Question

Name some standards that would be appropriate for comparing to 2-chloro-2-methylbutane when performing the halide test.

Answer 1

Halide test : Silver nitrate is used as a reagent to identify the presence of halide ions in particluar compound. The alkyl halides generally react with silver nitrate to form silver halide which forms coloured precipitates. For chloride, white precipitate is formed.

This reaction is for secondary and tertiary alkyl halides.

2-chloro-2-methyl butane is a tertiary alkyl halide which readily reacts with silver nitrate and quickly forms white precipitate. Tertiary alkyl halide forms tertiary carbocation which is more stable, forces the electrons from three alkyl groups which is electron donating groups leading to hyperconjugation. So that, chloride atom readily leaves the group and the free chloride reacts with silver to form silver nitrate.

Secondary alky halide that is 2-chloro-3-methyl butane when reacts with silver nitrate gives slight precipitate within few seconds and starts thicken with time.

For primary alkyl halide, chlorobutane, it does not show any precipitate with silver nitrate. It is because of high electronegativity between carbon and chloride bond which have low reactivity.

So, standards for 2-chloro-2-methyl butane are 2-chloro-3-methyl butane and chlorobutane.