Davydova, N. A.; Babkov, L. M.; Baran, J.; Kukielski, J. I.; Mel'nik, V. I.; Truchkachev, S. V.
For the first time Raman spectra of benzopinacol crystals, which are a result of photochemical decomposition of benzophenone crystals, have been measured over the range 10-3600 cm -1. A tentative model of benzopinacol molecule has been proposed to calculate Raman active modes. The comparison of the calculated frequencies with those experimentally observed shows good accordance. Thus, the proposed model of benzopinacol molecule apparently is quite adequate to the real structure.
Gao, Fang; Liu, Jian; Peng, Huayong; Hu, Nvdan; Li, Hongru; Zhang, Shengtao
In this article, we presented novel nitro-stilbene derivatives with one or two benzophenone groups as photoinitiators via multi-steps synthesis. The ultraviolet/visible spectroscopy and the emission spectroscopy of the compounds were determined in various solvents. The results showed that the ultraviolet/visible absorption spectroscopy of the derivatives with benzophenone moiety displayed overlap effects of nitro-stilbene and benzophenone parts. In non-polar solvents, the derivatives exhibited strong emission, while they displayed weak emission in modest and strong polar solvents. Dyes-linked benzopheonone groups displayed stronger fluorescence emission than simple chromophore parent molecules. Visible-light photoinitiating effects of the derivatives were investigated extensively. Methyl methacrylate could be photoinitiated efficiently by the derivatives with benzophenone moieties at very low concentration, even at 1 x 10(-5) mol/L. While the photopolymerization efficiency of styrene initiated by the derivatives was lower than that of methyl methacrylate. Our results showed that the dye-linked photoinitators had more efficient photoinitiating than the simple mixture of dye and photoinitator. Furthermore, the derivative with two benzophenone groups displayed more excellent photoiniatiating effects than the derivative with one benzophenone group. Thermodynamics driving for the occurrence of visible-light photoinduced intramolecular electron transfer from chromophore part to benzophenone part was evaluated. Benzopinacol moiety produced in photoreaction was confirmed by nuclear magnetic resonant spectroscopy. Thermal stability of the derivatives was analyzed.
Lead tetraacetate (LTA) in the presence of sulfonic acids was studied in the hope of producing a more potent oxidant than LTA (owing to displacement of the weaker acetic acid by strong sulfonic acids). LTA in the presence of CF/sub 3/SO/sub 3/H (greater than or equal to4 equiv.) will cleave benzopinacol to benzophenone. LTA in the presence of CH/sub 3/SO/sub 3/H will methanesulfonoxylate diethyl malonate, methyl acetoacetate, and ethyl cyanoacetate. In the presence of CH/sub 3/SO/sub 3/H, MeOH, and CHCl/sub 3/, LTA will convert dialkyl and diaryl disulfides to methyl sulfinate esters. In a variation with Pb/sub 3/O/sub 4/, CH/sub 3/SO/sub 3/H, and P/sub 2/O/sub 5/ in ChCl/sub 3/, diethyl malonate was converted to a methanesulfonoxymalonate ester and to the monochloro-and dichloromalonates. Pb/sub 3/O/sub 4/, CH/sub 3/SO/sub 3/H, and P/sub 2/O/sub 5/ in benzene gave phenyl methanoesulfonate. A camphor 1,10-episulfone was prepared by the reaction of D-(+)-10-camphorsulfonyl chloride with Et/sub 3/N and CH/sub 2/N/sub 2/. The episulfone was cleaved at the least-hindered carbon atom using p-thiocresolate to give the corresponding ..beta..-substituted ethanesulfinate salt. Also, thiirane 1,1-dioxide, prepared from SO/sub 2/ and CH/sub 2/N/sub 2/, was cleaved with sodium phenylmethanethiolate and p-thiocresolate, Li/sub 3/SPO/sub 3/, Na/sub 2/S/sub 2/O/sub 3/, and sodium p-toluenethiosulfate to give the corresponding ..beta..-substituted ethanesulfinates.