Chlorine atom traps

Scheme 8. In fact, when placed in the reaction medium in the dark, (23) gives a product distribution similar to that observed in the photochemical reaction. In contrast with reduction in alcohols, the quantum yield in aqueous HC1 drops rapidly with decreasing HC1 concentration ( = 0.11 in 12moll-1 HC1, but = 0.012 in 6 mol l-1 HC1 48 whereas in 50% aqueous propan-2-ol, is constant at >0.1 mol l-1 HQ 47). Both this dependence of quantum yield on acidity and some radical scavenging observed when phenol or anisole (chlorine atom traps) are present are in accord with the mechanism outlined in Scheme 8. Cu and Testa49 have found that the 313 nm irradiation of protonated 5-nitroquinoline...

Experiments designed to utilize spin trapping to monitor free-radical chemistry in the gas phase were first reported by Janzen and Gerlock (1969). In these, radicals generated by photolysis in a stream of carrier gas were passed over solid PBN. The PBN was then dissolved in benzene, and the solution was found to contain spin adducts of radicals present in the gas stream. Photolysis of t-butyl hypochlorite vapour in this way leads to a nitroxide whose spectrum reveals splitting from two chlorine atoms. This proved to be due to butyl nitroxide (Janzen, 1971 Janzen et al., 1970), and recalls the observation of other nitroxides which apparently result from further reaction of the initial spin adducts. 

At low temperature, propene behaves like another alkene and undergoes a simple addition of a halogen across the double bond to form 1,2-dichlo-ropropane. These conditions minimize the possibility of forming chlorine atoms (chlorine free radicals), and the presence of oxygen traps the few that do form. However, when the conditions promote the formation of chlorine atoms, a substitution occurs to produce 3-chloropropene. 

Flectrophilic addition of polychloroalkanes such as, e.g., chloroform or 1,1,2,2-tetrachloroethane to Cjq with AICI3 in a 100-fold excess gives the monoadduct with a 1,4-addition pattern (Scheme 8.12) [93, 94], The reaction proceeds via a CjqR cation (19, Scheme 8.12) that is stabilized by the coordination of a chlorine atom to the cationic center. The cation is trapped by Cl to give the product 20. The chloroalkyl fullerenes can be readily hydrolyzed to form the corresponding fullerenol 21. This fullerenol can be utilized as a proper precursor for the cation, which is easily obtained by adding triflic acid. The stability of CjqR is similar to tertiary alkyl cations such as the tert-butyl-cation [95],... 

Hydroxylation of alkanes preferentially occurs at the more nucleophilic C—H bonds, with a relatively low isotope effect (fcH/fcD = 2.8 for cyclohexane) and a significant amount of epimerization at the hydroxylated carbon atom. Radical carbon intermediates were revealed in this reaction by trapping experiments with chlorine atoms coming from CC14. 

Further purification of benzene The degree of purification of benzene is critically important in the determination of rate constant as well as product study of the reaction of benzene with chlorine. A purification procedure developed by Sokolov et al. [27] was used. CI2 was dissolved in the deoxygenated liquid benzene (Sigma Aldrich, 99- -%) by bubbling gaseous CI2 through the sample. Chlorine atoms react first with certain impurities, then with benzene. Thus we convert reactive impurities and a small fraction of fhe benzene into chlorinate compounds that are eliminated by trap-to-trap distillation. 

The haloenamines are first metallated in alpha to the amino group followed by an expulsion of the second chlorine atom. The intermediate chloroynamines could be trapped when using only one mole of butyllithium, but these ethynylogs of chloramines are too unstable when both groups R are alkyl Chloroynamines... 

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