Molecular addition compounds :|bI. Systems of p-dioxane with alkyl halides, anisole, and silicon tetrachloride ; II. Titanium tetrachloride chargetransfer complexes of benzene, p-xylene, and pseudocumene


Freezing-point diagrams were detennined tor a number or p-dioxane systems. The system, p-dioxane:carbon tetrachloride, was found to contain a 1:2 complex with a congruent melting point of 255.71 °K. This confirmed work reported in the literature. Solid solutions in the region between 0.0000 and 0.4796 mole fraction of p-dioxane were found in the present study. The system, p-dioxane:chloroform, was found to contain a 1:2 complex with a congruent melting point of 215.65 °K. It was determined that no other complexes formed in the solid state. This information resolved contradicting reports in the literature. The system, p-dioxane:dichloromethane, was found to contain a 1:2 complex with an incongruent melting point of 205.62 °K. The system, p-dioxane:anisole, was found to contain a 1:1 complex with an incongruent melting point or 248.18 °K. In each of the above systems a solid transition in p-dioxane was observed at 272.80 °K. The systems, p-dioxane:isopropylchloride and p-dioxane:trichlcrobromo-methane were found to contain a complex although the complete freezing-point diagrams were not determined. The system, p-dioxane:silicon tetrabromide, was found to contain no complex. A 4:1 complex with an incongruent melting point which was reported in the literature was found to have been mistakenly assigned to the solid transition of p-dioxane. Systems of p-dioxane with trichlorofluoromethane and silicon tetrachloride were shown to contain no 1:2, 1:1, or 2:1 complexes although the freezing-point diagrams were not detemined. Freezing-point diagrams for titanium tetrachloride systems of benzene, p-xylene, and pseudocumene were detemined. Complexes were shown to be absent from all three systems in the solid state. These data show that previously reported data which indicated a 1:3 complex in the titanium tetrachloride:benzene system are in error. The presence or charge-transfer spectra in solutions or titanium tetrachloride with benzene, or p-xylene, or pseudocumene confirms the presence of charge-transfer complexes in these systems. The complex absorption spectrum has been determined for the system of benzene and of p-xylene. It has been shown that the benzene system contains only a 1:1 complex with a formation constant or 0.042 ± 0.005 liter mole^-1 at 25° C. The extinction coefficients of the complex at 330mμ and 340mμ are 7678 liter mole^-1 cm^-1 and 6568 liter mole^-1 cm^-1 respectively at 25° C. Evidence suggests that the p-xylene system contains both a 1:1 and a 1:2 charge-transfer complex. The p-xylene and the pseudocumene systems both appear to undergo a slow irreversible reaction. The following extinction coefficients (liters mole^-1 on^-1 ) of titanium tetrachloride in n-heptane at 25° C were determined: 160.00 at 330mμ, 35.90 at 340 mμ, 8.00 at 3.50 mμ, 1.27 at 3.60 mμ and 0.00 above 360 mμ.



College and Department

Chemistry and Biochemistry



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Chemistry, Organic



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