Loss Of Ethylene Research Articles

Reactions of halofluorocarbons with group 6 complexes M(C(5)H(5))(2)L (M = Mo, W; L = C(2)H(4), CO). Fluoroalkylation at molybdenum and tungsten, and at cyclopentadienyl or ethylene ligands.

The molybdenum(II) and tungsten(II) complexes [MCp(2)L] (Cp = eta(5)-cyclopentadienyl; L = C(2)H(4), CO) react with perfluoroalkyl iodides to give a variety of products. The Mo(II) complex [MoCp(2)(C(2)H(4))] reacts with perfluoro-n-butyl iodide or perfluorobenzyl iodide with loss of ethylene to give the first examples of fluoroalkyl complexes of Mo(IV), MoCp(2)(CF(2)CF(2)CF(2)CF(3))I (8) and MoCp(2)(CF(2)C(6)F(5))I (9), one of which (8) has been crystallographically characterized. In contrast, the CO analogue [MoCp(2)(CO)] reacts with perfluorobenzyl iodide without loss of CO to give the crystallographically characterized salt, [MoCp(2)(CF(2)C(6)F(5))(CO)](+)I(-) (10), and the W(II) ethylene precursor [WCp(2)(C(2)H(4))] reacts with perfluorobenzyl iodide without loss of ethylene to afford the salt [WCp(2)(CF(2)C(6)F(5))(C(2)H(4))](+)I(-) (11). These observations demonstrate that the metal-carbon bond is formed first. In further contrast the tungsten precursor [WCp(2)(C(2)H(4))] reacts with perfluoro-n-butyl iodide, perfluoro-iso-propyl iodide, and pentafluorophenyl iodide to give fluoroalkyl- and fluorophenyl-substituted cyclopentadienyl complexes WCp(eta(5)-C(5)H(4)R(F))(H)I (12, R(F) = CF(2)CF(2)CF(2)CF(3); 15, R(F) = CF(CF(3))(2); 16, R(F) = C(6)F(5)); the Mo analogue MoCp(eta(5)-C(5)H(4)R(F))(H)I (14, R(F) = CF(CF(3))(2)) is obtained in similar fashion. The tungsten(IV) hydrido compounds react with iodoform to afford the corresponding diiodides WCp(eta(5)-C(5)H(4)R(F))I(2) (13, R(F) = CF(2)CF(2)CF(2)CF(3); 18, R(F) = CF(CF(3))(2); 19, R(F) = C(6)F(5)), two of which (13 and 19) have been crystallographically characterized. The carbonyl precursors [MCp(2)(CO)] each react with perfluoro-iso-propyl iodide without loss of CO, to afford the exo-fluoroalkylated cyclopentadiene M(II) complexes MCp(eta(4)-C(5)H(5)R(F))(CO)I (21, M = Mo; 22, M = W); the exo-stereochemistry for the fluoroalkyl group is confirmed by an X-ray structural study of 22. The ethylene analogues [MCp(2)(C(2)H(4))] react with perfluoro-tert-butyl iodide to yield the products MCp(2)[(CH(2)CH(2)C(CF(3))(3)]I (25, M = Mo; 26, M = W) resulting from fluoroalkylation at the ethylene ligand. Attempts to provide positive evidence for fluoroalkyl radicals as intermediates in reactions of primary and benzylic substrates were unsuccessful, but trapping experiments with CH(3)OD (to give R(F)D, not R(F)H) indicate that fluoroalkyl anions are the intermediates responsible for ring and ethylene fluoroalkylation in the reactions of secondary and tertiary fluoroalkyl substrates.

First rational synthesis of the thiothiono analogue of an unsymmetrically substituted phthalic anhydride

Treatment of the dithiolane derivative of an alpha-carboxyethyl benzaldehyde with LDA at -78 degrees C smoothly produced the thiothionophthalic anhydride. The mechanism is proposed to involve loss of ethene and attack of an intermediate dithiocarboxylate onto the ester. Heating the thiothionophthalic anhydride gave the 3, 3'-bithiophthalide.

