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Vanadium(IV) tetraphenylporphyrin dichloride and chromium(III) tetraphenylporphyrin chloride have been developed as catalysts for the acceptorless dehydrogenation of alcohols. The catalysts have been applied to the direct synthesis of imines in overall good yields from a variety of alcohols and amines. The transformations are proposed to proceed by metal–ligand bifunctional pathways with an outer-sphere transfer of two hydrogen atoms from the alcohol to the metal porphyrin complexes. The results show that vanadium and chromium catalysts can also be employed for the dehydrogenation of alcohols with the release of hydrogen gas, and they may represent valuable alternatives to other catalysts based on Earth-abundant metals.

We report the first example of copper-catalyzed α-alkylation of acetamides with alcohols via a borrowing hydrogen strategy. Catalyzed by the in situ-generated copper particles, acetamides and various substituted benzyl or alkyl alcohols were transformed into functionalized amides in good yields with excellent selectivity. Compared with previous work, this process is simple using commercially available Cu(OAc)2as a precatalyst, without an additional ligand or a metal complex, and easier. Mechanistic studies revealed that aldehyde and α,β-unsaturated amides were the intermediates of this reaction and also disclosed the role of copper in alcohol dehydrogenation and C═C bond hydrogenation.

ABSTRACTLiquid hyperbranched polycarbosilanes (LHBPCSs) with different reactant molar ratios of chloropropene/chloromethyltrichlorosilane were synthesised by Grignard coupling, followed by reduction. Different from traditional thermal cross-linking for LHBPCS, ultraviolet (UV) irradiation cross-linking was used. The molecular weight and hardness of LHBPCS increased with prolonging UV irradiation time. According to Fourier transform infrared result, the –Si–H, –Si–H2and allyl groups were consumed. Possible cross-linking reactions (hydrosilylation, allyl group polymerisation and dehydrocoupling) were discussed. The ceramic yield of LHBPCS showed an increase trend with increasing the UV irradiation time. After 1 h of UV irradiation for LHBPCS-1 (the molar ratio of chloropropene to chloromethyltrichlorosilane was 1:9), 78.0 wt-% ceramic yield was obtained. In addition, LHBPCS with higher allyl group content had fewer pores in it. By heating LHBPCS-1 cross-linked by UV irradiation to 1400°C, a non-porous SiC ceramic was obtained.

Liquid hyperbranched polycarbosilanes (LHBPCSs) with different reactant molar ratios of chloropropene/chloromethyltrichlorosilane were synthesised by Grignard coupling, followed by reduction. Different from traditional thermal cross-linking for LHBPCS, ultraviolet (UV) irradiation cross-linking was used. The molecular weight and hardness of LHBPCS increased with prolonging UV irradiation time. According to Fourier transform infrared result, the –Si–H, –Si–H2and allyl groups were consumed. Possible cross-linking reactions (hydrosilylation, allyl group polymerisation and dehydrocoupling) were discussed. The ceramic yield of LHBPCS showed an increase trend with increasing the UV irradiation time. After 1 h of UV irradiation for LHBPCS-1 (the molar ratio of chloropropene to chloromethyltrichlorosilane was 1:9), 78.0 wt-% ceramic yield was obtained. In addition, LHBPCS with higher allyl group content had fewer pores in it. By heating LHBPCS-1 cross-linked by UV irradiation to 1400°C, a non-porous SiC ceramic was obtained.

We report the first heterogeneous catalytic hydrogenation of N-substituted imides and polyimide to generate primary amines, diols, and lactones. Catalyzed by Ag/TiO2, this reaction proceeded smoothly in high yields and selectivities for N-alkyl and N-aryl phthalimides and N-aryl succinimides, which also had activity for the degradation of waste polyimide plastics. In contrast to the typical Gabriel process, this reaction does not need any toxic reagent, and the byproducts are also very useful. Recycling experiments showed that the catalyst Ag/TiO2could be easily recovered without a decrease in catalytic activity.

The irradiation behavior of materials is the key to evaluate the long-term behavior of waste forms. In this study, 1.5 MeV Xe20+ions with different fluences were utilized to investigate the irradiation effects on microwave sintered neodymium and cerium co-doped simulated radioactive contaminated soil glasses. The Grazing incidence X-ray diffraction (GIXRD) results disclosed the irradiation had no obvious influence on the structure of microwave sintered samples. The main elements were uniform and without enrichment by SEM-EDS analysis. The Vickers hardness values decreased after irradiation, which might be attributed to the non-bridging oxygen. With the leaching tests, it is shown that the 28 days leaching rates of Nd and Ce increased with the increase of irradiation fluence. This work has significant implications for the disposal of radioactive waste.

With the decommissioning of nuclear facilities, an increasing amount of radioactive graphite needs to be treated safely and effectively. In this work, microwave sintering technology was initially applied to treat simulated graphite waste. The effects of microwaves on the phase composition and microstructure of graphite were investigated. Combined with the mass loss results and fitting results of the phase, the mechanism for simulated graphite waste treatment via microwave sintering was obtained. According to the results, there are three stages regarding the effect of microwave sintering on the microstructure of graphite waste. This work reveals the potential application of microwave sintering technology in the treatment of graphite waste and its treatment mechanism.