The most commonly used preparation method of acyl chlorine is prepared by reaction of thionyl chloride, phosphorus trichloride, parathion and carboxylic acid.
R-cooh + SOCL₂→R-COCL + so₂+ HCl
3r-cooh + PCL₃→3R-COCL + H₃po₃
R-cooh + PCL5→R-COCL + pocl₃+ HCl One of the general use of thionyl chloride, because the product sulfur dioxide and hydrogen chloride are gas, easy to separate, good purity, high yield. The boiling point of thionyl chloride is only 79°c, and a slightly excessive amount of thionyl chloride can be separated by distillation.
The reaction of preparing acyl chlorine by thionyl chloride can be catalyzed by two methyl formamide.
Acyl chlorine can also be used as a chlorination reagent, and the carboxylic acid is prepared by reaction with carboxylate:
R-cooh + CLCOCOCL→R-COCL + CO + co₂+ HCl The reaction was also catalyzed by two methyl formamide.
Mechanism, the first step is to produce an active amine salt intermediates with two methyl formamide and glyphosate chloride.
The carboxylic acid then reacts with the intermediates, producing acyl chlorine and getting two methyl formamide back.
In addition, acyl chloride can also be appel by carboxylic acid, carbon tetrachloride and triphenylphosphine:
R-cooh + ph₃p + ccl₄→r-cocl + ph₃po + Chcl₃
The reaction of carboxylic acid with cyanuric chloride can also produce acyl chlorine. There are many new technologies in industry, if use chlorine, chlorine acid and two sulfur chloride reaction method, there is directly with sulfur, chlorine and chlorine acid directly reaction, but the latter reaction is intense, temperature is difficult to control, must reduce through chlorine and chilled water heat transfer to ensure the ideal reaction temperature.