Trithiacyclononane as a ligand for potential technetium and rhenium radiopharmaceuticals: synthesis of [M(9S3)(SC2H4SC2H4S)][BF4] (M = 99Tc, Re, 188Re) via C-S bond cleavage.

Chemical or electrochemical reduction of the 1,4,7-trithiacyclononane (9S3) complexes [MII(9S3)2][BF4]2 (M = Re (3a) or Tc (3b)) results in instantaneous C-S bond cleavage to yield ethene and the stable MIII thiolate complexes [MIII(9S3)L][BF4] (M = Re (4a) or Tc (4b), L = SCH2CH2SCH2CH2S). Compounds 4 have been characterized by 1H NMR spectroscopy, and the pseudo-octahedral geometry of 4b has been confirmed by X-ray crystallography. Upon electrochemical reduction 4a loses ethene, while 4b can be reversibly reduced to [TcII(9S3)L], which is then further reduced to Tc(I) with loss of ethene. Successive ethene loss is observed in the mass spectra of compounds 3 and 4. The radiosynthesis of 4a with 188Re can be comfortably completed within 10 min starting with 188ReO4- from a 188W/188Re generator, with a radiochemical yield in excess of 90%, and thus represents a practical approach to the preparation of stable 188Re (and 99mTc) thioether complex derivatives/conjugates for clinical use. Crystal data: 4b, C10H20S6Tc, orthorhombic Pbca, a = 12.233(2) A, b = 14.341(2) A, c = 20.726(3) A, Z = 8.

An electron energy loss spectroscopy study of resonance population in ethylene chemisorbed on Pd(110)

We investigated energy and angle dependencies of vibrational losses of ethylene chemisorbed on Pd(110) by means of high-resolution electron energy loss spectroscopy (HREELS). A resonant enhancement of the C–H stretching modes is observed at the electron primary energy of ∼1.3 eV. It is shown that the resonance cross section is significantly dependent on the electron incidence direction. The resonance is forbidden when the electron incidence direction is aligned along the C–C axis, which is qualitatively explained in terms of the overlap integral between the incident plane wave and the unoccupied orbital. Based on the previous finding that ethylene is anisotropically adsorbed with the C–C axis preferentially aligned along the [11̄0] direction, we assign the resonance state as 2b2u. The results are compared to those obtained by near-edge x-ray absorption fine structure (NEXAFS).

The involvement of ion–neutral complexes in ethylene loss from [PhC(CH 3) 2] + and its isomers

High-level ab initio calculations at the G2(MP2,SVP) level have been used to characterize the potential energy surface for ethylene loss from various [C 9H 11] + ions. There is good agreement between the theoretical predictions and available experimental thermochemical data. We have characterized an alternative pathway to the phenylated cyclopropane mechanism originally proposed to explain the results of 13C-labeling studies of ethylene elimination from [PhC(CH 3) 2] +. This alternative mechanism is found to be consistent with experimental results of both 13C- and deuterium-labeling experiments. We also examine the mechanism for ethylene loss and label exchange for several other isomeric [C 9H 11] + ions. It is found that the 13C-label exchange observed in protonated allylbenzene and some of the deuterium-labeling results for other ions can be explained by the intervention of intermediate ion–neutral complexes. Comparisons are made with previous theoretical work on related [C 3H 6X] + ions (X = Ph, OH, SH and NH 2). Keywords: [C 9H 11] +; Ethylene elimination; Label exchange; Heats of formation; Ion–neutral complex; G2(MP2,SVP)

An Optimal Control Application to an Industrial Hydrogenation Reactor

An optimal control system was designed and applied to the acetylene hydrogenation section in an industrial process (EP-300) producing ethylene and propylene. A first principles model was developed for the hydrogenation reactor using industrial palladium pellets as catalyst, and a real time optimization algorithm was devised and incorporated to accommodate changing process conditions. The industrial application continues to be harnessed as it reduced the ethylene loss and increased the catalyst life, rendering important gains.

