Alkane elimination

In contrast to the results obtained for dehydrogenation reactions, kinetic energy release distributions for alkane elimination processes can usually be fit with phase space theory. Results for the loss of methane from reaction 9 of Co + with isobutane are shown in Figure 10b. In fitting the... 

Alkane activation by metal atoms by osmium atoms, 273-274 by rhenium atoms, 265-271 by tungsten atoms, 270-272 description, 265 Alkane elimination reactions, processes, 20,22... 

These precursors are generally prepared by alkane elimination (Equation (7a)) or—especially useful with bulkier substituents—the coupling of metal chlorides with lithium pnictides or silyl arsines (Equation (7b)) or salt elimination or silyl halide elimination reactions (Equation (7c)) ... 

The starting material is always the chalcogenol and, consequently, is more used for thiols than selenols and tellurols. There are several types of reactions depending if the starting materials are metal hydrides (hydrogen elimination), complexes with M C (alkane elimination), M-N (transamination), or M-O (hydrolysis) bonds. 

Alkane elimination is readily used for lithium and magnesium organometallic compounds... 

Most five-coordinate aluminum alkyls are prepared by alkane elimination. The first structurally characterized five-coordinate simple aluminum alkyl chelate compound was reported in 1993.82 The compound AlMe[MeO2CC6H4-0-O]2 was formed by the reaction of Me3Al with 2 equiv. of MeO2GC6H4-0-OH. The commonly... 

The polarity of the Al-C bond allows easy derivatization of the five-coordinate aluminum alkyls by alkane elimination (Figure 9). For example, Salen aluminum alkyls LAlMe could be converted to dimeric or polymeric Salen aluminum phosphinates [LAl 02P(H)Ph ] 98 (n = 2 or oo, depending on the Salen ligand backbone)98,99 by reaction with phenyl phosphinic acid, Salen aluminum siloxides LA10SiPh3 by reaction with triphenyl silanol,96 or Salen aluminum alkoxides LAIOR by reaction with an alcohol.100... 

The first step in the hydrolysis reaction is the formation of the water adduct [Eq. (23)] [69], which subsequently eliminates alkane to yield the hydroxide R2A10H. At elevated temperatures, further alkane elimination is observed with the formation of alkyl-alumoxane [67, 68]. Structurally characterized alumoxanes are listed in... 

McAdoo, D.J. Bowen, R.D. Alkane Eliminations From Ions in the Gas Phase. Eur. Mass Spectrom. 1999,5, 389-409. 

Traeger, J.C. Hudson, C.E. McAdoo, D.J. Energy Dependence of Ion-Induced Dipole Complex-Mediated Alkane Eliminations From Ionized Ethers. J. Phys. Chem. 1990,94, 5714-5717. 

Alkane elimination was also observed upon heating of the adducts RaGa NH2-NR R" [4 to 7, Eq. (2)] in boiling toluene, which gave the hydrazides 15 to 18 in excellent yields [Eq. (6)] [17]. One compound (17) was characterized by a crystal structure determination. Similar gallium hydrazides were obtained directly at room temperature without the isolation of stable adducts when the phenylhydrazine derivatives H2N-N(H)CeH5 [18] and H2N-N(C6Hs)2 [17] were employed. The products (15 to 18) form dimers... 

Alkane elimination has a low yield during the photolysis of liquid n-alkanes (e.g., n-pentane [104,106]). This reaction takes place with high yield only for branched alkanes where it is likely to be a main primary-decomposition step [105,107]. 

Table 5 Quantum Yield of Alkane Elimination in the Photolysis of Some Liquid Alkanes...

Similarly to the fluorescence quantum yields, the yields of individual primary decomposition steps generally show considerable excitation energy dependence the yields of the unimolecular H2 and alkane eliminations and also those of the radical-type decompositions show a continuous variation with photon energy [27,39,42,107,115]. In cyclohexane photolysis the sum of the quantum yields of the two primary decompositions described by Reactions (5) and (6) is practically unity between photon energies 7.6 and 11.6 eV yield decreases with the energy, [Pg.382]

The uncertainty about the formation mechanism is eliminated when such method is used for the determination of the G(5 i) value, which is invariant to the formation route. Such method is the comparison of the yields of those products, which are formed only in one way in the reaction of the Si molecules. Such products come from the singlet decay channel fluorescence photons, products of H2 or alkane elimination. The triplet channel due to the large triplet yield originating from other processes than the Si Tn ISC (e.g., direct triplet excitation, or charge recombination with triplet product) cannot be used for the calculation of the Si yield. The calculations are based on the equation ... 

In the case of alkanes with tertiary or quaternary carbon atoms the characteristic decomposition mode is usually the fragment alkane elimination (Sec. 2.6) and its yield can be used to estimate G(S i) values. Based on the fragment alkane elimination yield Pitchuozhkin et al. [162] calculated a singlet G value of 3.3 1 for 2,2,4-trimethylpentane. 

Alkane elimination is a basic photodecomposition mode of highly branched alkanes, e.g., most of the excited neopentane molecules split directly to methane and isobutene. 

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