Neopentyl bromide, also known as 1-Bromo-2,2-dimethylpropane, is an alkyl halide with the molecular formula of C5H11Br and a molecular weight of 151.04484 [g/mol]. It has an average mass of 151.0448 Da and an monoisotopic mass of 150.00441 Da.
Due to stearic hindrance, neopentyl bromide has a low tendency to undergo an SN2 reaction. SN1 reactivity occurs in favorable conditions, such as in a solution of wet formic acid. In this condition, neopentyl bromide reacts at the same rate of ethyl bromide, another alkyl halide. This is one example of a Wagner-Meerwein rearrangement of carbocations and results in neopentyl bromide yielding 2-methyl-2-butanol.