Estimation by bond-additivity schemes of the relative thermodynamic stabilities of three-membered-ring systems and their open dipolar forms

Liebman, Joel F.; Greenberg, Arthur

doi:10.1021/jo00916a001

Cited by 51 publications

(19 citation statements)

References 21 publications

(32 reference statements)

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“…The relative stability of ring-closed form 1 vs ring-opened form 2 is dependent on the substituents R. Calculations have predicted that for the parent -lactone (R ¼ H), ring-closed form 1 is significantly lower in energy than ring-opened form 2. [6][7][8] Calculations have also shown that, as expected, substitution with electron-donating R groups, and also polar solvation, preferentially stabilize 2. 9 Nucleophilic attack of alcohols (e.g.…”

Section: Introductionmentioning

confidence: 71%

Time‐resolved IR studies of α‐lactones

Showalter

Toscano

2004

J of Physical Organic Chem

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epoc ABSTRACT: A series of -lactones were generated from the reaction of phenylchlorocarbene, 4-nitrophenylchlorocarbene, diphenylcarbene, bis(4-nitrophenyl)carbene and bis(4-methoxyphenyl)carbene with carbon dioxide and examined by nanosecond time-resolved infrared (TRIR) spectroscopy. Estimated second-order rate constants for the reaction of these carbenes with carbon dioxide indicate that more nucleophilic carbenes react at faster rates, in agreement with previous low-temperature matrix experiments. Spectral TRIR data confirms that the structure oflactones is dependent both on substituents at the -carbon and on solvent polarity, with electron-donating substituents and polar solvents favoring a zwitterionic ring-opened structure as opposed to the three-membered ring oxiranone form. B3LYP calculations using self-consistent reaction field (SCRF) methods also provide support for these experimental investigations.

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Section: Introductionmentioning

confidence: 71%

Time‐resolved IR studies of α‐lactones

Showalter

Toscano

2004

J of Physical Organic Chem

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“…Many of the chemical reactions of the a-lactones have been explained by invoking a higher-energy ring-opened zwitterionic form (2). The relative stability of ring-closed form (1) versus ring-opened form (2) is dependent on the substituent R. Calculations have predicted that for the parent a-lactone (R=H), ring-closed form (1) is significantly lower in energy than ring-opened form (2) [11][12][13][14][15]. It is well known that an exocyclic double bond increases the ring strain energy of three-membered rings carbocycles and heterocycles [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Theoretical characterization of the chemical bonds of some three-membered ring compounds through QTAIM theory

Duarte

Miranda

Silva³

et al. 2015

Struct Chem

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In this paper, we investigate the nature of the carbonyl and the intraring C-C, C-N, C-O, N-N, O-O and N-O bonds of cyclopropanone and the following cyclopropanone derivatives: aziridine-2-one (1); oxirane-2-one (2); 1,2-diaziridine-3-one (3); 1,2-dioxirane-3-one (4); 1,2-oxaziridine-3-one (5); cyclopropane-1,2-dione (6); aziridine-2,3-dione (7); and oxirane-2,3-dione (8). The intramolecular distribution of the electronic charge density and the L(r) = -r 2 q(r) function have been investigated within the framework of the quantum theory of atoms in molecule theory. This methodology allowed us to characterize the bonds of cyclopropanone and the cyclopropanone derivatives studied here.

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“…Quite probably, CH 2 COO corresponds to oxacyclopropanone (Scheme 4) because such a fragment is more stable by 279 kJ mol À1 than the isomeric methylenedioxirane. [24] Moreover, although the separated fragments CO and CH 2 O are thermodynamically more stable by about 98 kJ mol À1 than intact oxacyclopropanone, [25] we note the absence of signals indicative for the elimination of any of these molecules. Nevertheless, a stepwise scenario cannot be rigorously excluded based on the experimental results.…”

Section: Origins Of Ptchmentioning

confidence: 68%

The “Missing Link”: The Gas‐Phase Generation of Platinum–Methylidyne Clusters Pt_nCH⁺ (n=1, 2) and Their Reactions with Hydrocarbons and Ammonia

