Study On Crystallization Process Of 2-Isopropylthioxanthone

2-isopropylthioxanthone is abbreviated as ITX,which is commonly used as a photoinitiator.Because ITX has a long absorption wave and high light-initiating efficiency,it has become a hot research material.In recent years,the production of such photoinitiators,especially in the subsequent purification section,has problems such as low product purity,uneven particle size distribution,low process yield,and unfriendly process environment.Therefore,this paper systematically studies the ITX crystallization process.Firstly,the solubility of ITX in ethanol,acetonitrile,ethyl formate,n-propanol and isopropanol at different temperatures was determined by gravimetric method.The experimental data were simplified by Apelblat simplified empirical equation,NRTL model and Wilson model.And the fitting result is better.In addition,the thermodynamic properties of ITX in the test solvent were calculated using the NRTL model and experimental solubility data.The metastable zone of ITX in ethanol solvent was determined by direct method.The influence of stirring rate and cooling rate on the metastable zone was investigated.The effect of cooling rate on the width of metastable zone was fitted by Nyvlt equation and Sangwal equation.And the fitting result is better.Secondly,this paper studies the crystal morphology of ITX and explores the effect of solvent on crystal morphology.The single crystal of ITX was obtained by the volatile solvent method.The unit cell parameters of the ITX single crystal were obtained by X-ray single crystal diffraction technique,which indicated that the ITX crystal was monoclinic,the space group was P2₁,and there were two ITX molecules in the unit cell.The BFDH and AE models were used to simulate the crystal habit of ITX under vacuum conditions,and the main crystal plane was selected for modified simulation.The crystal habits of two different solvents were obtained by cooling crystallization experiments.The binding energy of solvent and crystal plane was calculated by Materials Studio 7.0 software,and the habits were corrected.The habits closer to the experimental results were obtained.Finally,in order to solve the problems of low purity,poor stability,uneven particle size distribution,poor fluidity and low process yield of domestic enterprises in ITX production,the ITX crystallization process was systematically studied and optimized,and the crystallization mode and cooling were investigated.The influence of factors such as solvent type,decolorization conditions of activated carbon,seed crystal,stirring rate and cooling rate on product quality and process efficiency in the crystallization process finally determined the ITX optimized crystallization process.The quality indexes of the products obtained by the process are superior to the original processes,and the process yield is high and the environment is friendly.