The radical cation of trimethylenemethane (TMM.+) and a derivative, 2-isopropylidenecyclopentane-1,3-diyl, were generated by electron ionization of methylenecyclopropane (MCP) and electron-ionization-induced loss of nitrogen from 7-isopropylidene-2,3-diazabicyclo[2.2.1]hept-2-ene, respectively, in a Fourier transform ion cyclotron resonance mass spectrometer. The two radical cations were isolated and their products and reaction rates with various gaseous reagents were measured. TMM.+ displays radical-type reactivity, e.g., it slowly abstracts a hydrogen atom from benzeneselenol and a thio- or selenomethyl radical from dimethyl disulfide and dimethyl diselenide, respectively. This reactivity distinguishes it from the isomeric 1,2- and 1,3-butadiene radical cations. Surprisingly, however, the TMM.+ undergoes electron transfer reactions in addition to radical reactions. The difference between the adiabatic recombination energy of TMM.+ (9.2 +/- 0.1 eV) and the adiabatic ionization energy of MCP (9.4 +/- 0.1 eV; the earlier literature estimate is less than or equal to 9.57 eV), which were experimentally determined in this work, indicates that the above electron abstraction reactions likely involve cyclization to yield MCP land not TMM) as the final neutral product. In sharp contrast to TMM.+, the sterically hindered 2-isopropylidenecyclopentane-1,3-diyl radical cation is unreactive toward most of the reagents studied, including benzeneselenol, dimethyl disulfide, and dimethyl diselenide. The recombination energy of this TMM-type radical cation land thus, the ionization energy of the 3-isopropylidenecyclopentane-1,3-diyl biradical) was measured to be 7.8 +/- 0.1 eV.

Molecular orbital calculations (at the Becke3LYP/6-31G(d) level of theory) indicate that the distonic ion (CH2C)-C-.(CH2)CO+ is planar and has C-2 upsilon symmetry. Most of the positive charge resides at the carbonyl carbon while the odd spin is delocalized over the allyl group. A similar spin distribution was calculated for the allyl radical. Hence, the reactivity of (CH2C)-C-.(CH2)CO+ toward spin traps may be expected to resemble that of the neutral allyl radical. This issue was examined experimentally by using Fourier transform ion cyclotron resonance mass spectrometry. Similar to other carbon-centered free radicals, the gaseous (CH2C)-C-.(CH2)CO+ abstracts H-. from benzeneselenol, CH3Se. from dimethyl diselenide, and I-. from allyl iodide. However, some of these reactions occur at efficiencies that suggest catalysis by the charged group. Further, the reaction of (CH2C)-C-.(CH2)CO+ with dimethyl disulfide was found to proceed in an unprecedented manner. In addition to the expected formation of CH3SCH2C(CH2)CO+ and CH3S. (via CH3S. abstraction), a new distonic ion, (CH3SCHC)-C-.(CH2)CO+, is generated. This ion is likely produced upon H-. abstraction by CH3S. from CH3SCH2C(CH2)CO+ within the collision complex (net CH2S abstraction). The latter reaction has not been reported for distonic radical cations with localized radical sites. Hence, the reaction must be driven by the regeneration of the delocalized allylic radical. This proposal is supported by the observation of CH2S abstraction for the product ion (CH3SCHC)-C-.(CH2)CO+ that also contains a delocalized radical site.

Examination of the reactions of the long-lived (>0.5-s) radical cations of CD3CH2COOCH3 and CH3CH2COOCD3 indicates that the long-lived, nondecomposing methyl propionate radical cation CH3CH2C(O)OCH 3 +· isomerizes to its enol form CH3CH=C(OH)OCH 3 +· (ΔH isomerization ≃ −32 kcal/mol) via two different pathways in the gas phase in a Fourier-transform ion cyclotron resonance mass spectrometer. A 1,4-shift of a β-hydrogen of the acid moiety to the carbonyl oxygen yields the distonic ion ·CH2CH2C+ (OH)OCH3 that then rearranges to CH3CH=C(OH)OCH 3 +· probably by consecutive 1,5- and 1,4-hydrogen shifts. This process is in competition with a 1,4-hydrogen transfer from the alcohol moiety to form another distonic ion, CH3CH2C+(OH)OCH 2 · , that can undergo a 1,4-hydrogen shift to form CH3CH=C(OH)OCH 3 +· . Ab initio molecular orbital calculations carried out at the UMP2/6-31G** + ZPVE level of theory show that the two distonic ions lie more than 16 kcal/mol lower in energy than CH3CH2C(O)OCH 3 +· . Hence, the first step of both rearrangement processes has a great driving force. The 1,4-hydrogen shift that involves the acid moiety is 3 kcal/mol more exothermic (ΔH isomerization=−16 kcal/mol) and is associated with a 4-kcal/mol lower barrier (10 kcal/mol) than the shift that involves the alcohol moiety. Indeed, experimental findings suggest that the hydrogen shift from the acid moiety is likely to be the favored channel.

