The Thermodynamics of the Formation of Polymethylbenzene-Halogens Charge Transfer Complexes ()

[摘要] Ultraviolet spectrophotometric investigations have been carried out on the system of durene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, C6H2(CH3)4¡¤X2 or C6H2(CH3)4¡¤IX(X denotes halogen atoms). The equilibrium constant were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. The thermodynamic parameters, ¥ÄH, ¥ÄG and ¥ÄS for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the durene complexes at each temperature decrease in the order, ICl > IBr > I2 > Br2. This order may be a measure of their relative acidities toward durene, which is explained in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order; Benzene < Toluene < Xylene < Durene < Mesitylene Thus, analysis of these finding is discussed.

[学科分类] 化学（综合）