Chem 220a Problem Set 5 Fall 2003

1. Arrange the compounds of each set in order of reactivity toward (i) S_N2 displacement and (ii) E2 elimination by KOH in ethanol.

(a) 2-bromo-2-methylbutane, 1-bromopentane, 2-bromopentane

(b) 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, 2-bromo-3-methylbutane

(c) 1-bromobutane, 1-bromo-2,2-dimethylpropane, 1-bromo-2-methylbutane

2. Predict the organic products of the following reactions. Label as major and minor, if multiple products are likely.

(a) Isopentyl bromide + NaOEt in EtOH

(b) Isobutyl bromide + NaOEt in EtOH

(c) Methyl bromide + KO-t-Bu in t-BuOH

(d) t-butyl bromide + KOCH₃ in CH₃OH

(e) 2-bromo-3-methylbutane + NaOEt in EtOH

(f) 2-bromo-3-methylbutane + KO-t-Bu in t-BuOH

3. Provide reasonable mechanisms to account for the following observations.

4. Starting with isopentane, devise efficient syntheses of (a) 2-methyl-2-butene and (b) 2-methyl-1-butene. Any common reagents may be used.

5. Explain the following observations.