Characterization and synthesis of mono- and diphytanyl ethers of glycerol

The methanolyzed lipids of the extreme halophile, Halobacterium cutirubrum, were separated into glycerol diether and glycerol monoether fractions. The diether was shown by synthesis to be 2,3-di-O-(3'R,7'R,11'R,15'-tetramethylhexadecyl)-sn-glycerol. The monoether fraction was separated by thin-layer chromatography on boric acid-impregnated silicic acid into about equal amounts of alpha- and -isomers. The alpha-isomer was found to be identical with the synthetic 3-O-(3'R,7'R,11'R,15'-tetramethylhexadecyl)-sn-glycerol, and the -isomer was identical with the synthetic 2-O-(3'R,7'R,11'R,15'-tetramethylhexadecyl) glycerol.     

Pathways of glyceride glycerol synthesis

Isolated rat liver parenchymal cells were incubated for various periods with [U-(14)C,2-(3)H]glycerol and the radioisotopic yields in the major products were determined, as well as the (3)H/(14)C ratios in glyceride glycerol and intracellular glycerol phosphate. Under the conditions used (0.1mm-glycerol+10mm-l-lactate or 10mm-glycerol as substrates), only small differences were found between these (3)H/(14)C ratios. The results suggest a minor role for a pathway of glyceride glycerol synthesis involving reduction of acylated dihydroxyacetone phosphate, under these experimental conditions.     

The synthesis of cholesteryl alkyl ethers

Seventeen cholesteryl alkyl ethers were synthesized through alcoholysis of cholesterol p-toluenesulfonate. This method was found superior to the etherification of sodium or potassium cholesterylate with alkyl halides or methanesulfonates, especially for the preparation of long-chain unsaturated alkyl ethers of [7(n)-³H]cholesterol of high specific activity.     

Lipase-catalyzed synthesis of glycerol carbonate from renewable glycerol and dimethyl carbonate through transesterification

Glycerol carbonate is a key multifunctional compound employed as solvent, additive, monomer, and chemical intermediate. Enzymatic synthesis of glycerol carbonate from renewable starting materials (glycerol and dimethyl carbonate) was successfully achieved by immobilized lipase from Candida antarctica (CALB, Novozym 435). Addition of molecular sieves as scavenger for the removal of methanol, which was generated from dimethyl carbonate during the reaction, accelerated a reaction rate. After the optimization, the equimolar use of glycerol and dimethyl carbonate in the Novozym 435-catalyzed reaction yielded a glycerol carbonate with almost quantitative yield. The resulting glycerol carbonate from 60 °C reaction has shown the low enantiomeric excess (13% ee) as configuration of (R)-enantiomer.     

Lipase-catalyzed synthesis of glycerol carbonate from renewable glycerol and dimethyl carbonate through transesterification

Glycerol carbonate is a key multifunctional compound employed as solvent, additive, monomer, and chemical intermediate. Enzymatic synthesis of glycerol carbonate from renewable starting materials (glycerol and dimethyl carbonate) was successfully achieved by immobilized lipase from Candida antarctica (CALB, Novozym 435). Addition of molecular sieves as scavenger for the removal of methanol, which was generated from dimethyl carbonate during the reaction, accelerated a reaction rate. After the optimization, the equimolar use of glycerol and dimethyl carbonate in the Novozym 435-catalyzed reaction yielded a glycerol carbonate with almost quantitative yield. The resulting glycerol carbonate from 60 °C reaction has shown the low enantiomeric excess (13% ee) as configuration of (R)-enantiomer.     

Acrolein synthesis from glycerol in hot-compressed water

Glycerol conversion was conducted in hot-compressed water (HCW: 573-673 K, 25-34.5 MPa) using a batch and a flow apparatus and the influences of temperature, H(2)SO(4), glycerol concentration, and pressure, were examined. The yield of acrolein was enhanced by higher glycerol and H(2)SO(4) concentration, and higher pressure. Approximately 80% selectivity of acrolein was obtained at 90% of glycerol conversion with an acid catalyst in supercritical condition (673 K and 34.5 MPa). The rate constant of acrolein decomposition was always higher than that of acrolein formation in the absence of acid catalyst but the rate constant of acrolein formation could be overcome that of acrolein decomposition by addition acid in supercritical condition.     

