Elimination Of Acetaldehyde Research Articles

Characterization of ethylguanine isomers and structurally related compounds by laser-desorbed cationization in a Fourier transform mass spectrometer

Laser-desorption Fourier transform mass spectrometry (LD-FTMS) was used to investigate and compare the fragmentation patterns of O 6-, 7- and 9-ethylguanines. LD-FTMS of all ethylguanine isomers studied here gave characteristic fragmentations in addition to pseudomolecular ions. These ethylguanine isomers lose ethylene leading to the formation of protonated guanine. O 6-Ethylguanine readily loses acetaldehyde from molecular and pseudomolecular ions, however, acetaldehyde elimination was not observed in the spectra of 7- and 9-ethylguanines. Ionized O 6- and 7-ethylguanines both lose methyl radicals whereas ionized 9-ethylguanine does not. Fragmentation pathways for formation of some of the distinguishing ions are proposed. Collision-induced dissociation was also carried out to identify some of the fragment ions.

Theoretical study on H2-induced acetaldehyde elimination from cobalt complex CH3(O)CCo(CO)3

Approximate Density Functional calculations have been carried out on the addition of H{sub 2} to CH{sub 3}(O)CCo(CO){sub 3} as well as the product elimination step in which CH{sub 3}(O)CH and HCo(CO){sub 3} are subsequently formed. These reactions represent the last step, e, of the catalytic hydroformylation cycle according to the mechanism proposed by Heck and Breslow. H{sub 2} was found to form stable bipyramidal {eta}{sup 2} adducts with the coordinatively unsaturated acyl intermediate CH{sub 3}(O)CCo(CO){sub 3}. The oxidative addition reaction was investigated further by modeling the energy profile with a linear transit procedure. The profile from the linear transit revealed an activation energy {delta}E* of 77 kJ/mol. The activation energy stems primarily from the stretching of the H-H bond during the initial stages of the reaction. The total activation energy for step e along the oxidative addition/reductive elimination path was calculated to be 77 kJ/mol, with the oxidative addition being rate determining. Step e was also studied for an alternative mechanism in which the {eta}{sup 2}-H{sub 2} complex is converted to an aldehyde molecule and the catalyst HCo(CO){sub 3} by direct hydrogen transfer from the coordinated H{sub 2} molecule to the acyl ligand. A stable intermediate in which H{sub 2}more » has moved toward the acyl group, thereby forming a four-center species, was found to be 83 kJ/mol higher in energy than the initial {eta}{sup 2}-H{sub 2} compound. The corresponding reaction profile, modeled by a linear transit procedure, revealed only a minimal activation barrier. The subsequent separation of the molecular structure into the products resulted in a decrease of the energy. Both mechanisms for step e seem to be viable. On the basis of these results, the activation energy for the entire process, H{sub 2} + CH{sub 3}(O)CCo(CO){sub 3} {yields} CH{sub 3}(O)CH + HCo(CO){sub 3}, was estimated to be {approximately}75-85 kJ/mol.« less

Unimolecular decomposition of ethoxytrimethylsilane

AbstractA study of the metastable spectra from ethoxytrimethylsilane and the mass shifts of the deuterium‐labeled species permitted the rationalization of the fragmentation mechanism for forming all major ions in the mass spectrum. A new mechanistic pathway for the formation of [Si(CH3)3]+ (m/z 73) is demonstrated. A strong metastable ion for elimination of neutral acetaldehyde from the parent ion was observed despite the absence of a detectable daughter ion.

ChemInform Abstract: Combined 2H and 18O Isotope Effects in Support of a Concerted, Synchronous Elimination of Acetaldehyde from a Bis(benzyl ethyl ether) Radical Cation.

