Ethanol—continued isomers

Geometrical isomerisations involving the azobenzene chromophore continue to attract attention. Low temperature flash photolysis studies of 4-aminoazobenzene and 4-(N,N-dimethylamino)azobenzene in an ethanol glass on the microsecond timescale indicate that for both compounds the photoexcited Z-isomer produces two species. One of these is the JF-isomer the other is a short-lived intermediate, tentatively identified as a zwitterionic species, which decays to form the E-isomer. The donor-acceptor substituted azobenzene sodium 4-(4 -aminophenyl-azo)benzoate has been reported to complete the E- to Z-photoisomerisation... 

Interest continues in conformationally-locked bicyclic nucleosides and their oligomers. A report from Wengel s laboratory describes details of the synthesis of the a-L-LNA (locked nucleic acid) nucleoside 129, in which a key step is the treatment of ditosylate 128 with NaOH in aqueous ethanol to establish the bicycle, a reaction thought to involve a 2,2 -anhydronucleoside as an intermediate. Also reported is the similar conversion of 130 into the a-L-xy/o-LNA nucleoside 131." The effect on RNA binding of the incorporation of these two compounds, and the previously-prepared P-D-xyfo-isomer and LNA nucleoside itself, into oligonucleotides has been studied the behaviour of the other four stereoisomers of LNA, enantiomeric with those synthesized, was also studied... 

In solvent extraction crude vegetable oil and other useful materials are dissolved in a solvent to separate them from the insoluble meal. Many solvents have been evaluated for commereial extraction. Commercial hexane has been the main solvent for the oilseed processing industry since the 1940s because of its availability at reasonable eost and its suitable fiinetional characteristics for oil extraction. However, the interest in alternative solvents to hexane has continued and is motivated by one of a eombination of faetors desire for a nonflammable solvent, more efficient solvent, more energy efficient solvent, less hazardous and environmentally friendly solvent, solvent with improved produet quality, and solvents for niche/specialty markets. Today eommereial isohexane (hexane isomers) is replacing commercial hexane in a few oilseed extraction operations and other solvents (e.g., isopropanol, ethanol, acetone, etc.) are also being used for various extraction processes or have been evaluated for use as extracting solvents. ... 

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