Laccase-generated quinones in naphthoquinone synthesis via Diels-Alder reaction

The tandem synthesis of naphthoquinones was conducted from the reaction of laccase-generated quinones and acyclic dienes via Diels-Alder reaction. This reaction was carried out under mild condition in aqueous medium and yielded naphthoquinones up to 80%. In addition, the effect of solvent was also investigated and water was shown to be optimal for this reaction.     

Deuterium incorporation in biomass cell wall components by NMR analysis

A commercially available deuterated kale sample was analyzed for deuterium incorporation by ionic liquid solution (2)H and (1)H nuclear magnetic resonance (NMR). This protocol was found to effectively measure the percent deuterium incorporation at 33%, comparable to the 31% value determined by combustion. The solution NMR technique also suggested by a qualitative analysis that deuterium is preferentially incorporated into the carbohydrate components of the kale sample.     

Picosecond time-resolved kinetic studies on the formation of short-lived pseudoisocyanine iodide photoisomers in methanol and ethylene glycol

Upon exciting pseudoisocyanine iodide with 20 ps pulses at wavelengths between 490 and 530 nm within the absorption band, formation of a new transient absorption with a maximum at 545 nm was observed. It is attributed to an unstable photoisomer of pseudoisocyanine iodide. The quantum yield of the photoisomer is 31% in methanol and 6% in ethylene glycol     

Stereoselective Hydrogenation of Olefins Using Rhodium‐Substituted Carbonic Anhydrase—A New Reductase

One useful synthetic reaction missing from nature's toolbox is the direct hydrogenation of substrates using hydrogen. Instead nature uses cofactors like NADH to reduce organic substrates, which adds complexity and cost to these reductions. To create an enzyme that can directly reduce organic substrates with hydrogen, researchers have combined metal hydrogenation catalysts with proteins. One approach is an indirect link where a ligand is linked to a protein and the metal binds to the ligand. Another approach is direct linking of the metal to protein, but nonspecific binding of the metal limits this approach. Herein, we report a direct hydrogenation of olefins catalyzed by rhodium(I) bound to carbonic anhydrase (CA‐[Rh]). We minimized nonspecific binding of rhodium by replacing histidine residues on the protein surface using site‐directed mutagenesis or by chemically modifying the histidine residues. Hydrogenation catalyzed by CA‐[Rh] is slightly slower than for uncomplexed rhodium(I), but the protein environment induces stereoselectivity favoring cis‐ over trans‐stilbene by about 20:1. This enzyme is the first cofactor‐independent reductase that reduces organic molecules using hydrogen. This catalyst is a good starting point to create variants with tailored reactivity and selectivity. This strategy to insert transition metals in the active site of metalloenzymes opens opportunities to a wider range of enzyme‐catalyzed reactions.     

Selective aerobic oxidation of activated alcohols into acids or aldehydes in ionic liquids

Selective aerobic oxidation of activated primary alcohols into acids or aldehydes has been developed in ionic liquids. Under optimal conditions, various alcohols could be selectively converted into their corresponding acids or aldehydes in good to excellent yields. The newly developed catalytic systems could also be recycled and reused for three runs without any significant loss of catalytic activity.     

Generation and control of a powerful electron-beam current in an accelerator based on a secondary-emission source and its application

An electron accelerator in which magnetron guns with secondary-emission cathodes of two types are used as a particle source is described. The electron-beam parameters are investigated in an electron energy range of 20–150 keV at a pulse length of 10–50 μs. Results of target irradiation by an electron beam are represented. The target surface structure is studied by the metallographic method, and the microhardness and strength of zirconium materials are measured. The possibility of beam current control by factors of 2.5–3.5 with various methods is shown.