Metastable Ion Study of Organosilicon Compounds. Part XII. 2-Propoxytrimethylsilane, (CH3)3SiOCH(CH3)2.

Unimolecular decomposition of 2-propoxytrimethylsilane, (CH3)3SiOCH(CH3)2 (Mw: 132, 1), upon electron impact ionization, has been studied by use of mass-analyzed ion kinetic energy (MIKE) spectrometry and D-labeling technique. The abundance of the molecular ion of 1 is too low to measure the MIKE spectrum. A methyl radical loss occurs from two different groups in 1+.; i.e., from either trimethylsilyl group or 2-propyl group. The ion at m/z 117 formed via the latter reaction decomposes into the m/z 73 ion, trimethylsilyl ion, by the loss of acetaldehyde, whereas the ion via the former reaction decomposes exclusively into the m/z 75 ion, hydroxydimethylsilyl ion, by the loss of propene. The methyl loss from the trimethylsilyl group prevails over that from the 2-propyl one.

Study of gas-phase reactivity of positive and negative even-electron ions prepared from diethylmethylphosphonate ester in an external chemical ionization source of orthogonal tandem quadrupole/ion trap instrument

Gas phase reactivity of the protonated and deprotonated diethylmethylphosphonate (DEMP), prepared under positive chemical ionization (PICI) and negative chemical ionization (NICI) conditions in an external high pressure source, was investigated using a recent homemade quadrupole filter/ion trap tandem with an orthogonal ion beam transmission. Ion chemical study with regard to unimolecular dissociation is described, especially with regard to the ion stability at different injection rf levels. The selective injection of the DEMPH + and [DEMP − H] − ions seems to be a very critical step that depends upon the helium buffer gas pressure and the injection low m/z cutoff values (LMCO). Indeed, if the parent ion abundance rises up to 50% of total ion current at a low injection rf level (LMCO of 25 Th), as LMCO is increased extend fragmentations are favored. Such decompositions mainly involved 1–5 proton transfers leading to competitive and/or consecutive losses of ethylene and water. The ion abundance versus the injection rf level presents real energy resolved dependence. Ion/molecule reactions initiated by reactive fragments of externally prepared DEMPH + [e.g. PO +, P(OH) 2 +, H 2CP(OH) 2 +, OP(OH) 2 +, H 3C–POEt +, H 3C–PO(OCH 3) +, H 3C(OH) 2POH +, H 3C–PO(OEt) +, CH 3(OEt)HPOH +, CH 3(OH)(CH 2CHO)POH +, CH 3(OH)(OEt)POH +, CH 3(OCH 3)(CH 2CHO)POH +] have been investigated. These fragment ions, selected using a quadrupole filter, induce selective ion/molecule reactions with the DEMP molecules directly introduced into the ion trap cell. The exothermic reactions observed are (1) a proton transfer process and (2) proton-bound dimer formation, as well as stepwise addition/elimination reactions in which the first electrophilic attack at the phosphorous site of the DEMP is followed by ethylene loss. On the other hand, by selecting and injecting negative ions like alkoxide species (externally formed from aliphatic alcohols in NICI), nucleophilic attacks such as a S N 2-P pathway on DEMP can occur. However, most of the ions are generated by elimination and/or deprotonation mechanisms. Alkoxide size and alcohol nucleophilic character significantly influence the orientation of the various ion/molecule reactions.

Selective Hydrogenation of an Acetylene Process: An Example of Modeling an Industrial Reactor Process

Acetylene obtained from the hydrocarbon mixture in cracking plants is hydrogenated to form ethylene; however, losses of ethylene in further reactions is not economical. The reduction of these losses and improved catalyst performance are presented by the authors, who illustrate the modeling and simulation of selective hydrogenation of acetylene as convenient methods for analyzing, optimizing operating conditions or even designing processes.

