L-Bromobutane

The spectra shown in Figure 4.4 were obtained from a reaction of fert-butyl-lithium with l-bromobutane. ° One deduces that both the fert-butyl and the butyl radical were produced and that they reacted in disproportionation reactions to give in part isobutylene and 1-butene, respectively. In the spectrum recorded at 30 s, vinyl proton signals from 1-butene are in emission (5 5.0 and 5 6.1) and enhanced absorption (5 5.6). The isobutylene vinyl proton signal at 5 4.6 is in emission on the left side and enhanced absorption is on the right side. This phenomenon is known as a multiplet effect, and it is due to differences in ISC rates for radical pairs containing rcrt-butyl radicals with different proton nuclear spins. Note that the tert-butyl-lithium sample contained an impurity of isobutylene before the reaction, and the amount of isobutylene was increased after the reaction. 

Problem 6.53 Outline the steps needed for the following syntheses in reasonable yield. Inorganic reagents and solvents may also be used, (a) IXhloropentane to 1,2-dichloropentane. (b) IXhloropentane to 2-chloro-pentane. (c) IXhloropentane to 1-bromopentane. (d) l-Bromobutane to 1.2-dihydroxybutane. (e) Isobutyl chloride to... 

Problem 6.10 Give the structural formulas for the alkenes formed on dehydrobromination of the following alkyl bromides and underline the principal product in each reaction (a) l-bromobutane, (b) 2-bromobutane,... 

Problem 11.20 IVl) whether esch of the folkiwiug reactions is likely to be ttl, 3k2i >L or E2 (d> l Bromobutane f NaNs ------------------ l-Azidobutanc... 

What is an immediate precursor of 1-hexyne " Perhaps acetylene and l-bromobutane. 

In contrast to the behavior of the foregoing nickel(I) complexes as catalysts, the catalytic reactions of alkyl halides with cobalt(I) species such as vitamin Bi2s, cobaloximes(I), and cobalt(I) salen exhibit a significant difference. Cobalt(I) species, acting as potent nucleophiles in Sn2 reactions with alkyl halides, give stable alkylcobalt(III) intermediates. Lexa and coworkers [318] have discussed this mechanistic scheme for the catalytic reduction of l-bromobutane by the electrogenerated cobalt(I) tetraphenylpor-phin complex, where TPP denotes the ligand. Reversible one-electron reduction of the parent cobalt(II) species... 

Alkylbenzenes and alkylnaphthalenes were studied on a silica colunui using hexane, hexane/1-chlorobutane, hexane/l-bromobutane, or hexane/IPA as the mobile phase [619]. Modifier levels ranged fiom 0.005% to 10%. Capacity fiictors versus carbon number were plotted for each solvent mixture. Selectivity decreased for all solvent modifiers except 1-chlorobutane, for which selectivity increased as the level increased from 2% to 8%. The authors attribute diis to the formation of n-complexes between the 1-chlorobutane and the PAH solutes. Selectivity decreased, as expected, for the alkylnaphthalenes when I-bromobutane was used. Selectivity was lost rapidly as the level of IPA increased from 0.01%0.05% indicating that at low IPA concentrations IPA (or the water contained in the IPA) readily modifies or deactivates the silica support. 

Ethyl Nitrate (amtiniied) 2-Butanone Dioxane l Bromobutane 2-Bromobutane... 

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