Reversing Intramolecular Kinetic Carbon Isotope Effect in the Gas Phase Decomposition of Oxalic Acid

Lapidus, Gabriel; Barton, Donald; Yankwich, Peter E.

doi:10.1021/j100882a020

Cited by 15 publications

(18 citation statements)

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“…The absence of the cis,cisrotamer is apparently due to the low internal energy content of gas-phase trans,cis-HOCOH, which cannot rotationally interconvert prior to being captured by a He droplet. These results strongly support the oxalic acid decomposition mechanism proposed by Lapidus et al [68][69][70][71] It is more difficult to rationalize the extent to which formic acid is produced in these experiments. In the Ar matrix study, Schriener et al reported a 1:5 ratio of dihydroxycarbene to formic acid upon pyrolysis of oxalic acid.…”

Section: Resultssupporting

confidence: 78%

“…Again, there is no evidence for the cis,cis-rotamer in He droplets, and there was also no evidence for it in the Ar matrix. 36 These observations are consistent with a unimolecular decomposition mechanism of oxalic acid, [68][69][70][71][72] in which a concerted hydrogen migration and C-C bond cleavage produces dihydroxycarbene and CO 2 . Assuming this mechanism, it is expected that the thermal extrusion of CO 2 from the cTc oxalic acid isomer produces trans,trans-HOCOH, whereas the cTt isomer decomposes to trans,cis-(see Fig.…”

Section: Resultssupporting

confidence: 75%

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Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

Broderick

McCaslin

Moradi

et al. 2015

The Journal of Chemical Physics

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Singlet dihydroxycarbene (HOC̈OH) is produced via pyrolytic decomposition of oxalic acid, captured by helium nanodroplets, and probed with infrared laser Stark spectroscopy. Rovibrational bands in the OH stretch region are assigned to either trans,trans- or trans,cis-rotamers on the basis of symmetry type, nuclear spin statistical weights, and comparisons to electronic structure theory calculations. Stark spectroscopy provides the inertial components of the permanent electric dipole moments for these rotamers. The dipole components for trans, trans- and trans, cis-rotamers are (μa, μb) = (0.00, 0.68(6)) and (1.63(3), 1.50(5)), respectively. The infrared spectra lack evidence for the higher energy cis,cis-rotamer, which is consistent with a previously proposed pyrolytic decomposition mechanism of oxalic acid and computations of HOC̈OH torsional interconversion and tautomerization barriers.

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Section: Resultssupporting

confidence: 78%

Section: Resultssupporting

confidence: 75%

Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

Broderick

McCaslin

Moradi

et al. 2015

The Journal of Chemical Physics

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“…But, the, various types of orientations between different functional groups may have the conformers formed in different types of bonding effect. The most important bonding in the oxalic acid system is the interfunctional hydrogen bond, which has been reported in several experimental 1–7 and theoretical studies 7–13. From our recent theoretical study of the simple carboxylic acid RCOOH (R=H, CH 3 , C 2 H 5 , C 6 H 5 , etc.…”

Section: Introductionmentioning

confidence: 85%

Conformers and intramolecular hydrogen bonding of the oxalic acid monomer and its anions

Chen¹,

Shyu²

2000

Int. J. Quant. Chem.

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Density functional theory, B3LYPr6-31G** and B3LYPr6-311 q G 2d,p , and ab initio MP2r6-31G** calculations have been carried out to investigate the conformers, transition states, and energy barriers of the conformational processes of oxalic acid and its anions. QCISDr6-31G** geometrical optimization is also performed in the stable forms. Its calculated energy differences between the two most stable conformers are very near to the related observed value at 7.0 kJrmol. It is found that the structures and relative energies of oxalic acid conformers predicted by these methods show similar Ž . results, and that the conformer L1 C with the double-interfunctional-groups hydrogen 2 h bonds is the most stable conformer. The magnitude of hydrogen bond energies depends on the energy differences of various optimized structures. The hydrogen bond energies will be about 32 kJrmol for interfunctional groups, 17 kJrmol for weak interfunctional Ž . groups, 24 kJrmol for intra-COOH in COOH , and 60 kJrmol for interfunctional 2 Ž . y1 Ž . groups in COOH COO ion if calculated using the B3LYPr6-311 q G 2d,p method.

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“…This is in complete agreement with experimental and theoretical studies on the thermal decomposition of oxalic acid. 7,8 Experimental studies have firmly established that the major decomposition products of pure oxalic acid over the temperature range 400-430 K are equimolar quantities of formic acid and carbon dioxide 7 if other reaction routes, such as metal ion catalysis, catalysis by strong acids or decomposition at the walls of the reaction vessel, which lead to formation of equimolar amounts of CO 2 , CO and water, can be excluded. High-level quantum mechanical calculations 8 indicate that this reaction is a bimolecular process: in a first step oxalic acid fragments into carbon dioxide and dihydroxycarbene.…”

Section: Resultsmentioning

confidence: 99%

A Solvent-Free and Formalin-Free Eschweiler-Clarke Methylation for Amines

Rosenau¹,

Potthast²,

Röhrling³

et al. 2002

Synth Comm

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Primary and secondary amines are N-methylated by a mixture of paraformaldehyde and oxalic acid dihydrate in good to excellent yields. The reaction proceeds without involvement of organic solvents and toxic formalin. Reaction temperatures of 100 C are required for the decomposition of oxalic acid into the intermediate formic acid which acts as the actual reductant. The reaction conditions have been optimized, and the mechanism has been elucidated by means of deuteration experiments.

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Reversing Intramolecular Kinetic Carbon Isotope Effect in the Gas Phase Decomposition of Oxalic Acid

Cited by 15 publications

References 1 publication

Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

Reactive intermediates in 4He nanodroplets: Infrared laser Stark spectroscopy of dihydroxycarbene

Conformers and intramolecular hydrogen bonding of the oxalic acid monomer and its anions

A Solvent-Free and Formalin-Free Eschweiler-Clarke Methylation for Amines

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