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At least 19 recordsLinked to original sources
PubMed1985

Reversed-phase high-performance liquid chromatographic separation of molecular species of alkyl ether, vinyl ether, and monoacyl lysophospholipids.

An isocratic reversed-phase high-performance liquid chromatographic method was developed which resolved individual molecular species of choline and ethanolamine lysophospholipids utilizing a C13 bonded porous silica stationary phase with a mobile phase comprised of methanol--water--acetonitrile (57:23:20) containing 20 mM choline chloride. Solute retention was primarily determined by hydrophobic interactions with the stationary phase permitting separation of individual molecular species of lysophospholipids according to the composition of the aliphatic chain and the nature of its covalent attachment to the sn-1 hydroxyl group. The elution profile of unsaturated monoacyllysophospholipid or lysoplasmalogen molecular species was readily obtained by measuring UV absorbance at 203 nm. Identification of column eluates containing saturated monoacyl and alkyl ether lysophospholipids was possible utilizing relative retention factors that were obtained for the majority of molecular species present in animal tissues.

Animals↗
PubMed2005

Pressure-enhanced dynamic heterogeneity in block copolymers of poly(methyl vinyl ether) and poly(isobutyl vinyl ether).

The static structure factor and associated dynamics have been investigated in a series of block copolymers of poly(methyl vinyl ether) (PMVE) and poly(isobutyl vinyl ether) (PiBVE) using x-ray scattering and dielectric spectroscopy (DS). The origin of the dynamic arrest at the glass temperature (T(g)) of PiBVE has been explored by temperature- and pressure-dependent DS and pressure-volume-temperature measurements. Both temperature and volume are responsible for the segmental dynamics but temperature has a stronger effect. The copolymers display a minimal dynamic asymmetry (Delta T(g) approximately 7 K), nevertheless, are spatially and dynamically heterogeneous. Increasing pressure, unlike temperature, enhances the dynamic heterogeneity. This effect originates from the distinctly different pressure sensitivities of the homopolymers and can be traced back to differences in local packing.

Journal Article↗
PubMed2002

Complexation between poly(maleic acid/octyl vinyl ether) and poly(vinyl caprolactam) in aqueous solution and at the alumina/water interface.

Solution and interfacial properties of binary polymer mixtures of poly(maleic acid/octyl vinyl ether) (PMAOVE) and poly(vinyl caprolactam) (PVCAP) have been studied for the alumina/water system. To test the hydrophobic effect, mixtures of poly(maleic acid/methyl vinyl ether) (PMAMVE) and PVCAP are also investigated and compared to the behavior of PMAOVE/PVCAP. At low pH, both polymer mixtures become turbid upon mixing. The turbidity increases at low mixing ratios of PVCAP to the vinyl ether component, reaches a maximum, and then decreases at higher mixing ratios. Upon shifting the pH to the alkaline range, i.e., pH 7.5 and above, the turbid solution becomes clear for both the polymer mixtures. Cloud point measurements indicate the absence of complexation of PVCAP with PMAMVE under the alkaline conditions, but strong interaction with PMAOVE. This is attributed to the different forces involved in the complexation among the polymers: H bonding for PVCAP/PMAMVE and both H bonding and hydrophobic effects for PVCAP/PMAOVE. At the alumina/water interface, the normally nonadsorbing PVCAP is triggered to adsorb by PMAOVE, attributed to the hydrophobic complexation between the two. However, the adsorption of PVCAP shows a maximum as a function of the concentration of PMAOVE. At concentrations of PMAOVE above the onset of its own plateau adsorption, the amount of PVCAP triggered to adsorb is reduced possibly due to the polymer complex formation in solution.

Journal Article↗
PubMed1967

Conversion of fatty aldehyde dimethyl acetals to the corresponding alk-1-enyl methyl ethers (substituted vinyl ethers) during gas-liquid chromatography.

The behavior of palmitaldehyde and linolealdehyde and of their dimethyl acetals during gas-liquid chromatography on beta-cyclodextrin acetate (beta-CDX acetate) and ethylene glycol succinate polyester-phosphoric acid (EGSP) columns was studied. The aldehydes were well separated from their dimethyl acetals on the beta-CDX acetate column. However, on the EGSP column the retention times of palmitaldehyde and its dimethyl acetal were identical; a mixture of linolealdehyde and its dimethyl acetal gave a split peak. The aldehydes were recovered unchanged in 80-85% yield by preparative GLC from both columns, but the dimethyl acetals were quantitatively converted to the corresponding alk-1-enyl methyl ethers. The structure of these compounds was elucidated by infrared spectroscopy, mass spectrometry, and chemical means. Upon hydrolysis at low temperatures with 100% H(2)SO(4) they yielded the corresponding aldehydes, which were identified as 2,4-dinitrophenylhydrazones.