Insights into the C(4)H(8)(+.) potential energy surface: fourier transform ion cyclotron resonance studies of ion-molecule reactions of D-labeled partners

Reactions of [ethylene](+.) with ethylene and of [acetylene](+.) with ethane were studied by Fourier transform ion cyclotron resonance spectrometry using labeled reactants. The results confirm and clarify the different steps of the mechanism proposed previously and elaborated with other methods. The [[acetylene](+.), ethane] system can either dissociate to give the ethyl cation product, or isomerize into [[ethylene](+.), ethylene]. The latter system can either dissociate to yield ionized ethylene or convert into ionized but-2-ene, which undergoes a complete H-exchange prior to dissociation, leading to methyl radical, hydrogen radical and ethylene losses. The transfers of labeled atoms and the existence of H-exchange prior to formation of the products were used as a probe to check the different steps of the mechanism. The influence of the initial energy of the system on the reaction pathway is discussed. Copyright 1999 John Wiley & Sons, Ltd.

Insights into the C4H8+· potential energy surface: Fourier transform ion cyclotron resonance studies of ion–molecule reactions of D-labeled partners

Reactions of [ethylene]+· with ethylene and of [acetylene]+· with ethane were studied by Fourier transform ion cyclotron resonance spectrometry using labeled reactants. The results confirm and clarify the different steps of the mechanism proposed previously and elaborated with other methods. The [[acetylene]+·, ethane] system can either dissociate to give the ethyl cation product, or isomerize into [[ethylene]+·, ethylene]. The latter system can either dissociate to yield ionized ethylene or convert into ionized but-2-ene, which undergoes a complete H-exchange prior to dissociation, leading to methyl radical, hydrogen radical and ethylene losses. The transfers of labeled atoms and the existence of H-exchange prior to formation of the products were used as a probe to check the different steps of the mechanism. The influence of the initial energy of the system on the reaction pathway is discussed. Copyright © 1999 John Wiley & Sons, Ltd.

Synthesis of B- and P-Heterocycles by Reaction of Cyclic Acetals and Ketals with Borinium and Phosphonium Ions.

Tricoordinated cyclic boron cations result from gas-phase ion/molecule reactions of dicoordinated borinium ions with neutral acetals and ketals and thiazolidine. The reaction, which proceeds via initial cationic binding to a heteroatom followed by a consecutive ring-opening and ring-reclosing process, resembles the Eberlin transacetalization of acylium ions (Eberlin, M. N.; Cooks, R. G. Org. Mass Spectrom. 1993, 28, 679). The cyclic structure of the tricoordinated boron cation is demonstrated by tandem mass spectrometry and further confirmed by comparison with authentic cyclic tricoordinated boron cations. The five-membered cyclic boron cations dissociate by ethylene oxide loss to thus reform the reactant-dicoordinated borinium ion; the six-membered boron cations fragment instead by ethylene loss. Consistent with the proposed mechanism, the ion/molecule reaction efficiency falls in the order CH(3)OB(+)C(2)H(5) > CH(3)OB(+)OCH(3) >> CH(3)B(+)CH(3); i.e., the higher the nucleophilicity of the borinium ion, the higher the reaction efficiency. A potential energy surface is calculated for the reaction of CH(3)OB(+)OCH(3) with 2-methyl-1,3-dioxolane, and the reaction is found to be 43.3 kcal/mol exothermic due to initial formation of a strong B-O bond. The analogous reactivity displayed by phosphonium ions is also investigated by both experiment and ab initio calculations. In contrast to the borinium ions, the phosphonium ions exhibit higher regioselectivity for sulfur compared to nitrogen and oxygen. Finally, the present findings indicate that the reaction exothermicity and the regioselectivity are controlled by both the Lewis acidity of the reactant cations and the leaving ability of the released neutrals in the rate-limiting nucleophilic-induced recyclization step.

