield was 75.2 (in TCA dollars), a purity of 99. . Melting point of 230 ~ 2 (decomposition) (literature 232C) decomposition). Methanol solution filtration down to be recycled. Twice distilled methanol recovery can be reused. Distillation recovery 7O ~ 80, after the recovery of the remaining methanol solution was active carbon, concentration, crystallization, ammonium chloride can be obtained. The purity of a glycine by HG3 II10-77 standard method. Taiwan into the conditions of the synthesis of the discussion to explore the conditions better, we studied the reaction medium, catalyst, reaction substrate, reaction pH, reaction temperature on the reaction (Table I), to yield and purity of refined products Evaluation of glycine synthesis conditions Table 1 Comparison Table1C. onditionsforsynthesisofglycJne �� catalyst products for the birds Lotto, @ yield of chlorine boat, I} ��account for the fine product yield. Table 1 shows that water as reaction medium, the amount of 3.8g methenamine or 7.0g, within the temperature controlled at 65 ~ 70 �� substrate with a reaction of ammonium monochloroacetic acid,[link widoczny dla zalogowanych], the reaction solution acidity control in the yield and purity of about pH7 are the highest, while the use of chloroacetic acid as substrate the yield and purity are generally less oxygen ammonium acetate. Reduce the amount of temperature decrease or methenamine not favor the reaction (Table I). High temperature hydrolysis of the glycolic acid to chloroacetic acid. 90 purity ethanol as the reaction medium is better, but the yield is low. We are trying to change other conditions to increase yield without success.