Insertion saturated hydrocarbon

Introduction of a sulfur atom into saturated hydrocarbons leads to a considerable decrease, by an order of magnitude, in the yield of radicals [G(radicals) for hydrocarbons 420]. This was explained as due to the existence of low-lying d-orbitals at the sulfur atom. This explanation agrees with the observation that this decrease is smaller in the case of insertion of a SO group, as there are four p electrons of the S atoms which may be excited at the d-orbital for sulfide and only two p electrons in the case of sulfoxides. Additional proof is that for sulfones, where there is no available p electron, the yield of the radicals [G(radicals) = 3.7 for tetramethylene sulfone] is about the same as for hydrocarbons. 

These intermediates undergo addition reactions with alkenes and aromatic compounds and insertion reactions with saturated hydrocarbons.254... 

Sulfonylnitrenes are formed by thermal decomposition of sulfonyl azides. Insertion reactions occur with saturated hydrocarbons.255 With aromatic compounds the main products are formally insertion products, but they are believed to be formed through addition intermediates. 

Examples of such reactions are well known. Sloan, Breslow, and Renfrow found that both alkane and arenesulphonyl azides insert into the carbon-hydrogen bonds of saturated hydrocarbons 12>. Thus, 1-pentane,- 2-propane- and -toluene-sulphonyl nitrene inserted into cyclohexane to give 54, 60, and 58% yields of the corresponding IV-cyclohexylamide derivatives 8>. Similarly, 2-phenoxybenzene-, diphenyl sulphide-2-, and... 

The interaction of saturated hydrocarbons with carbon monoxide-aluminium chloride is of great interest. In this case the CO group is inserted into the chain,1 e.g. 

The next step in the TCA cycle, the oxidation of succinate to fumarate, involves insertion of a double bond into a saturated hydrocarbon chain. 

Figure 9.8 7-monoenes, 7,11-dienes and linear saturated hydrocarbons in male and female adult flies of either wild type (+) or heterozygous for the P-element insertion (P) or homozygous for the P-element (P/P). + and P flies were obtained by crossing Canton-S females with P-males (+ XP) or vice versa (PX +). 

Cyclohexane is a saturated hydrocarbon in which no regioselectivity problems of C-H insertion can occur. The reaction of cyclohexane with ethyl diazoacetate was investigated in a thorough study by Perez et al.14 The /V-heterocyclic carbene ligand IPr (IPr= l,3-bis(diisopropylphenyl)imidazol-2-yliden) was used, all three compounds IPrMCl (M = Cu, Ag, Au) were inactive as catalysts in cyclohexane (Table 12.2, entry 1). Addition of the sodium BARF salt (NaB[3,5-(CF3)2C6H3]4) gave ethyl cyclohexyl acetate as the C-H insertion product of the carbene (Scheme 12.4). 

The OH product rotational distributions from the reactions of 0 (1D) with saturated hydrocarbons [CH4, C2H6, C3H8 and C(CH3)4] are observed to have a bimodal structure [474]. The population of the lowest rotational levels corresponds to an insertion mechanism in which the O atom approaches the R—H perpendicularly. The higher rotational levels correspond to production of OH by abstraction following a collinear... 

The activation of dioxygen for the monooxygenation of saturated hydrocarbons by the methane monooxygenase enzyme systems (MMO hydroxylase/reductase) represents an almost unique biochemical oxygenase, especially for the transformation of methane to methanol. The basic process involves the insertion of an oxygen atom into the C-H bond of the hydrocarbon via the concerted reduction of O2 by the reductase cofactor (equation 120). 

Reactivity with Diazo Oxides and Azides. Diazo oxides, e.g. 2,6-di-f0rf-butyl-4-diazo-2,5-cyclohexadiene-l-one (184, R = terr-butyl) or 2,6-diphenyl-4-diazo-2,5-cyclohexadiene-l-one (184, R = phenyl) are thermolabile and photolabile. Car-benes 185 are formed from 184 as reactive intermediates. The process proceeds in a one-step mechanism in which the carbene species reacts in the singlet state [238], The attachement of 185 to saturated hydrocarbon chains proceeds via insertion in C—H bond during processing. LDPE and PP were modified in this way [239, 240]. Poly(oxymethylene) was modified similarly. 

Why are these reactions considered to be that peculiar The insertion of carbene into a non-activated C-H bond of a saturated hydrocarbon is a well-known but not a very efficient process in the absence of catalysts. The fact that the insertion of carbene (both inter- and intramolecular) at the C-H bond of dodecahedrane frameworks proceeds with such an amazing ease has to be taken as a strong evidence for suggesting the operation of previously unknown and little-understood activating factors in this system. 

Oxygen atom from Cpd I is inserted into the C-H bond of saturated hydrocarbons (Scheme la) by means of hydrogen atom abstraction followed by recombination of the transient hydroxyl with the carbon radical [the so-called oxygen rebound mechanism proposed by Groves in 1976 (8, 10)]. Another possibility can be the concerted oxygen insertion into the C-H bond. Both pathways are rationalized by the two-state mechanism developed by Shaik et al. (6, 9), which describes different reactivities... 

The H—C bond cleavage in saturated hydrocarbons is only realized in low-T matrices and in homogeneous solution. Reactions of methane and ethane with Ni are calculated theoretically. Metals (Mn, Fe, Co, Cu, Zn, Ag and Au) in CH matrices insert into the H—C bonds when irradiated at 15K to form HMCH,. 

To 2 ml of one per cent solution of bromine in carbon tetrachloride add 0.2-0.3 ml (3-4 drops) of cyclohexene or amylene. Repeat the test, using a saturated hydrocarbon. Explain the results and insert in your notebook the equation for each reaction. 

Sulfur dioxide insertion into a titanium-carbon bond was first reported in 1971 Reaction (h) is too vigorous at dry-ice temperature with neat sulfur dioxide, and must be moderated by using a solvent such as a saturated hydrocarbon or dichloromethane. 

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