Ethene loss kinetics of methyl butanoate ions studied by threshold photoelectron–photoion coincidence:: The enol ion of methyl acetate heat of formation

Threshold photoelectron–photoion coincidence spectroscopy has been used to investigate the unimolecular chemistry of gas-phase methyl butanoate ions (CH 3CH 2CH 2COOCH 3 ·+). This ester ion isomerizes to a lower energy distonic ion (CH 2CH 2CH 2COHOCH 3 ·+) prior to dissociating by the loss of C 2H 4. The asymmetric time of flight distributions, which arise from the slow rate of dissociation at low ion energies, provide information about the ion dissociation rates. By modeling these rates with assumed k( E) functions, the thermal energy distribution for room temperature and molecular beam samples, and the analyzer function for threshold electrons, it was possible to extract the dissociative photoionization limit for methyl butanoate which at 0 K is 10.275 ± 0.010 eV as well as the dissociation barrier of the distonic ion of 0.735 ± 0.010 eV. By combining these with an estimated heat of formation of methyl butanoate, we derive a 0 K heat of formation of the distonic ion CH 2CH 2CH 2COHOCH 3 ·+ of 119.0 ± 2.0 kcal/mol. The product ion is the enol of methyl acetate, CH 2COHOCH 3 ·+, which has a derived heat of formation at 0 K of 122.0 ± 2.0 kcal/mol. This energy agrees well with a derived energy obtained recently from the rate analysis of energy selected methyl acetate ions. Also measured was the adiabatic ionization energy of the methyl butanoate, 9.95 ± 0.05 eV.

Ethene loss kinetics of methyl 2-methyl butanoate ions studied by threshold photoelectron–photoion coincidence: the enol ion of methyl propionate heat of formation

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the unimolecular chemistry of gas-phase methyl 2-methyl butanoate ions [CH 3CH 2CH(CH 3)COOCH 3 ·+]. This ester ion isomerizes to a lower energy distonic ion [CH 2CH 2CH(CH 3)COHOCH 3 ·+] prior to dissociating by the loss of C 2H 4. The asymmetric time of flight distributions, which arise from the slow rate of dissociation at low ion energies, provide information about the ion dissociation rates. By modeling these rates with assumed k( E) functions, the thermal energy distribution for room temperature sample, and the analyzer function for threshold electrons, it was possible to extract the dissociative photoionization threshold for methyl 2-methyl butanoate which at 0 K is 9.80 ± 0.01 eV as well as the dissociation barrier of the distonic ion of 0.86 ± 0.01 eV. By combining these with an estimated heat of formation of methyl 2-methyl butanoate, we derive a 0 K heat of formation of the distonic ion CH 2CH 2CH(CH 3)COHOCH 3 ·+ of 101.0 ± 2.0 kcal/mol. The product ion is the enol of methyl propionate, CH 3CHCOHOCH 3 ·+, which has a derived heat of formation at 0 K of 106.0 ± 2.0 kcal/mol.

An investigation of C–S bond activation in transition metal crown thioether complexes using extended Hückel theory and electrospray mass spectrometry

