Hydrogenation Of Carbon-carbon Double Bonds Research Articles

Recombinant expression and characterisation of the oxygen-sensitive 2-enoate reductase from Clostridium sporogenes.

‘Ene’-reductases have attracted significant attention for the preparation of chemical intermediates and biologically active products. To date, research has been focussed primarily on Old Yellow Enzyme-like proteins, due to their ease of handling, whereas 2-enoate reductases from clostridia have received much less attention, because of their oxygen sensitivity and a lack of suitable expression systems. A hypothetical 2-enoate reductase gene, fldZ, was identified in Clostridium sporogenes DSM 795. The encoded protein shares a high degree of homology to clostridial FMN- and FAD-dependent 2-enoate reductases, including the cinnamic acid reductase proposed to be involved in amino acid metabolism in proteolytic clostridia. The gene was cloned and overexpressed in Escherichia coli. Successful expression depended on the use of strictly anaerobic conditions for both growth and enzyme preparation, since FldZ was oxygen-sensitive. The enzyme reduced aromatic enoates, such as cinnamic acid or p-coumaric acid, but not short chain unsaturated aliphatic acids. The β,β-disubstituted nitroalkene, (E)-1-nitro-2-phenylpropene, was reduced to enantiopure (R)-1-nitro-2-phenylpropane with a yield of 90 %. By contrast, the α,β-disubstituted nitroalkene, (E)-2-nitro-1-phenylpropene, was reduced with a moderate yield of 56 % and poor enantioselectivity (16 % ee for (S)-2-nitro-1-phenylpropane). The availability of an expression system for this recombinant clostridial 2-enoate reductase will facilitate future characterisation of this unusual class of ‘ene’-reductases, and expand the biocatalytic toolbox available for enantioselective hydrogenation of carbon-carbon double bonds.

NICKEL CATALYTIC PROPERTIES IN REACTION OF LIQUID-PHASE HYDROGENATION OF CARBON-CARBON DOUBLE BOND

The hydrogenating of carbon-carbon double bond in a molecule of sodium maleate over a partially deactivated catalysts based on nickel in a water solution at atmospheric pressure was investigated. Kinetic regularities of the investigated processes were obtained. It was found that sulfide additives lead to the decrease in an order of the reaction for both skeletal and supported nickel catalysts, however, the correlation of activity versus the amounts of sulfur introduced is complex and independent on the amount of active metal on the catalyst surface. We proposed the method for the synthesis of a supported nickel catalyst resistant to oxidation with atmospheric oxygen and an activity of the one is more than twice better then activity of Raney nickel. The stability of the nickel catalyst (Raney nickel and nickel supported on silica) in the presence of sulfide ions impurities in the reaction system was shown. It was found that the supported nickel catalyst has a much higher resistance to deactivation than the skeletal catalyst. The role of the support at the adsorption of sulfide from solution during deactivation of the investigated catalysts was demonstrated. It was suggested that the higher stability of the supported catalyst for deactivation is due to the sorption of the catalytic poison by silica gel. It is suggested the possibility of adjusting the selectivity of the catalyst deactivation character without changing the nature of the solvent. It was presented the possibility of purposeful variation in a wide range of adsorption properties of the active metal surface relative to the reactants, which makes possible to develop approaches to the synthesis of catalysts with given parameters of activity and selectivity relative to certain classes of organic compounds.Forcitation:Afineevskii A.V., Prozorov D.A., Osadchaya T.Yu., Sukhachev Ya.P., Lukin M.V. Nickel catalytic properties in reaction of liquid-phase hydrogenation of carbon-carbon double bond. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60.N 6. P. 95-101.

Partial Hydrogenation of Sunflower Oil-derived FAMEs Catalyzed by the Efficient and Recyclable Palladium Nanoparticles in Polyethylene Glycol.