ChemInformVolume 19, Issue 52 Preparative Organic Chemistry ChemInform Abstract: Combined 2H and 18O Isotope Effects in Support of a Concerted, Synchronous Elimination of Acetaldehyde from a Bis(benzyl ethyl ether) Radical Cation. C. E. ALLISON, C. E. ALLISON Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorM. B. STRINGER, M. B. STRINGER Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorJ. H. BOWIE, J. H. BOWIE Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorP. J. DERRICK, P. J. DERRICK Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this author C. E. ALLISON, C. E. ALLISON Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorM. B. STRINGER, M. B. STRINGER Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorJ. H. BOWIE, J. H. BOWIE Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this authorP. J. DERRICK, P. J. DERRICK Dep. Org. Chem., Univ. Adelaide, Adelaide, South Aust. 5001, Aust.Search for more papers by this author First published: December 27, 1988 https://doi.org/10.1002/chin.198852075Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume19, Issue52December 27, 1988 RelatedInformation

Combined deuterium and oxygen-18 isotope effects in support of a concerted, synchronous elimination of acetaldehyde from a bis(benzyl ethyl ether) radical cation

No evidence has been found of hydrogen scrambling accompanying decomposition of the benzyl ether molecular ion at times approaching 100 ..mu..s. Isotope effects upon produce ion abundances have been measured for elimination of acetaldehyde from the molecular ions of multiply labeled diethoxyxylenes and compared with the results of calculations of kinetic isotope effects using the quasi-equilibrium theory. It is concluded that this rearrangement involving a 6-membered cyclic transition state can be described as a concerted, synchronous process. 31 references, 7 figures, 1 table.

Catalase activity measured in rats naive to ethanol correlates with later voluntary ethanol consumption: possible evidence for a biological marker system of ethanol intake.

Catalase activity in blood collected from young rats naive to ethanol (65 days) was significantly and positively correlated with later voluntary consumption of ethanol. Catalase activity levels were also correlated with catalase activity in brain and blood sampled after exposure to ethanol. The results obtained in the present study extend and confirm earlier findings (Aragon et al. 1985c) that brain catalase activity and voluntary ethanol intake are unidirectionally and causally related. The results also suggest that brain catalase activity may be part of an enzymatic system controlling the production and elimination of acetaldehyde in brain. This system may be a biological marker system mediating the affinity of organisms to ingest ethanol.

Contrasts in the chemistry of trinuclear cluster complexes of osmium and ruthenium. Formation of a fischer carbene or a functionalized μ 3,η 2-vinylidene group

The complex Os 3(CO) 12 ( 1) is alkylated with organolithium reagents to give [Li][Os 3{η 1-C(O)R}(CO) 11 −] ([Li][ 2]). Attempts at electrophilic alkylation of such salts has been unsuccessful. Acidification of a tetrahydrofuran (THF) solution of [Li][ 2] leads to Os 3(CO) 11(THF) ( 3). Metathesis of [Li][ 2] with [PPN]Cl ([PPN] + = (Ph 3P) 2N] +) accompanied by exchange of THF by CHCl 3, leads to a solution of [PPN][Os 3{1,2-μ-OC(Me)}(CO) 10] ([PPN][ 4]). Acidification of the latter gives Os 3{1,2-μ-H; 1,2-μ-OC(Me)}(CO) 10 ( 5). Alkylation of [PPN][ 4] with ROSO 2CF 3 gives the bis-acyl derivative Os 3{η x -C(O)R}{μ-OC(Me)}(CO) 9 ( 6). This reacts with water to give a small amount of Os 3{1,2-μ-X; 1,2-μ-OC(Me)}(CO) 10 ( 7, X = Cl, or I) along with the two principal products, the Fischer carbene complex Os 3{1,2-μ-H; 1,2-μ-OC(Me)}{1-C(OR)Me}(CO) 9 ( 8, R = CH 3, CD 3, C 6H 5), and Os 3{1,2-μ-(OH); 1,2-μ-OC(Me)}(CO) 10 ( 9). Complex 5 is deprotonated by alkyl lithium reagents at 25°C; at −30°C, however, it is alkylated to give [Li][Os 3{C(O)R}{μ-H,μ-OC(Me)}(CO) 9] ([Li]( 10)). Electrophilic alkylation of this salt with R′OSO 2CF 3 at 25°C leads to cluster complexes containing a Fischer carbene group, Os 3{1-η 1-C(OR′)R}{1,2-μ-H; 1,2-μ-OC(Me)}(CO) 9 ( 8, R = R′= Me; R = Me, R′ = Et; R = Ph, R′ = Et) in high yield. Treatment of Ru 3{1,2-μ-H; 1,2-μ-OC(Me)}(CO) 10 ( 11) with LiR at −30°C leads to [Li][Ru 3{C(O)R}{μ-H,μ-OC(Me)}(CO) 9] ([Li][ 12]). Electrophilic alkylation of these salts, however, leads to the elimination of acetaldehyde along with the formation of double CH oxidative addition products, Ru 3{μ-H} 2 {η 2,μ 3-C(OEt)C(H)}(CO) 9 ( 13). Starting with Me 2NH instead of alkyllithium in this sequence gives Ru 3{μ-H} 2{η 2,μ 3-C(OEt)N(Me)C(H)}(CO) 9 ( 14).