Complexes of Re and Tc with 1,4,7-trithiacyclononane (9S3) differ from their later transition metal analogues in that their d6 form ([M(9S3)2]+) undergoes instantaneous C–S bond cleavage yielding ethene and [M(9S3)L]+ (L = SCH2CH2SCH2CH2S), a stable metal(III) thiolate complex, cleanly in aqueous solution. This contrast is interpreted as signifying increased π-back donation by Re and Tc, compared to later metals, into ligand C–S σ* orbitals. In order to validate this hypothesis within an established theoretical framework, and to compare the predicted relative C–S bond lability with relative experimental lability in a series of d6 analogues, extended Hückel theory (EHT) was used to investigate the bonding (M = Mo, Tc, Ru, Rh or Pd) while electrospray mass spectrometry (ES-MS) was used to compare ethene loss, in a series of analogous complexes (M = Tc, Re, Ru or Os). The C–S overlap populations were smaller for M = TcII and TcI than for later metal(II) analogues, and were smaller for TcI than for TcII. Fragment molecular orbitals corresponding to C–S σ* were more highly populated for M = TcII and TcI than for later analogues, and also more highly populated for TcI than for TcII. ES-MS showed that ethene loss from Tc/ReI and Tc/ReII complexes occurred at much lower energies than from the Ru/OsII analogues. EHT supports the hypothesis that C–S activation is caused by π-back donation into C–S σ* orbitals, and correctly predicts that ethene loss occurs more readily from rhenium and technetium d5 and especially d6 complexes than from later transition metal analogues.

Mass spectrometry of di-tert-butylnaphthalenes and benzyl- tert-butylnaphthalenes: hydrogen migration and intermediate ion–molecule complexes in tert-butylated naphthalene ions

The mass spectrometric fragmentations of isomeric di-tert-butylnaphthalenes 1-6 and benzyl-tert-butylnaphthalenes 8 and 9 have been studied using deuterated derivatives and the methods of tandem mass spectrometry. The molecular ions of 1-6, 8 and 9 decompose almost exclusively by the loss of a methyl radical. The unimolecullar fragmentations of the resulting substituted 2-naphthyl-2-propyl cations 1a-6a, 8a and 9a show analogies to the fragmentation of unsubstituted 2-naphthyl-2-propyl cations but exhibit an interesting dependence of the reactions on the relative orientation of the tert-butyl or the benzyl substituent. Thus, the losses of ethene and of a methyl radical are observed as for the unsubstituted 2-naphthyl-2-propyl cation ions by rearrangements of the ionized propyl side chain. However, in the case of tert-butyl substituted 2-naphthyl-2-propyl cations 1a-6a, the loss of methyl increases distinctly if a naphthoquinodimethane radical cation can be formed by loss of methyl from the tert-butyl substituent, This is proven by D-labeling and indicates a particular stability of the quinoid radical cations. Further, the mass-analyzed ion kinetic energy spectra of the cations 1a-6a, 8 and 9 are characterized by intense signals owing to the tert-butyl cation or benzyl cation. The exception is metastable 4a which expels almost exclusively propene, This latter fragmentation is attributed to reactive interactions between the two side chains in a crowded 2,3-position at the naphthalene ring of 4a, The release of cations corresponding to the tert-butyl or benzyl substitueut from metastable substituted 2-naphthyl-2-propyl cations occurs by proton transfer from the ionized propyl side chain to the naphthalene ring, followed by protolytic cleavage of the substituent and involves the formation of intermediate ion-molecule complexes. This is shown in the case of tert-butylated ions 1a-6a by proton transfer from the tert-butyl cation to the naphthalene moiety and subsequent elimination of isobutene, In the case of the benzylated ions 8a and 9a, the benzyl cation within the complex abstracts a hydride and dissociates as a toluene molecule. Independent proof of intermediate ion-molecule complexes, consisting of a tert-butyl or a benzyl cation and a propenylnaphthalene molecule, comes from the observation of unexpected fragmentations which require addition of the carbenium ion within the complex to the double bond of the propenyl side chain. Both for the tert-butyl cation and for the benzyl cation, the abundance of these intermolecular reactions exhibits a hitherto unknown dependence on the orientation of the two side chains and are most intense in the case of a 1,4-orientation. A possible explanation is a dependence of the excess energy and life time of the intermediate ion-molecule complex on the structure of the precursor.