One approach to improve the oxidative stability of biodiesel is the partial hydrogenation of carbon-carbon double bonds. In the current work, an efficient catalytic system using Pd(OAc)2 dissolved in polyethylene glycol (PEG) which in situ generates palladium nanoparticles was developed in order to promote a selective partial hydrogenation reaction of sunflower oil FAMEs into mono-hydrogenated products avoiding the formation of saturated compounds or trans-isomers. High content of methyl oleate (85.0±1.4%) was obtained by hydrogenation of sunflower oil biodiesel with only 7.0±0.2% stearic acid. Through evaluating the palladium nanoparticles by TEM analysis, it is observed that 4 nm palladium nanoparticles generated in situ in PEG4000 are highly selective for the partial hydrogenation of sunflower oil biodiesel. And the Pd-PEG4000 catalyst can be resued for five times without obvious loss of activity or methyl oleate selectivity.

Graphene from Alginate Pyrolysis as a Metal‐Free Catalyst for Hydrogenation of Nitro Compounds

Graphene obtained by pyrolysis of alginate at 900 °C under inert atmosphere and exfoliation is used as a metal-free catalyst for reduction of nitro to amino groups with hydrogen as a reagent. The process is general for aromatic and aliphatic, conjugated and isolated nitro groups, and occurs with low selectivity over hydrogenation of carbon-carbon double bonds.

Constructing Tailored Isoprenoid Products by Structure-Guided Modification of Geranylgeranyl Reductase

The archaeal enzyme geranylgeranyl reductase (GGR) catalyzes hydrogenation of carbon-carbon double bonds to produce the saturated alkyl chains of the organism's unusual isoprenoid-derived cell membrane. Enzymatic reduction of isoprenoid double bonds is of considerable interest both to natural products researchers and to synthetic biologists interested in the microbial production of isoprenoid drug or biofuel molecules. Here we present crystal structures of GGR from Sulfolobus acidocaldarius, including the structure of GGR bound to geranylgeranyl pyrophosphate (GGPP). The structures are presented alongside activity data that depict the sequential reduction of GGPP to H6GGPP via the intermediates H2GGPP and H4GGPP. We then modified the enzyme to generate sequence variants that display increased rates of H6GGPP production or are able to halt the extent of reduction at H2GGPP and H4GGPP. Crystal structures of these variants not only reveal the structural bases for their altered activities; they also shed light onto the catalytic mechanism employed.

Facile hydrogenation of carbon-carbon double bonds using catalytic noble nanoparticles immobilized in microfluidic reactors

Abstract Facile hydrogenation of carbon-carbon double bonds was achieved in a poly(dimethylsiloxane) (PDMS) microfluidic reactor with immobilized noble nanoparticles, using the conversion of 6-bromo-1-hexene to 1-bromo-hexane as a model reaction. The microreactor was used to measure the intrinsic catalytic activity and turnover frequencies (TOF) of palladium (Pd), platinum (Pt) and ruthenium (Ru) nanocatalysts. The TOF of reactions run with immobilized nanocatalysts in the microfluidic reactor were hundreds of times larger than those measured in identical reactions in batch reactors. The combination of well-defined nanocatalysts and microfluidics significantly enhances hydrogen diffusion to catalytic sites, thus eliminating mass transfer limitations and enabling evaluation of the intrinsic catalytic activity. The system provides an excellent platform for high throughput screening of catalysts, and for conducting mechanistic studies of reaction kinetics.

Selective Hydrogenation of Alkene in (3-Trifluoromethyl) Phenyldiazirine Photophor with Wilkinson's Catalyst for Photoaffinity Labeling

Selective hydrogenation of carbon-carbon double bond in the presence of nitrogen-nitrogen double bond in (3-trifluoromethyl) phenyldiazirine achieved with Wilkinson's catalyst.

Effect of growth substrate and electron donor on hydrogenation of carbon-carbon double bonds by Acetobacterium woodii

Acetobacterium woodii was grown on fructose, methanol, 3,4,5-trimethoxycinnamate, or 3-(3,4,5-trimethoxyphenyl)-propanoate in the presence or absence of caffeate. The cells were harvested and tested for their ability to hydrogenate CC bonds using caffeate as a model substrate. Except for cells grown on methanol, the growth substrate was a poor electron donor for the biotransformation. 3-(3,4,5-Trimethoxyphenyl)-propanoate was the best donor for fructose-grown cells while fructose was the best donor for cells grown on methoxy-substituted aromatics. Caffeate reductase activity was inducible by caffeate or trimethoxycinnamate. The highest rates of caffeate reduction were obtained using cells which had been grown on 3,4,5-trimethoxycinnamate plus caffeate and by providing fructose as the electron donor.