On the role of 2,3-butanediol in the metabolism of ethanol

A new mechanism is proposed for the enzymatic formation of 2,3-butanediol. It could be related to the elimination of ethanol and acetaldehyde in chronic alcoholic subjects.

A two dimensional model of alcohol consumption: Possible interaction of brain catalase and aldehyde dehydrogenase

The possible existence of a biological marker system mediating voluntary consumption of ethanol in rats has been examined in a series of studies. The working hypothesis underlying this research was that acetaldehyde, the primary metabolite of ethanol, mediates the positive reinforcing properties of ethanol and thus underlies the voluntary consumption of ethanol in both animals and humans. We further hypothesized that brain catalase and aldehyde dehydrogenase, the enzymes controlling the production and elimination of acetaldehyde in the brain, may represent a biological marker system underlying the affinity of the animals to consume ethanol. Data demonstrating that the activity levels of these enzymes are positively correlated with alcohol ingestion seems to suggest that it is likely that the enzyme activity can serve as a predictor of the propensity to drink alcohol. A predictive model is proposed which describes the modulation of voluntary ethanol intake through the activity of these enzymes and their role in determining rates of formation and degradation of acetaldehyde in the brain.

Distonic radical ions. Stepwise elimination of acetaldehyde from ionized benzyl ethyl ether

Distonic radical ions. Stepwise elimination of acetaldehyde from ionized benzyl ethyl ether

Influence of cefoperazone on ethanol and acetaldehyde metabolism in vitro.

The effect of cefoperazone on ethanol and acetaldehyde metabolism was studied in rat liver homogenates and with a purified aldehyde dehydrogenase. Rat liver homogenates were incubated with ethanol (30 mM) alone or in combination with cefoperazone (15 or 150 micrograms/g liver). Ethanol and acetaldehyde concentrations were determined at 6, 12, 18 and 24 minutes. Cefoperazone added to the incubation medium inhibited ethanol and acetaldehyde metabolism in a concentration-dependent manner. The addition of cefoperazone to rat liver homogenates incubated with acetaldehyde (300 microM), however, did not inhibit acetaldehyde disappearance for a period of 15 minutes. Purified aldehyde dehydrogenase was incubated with 300 microM acetaldehyde. When cefoperazone was added, acetaldehyde disappearance was significantly slower than without cefoperazone. The data indicate that cefoperazone inhibits ethanol metabolism in rat liver homogenates in a concentration-dependent manner. The effect of the antibiotic on acetaldehyde elimination in liver homogenate, however, depends on the concentration of acetaldehyde in the medium. The acetaldehyde dehydrogenase obtained from yeast is inhibited by cefoperazone.

