Reactions of alkanes

Acid-catalyzed isomerization reactions of alkanes as well as alkylation and condensation reactions are initiated by protolytic ionization. Available evidence indicates nonlinear but not necessarily triangular... 

As we have just seen the reaction of alkanes with oxygen to give carbon dioxide and water IS called combustion A more fundamental classification of reaction types places it m the oxidation—reduction category To understand why let s review some principles of oxidation-reduction beginning with the oxidation number (also known as oxidation state)... 

In the laboratory it is more convenient to use light either visible or ultraviolet as the source of energy to initiate the reaction Reactions that occur when light energy IS absorbed by a molecule are called photochemical reactions Photochemical techniques permit the reaction of alkanes with chlorine to be performed at room temperature... 

The few known cases of azo coupling reactions of alkane- and alkenediazonium ions will be reviewed in the forthcoming second book (Zollinger, 1995, Sec. 6.1). We will not discuss systematically the chemical, spectroscopic, or other properties of the azo compounds formed in azo coupling reactions (see Zollinger, 1991, Ch. 7). However, two phenomena are important for this book, as discussed below. 

Sulfmyl radicals have also been invoked in the synthetically useful reaction of alkane-and arenesulfinyl chlorides with activated zero-valent metals (Ag, Cu, Zn) to give the corresponding symmetrical thiosulfonates21. 

The product of substitution reactions of alkanes with the halogens is typically a complex mixture of haloalkanes (halogenated alkanes). One way to limit the production of the more highly substituted alkanes is to use a large excess of the alkane then most reactions take place with the original hydrocarbon rather than with any haloalkanes produced in the reaction. 

A range of transformation products has been identified from simulated reactions of alkanes. These include alkyl nitrates by reactions that have already been given, but also include a range of hydroxy-carbonyls that are summarized in Table 1.2 (Reisen et al. 2005). 

Rabus R, H Wilkes, A Behrends, A Armstroff, T Fischer, AJ Pierik, F Widdel (2001) Anaerobic initial reaction of -alkanes in a denitrifying bacterium evidence for (1-methylpentyl) succinate as initial product and for involvement of an organic radical in -hexane metabolism. J Bacteriol 183 1707-1715. 

For transition-metal catalyzed hydroxylation of alkane C-H bonds, the reactions of alkanes with platinum(II) complexes were the most successful. In an aqueous solution of hexachloroplatinic acid and Na2PtCl4, alkanes were converted into a mixture of isomeric alkyl chlorides, alcohols, and ketones, and the platinum(IV) is reduced to platinum(II).7 The kinetics of the reaction with methane as the alkane have been described in detail.8... 

When the reactions of alkane molecules larger than the butanes or neopentane are studied, and in particular when the molecule is large enough to form a Cs or a Ce ring, the complexity of the reaction pathway is considerably increased and an important feature is the occurrence, in addition to isomerization product, of important amounts of cyclic reaction products, particularly methylcyclopentane, formed by dehydrocycliza-tion this suggests the existence of adsorbed cyclic species. The question is whether the reaction paths for dehydrocyclization and isomerization are related. There is convincing evidence that they are. Skeletal interconversions involving n-hexane, 2- and 3-methylpentane may be represented. 

Table XV summarizes kinetic parameters for hydrogenolysis reactions of alkanes and cycloalkanes over film catalysts and over supported catalysts for which it can be reasonably assumed that reaction is confined to the metallic phase. These kinetic parameters refer to the overall reaction, i.e., to the rate of disappearance of the parent molecule. It will be evident from Table XV that the catalytic activity of a given metal with a given...

The proposed surface intermediates are summarized in Table II. The intermediates in each reaction of alkanes includes alkox-ide ions, regardless of the type of active oxygen species. Although carboxylate ions are believed to be the intermediate in the reactions of C2 and C3 alkenes, the type of carboxylate formed with 0 as a reactant is different from the type of carboxylate ion formed when 07 or 07 was a reactant. With 0 ions the carbon number of the carboxylate ions is the same as that of the hydrocarbon reactant, but with 07 or 07 the carboxylate ions have carbon numbers smaller than the parent hydrocarbon. The reaction schemes of Ci alkenes are somewhat complicated, yet it appears that they react in a manner more similar to C2-C1 alkanes than to C2 or C3 alkenes. 

Olah, G. A. Germain, A. Lin, H. C. Forsyth, D. Electrophilic reactions at Single Bonds. XVIII.1 Indication of Protosolvated de facto Substituting Agents in the Reactions of Alkanes with Acetylium and Nitronium Ions in Superacidic Media. J. Am. Chem. Soc. 1975, 97, 2928-2929. 

Ruthenium complexes are capable of catalyzing halogen atom transfer reactions to olefins. This has been illustrated in the enantioselective atom transfer reactions of alkane and arene-sulfonyl chlorides and bro-motrichloromethanes to olefins using chiral ruthenium complexes. Moderate ee s up to 40% can be achieved for these transformations [74-77]. These specific reactions are believed to follow a radical redox transfer chain process. 

Many related complexes of iridium and rhodium undergo the oxidative addition reaction of alkanes and arenes [1]. Alkane C-H bond oxidative addition and the reverse reaction is supposed to proceed via the intermediacy of c-alkane metal complexes [4], which might involve several bonding modes, as shown in Figure 19.5 (for an arene the favoured bonding mode is r 2 via the K-electrons). 

Anodic Reactions of Alkanes, Alkenes, and Aromatic Compounds... 

---