Butschke

Schwarz

2011

Chemistry A European J

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Electrospray ionization (ESI) of tetrameric platinum(II) acetate, [Pt(4)(CH(3)COO)(8)], in methanol generates the formal platinum(III) dimeric cation [Pt(2)(CH(3)COO)(3)(CH(2)COO)(MeOH)(2)](+), which, upon harsher ionization conditions, sequentially loses the two methanol ligands, CO(2), and CH(2)COO to form the platinum(II) dimer [Pt(2)(CH(3)COO)(2)(CH(3))](+). Next, intramolecular sequential double hydrogen-atom transfer from the methyl group concomitant with the elimination of two acetic acid molecules produces Pt(2)CH(+) from which, upon even harsher conditions, PtCH(+) is eventually generated. This degradation sequence is supported by collision-induced dissociation (CID) experiments, extensive isotope-labeling studies, and DFT calculations. Both PtCH(+) and Pt(2)CH(+) react under thermal conditions with the hydrocarbons C(2)H(n) (n=2, 4, 6) and C(3)H(n) (n=6, 8). While, in ion-molecule reactions of PtCH(+) with C(2) hydrocarbons, the relative rates decrease with increasing n, the opposite trend holds true for Pt(2)CH(+). The Pt(2)CH(+) cluster only sluggishly reacts with C(2)H(2), but with C(2)H(4) and C(2)H(6) dihydrogen loss dominates. The reactions with the latter two substrates were preceded by a complete exchange of all of the hydrogen atoms present in the adduct complex. The PtCH(+) ion is much less selective. In the reactions with C(2)H(2) and C(2)H(4), elimination of H(2) occurs; however, CH(4) formation prevails in the decomposition of the adduct complex that is formed with C(2)H(6). In the reaction with C(2)H(2), in addition to H(2) loss, C(3)H(3)(+) is produced, and this process formally corresponds to the transfer of the cationic methylidyne unit CH(+) to C(2)H(2), accompanied by the release of neutral Pt. In the ion-molecule reactions with the C(3) hydrocarbons C(3)H(6) and C(3)H(8), dihydrogen loss occurs with high selectivity for Pt(2)CH(+), but in the reactions of these substrates with PtCH(+) several reaction routes compete. Finally, in the ion-molecule reactions with ammonia, both platinum complexes give rise to proton transfer to produce NH(4)(+); however, only the encounter complex generated with PtCH(+) undergoes efficient dehydrogenation of the substrate, and the rather minor formation of CNH(4)(+) indicates that C-N bond coupling is inefficient.

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Estimation by bond-additivity schemes of the relative thermodynamic stabilities of three-membered-ring systems and their open dipolar forms

Cited by 51 publications

References 21 publications

Time‐resolved IR studies of α‐lactones

Time‐resolved IR studies of α‐lactones

Theoretical characterization of the chemical bonds of some three-membered ring compounds through QTAIM theory

The “Missing Link”: The Gas‐Phase Generation of Platinum–Methylidyne Clusters Pt_nCH⁺ (n=1, 2) and Their Reactions with Hydrocarbons and Ammonia

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Estimation by bond-additivity schemes of the relative thermodynamic stabilities of three-membered-ring systems and their open dipolar forms

Cited by 51 publications

References 21 publications

Time‐resolved IR studies of α‐lactones

Time‐resolved IR studies of α‐lactones

Theoretical characterization of the chemical bonds of some three-membered ring compounds through QTAIM theory

The “Missing Link”: The Gas‐Phase Generation of Platinum–Methylidyne Clusters PtnCH+ (n=1, 2) and Their Reactions with Hydrocarbons and Ammonia

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The “Missing Link”: The Gas‐Phase Generation of Platinum–Methylidyne Clusters Pt_nCH⁺ (n=1, 2) and Their Reactions with Hydrocarbons and Ammonia