Photochemistry of ketene and of ketene-benzene mixtures.  Reactions of methylene radicals

Ho, S. K.; Noyes, W. Albert

doi:10.1021/ja00996a001

Cited by 34 publications

(11 citation statements)

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“…Hence ci would be expected to decrease if k, is fairly constant. This could saccount for the much lower value of ci found by DeGraff and Kistiakowsky (10) at 50 "C as compared with the values reported by others (8,12) working at 24 and 27 "C.…”

Section: Plotsmentioning

confidence: 59%

“…On the basis of [I]- [9], the fraction of methylenes formed which are singlet is ci = k2/A and should therefore be independent of pressure. Other workers (8,12), while disagreeing on the exact value of ci at this wavelength, agree that it shows little variation with pressure. The slopes listed in Table I decrease with increasing temperature.…”

Section: Plotsmentioning

confidence: 81%

“…Reaction [2] is decomposition into singlet methylene ('cH,) and carbon monoxide. There is evidence that some singlet methylenes are formed at 3660 A, although estimates of the percentage of the total methylenes which are singlet at this wavelength vary (7,8,10,12).…”

Section: Methodsmentioning

confidence: 99%

“…However, evidence has been mounting that triplet methylene as well as singlet methylene is formed during the photolysis at all wavelengths, the proportion increasing as the wavelength is lengthened (6)(7)(8)(9)(10)(11)(12). This has necessitated postulating the formation of triplet ketene as the precursor of triplet methylene and thrown doubts on the validity of the simple mechanism upon which the comparisons of reaction rate theory with experiment have been based.…”

Section: Introductionmentioning

confidence: 99%

“…This has necessitated postulating the formation of triplet ketene as the precursor of triplet methylene and thrown doubts on the validity of the simple mechanism upon which the comparisons of reaction rate theory with experiment have been based. Several new mechanisms for the photolysis have recently been proposed (12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

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Photolysis of ketene. I

Strachan¹,

Thornton²

1968

Can. J. Chem.

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Ketene has been photolyzed at 3660 and 3130 A both alone and in the presence of the inert gases CqF8 and SF,. The quantum yield of carbon monoxide has been determined a t both wavelengths as a function of pressure and temperature. At 3660 A the quantum yield decreases with increasing pressure but increases with increasing temperature. At 3130 A the quantum yield with ketene alone remains 2.0 at both 37 and 100 "C at pressures up to 250 mm. At higher pressures of ketene or with added inert gas the quantum yield decreases with increasing pressure. The results are interpreted in terms of a mechanism in which intersystem crossing from the excited singlet state to the triplet state occurs at both wavelengths, and collisional deactivation of the excited singlet state by ketene is single stage at 3660 A but multistage at 3130 A.

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Section: Plotsmentioning

confidence: 59%