Acetals↗
PubMed1989

Comparative studies on the metabolism and mutagenicity of vinyl ethers.

4-Nitrophenyl vinyl ether (1), umbelliferyl vinyl ether (2), 4-cyanophenyl vinyl ether (3), and 4-acetylphenyl vinyl ether (4) were mutagenic toward Salmonella typhimurium TA100 and TA100NR in the presence of the hepatic 9000 x g supernatant fraction fortified with a reduced nicotinamide adenine dinucleotide phosphate generating system (S9mix), but no significant mutagenicity of 4-chlorophenyl vinyl ether (5), phenyl vinyl ether (6), n-butyl vinyl ether (7), and ethyl vinyl ether (8) was found. The epoxides of 1-4 were highly mutagenic toward the bacteria without the S9mix. Also, epoxides of 5 and 6 showed relatively weak mutagenicity. Studies on the metabolism of 1 showed that the epoxide (1a) formed from 1 by microsomes behaved as a labile intermediate in the incubation mixture. Untreated rat hepatic microsomes accumulated 1a and induced mutagenicity of 1 most effectively among the activation systems used. Mutagenic activities of vinyl ethers in the presence of the S9mix were correlated with stabilities of their epoxides. From these results, it is suggested that the critical factor for the mutagenicity of vinyl ethers is the formation and stability of epoxide intermediate in the biological system.

Animals↗
PubMed1995

Depletion of glutathione and hepato-toxicity caused by vinyl ethers in mice.

4-Nitrophenyl vinyl ether (NPVE) and phenyl vinyl ether (PVE) administered i.p. in mice lowered hepatic non-protein sulfhydryl (NP-SH) content, but did not elevate the serum glutamate pyruvate transaminase (GPT) activity. n-Butyl vinyl ether (BVE) showed no significant effects either on the NP-SH content or on the serum GP activity. Mice pretreated with buthionine sulfoximine were sensitive to the potential toxicity of NPVE. These results showed that aryl vinyl ethers, NPVE and PVE, are more toxic than the alkyl vinyl ether, BVE, and that glutathione plays an important role on the protection of hepatic injury by reactive metabolite(s) derived from vinyl ethers.

Alanine Transaminase↗
PubMed2006

Thermodynamic properties (enthalpy, bond energy, entropy, and heat capacity) and internal rotor potentials of vinyl alcohol, methyl vinyl ether, and their corresponding radicals.

Vinyl alcohols (enols) have been discovered as important intermediates and products in the oxidation and combustion of hydrocarbons, while methyl vinyl ethers are also thought to occur as important combustion intermediates. Vinyl alcohol has been detected in interstellar media, while poly(vinyl alcohol) and poly(methyl vinyl ether) are common polymers. The thermochemical property data on these vinyl alcohols and methyl vinyl ethers is important for understanding their stability, reaction paths, and kinetics in atmospheric and thermal hydrocarbon-oxygen systems. Enthalpies , entropies , and heat capacities (C(p)()(T)) are determined for CH(2)=CHOH, C(*)H=CHOH, CH(2)=C(*)OH, CH(2)=CHOCH(3), C(*)H=CHOCH(3), CH(2)=C(*)OCH(3), and CH(2)=CHOC(*)H(2). Molecular structures, vibrational frequencies, , and C(p)(T) are calculated at the B3LYP/6-31G(d,p) density functional calculation level. Enthalpies are also determined using the composite CBS-Q, CBS-APNO, and G3 methods using isodesmic work reactions to minimize calculation errors. Potential barriers for internal rotors are calculated at the B3LYP/6-31G(d,p) level and used to determine the hindered internal rotational contributions to entropy and heat capacity. The recommended ideal gas phase values calculated in this study are the following (in kcal mol(-1)): -30.0, -28.9 (syn, anti) for CH(2)=CHOH; -25.6, -23.9 for CH(2)=CHOCH(3); 31.3, 33.5 for C(*)H=CHOH; 27.1 for anti-CH(2)=C(*)OH; 35.6, 39.3 for C(*)H=CHOCH(3); 33.5, 32.2 for CH(2)=C(*)OCH(3); 21.3, 22.0 for CH(2)=CHOC(*)H(2). Bond dissociation energies (BDEs) and group additivity contributions are also determined. The BDEs reveal that the O-H, O-CH(3), C-OH, and C-OCH(3) bonds in vinyl alcohol and methyl vinyl ether are similar in energy to those in the aromatic molecules phenol and methyl phenyl ether, being on average around 3 kcal mol(-1) weaker in the vinyl systems. The keto-enol tautomerization enthalpy for the interconversion of vinyl alcohol to acetaldehyde is determined to be -9.7 kcal mol(-1), while the activation energy for this reaction is calculated as 55.9 kcal mol(-1); this is the simplest keto-enol tautomerization and is thought to be important in the reactions of vinyl alcohol. Formation of the formyl methyl radical (vinoxy radical/vinyloxy radical) from both vinyl alcohol and methyl vinyl ether is also shown to be important, and its reactions are discussed briefly.