Chlorpropamide-alcohol flushing and diabetes

SUMMARY. Chlorpropamide alcohol flushing (CPAF) has been suggested as a genetic marker for a type of non-insulin dependent diabetes mellitus characterized by a strong genetic disposition and a low frequency of retinopathy. This theory has not been supported by later investigations. Studies indicate that the most likely primary event in the CPAF phenomenon is an increased blood acetaldehyde level as a consequence of decreased acetaldehyde degradation. Probably the decreased elimination of acetaldehyde is elicited through an inhibitory effect of chlorpropamide on acetaldehyde dehydrogenase, the effect being most pronounced in subjects who have a genetically determined low activity of this enzyme. Key words: Diabetes, chlorpropamide, ethanol, acetaldehyde.

Elimination of artifactual acetaldehyde in the measurement of human blood acetaldehyde by the use of polyethylene glycol and sodium azide: normal blood acetaldehyde levels in the dog and human after ethanol.

A new procedure is described for the preparation of human blood samples for analysis of acetaldehyde and ethanol by head space gas chromatography. High concentrations of polyethylene glycol were used to remove the hemoglobin and approximately 50% of the plasma protein. Artifactual formation of acetaldehyde from ethanol was inhibited by sodium azide. Using this method, no artifactual acetaldehyde was detectable in human, dog, sheep, and rat blood when spiked with ethanol in final concentrations of 65 mM. The recovery of added acetaldehyde was approximately 80% for human dog, and sheep blood, whereas it was only 30% for rat blood. Following ethanol administration, acetaldehyde levels were determined in blood taken from the pulmonary artery and descending aorta of the dog and human, and also from the hepatic vein of the latter. The relative blood acetaldehyde concentrations at these sites were hepatic vein greater than pulmonary artery greater than descending aorta.

Alcohol-induced euphoria enhanced by disulfiram and calcium carbimide.

In a double-blind study, subjects were treated with either disulfiram or calcium carbimide, inhibitors of acetaldehyde elimination, prior to consumption of low doses of alcohol. Self-rating scales, individual interviews, and observations by independent judges revealed that experimental subjects manifested enhanced changes in mood and euphoria compared to placebo control subjects.

Mechanistic studies of unimolecular ionic decompositions by deuterium and heavy-atom isotope effects. Concerted elimination of acetaldehyde from the benzyl ethyl ether radical cation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanistic studies of unimolecular ionic decompositions by deuterium and heavy-atom isotope effects. Concerted elimination of acetaldehyde from the benzyl ethyl ether radical cationD. Stone, John Bowie, D. Underwood, K. Donchi, C. Allison, and P. DerrickCite this: J. Am. Chem. Soc. 1983, 105, 6, 1688–1689Publication Date (Print):March 1, 1983Publication History Published online1 May 2002Published inissue 1 March 1983https://doi.org/10.1021/ja00344a064RIGHTS & PERMISSIONSArticle Views60Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (305 KB) Get e-Alerts Get e-Alerts

Reactions of coordinated molecules : XXV. The preparation of several bis[(hydroxy)(methyl)]carbenoid complexes of rhenium

When the rhenium(I) complexes, XRe(CO) 5 (where X is Cl, Br or I), are treated with two molar-equivalents of methyllithium, dianionic complexes of the type, fac-(OC) 3(X)Re[C(CH 3)O] 2 –, are formed. The diprotonation of these dianions with HX affords the neutral, bis-carbenoid complexes, fac-(OC) 3(X)Re[C(CH 3)(OH)] 2. When X is methyl, the reaction with methyllithium gives only a monoanion. The iodo, bis-carbenoid complex decomposes in solution with the elimination of acetaldehyde and with the formation of the known dimeric complex, [Re(CO) 4I] 2. The X-ray molecular structure determination of this dimeric complex is reported. The 13C NMR data of the chloro and bromo biscarbenoid complexes are also presented.

