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Synthesis of trichloro-acetyl chloride


. 45 grams, the stirring reaction solution was gradually heated to a temperature of 100 ℃, and reaction at this temperature for 2 hours, and then the reaction solution into the distillation flask, atmospheric distillation, collecting the fraction l14 ~ 118 ℃ may trichloro-acetyl chloride 81.7 g, 98.3 content, yield 98.1. On one or the key to improve the yield of TCA chlorine and oil as chloral hydrate, chloral mixture of alcohol units, because of its acetal structure and a base ClC electron effect. To chlorine than the aldehyde oil is difficult to be oxidized; reaction system there are a lot of water,[link widoczny dla zalogowanych], ethanol and hydrogen ions,[link widoczny dla zalogowanych], and the free formation of chloral and prone trichloroacetic acid hydrolysis, esterification and decarboxylation and other side effects: OOcclcHo a 2H. 0 - Hc-c0H +3 Hc】 OOCCICOOH +2 H20 a H0-C-C-_OH +3 HCICC1jCOOH + C2HH-ccbCOOC2H ~ + H20CUc. . + H + cHcl + CO2 'Therefore, the use of appropriate acid catalyst is to increase the yield of the three key oxygen. Through a series of comparative test catalyst, select the composite catalyst A, the main reaction at lower temperatures can still be rapidly and effectively suppressed side reactions, the oxygen concentration of sulfuric acid without the oil can be directly refined into three oxygen acid oxidation, and the yield of 90 or more,[link widoczny dla zalogowanych], while greatly reducing the \Second, improve the yield of trichloro key trichloro acetyl chloride is a very active chloride compounds, prone to hydrolysis and thermal decomposition and other side effects: CCICOC1 + H2O - ・ CC】 3COOH-HCICCIaCOC] blue clzc-c one. - + C】 zcC-cc1zO-C =;. The reaction must be carried out under anhydrous conditions. Since the boiling point of thionyl chloride (79 ℃) lower, and to avoid thermal decomposition side reactions,[link widoczny dla zalogowanych], the reaction to be carried out at a lower temperature (≤ 100 \The reaction conditions can significantly speed up the reaction speed, reaction time in the more limited greatly increase the yield of acylation. In addition, during the reaction, a large number of by-product of hydrogen peroxide and sulfur dioxide gas will take a portion of thionyl chloride, so the amount of thionyl chloride excess to be appropriate to over 10 to 20 is appropriate. As a result of these measures, two-step total yield of the reaction of 90 or more.
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