Study On Acly Chlorination In Microreactor

Acyl chloride compounds are widely used in pesticides,medicine and other fields,and it is very important to improve the process and efficiency of various acyl chloride reactions in industrial production.The chlorinating reagents commonly used in the traditional acyl chloride reaction are thionyl chloride,phosphorus pentachloride,phosphorus trichloride,phosgene,etc.However,in traditional industrial production,the above methods have disadvantages such as difficulty in separating solvent and product,large amount of chlorinating reagent,high production cost,serious equipment corrosion,potential danger in use,transportation and storage.In this study,solid phosgene（BTC）was used as the acid chloride reagent to synthesize p-toluoyl chloride（C₈H₇Cl O）and n-octanoyl chloride(C₈H₁₅Cl O)in a continuous flow process in a microreactor with an inner diameter of 1.7 mm and a liquid holding capacity of 80 ml.,and the traditional process was optimized and improve.Firstly,the effects of different parameters such as catalyst DMF dosage,catalyst type,residence time,reaction temperature,M-ratio between R-COOH and solid phosgene on the yields of target products C₈H₇Cl O and C₈H₁₅Cl O were analyzed by single factor experiments in a microreactor and through the comparative experiment with the batch reaction,it is found that the rate of the acyl chloride reaction in the microreactor is increased by about 6 times.Then,the degree of significant influence of different parameters on the yield of target product was further determined by orthogonal experiments and response surface analysis and the optimal synthesis conditions of C₈H₇Cl O and C₈H₁₅Cl O under continuous flow conditions:when the temperature is 52℃,the amount of DMF is 1.37 ml（100 ml solvent THF）,the residence time is 16 min,and the M-ratio is 1:0.4,the yield of C₈H₇Cl O can reach92.28%;When the temperature is 60℃,the amount of DMF is 1.45 ml（100 ml THF）,the residence time is 14 min,and the M-ratio is 1:0.43,the yield of C₈H₁₅Cl O can reach 97.58%.A kinetic model for the synthesis of C₈H₇Cl O in a microreactor was established on the basis of the predicted DMF-catalyzed mechanism of the acyl chloride reaction involving solid phosgene.The activation energy of the n-octanoic acid in the acyl chlorination reaction in the microreactor was 19.945（±1.826）k J·mol^-1,and the pre-exponential factor was 6402.The distribution cloud map of temperature,pressure and C₈H₁₅Cl O mass fraction inside the microchannel was investigated by combining kinetics and computational fluid dynamics（CFD）and the simulation results are verified by experimental data.It is considered that the model provides a reliable platform for the design and optimization of continuous flow process for acyl chloride reaction.