Ethane radical halogenation

The chlorination of ethane illustrates the three distinct parts of radical halogenation (Mechanism 15.1) ... 

The ethane byproduct formed by coupling then reacts with chlorine in a radical halogenation reaction (see Section 10.5) to form chloroethane. 

To account for the products fornaed from halogenation of alkanes, chemists propose a radical chain mechanism involving three types of steps (1) chain initiation, (2) chain propagation, and (3) chain termination. We illustrate radical halogenation of alkanes by the reaction of chlorine with ethane. 

The cycle of chain propagation steps from the halogenation of ethane radical chain mechanism. 

What happens in the radical halogenation of other alkanes Will the different types of R-H bonds—namely, primary, secondary, and tertiary— react in the same way as those in methane As we saw in Exercise 3-4, the monochlorination of ethane gives chloroethane as the product. 

In a chain reaction, the step that determines what the product will be is most often an abstraction step. What is abstracted by a free radical is almost never a tetra- or tervalent atom (except in strained systems, see p. 989) and seldom a divalent one. Nearly always it is univalent, and so, for organic compounds, it is hydrogen or halogen. For example, a reaction between a chlorine atom and ethane gives an ethyl radical, not a hydrogen atom ... 

Wallington, T.J., Neuman, D.M., Kurylo, M.J. (1987) Kinetics of the gas phase reaction of hydroxyl radicals with ethane, benzene, and a series of halogenated benzenes over the temperature range 234 -38 K. Int. J. Chem. Kinet. 19, 725-739. 

Hsu, K. J., and W. B. DeMore, Rate Constants and Temperature Dependences for the Reactions of Hydroxyl Radical with Several Halogenated Methanes, Ethanes, and Propanes by Relative Rate Measurements, J. Phys. Chem., 99, 1235-1244 (1995). 

Alkanes such as ethane are relatively unreactive and reactions involving alkanes require high-energy atoms or free radicals. Three general types of reactions involving alkanes are combustion, halogenation, and pyrolysis. The most common reactions of alkanes involve combustion. Combustion of alkanes has been the primary source of heat for human civilizations throughout... 

The effect of wavelength upon the relative proportion of the products is very marked. When the 2537 A. line from a low-pressure mercury arc is used, the yield of all three ethanes is drastically reduced, while the yield of both halogenated methanes is enhanced. The 1,3-dichlorohexafluoropropane can no longer be detected. This effect is unlikely to be due to alternative primary processes, such as mercury photosensitization, since it is also observed under flash photolysis conditions. As before, it is considered that the additional energy given to the radicals at shorter wavelengths, increases the rate of abstraction and decreases the rate of combination because of the third-body restriction. Some evidence for this... 

Hydroxyl Substitution Products.— All of the preceding facts lead to the conclusion that alcohol is a compound in which the ethyl radical is linked to the hydroxyl radicalj i.e, it is the hydroxyl substiltUion product of ethane or hydroxy ethane. Alcohols thus belong to the same general class of compounds as the halogen substitution products. The relationship between the hydrocarbons, the halogen substitution products, alkyl halides and the hydroxyl substitution products, alcohols, may be shown as follows ... 

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