Electron ionization induced metastable decompositions of isomeric trimethylsilylmethanol, (CH 3) 3SiCH 2OH, and methoxytrimethylsilane, (CH 3) 3SiOCH 3

The metastable decompositions of trimethylsilylmethanol, (CH 3) 3SiCH 2OH (MW: 104, 1) and methoxytrimethylsilane, (CH 3) 3SiOCH 3 (MW: 104, 2) upon electron ionization have been investigated by use of mass-analyzed ion kinetic energy (MIKE) spectroscopy and D labeling. The metastable ions of 1 ·+ decompose to give the fragment ions m/ z 89 (CH 3 · loss) and 73 ( ·CH 2OH loss), whereas those of 2 ·+ only yield the fragment ion m/ z 89 (CH 3 · loss). The latter fragment ion is generated by loss of a methyl radical from the trimethylsilyl group via a simple cleavage reaction as shown by D labeling. However, the fragment ions m/ z 89 and 73 from 1 ·+ are generated following an almost statistical exchange of the original methyl and methylene hydrogen atoms in the molecular ion as shown also by D labeling. This exchange indicates a complex rearrangement of the molecular ion of 1 ·+ prior to metastable decomposition for which as key step a 1,2-trimethylsilyl group migration from carbon to oxygen is suggested. A different behavior is also found between the source-generated m/ z 89 ions from 1 ·+ which decompose in the metastable time region to give ions m/ z 61 by loss of ethylene and those from 2 ·+ which decompose in the metastable region to yield ions m/ z 59 by elimination of formaldehyde.

Real-Time Optimization and Control of Industrial Alkyne Hydrogenation

An optimal control system was designed and applied to the alkyne hydrogenation section in an industrial process (EP-300) producing ethylene and propylene. A nonlinear model was developed for the catalytic hydrogenation reactor and a real time optimization algorithm was devised and incorporated. The application reduced the ethylene loss and increased the catalyst life, rendering important gains.

A Kinetic Study of the Thermal Loss of Ethylene from CpNb(CO)3(η2-C2H4) in Supercritical Fluid Solvents

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Kinetic Study of the Thermal Loss of Ethylene from CpNb(CO)3(η2-C2H4) in Supercritical Fluid SolventsJohn C. Linehan, Clement R. Yonker, J. Timothy Bays, S. Thomas Autrey, Thomas E. Bitterwolf, and Skip GallagherView Author Information Chemical Sciences Department Pacific Northwest National Laboratory† P.O. Box 999, Richland, Washington 99352 Chemistry Department University of Idaho Moscow, Idaho 83844-2343 Cite this: J. Am. Chem. Soc. 1998, 120, 23, 5826–5827Publication Date (Web):May 29, 1998Publication History Received1 December 1997Published online29 May 1998Published inissue 1 June 1998https://doi.org/10.1021/ja974054tCopyright © 1998 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views84Altmetric-Citations12LEARN 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 Read OnlinePDF (33 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Hydrocarbons,Kinetics,Photodissociation,Solvents,Transition metals Get e-Alerts

Fragmentation of organosulfur compounds upon electron impact. Part III. Metastable decomposition of the molecular ions of methyl thioglycolate and ethyl thioglycolate

The metastable decompositions of the molecular ions of methyl thioglycolate (1) and ethyl thioglycolate (2) were investigated by means of mass analyzed ion kinetic energy (MIKE) spectra and deuterium labeling. The loss of methanol is the only metastable decomposition of 1+·. This fragmentation occurs via two distinct pathways. The molecular ions of 2 decompose in a variety of ways, i.e., the losses of water, ethene, ethanol or Ċ2H3O2. All of these decompositions, except the loss of ethene, occur through two distinct mechanisms. During the loss of Ċ2H3O2, the ethyl group or ethene migrates from the oxygen to the sulfur atom. The loss of HĊS, which corresponds to the loss of HĊO with a concomitant double hydrogen transfer observed in the case of methyl glycolate (3), does not participate in the metastable decomposition of 1+· and 2+·. This is due to the energetic favorableness of the loss of methanol.