The adsorption of triphenylphosphine, tri(p-tolyl)phosphine, tri(m-tolyl)phosphine, and tri(p-chlorophenyl)phosphine has been studied on SiO2, Al2O3, and a SiO2−Al2O3 cracking catalyst. 31P solid-state NMR shows that all of these molecules are rotationally mobile in the physisorbed state. The interaction of the phosphines with Lewis and Brønsted acid sites on the surface can be observed. For these phosphines the chemical shifts of physisorbed and Lewis-bound species are too close to permit quantitative determination of the concentration of the latter. The concentration of Brønsted sites on SiO2−Al2O3 can, however, be measured. Using triphenylphosphine, we detect 0.18 μmol/m2 Brønsted sites, somewhat less than previously detected with stronger bases, indicating a spectrum of acid strengths on this catalyst. Steric effects appear to reduce the acid detectable with the tolylphosphines, and it is not clear that they are useful in studying the strength of acid sites on this catalyst. We find evidence for a small concentration of basic sites on the SiO2−Al2O3 catalyst.

A “three sections, three periods” mechanism is proposed to discuss the formation and transformation of confined species and its effects on catalyst deactivation and product selectivity.

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A copper and iodine-mediated C-H oxidative sulfenylation of olefins with diaryl disulfides has been developed for the stereospecific synthesis of vinyl thioether. With the combination of Cu(OTf)2 and I2, a variety of terminal alkenes underwent oxidative coupling reaction with various diaryl disulfides successfully to afford the corresponding E-vinyl sulfides in moderate to good yields.

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We have examined the acidic properties of a SiO 2 -on-Al 2 O 3 monolayer catalyst by 31 P NMR of adsorbed tricyclohexylphosphine and triphenylphosphine. These large probe molecules permit the assessment of steric effects, by comparison with trimethylphosphine, and reveal differences in acid strengths of surface sites. We find that there are significant constraints to accessing Lewis sites, but not Brønsted sites. The concentration of strong Brønsted sites is slightly less than half of the total concentration of Brønsted sites.