Study On Intermediate Of Musk Ketone Catalyzed By Ionic Liquid And Related Solubility

Musk Ketone(MK)is a synthetic nitro-musk fragrance additive,which is widely used in cosmetics and other daily chemical products.However,it has been criticized because of the difficulty in recycling acid catalysts and serious pollution in its synthesis process.This article intends to use the prepared ionic liquid as a catalyst to catalyze the Friedel-Crafts reaction of m-xylene to synthesize musk ketone intermediates I(5-tert-butyl m-xylene,MK-I)and II(4-tert-butyl-2,6)-Dimethyl acetophenone,MK-?);The solubility of musk ketone in binary mixed solvents was studied,and the thermodynamic properties and dissolution behavior of musk ketone solution were discussed,so as to provide technical support for improving the green production process of musk ketone.Preparation and characterization of ionic liquids.Four ionic liquids,[Bmim]Cl-AlCl₃(or FeCl₃),[Et₃NH]Cl-AlCl₃(or FeCl₃)were synthesized by the reaction of 1-butyl-3-methylchloroimidazole([Bmim]Cl)and triethylamine hydrochloride([Et₃NH]Cl)with AlCl₃ and FeCl₃,respectively.Their structures were characterized by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance spectroscopy(¹H NMR,¹³C NMR).The analysis results show that the density of the four ionic liquids is about 1.34 g/m L,the viscosity and surface tension are:aluminum-based ionic liquid<iron-based ionic liquid,and the acid strength is:[Bmim]Cl-AlCl₃>[Et₃NH]Cl-AlCl₃>[Bmim]Cl-FeCl₃>[Et₃NH]Cl-FeCl₃.The synthesis of MK-?by Friedel crafts alkylation of m-xylene catalyzed by ionic liquids showed that the four ionic liquids had high catalytic activity,and the yield of MK-?could reach over 93.7%.Among them,[Bmim]Cl-AlCl₃ was the best with stable yield and could be recycled for seven times.With[Bmim]Cl-AlCl₃ as the catalyst,the synthesis process conditions optimized by Box-Behnken response surface method are:n(m-xylene)/n(chloro-tert-butane)/n(catalyst)=1/1.2/0.1,The reaction temperature is13?,the reaction time is 73 min,and the product yield can reach 95.11%after verification.Ionic liquid catalyzed MK-I Friedel-Crafts acylation reaction to synthesize MK-II process research found that in the presence of 1,2-dichloroethane solvent,[Bmim]Cl-AlCl₃ and[Et₃NH]Cl-AlCl₃ both have relatively high catalytic activity,the yields of MK-II are 90.01%and 96.22%,respectively;while under solvent-free conditions,the product yields are 91.23%and 53.71%,respectively.Therefore,[Bmim]Cl-AlCl₃ with catalytic and solvent functions is selected as the catalyst,and the synthesis process conditions optimized by Box-Behnken response surface method are:n(MK-?)/n(acetyl chloride)/n(catalyst)=1/3.98/1.42,the reaction temperature is 30?,and the reaction time is 3.5 h.It has been verified that the yield of MK-II can reach 92.91%.Determination and correlation of the solubility of musk ketone in binary mixed solvents.Under normal pressure,in the temperature range of 273.15K?313.15K,the solubility of musk ketone in mixed solvents composed of ethyl acetate and methanol,isopropanol,n-hexane and n-heptane in different molar ratios was determined by the equilibrium method.the thermodynamic properties and dissolution behavior of its solution results show that the solubility of musk ketone increased with the increase of temperature and the mole fraction of ethyl acetate;The five thermodynamic models can be used to correlate the solubility data,and the improved Apelblat equation has better correlation;The increase of solubility of musk ketone is related to the interaction of hydrogen bond and dispersion force;The dissolution process is an endothermic process driven by entropy.