2-Isobutyl bromide

Isobutyl bromide (l-bromo-2-methylpropane) [78-77-3] M 137.0, b 91.2 , d 1.260, n 1.437. Partially hydrolysed to remove any tertiary alkyl halide, then fractionally distd, washed with cone H2SO4, water and aqueous K2CO3, then redistd from dry K2CO3. [Dunbar and Hammett J Am Chem Soc 72 109 7950.1... 

C,HifC 60736-79-0) see Ibuprofen isobutyl bromide (QH Br 78-77-3) see Butalbital isobutyl chloride... 

Methylpropene tert-Butyl bromide Isobutyl bromide... 

The formation of a 1° carbocation is required => isobutyl bromide is not obtained as a product of the reaction. 

Isobutyl bromide, b371 Isobutyl chloride, cl79 Isobutyl chlorocarbonate, i68 Isobutyl ether, d458 Isobutyl mercaptan, m3 9 5 Isobutyl methyl ketone, m3 70... 

Bodroux 4 has prepared allyl, propyl, and isobutyl bromides by means of a modified Norris method. Bromine was reduced by means of sulfur dioxide, the alcohol was added and the mixture distilled. The yields were not the highest, however. The method described above is an improvement of the Norris-Bodroux method. Two essential modifications consist in the addition of concentrated sulfuric acid, and in the recommendation of a refluxing period preliminary to the distillation. The sodium bromide method has been improved by the introduction of similar modifications. 

SAMPLE SOLUTION (a) Isopropyl bromide, (CH3)2CHBr, is a secondary alkyl halide, whereas isobutyl bromide, (CH3)2CHCH2Br, is primary. Because the ratedetermining step in an SN1 reaction is carbocation formation and secondary car-bocations are more stable than primary ones, isopropyl bromide is more reactive Jthan isobutyl bromide in nucleophilic substitution by the SN1 mechanism. ... 

Subsequent reactions of the cations with bromide ion give fert-butyl bromide and isobutyl bromide. In the usual way of running these additions, the product is very pure tert-butyl bromide. 

But the addition product is 99+% tert-butyl bromide so the reaction clearly is kinetically controlled, tert-butyl bromide being formed considerably faster than isobutyl bromide. The slow, or rate-determining, step in this reaction is the formation of the intermediate cation rather than the reaction of the cation with bromide ion. So to account for the formation of tert-butyl bromide we have to consider why the tert-butyl cation is formed more rapidly than the isobutyl cation ... 

The following qualitative observations on the action of liquid ammonia on organic compounds are mainly by E. C. Franklin and C. A. Kraus, those in brackets are by G. Gore. Aliphatic compounds.—Halides methyl iodide, m. chloroform, reacts, and m. bromoform, m. iodoform, v.s., ethyl bromide and iodide, s. ethylene bromide, s. ethylidene chloride, m. isobutyl bromide, s. amyl bromide, s.s. tribromomethane, v.s. nitrotriohloromethane, m. perehloroethane (n.s.) perchloroethylene (m.) dichloroacetylene (s.). Alcohols methyl, m. ethyl, m. propyl, m. normal butyl,... 

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