The 4875 Å Band System of <i>cis</i> Glyoxal

Currie, G. N.; Ramsay, D. A.

doi:10.1139/p71-037

Cited by 122 publications

(22 citation statements)

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“…t' p b . byl4 po ariza ion, d' can e given ( 1) where N 0 = Avagadro's number °" = polarizability of the molecule In addition to the distortion polarization, polar molecules also have orientation polarization, P, due to u the presence of a permanent dipole moment. 14 …”

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confidence: 99%

Intramolecular torsional potential and dielectric properties of 2,3-butanedione

Henderson¹,

Meyer²

1976

J. Phys. Chem.

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confidence: 99%

Intramolecular torsional potential and dielectric properties of 2,3-butanedione

Henderson¹,

Meyer²

1976

J. Phys. Chem.

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“…This biradical would also be stabilized relative to CBD by relief of the repulsion between the carbonyl groups, which can be taken as about 3 kcal/mol, the difference between the heats of formation of cis-and trans-glyoxal (6,14). Taking this into account, an additional 10 kcal/mol of stabilization, persisting in the transition state, would still be needed to reach the 39.3 kcal/mol activation energy measured for CBD.…”

Section: Discussionmentioning

confidence: 99%

The thermal decomposition of cyclobutane-1,2-dione

Cao¹,

Back²

1985

Can. J. Chem.

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J.-R. CAO and R. A. BACK. Can. J. Chem. 63, 2945 (1985). The thermal decomposition of cyclobutane-l,2-dione has been studied in the gas phase at temperatures from 120 to 25OoC and pressures from 0.2 to 1.5 Tom. Products were CzH4 + 2C0, apparently formed in a simple unimolecular process. The first-order rate constant was strongly pressure dependent, and values of k" were obtained by extrapolation of plots of Ilk vs. l l p to I l p = 0. Experiments in a packed reaction vessel showed that the reaction was enhanced by surface at the lower temperatures. Arrhenius parameters fork", corrected for surface reaction, were log A (s-') = 15.07 (20.3) and E = 39.3 ( k 2 ) kcal/mol. This activation energy seems too low for a biradical mechanism, and it is suggested that the decomposition is probably a concerted process. The vapor pressure of solid cyclobutane-l,2-dione was measured at temperatures from 22 to 62°C and a heat of sublimation of 13.1 kcallmol was estimated.J.-R. CAO et R. A. BACK. Can. J. Chem. 63, 2945 (1985).OpCrant h des tempkratures allant de 120 a 250°C et dans un intervalle de pression allant de 0,2 a 1,5 Torr, on a CtudiC la dCcomposition thermique de la cyclobutanedione-l,2. Les produits de la reaction sont le C2H4 + 2C0 qui sont apparemment formCs par une reaction unimolCculaire simple. La constante de vitesse d'ordre un dCpend beaucoup de la tempCrature et l'exhapolation des courbes de Ilk vs. l l p jusqu'a Ilp = 0 permet d'obtenir la valeur de k". Des expkriences conduites dans un rCacteur contenant un remplissage-montrent que, a basse tempkrature, la surface de contact augmente la vitesse de la reaction. Les paramkhes dlAmhCnius pour k", comigCes pour tenir compte de la surface de contact, sont: log A (s-') = 15,07 (20,3) et E = 39,3 (?2) kcal/mol. Cette Cnergie d'activation semble &tre trop faible pour un mecanisme biradicalaire et on suggkre que la dCcomposition se fait probablement selon un mecanisme concert&. On a mesurk la tension de vapeur de la cyclobutanedione-l,2 solide a des tempkratures allant de 22 a 62°C et on a CvaluC que sa chaleur de sublimation est Cgale ti 13,l kcal/mol.[Traduit par le journal] Introduction Although cyclobutane-1 ,2-dione (hereafter CBD) was first prepared 14 years ago (I), no studies of its thermal or photochemical decomposition have been reported. It is an interesting example of an a-dicarbonyl compound locked into the usually less stable cis configuration; it is also of interest in relation to other cyclic ketones, especially cyclobutanone. Both cyclobutanone (2) and several simple a-dicarbonyl compounds (3-6) have been the subjects of recent research in this laboratory, and for comparison with these systems we have undertaken studies of the spectroscopy, photochemistry, and thermal decomposition of CBD in the vapor phase. The present paper describes the thermal decomposition.

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“…Looking at the absorption spectrum, we noticed that the rotational structure, while similar to that of glyoxal, showed about twice the number of sub-bands. Rotational analysis showed that the band was produced by a cis-isomer of the molecule (96). The molecule in this configuration has a dipole moment and the microwave spectrum was subsequently found.…”

Section: Asyrotmentioning

confidence: 95%

Molecular Spectroscopy: Some Personal Reminiscences

Ramsay¹

1994

Annual Review of Physical Chemistry

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The 4875 Å Band System of cis Glyoxal

Cited by 122 publications

References 2 publications

Intramolecular torsional potential and dielectric properties of 2,3-butanedione

Intramolecular torsional potential and dielectric properties of 2,3-butanedione

The thermal decomposition of cyclobutane-1,2-dione

Molecular Spectroscopy: Some Personal Reminiscences

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