Computer Simulation↗
PubMed2005

Inhibition of diethyl ether degradation in Rhodococcus sp. strain DEE5151 by glutaraldehyde and ethyl vinyl ether.

Alkyl ether-degrading Rhodococcus sp. strain DEE5151, isolated from activated sewage sludge, has an activity for the oxidation of a variety of alkyl ethers, aralkyl ethers and dibenzyl ether. The whole cell activity for diethyl ether oxidation was effectively inhibited by 2,3-dihydrofurane, ethyl vinyl ether and glutaraldehyde. Glutaraldehyde of less than 30 microM inhibited the activity by a competitive manner with the inhibition constant, K(I) of 7.07+/-1.36 microM. The inhibition type became mixed at higher glutaraldehyde concentrations >30 microM, probably due to the inactivation of the cell activity by the Schiff-base formation. Structurally analogous ethyl vinyl ether inhibited the diethyl ether oxidation activity in a mixed manner with decreasing the apparent maximum oxidation rate, v(max)(app), and increasing the apparent Michaelis-Menten constant, K(M)(app). The mixed type inhibition by ethyl vinyl ether seemed to be introduced not only by the structure similarity with diethyl ether, but also by the reactivity of the vinyl ether with cellular components in the whole cell system.

Biodegradation, Environmental↗
PubMed2001

Reactive chlorinating species produced by myeloperoxidase target the vinyl ether bond of plasmalogens: identification of 2-chlorohexadecanal.

Plasmalogens contain a vinyl ether bond linking the sn-1 aliphatic chain to the glycerol backbone of this predominant phospholipid molecular subclass, which is found in many mammalian tissues. The present study demonstrates that the vinyl ether bond of plasmalogens is a molecular target of the reactive chlorinating species produced by myeloperoxidase. Analysis by thin layer chromatography revealed that reactive chlorinating species produced by myeloperoxidase target the vinyl ether bond of the plasmalogen, lysoplasmenylcholine (1-O-hexadec-1'-enyl-sn-glycero-3-phosphorylcholine), resulting in the production of a neutral lipid. Capillary gas chromatographic analyses demonstrated that the neutral lipid generated from lysoplasmenylcholine was neither hexadecanal nor did it contain masked hexadecanal (i.e. the vinyl ether) because the dimethyl acetal of hexadecanal produced by acid methanolysis derivatization was no longer present. Electrospray ionization mass spectrometry of the myeloperoxidase-generated neutral lipid product was consistent with the production of a 16-carbon fatty aldehyde containing one chlorine atom. Furthermore, proton NMR analysis indicated that this neutral lipid product was a 2-chloro-fatty aldehyde. Additional structural analysis of this neutral lipid by gas chromatography-mass spectrometry of the underivatized product as well as its pentafluorobenzyl oxime-derivative product was consistent with the neutral lipid being 2-chlorohexadecanal. The reactive chlorinating species, hypochlorous acid and chlorine gas, both attacked the vinyl ether bond of lysoplasmenylcholine resulting in the production of 2-chlorohexadecanal. The production of 2-chlorohexadecanal was dependent on the presence of the plasmalogen masked aldehyde (i.e. the vinyl ether) in the substrate because the free fatty aldehyde, hexadecanal, was not converted to 2-chlorohexadecanal by the reactive chlorinating species generated by myeloperoxidase. Taken together, the present studies demonstrate for the first time the targeting of the vinyl ether bond of plasmalogens by the reactive chlorinating species produced by myeloperoxidase resulting in the production of novel chlorinated fatty aldehydes.

Aldehydes↗
PubMed1976

Vinyl ethers of choline and congeners.

The vinyl ethers of choline and of its alpha- and beta-methyl homologues were prepared to determine their cholinergic effects and to determine whether a separation of the dual physiologic activity (nicotinic and muscarinic) reported for the vinyl ether of choline could be achieved by this modification. A literature method of vinyl transetherification of amino alcohols has been studied and modified. The ethyl ethers of choline and of alpha- and beta-methylcholine were prepared for comparison with the vinyl ethers. Two independent, unequivocal syntheses of the ethyl ether of beta-methylcholine have been accomplished. This study showed that the two literature methods for synthesis of this compound are equivocal, and, hence, the biological data reported for this compound in the older literature may not be valid. Certain of the ethers showed marked nicotinic or muscarinic activities.

Animals↗