Triplet Methylene Formation on Photolysis of Ketene and Diazomethane<sup>1</sup>

Rabinovitch, B. S.; Watkins, K. W.; Ring, D. F.

doi:10.1021/ja00949a054

Cited by 26 publications

(8 citation statements)

References 1 publication

(1 reference statement)

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“…T h e high pressure results suggest that a t least 20Y0 abstraction is occurring. Abstraction could be due to ground state triplet methylene radicals which have been observed in both ketene and diazomethane photolysis systems (4-7); however, the amount of abstraction may be somewhat larger than the proportion of triplet radicals expected from diazomethane photolysis systems (4)(5)(6)(7).…”

mentioning

confidence: 99%

Gas phase reaction of methylene radicals with monosilane

Simons¹,

Mazac²

1967

Can. J. Chem.

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confidence: 99%

Gas phase reaction of methylene radicals with monosilane

Simons¹,

Mazac²

1967

Can. J. Chem.

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“…These trends were repeated when the "triplet" products were taken in ratio with CP2. Earlier [2], we had described preliminary data as suggesting a maximum, or a plateau, in the ratio of (tripletlsinglet) products. The present data are suggestive of a slight maximum for the ratio TDMCICDMC, and of a monotonic decreasing trend for the other triplet product ratios, 3MBI/CDMC and TP2/CDMC.…”

Section: Ketene 23"mentioning

confidence: 95%

“…Recently, some additional characteristics were described [2] ; the truns-dimethylcyclopropane product increases with pressure relative to cis-dimethylcyclopropane. Originally, it was suggested that the triplet methylene component of the reaction [ lk] may increase with pressure and pass through a maximum or plateau a t reaction pressures of one to two atmospheres [2] ; more recently [3], it has been found that a n alternative explanation of product variation with pressure may lie in a n intrinsic pressure dependence of the product amounts formed from the triplet radical.…”

Section: Introductionmentioning

confidence: 99%

Methylene radical reaction with cis‐butene‐2

Ring

Rabinovitch

1969

Int J of Chemical Kinetics

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A study of the pressure dependence of the C, products from the reaction of cis-butene-2 and methylene is reported. Methylene was produced by the photolysis of diazomethane with 4358 A light at 23" or 56", and by photolysis of ketene with 3200 A radiation at 23" or 100". The change with increasing pressure of the relative amounts of the characteristically "triplet products" (trans-1,2-dimethylcyclopropane, trans-pentene-2 (TP2), and 3-methylbutene-1 (3MB 1)) and "singlet products" (cis-1,2-dimethylcyclopropane (CDMC) and cis-pentene-2 (CP2)) are discussed. The behavior is reminiscent of that found in 3CH2cis-butene-2 systems and can be interpreted in terms of the rapid rate of rearrangement of an initial triplet diradical product component, due to 3CH2, relative to the slower rate and readier collisional stabilization of an initial vibrationally-excited dimethyl cyclopropane product component, due to lCH, . Relative rates of reactions of 'CH, with allylic CH:vinyl CH:C =C in the neat liquid were, for diazomethane, 1 : 1.1 : 7.2 and, for ketene, 1 : 1.2 :6.7.

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“…A reasonable estimate of the relative steady-state concentration of .CH3 is given by the sum, OR,,' + .Rss; this estimate will be supported below. The amounts of the C,,,, products formed by reactions [9] and [lo] were calculated with use of the values of .Rss, ( . R ' + .…”

Section: Calculationsmentioning

confidence: 99%

“…The mechanism for the production of singlet and triplet methylene on photolysis of diazomethane and ketene is still open to speculation (9,10). The mechanisms of photolysis are of no concern for the systems which are studied here in the presence of a large excess of inert gas.…”

Section: Introductionmentioning

confidence: 99%

Reactions of triplet methylene radicals with alkanes

Ring¹,

Rabinovitch²

1968

Can. J. Chem.

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Studies have been made of the products resulting from reaction between triplet methylene and several alkanes, propane, ti-butane, and isobutane. Triplet methylene was produced by photolysis of diazomethane in the presence of a large excess of inert nitrogen gas. Complicating side reactions involving diazomethane were encountered.Observation of higher products allowed the determination of the relative rates of 1°:2":3" H abstraction from C-H bonds; these are -1:14:150. The rate of addition of 3CHt to the C=C bond in ethylene appears to proceed -3.5 times faster than H abstraction from a 3 C-H bond. The possible occurrence of insertion by into C-H bonds is discussed and relative rates of insertion for 1°:2":3" bonds are deduced to be -1 :2:7. Comparisons of the relative rates of inserti0n:abstraction are also given. Studies with propane-d, indicated an isotope effect for abstraction of H:D from the l o position of -3.9; insertion by 3CHz into the same position showed an isotope effect of --2.

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Triplet Methylene Formation on Photolysis of Ketene and Diazomethane¹

Cited by 26 publications

References 1 publication

Gas phase reaction of methylene radicals with monosilane

Gas phase reaction of methylene radicals with monosilane

Methylene radical reaction with cis‐butene‐2

Reactions of triplet methylene radicals with alkanes

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Triplet Methylene Formation on Photolysis of Ketene and Diazomethane1

Cited by 26 publications

References 1 publication

Gas phase reaction of methylene radicals with monosilane

Gas phase reaction of methylene radicals with monosilane

Methylene radical reaction with cis‐butene‐2

Reactions of triplet methylene radicals with alkanes

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Triplet Methylene Formation on Photolysis of Ketene and Diazomethane¹