The role of liver cytosolic aldehyde dehydrogenase in ethanol metabolism in DBA and C57Bl mice.

Cytosolic aldehyde dehydrogenase (AlDH) activity was increased in DBA and C57Bl mice following phenobarbital (Pb) treatment. The kinetic constants for the control and induced enzymes were similar in both inbred strains. The DBA mice showed enhanced rates of ethanol and acetaldehyde metabolism after Pb treatment, whereas the C57Bl mice did not. It was concluded that the cytosolic enzyme is more important for acetaldehyde metabolism in the DBA than in the C57Bl mice.

Reaction of bis (?-aminoethylato) ethanolamineaquochromium chloride [(NH2CH2O)2Cr�(NH2CH2CH2OH)�H2O]C1 with aldehydes

1. In bis(β-aminoethylato)ethanolamineaquochromium chloride only one of the three amino groups reacts with aldehydes. The condensation is accompanied by the elimination of acetaldehyde and rupture of the C -N bond, and leads to the aldimine. 2. The formed coordinated aldimine exhibits a high activity in the crotonic type of condensation and is quickly converted to a polyunsaturated ligand, which then is cyclized to either the pyridine or quinoline base.

Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 4. Polyester und copolyester der milchsäure und glykolsäure

AbstractPolyesters and copolyesters of 2‐hydroxyacetic acid (glycolic acid) and 2‐hydroxypropionic acid (lactic acid) were investigated by direct pyrolysis in the ion source of a mass spectrometer. Thermal degradation of these polyesters and copolyesters at 10−6 mbar yields cyclic oligomers which are further degraded by an electron impact induced mechanism by elimination of formaldehyde or acetaldehyde and CO2 to give characteristic series of linear ions. In the pyrolysis mass spectrum of a copolyester (mole ratio of monomeric units ≈1:1) intact sequences up to 8 monomeric units can be observed.

Ethanol metabolism in the liver.

Summary: Ethanol elimination by the liver, a relatively constant process, may be increased at high concentrations of ethanol, when certain substances like fructose or pyruvate are metabolized together with ethanol or after prolonged exposure for ethanol. The metabolic effects on the liver are different at high and at low concentrations of ethanol. A number of enzymes or enzyme systems, – liver alcohol dehydrogenase, catalase and mixed‐function oxidase – can in vitro catalyze the oxidation of ethanol, but little is known about the actual role of each enzyme at different metabolic conditions. The existence of more than one pathway for ethanol metabolism in the liver is now becomming increasingly evident, but whether the non‐ADH mediated ethanol oxidation occurs via catalase, or mixed‐function oxidase system, or both, cannot at present be decided.The activity of liver alcohol dehydrogenase cannot be induced by continuous use of ethanol. The ADH‐mediated ethanol oxidation may be increased when the steady state concentration of free NADH in the cytoplasm is lowered. The rate of ethanol oxidation under in vivo conditions seems not to be determined by the rate of acetaldehyde elimination, although acetaldehyde is a product of ethanol metabolism. The reoxidation of NADH may proceed by NADH‐linked substrate system, by transhydrogenation to NADP+ or by transporting reducing equivalents into mitochondria where they are oxidized.In this review an attempt is made to examine the effects of a number of substrates or metabolic conditions which may enhance ethanol oxidation (concentration of ethanol, fructose, pyruvate, D‐glyceraldehyde, oxygen, CO2 and 2,4‐dinitrophenol) and to discuss the mechanisms involved in this action. It is concluded that the effect of pyruvate and fructose (maybe also CO2 and D‐glyceraldehyde) proceeds via ADH‐mediated pathway (possibly involving the so‐called “malic enzyme shuttle”) whereas the acceleration in ethanol metabolism, observed in rat liver preparations when high concentrations of ethanol are metabolized, is associated with the participation of non‐ADH pathway (s) in ethanol metabolism.