Effect of glycerol on thermolysin-catalyzed peptide bond synthesis

The effect of glycerol on the hydrolytic activity of thermolysin (EC 3.4.24.4) has been compared with the effect on the condensation of N-benzyloxycarbonyl-L-aspartic acid with L-phenylalanine methyl ester to form N-benzyloxycarbonyl-L-aspartyl-L-phenylalanine methyl ester (Z X Asp X Phe X OMe), the precursor to the sweet-tasting compound L-aspartyl-L-phenylalanine methyl ester. Hydrolytic activity was measured by the degradation of azocasein and furylacryloyl-L-glycyl-L-leucinamide. Increasing concentrations of glycerol reversibly inhibited the hydrolytic activity of the enzyme toward both substrates. The inclusion of glycerol in the synthetic medium facilitated the production of Z X Asp X Phe X OMe in a water-soluble system but reduced the initial rate of peptide synthesis. Glycerol stabilized thermolysin against thermal denaturation.     

Effect of glycerol on thermolysin-catalyzed peptide bond synthesis

The effect of glycerol on the hydrolytic activity of thermolysin (EC 3.4.24.4) has been compared with the effect on the condensation of N-benzyloxycarbonyl-l-aspartic acid with l-phenylalanine methyl ester to form N-benzyloxycarbonyl-l-aspartyl-l-phenylalanine methyl ester (Z · Asp · Phe · OMe), the precursor to the sweet-tasting compound l-aspartyl-l-phenylalanine methyl ester. Hydrolytic activity was measured by the degradation of azocasein and furylacryloyl-l-glycyl-l-leucinamide. Increasing concentrations of glycerol reversibly inhibited the hydrolytic activity of the enzyme toward both substrates. The inclusion of glycerol in the synthetic medium facilitated the production of Z · Asp · Phe · OMe in a water-soluble system but reduced the initial rate of peptide synthesis. Glycerol stabilized thermolysin against thermal denaturation.     

Three different types of chirality-driven crystallization within the series of uniformly substituted phenyl glycerol ethers

Seven chiral arylglycerol ethers 2-R-C(6)H(4)-O-CH(2)CH(OH)CH(2)OH (R = H, Me, Et, Allyl, n-Pr, i-Pr, tert-Bu) were synthesized in racemic and scalemic form. The IR spectra, melting points, and enthalpies of fusion for racemic and scalemic samples of every species were measured, the entropies of enantiomers mixing in the liquid state and Gibbs free energies of a racemic compound formation were derived and binary phase diagrams were reconstructed for the whole family. Solid racemic compounds stabilities were ranked for the four substances. Spontaneous resolution was established for the registered chiral drug mephenesin and its ethyl analogue. Metastable anomalous conglomerate, forming crystals having three independent R* and one independent S* molecules in the unit cell, is formed during solution crystallization of tert-butyl derivative; metastable phase transforms slowly into traditional racemic conglomerate.     

The synthesis of A 1-alkenyl thioether of glycerol

The synthesis of 3-(1-heptenylthio)-1, 2-propanediol has been achieved by the reaction of 1-ethylthio-1-heptene with lithium in ammonia followed by the addition of 1-bromo-2, 3-propanediol.     

A simple method for the synthesis of cholesteryl ethers

A novel method for the synthesis of cholesteryl ethers is described. The mesylates of fatty alcohols were treated with the sodium salt of cholesterol in toluene at 80 degrees C in the presence of anhydrous dimethyl formamide. The hexyl, tetradecyl, and oleyl cholesteryl ethers were synthesized in yields varying between 55 and 70%. Tritiated cholesteryl oleyl ether was also synthesized in good chemical (45%) and radiochemical (45%) yields.