Efficient mediator-independent hydrogenation of carbon-carbon double bonds, using the obligate anaerobe, Acetobacterium woodii , with fructose as an electron donor

Fructose and H2 were compared as electron donors for hydrogenation of carbon-carbon double bonds using Acetobacterium woodii. Caffeate was used as a model substrate. An electron donor was required and both fructose and H2 were suitable. With fructose as the donor, the Ks for caffeate was 0.5 mM and the Vmax was 678 mmol kgdry weight−1 h−1.␣Fructose oxidation was coupled very efficiently to caffeate reduction by an alteration in the fructose fermentation so that acetate was no longer produced.

A selective reduction of α,β-unsaturated ketones

A selective hydrogenation of carbon-carbon double bond of α,β-unsaturated ketones are obtained when a mixture of limonene, α,β-unsaturated ketone and 10% Pd/C is refluxed with vigorous stirring for 15–45 min. The best results are obtained when a molar ratio limonene:α,β-unsaturated ketone of 3:1 and 4 molar % palladium/ketone are used. The stereoselectivity is similar to the results obtained when H 2 and Pd/C have been used in neutral solvent.

コロイド状の金属ニッケル触媒を用いるスチレン同族体の水素化反応

Colloidal nickel was easily prepared by reaction of nickel bromide with zinc powder. It was an active catalyst for hydrogenation of carbon-carbon double bonds. Styrene homologs were hydrogenated to afford the corresponding alkanes quantitatively in the presence of the colloidal nickel under an atmospheric pressure of hydrogen. A plot of the volume of hydrogen uptake vs. time gave a straight line. The hydrogenation rates of styrene homologs were compared with that of styrene. The steric and electronic factors of substituent on the double bond affected the rate of hydrogenation significantly.

Charge-Transfer Complexes in Kraft Lignin Part 2: Contribution to Color

Abstract Chelation and removal of transition metals from the kraft lignin employed in this study did not reduce the lignin's visible absorbance. Likewise, hydrogenation of carbon-carbon double bonds in this lignin also had no effect on its visible spectrum. This indicated that extended conjugated systems were not a significant contributor to the color of this lignin. Of the structures investigated, quinones were found to be the major visible-light absorbing chromophores. Since a large component of the quinone's absorption results from their participation in charge-transfer complexes (CTC's),1 CTC's were a significant contributor to the color of this lignin.

Selective hydrogenation of carbon-carbon double bonds of chalcones by Corynebacterium equi IFO 3730.

l,3-Diphenyl-2-propen-l-one (chalcone) was selectively hydrogenated at the carbon-carbon double bond on incubation with Corynebacterium equi IFO 3730, to give the corresponding saturated ketone, 1,3-diphenyl-l-propanone. Practically no alcoholic compounds were detected in the reaction mixture. This highly selective hydrogenation reaction was also successful with substrates having substituents on aromatic rings. On the other hand, two hydrogen atoms on the olefinic carbons were essential, because substitution of either one of the hydrogens by a methyl group completely inhibited the reaction.

Formic Acid Reduction. IX. Reactions of 5, 5-Dimethyl-1, 3-cyclohexanedione with TEAF and Their Reaction Routes

On heating 5, 5-dimethyl-1, 3-cyclohexanedione with a reagent, triethyl ammoniumformate, given by 5HCOOH·2N (C2H5) 3, methylation at its 2-position was induced. Thisreaction appears refered to as a methylation of active methylene compound as is previouslyrealized in 5-methylation of barbituric acids. Route of the reaction was revealedand found to involve some characteristic intermediate reduction steps induced by formicacid, that is, hydrogenation of carbon-carbon double bond and reductive fission of carboncarbonsingle bond of intermediate compounds.