Hydrocondensation of CO2: Reaction of CO2(CO)/H2 on CuO/ZnO contact masses

The hydrocondensation of CO₂ and CO with and without added MeOH, HCHO and (CH₃)₂CHOH has been studied on CuO/ZnO contact masses in a static reactor at different pressures and reaction times.

---

CO₂ CO MeOH, HCHO (CH₃)₂CHOH CuO/ZnO .

     

Hydrocondensation of CO on iron-alumina catalysts. Influence of ethylene

The transformations of H₂/C₂H₄ and H₂/C₂H₄/CO mixtures on activated and carbided 10% Fe/Al₂O₃ catalysts have been studied in terms of the role of ethylene in Co hydrocondensation, and specifically its influence on the selectivity to C₃–C₄ hydrocarbons.

---

H₂/C₂H₄ H₂/C₂H₄/CO 10% Fe/Al₂O₃ CO C₃–C₄ .

     

Sigma-Bonded Organochromium Compounds. Hydrogen Transfer Reactions

The preparation and properties of two classes of organochromium compounds and their interconversion have been studied actively in recent years. These are the σ-bonded organochromium compounds in which alkyl, aryl, or aralkyl groups are covalently bonded to chromium (II or III) and the π-arenechromium complexes in which “aromatic” nuclei are covalently bonded to chromium (0 or I). From certain reactions of the σ-bonded organochromium compounds, evidence has accumulated which shows that the chromium atom acts not only as a coordination center, but also as a hub for hydrogen transfer and H/D exchange^[1,2]. σ-Organochromium compounds may act as sources of radicals and carbanions. The present paper deals with the preparation and properties of σ-bonded organochromium compounds; particular attention is given to hydrogen transfer reactions and rearrangements to bis(π-arene)chromium complexes.     

Hydrocondensation of CO2

New bis(diphenylphosphino) methane, (dpm) complexes of palladium have been prepared from PdCl₂dpm, either by borohydride reduction or halide abstraction in the presence of added ligand. The catalytic activities of these and other polynuclear palladium and copper complexes in the CO₂/H₂ reaction have been tested. The result confirm the catalytic formation of alkyl formate and dialkyl formamide, but the juxtaposition of two or more metal centres does not appear to promote the catalytic formation of C₂-compounds (oxalate)     

Hydrogenation of CO on thoria supported group VIII (Pd, Pt, Ir) metal catalysts

Comparative studies of the transformation of CO/H₂ mixtures on Pd supported (MgO, Al₂O₃, ThO₂) catalysts reveal the promoting effect of thoria, particularly towards hydrocarbon products.

---

CO/H₂ Pd MgO, Al₂O₃ ThO₂ ThO₂, .

     

Use of alcohols as sources of hydrogen in the transformation of co-olefin mixtures

A study has been made of the catalytic activities of various ruthenium complexes in the synthesis of ketones from olefin-carbon monoxide mixtures and an alcohol as source of hydrogen: major side products were shown to be the alkyl propionates and ethane. The effects of base, concentration of catalyst (for RuCl₃- and Ru₃(CO)₁₂- based systems), pressure, temperature, CO/olefin ratio and the water content of the alcohol have been examined.     

Synthesis and Structure of Tris (2′-[2-phenyl-1,3-dioxolano])-chromium(III)

Tris(2′-[2-phenyl-1,3-dioxolano])chromium(III) 3 has been synthesised and has been shown to have the cis (or fac) configuration 3a by X-ray analysis: the Cr? C bond length is 2.037 (10) Å.     

The sulfur chemistry of shiitake mushroom

Allium herbs, such as Chinese chive, garlic, and onion, share a common sulfur biochemistry that occurs on cell breakage. Sulfoxide precursors are converted enzymatically to sulfenic acid intermediates and thence to a variety of pungent and in some cases noxious sulfur species that probably act to deter herbivores. Very similar biochemistry has been proposed to occur in shiitake mushrooms. Prior to the present work, our understanding of the sulfur biochemistry of these plants and fungi has been derived largely from conventional analysis procedures. We have used in situ sulfur K-edge X-ray absorption spectroscopy in intact and disrupted allium plants and shiitake mushroom. The expected changes in sulfur forms following cell breakage are indeed observed for the alliums, but no significant changes occur for the fungus. Thus, any changes involving the sulfur-containing compounds of shiitake mushroom following cell breakage occur to a far smaller extent than those involving allium plants, presumably reflecting the need in shiitake for action by multiple enzymes, namely a gamma-glutamyl transpeptidase and a C-S lyase. The shiitake C-S lyase occurs in far lower concentrations than the corresponding enzyme in garlic. Furthermore, cleavage of the flavorant precursor by the shiitake C-S lyase is reported to cease before cleavage of the precursor has been completed, presumably due to a product or suicide inhibition mechanism.