Constants of Alcohols in the Infrared observed from thiophene adsorbed on silica gel is in marked contrast to the result for adsorbed benzene and its methyl derivatives where both monomeric and dimeric cation radicals are produced by y irradiation.13The triplet with substructures is tentatively assigned to the 3-thienyl radical formed by H atom loss from C3. The 3-thienyl radical, by analogy with the phenyl radical,14 would give a complex spectrum with principal triplet splitting of ca. 17 G. Alternative assignment to the 2thienyl radical is not possible since the radical would exhibit a primary splitting of the doublet instead of the triplet observed.The doublet of triplets (Figure 3b) produced at the expense of the triplet with substructures resembles signal B in thiophene crystals except for the splitting value of the doublet, 20 G vs. 32 G for signal B. Since the hyperfine splitting values of 20 and 12.8 G are characteristic of the ß proton and. a proton, respectively, in the allyl radical, the doublet of triplets is ascribed to an allyl-type radical containing two a protons and one ß proton. A possible structure for such a radical is either radical II or III, the latter being more likely since the doublet of triplets appears concomitantly with decay of the triplet spectrum tentatively assigned to the 3-thienyl radical. Although the difference in the doublet splitting value between the doublet of triplets in the crystalline and adsorbed states is not understood at present, it may arise from the different conformation of the radical responsible in both matrices.
K in the pulse reactor and its activity was measured at 403 K under standardized conditions. Only 2% of the cyclopropane pulses were converted to propylene. Isobutyl alcohol was then adsorbed in a way that the irreversibly adsorbed amount corresponding to the temperature of 403 K (40% coverage) was attained. The conversion, measured under the same conditions as before, was then found to be 20%. One must therefore conclude that the chemisorption of the alcohol provides protons due to the strong polarization or activates intrinsically present protons, so that they become able to catalyze hydrocarbon reactions. This phenomenon may probably be important for catalytic transformations of alcohols.Two subsequent papers46,46 will deal with pulsed nuclear magnetic resonance, conductivity, and dielectric loss measurements of the isobutyl alcohol/??-Al203 system. Results from these studies will give a detailed insight into the dynamic behavior of this adsorption system.
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