Neopentane chlorination

Radical chlorination of pentane is a poor way to prepare 1-chloropentane, but radical chlorination of neopentane, (CI- C, is a good way to prepare neopentyl chloride, (CHj CO Cl. Explain. 

As a result, free-radical chlorination of alkanes is a nonselective process. Except when only one type of replaceable hydrogen is present (methane, ethane, neopentane, unsubstituted cycloalkanes), all possible monochlorinated isomers are usually formed. Although alkyl chlorides are somewhat less reactive than alkanes, di- and polychlorinations always occur. The presence of a chlorine atom on a carbon atom tends to hinder further substitution at that carbon. The one exception is ethane that yields more 1,1-dichloroethane than 1,2-dichloroethane. The reason for this is that chlorination of an alkyl chloride occurs extremely slowly on the carbon atom adjacent to the one bearing the chlorine atom (vicinal effect).115... 

Problem 3.17 On chlorination, an equimolar mixture of ethane and neopentane yields neopentyl chloride and ethyl chloride in the ratio of 2.3 1. How does the reactivity of a primary hydrogen in neopentane compare with that of a primary hydrogen in ethane ... 

Petway, S. V. Application of Automatic Reaction Model Generation to Chlorine-Initiated Neopentane Oxidation, (Poster Presentation) 6th International Conference on Chemical Kinetics, NIST (Gaithersburg, MD) (2005). 

Chlordane is prepared by reacting hexachlorocyclopentadiene (40) formed as the main product in the chlorination of cyclopentadiene (42) with hypochlorite or in the high temperature chlorination (470°C) of pentane, neopentane or cyclopentane with cyclopentadiene (Diels-Alder reaction), and chlorinating the 4,5,6,7,8,8-hexa-chloro-4,7-methano-3a,4,7,7a-tetrahydroindene (chlordene, 43) yielded by this reaction until two additional chlorine atoms are absorbed, obtaining 4,7-methano-... 

Figure 4.4-6 Ratio of mono- to polychlorides produced in the free radical chlorination of 2,3-dimethylbutane (23DMB), neopentane, and cyclohexane in conventional and supercritical fluid solvents as a function of inverse viscosity at 40 °C (data taken from References SO and 51).

Hie free radical chlorination of three alkanes (cyclohexane, 2,3-dimethylbutane, and neopentane) was examined both in SC-CO2, and, for comparison purposes, in conventional organic solv ts. All of these experiments were carried out at 40 °C, and at alkane concentrations < 0.03 M 20). At such low alkane concentrations, little monochloride arises from reaction of Cl with alkane comprising die cage walls, ku (Scheme 1). 

Figure 6. Ratio of 1,3- to 1, l-dicMoro-2,2-dimethylpropane produced in the free radical chlorination of neopentane in SC-COj at 40 C as a junction ofvisosity...

The N-haloimide halogenations are also controlled partially by the fact that Cl or the iV-succinimidyl radical are much more reactive than Br in hydrogen abstracting reactions and, towards a hydrocarbon of low reactivity such as neopentane, a bromine atom chain would be quite ineffective. With mixtures of NBS and CI2, halogenation occurs to form the alkyl bromides but with the selectivity expected for chlorine atom attack Apparently ClBr is formed and reacts with the alkyl radical to form RBr and a chlorine atom. A similar situation exists for the bromination of alkanes using a mixture... 

Various perovsldtes have already demonstrated their efficiency in the total oxidation of hydrocarbons and chlorinated hydrocarbons in plasma-assisted processes. Thus, the total oxidation of propane and neopentane was investigated in a ferroelectric packed-bed reactor (FPR) in which the catalyst was a BaTiOs perovskite (Figure 17.12a) [57]. The gas streams were passed through the gas inlet and dispersed into the plasma zone. To explain the variation of CO and CO2 concentrations, a reaction pathway involving different precursors for the production of CO has been proposed. 

Neopentane, for example, can form only one monohalogenation product, and the use of a large excess of neopentane minimizes poly chlorination ... 

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