The reactivity of the prototypical phosphorus-containing ylidion (alpha-distonic ion) (CH2PH3+)-C-. has been investigated in the gas phase by using a dual cell Fourier-transform ion cyclotron resonance mass spectrometer. The ion (CH2PH3+)-C-. and its more stable conventional isomer CH3PH2.+ show distinctly different reactivities toward neutral reagents. This observation contrasts the facile interconversion of the analogous sulfur- and oxygen-containing distonic ions (CH2SH2+)-C-. and (CH2OH2+)-C-. with their conventional isomers CH3OH.+ and CH3SH.+, respectively, within collision complexes in the gas phase. Bracketing experiments yield a proton affinity of 190.4 +/- 3 kcal mol(-1) for the phosphorus atom in (CH2PH2)-C-.. Together with a calculated heat of formation for (CH2PH2)-C-., this value yields a heat of formation of 217 +/- 3 kcal mol(-1) (at 298 K) for the distonic ion (CH2PH3+)-C-..

The intrinsic chemical properties of the prototype organosulfur distonic ion (CH2SH2+)-C-. have been examined in the gas phase in a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. These studies reveal that the reactivity of the ion (CH2SH2+)-C-. is quite different from that reported recently for the analogous oxygen-containing distonic ion (CH2OH2+)-C-.. Facile deprotonation and hydrogen atom abstraction reactions have been reported for the latter ion. However, reaction of (CH2SH2+)-C-. with neutral molecules often yields the radical cation of the neutral reagent. This reaction likely occurs via deprotonation of the ion followed by other reactions within the collision complex. Collisions with neutral reagents with ionization energies greater than or equal to 9.9 eV can result in base-catalyzed isomerization of the distonic ion to the more stable conventional isomer CH3SH.+. The isomerization is revealed by curved kinetics plots and, at long reaction times, by product ions identical to those observed fur the conventional isomer. At short reaction times, however, the reactivity of the unrearranged distonic ion can be probed. Examination of deprotonation reactions yields a gas-phase proton affinity of less than or equal to 176 kcal mol(-1) for (CH2SH)-C-. at the sulfur atom, In combination with the known heats of formation of H+ and (CH2SH)-C-., the new proton affinity value yields a lower limit of 227 kcal mol(-1) for the heat of formation of (CH2SH2+)-C-.. This value is higher than the previously reported experimental value (219 kcal mol(-1)).

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Acyclic Distonic Isomer of Ionized Cyclopentanone: .bul.CH2CH2CH2CH2CO+Rebecca L. Smith, Leonard J. Chyall, Phillip K. Chou, and Hilkka I. KenttaemaaCite this: J. Am. Chem. Soc. 1994, 116, 2, 781–782Publication Date (Print):January 1, 1994Publication History Published online1 May 2002Published inissue 1 January 1994https://pubs.acs.org/doi/10.1021/ja00081a054https://doi.org/10.1021/ja00081a054research-articleACS PublicationsRequest reuse permissionsArticle Views47Altmetric-Citations9LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of amphiphilic ketone epimerizations in cleavable surfactant hostsDavid A. Jaeger, Phillip K. Chou, Durgadas. Bolikal, Dong. Ok, Kwang Yoo. Kim, Jeffrey B. Huff, Eun. Yi, and Ned A. PorterCite this: J. Am. Chem. Soc. 1988, 110, 15, 5123–5129Publication Date (Print):July 1, 1988Publication History Published online1 May 2002Published inissue 1 July 1988https://pubs.acs.org/doi/10.1021/ja00223a035https://doi.org/10.1021/ja00223a035research-articleACS PublicationsRequest reuse permissionsArticle Views193Altmetric-Citations14LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ChemInformVolume 19, Issue 46 Article ChemInform Abstract: Kinetics of Amphiphilic Ketone Epimerizations in Cleavable Surfactant Hosts. D. A. JAEGER, D. A. JAEGER Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorP. K. CHOU, P. K. CHOU Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorD. BOLIKAL, D. BOLIKAL Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorD. OK, D. OK Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorK. Y. KIM, K. Y. KIM Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorJ. B. HUFF, J. B. HUFF Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorE. YI, E. YI Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorN. A. PORTER, N. A. PORTER Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this author D. A. JAEGER, D. A. JAEGER Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorP. K. CHOU, P. K. CHOU Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorD. BOLIKAL, D. BOLIKAL Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorD. OK, D. OK Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorK. Y. KIM, K. Y. KIM Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorJ. B. HUFF, J. B. HUFF Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorE. YI, E. YI Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this authorN. A. PORTER, N. A. PORTER Dep. Chem., Duke Univ., Durham, NC 27706, USASearch for more papers by this author First published: November 15, 1988 https://doi.org/10.1002/chin.198846070Read 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 onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue46November 15, 1988 RelatedInformation