CH2 reactions

Transformations of the more highly substituted styrenyl ethers are notably more facile under an atmosphere of ethylene due to the presence of the more reactive LnRu=CH2 (formed by the reaction of la or lb with ethylene) [20]. Under an atmosphere of Ar and after the first turnover has transpired, LnRu= CHCH3 is likely the participating catalyst. When the reaction is performed under ethylene, LnRu=CHCH3 is immediately converted to LnRu=CH2. Reactions of monosubstituted styrenes do not require ethylene to proceed smoothly because, as illustrated in Scheme 10, with this class of starting materials, the more reactive LnRu=CH2 is formed following the first catalytic cycle. 

Bell and Kistiakowsky found that addition of about 2% 02 in the photolysis of CH2N2-H2 mixtures had little effect on the yields of CH4 and C2H4, which were formed by CH2 reactions, but greatly reduced the yield of ethane by scavenging methyl radicals. 

Failure of added 02 to affect CH2 reactions in the experiments described above does not prove that the reaction of CH2 with 02 is slow, because methylene reacts with CH2CO, olefins, H2, and CH4 very rapidly, and in most cases 02 was added in relatively small amount. The reaction... 

The lowest-lying potential energy surfaces for the 0(3P) + CH2=C=CH2 reaction were theoretically characterized using CBS-QB3, RRKM statistical rate theory, and weak-collision master equation analysis using the exact stochastic simulation method. The results predicted that the electrophilic O-addition pathways on the central and terminal carbon atom are dominant up to combustion temperatures. Major predicted end-products are in agreement with experimental evidence. New H-abstraction pathways, resulting in OH and propargyl radicals, have been identified.254... 

The products of the (e q + RCH=CH2) reaction are RCH—CH2 earbanions. Some of these have been identified by their chemical reactivity. Others have been observed through their absorption spectra by means of pulse-radiolysis techniques. The carbanion of acrylamide, for instance, has been shown to dimerize, to react with other free radicals, inducing anionic polymerization, and to react with oxygen, Ag+ and Fe(CN) - ions, presumably by electron-transfer reactions (Chambers et al., 1967). The absorption spectrum of the product of the (dimethyl fumarate + ey5) reaction has been observed in alkaline solution. The rate... 

For sulfur, s, the number of internal degrees of freedom will be somewhat less than for CH2. Also the ring strain in the episulfide molecule is less than in cyclopropane which will increase A and decrease E relative to the CH2 reaction. The A factor may also be larger because the presence of the heavy sulfur atom may facilitate spin inversion. There should therefore be an increase in the value of fcj. The exothermicity of the reaction and the excess energy remaining in the radical should, however, be somewhat less in the sulfur case. If we accept the recently suggested high value of 66.0 kcal./mole for AH/ of sulfur atoms, the overall exothermicity is ca. 

C2H5)3GeC=CCH=CH2 Reaction with RCaX, RBaX 5.4.3.4.1... 

Fe( / -C5H5XCO)2CHCH2CH2 a-Hydride abstraction 5.8.225 Fe( / -C5H5XCO)2CH2CH=CH2 Reaction with Fp(olefin) S.8.2.3.4 Reaction with [PhjClCBF ] 5.8.2.2.S Reaction with TCNE 5.8.23.4... 

Fig. 19. Boltzmann plots for the CO formed in the 0( / )+CH3C2H and CH2 C=CH2 reactions. Solid lines theoretically predicted population distributions. Reprinted with permission from Chem. Phys., 20, 271 (1977). Copyright by North-Holland Publishing Company.

The 0( F)-1-CH2 reaction, an important process in combustion chemistry, has been proposed to proceed by two major channels " ... 

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