5A In the following reactions, mixtures of alkenes and ethyl ethers are formed. Draw their structures. Explain which is or are likely to be the main product(s) in each reaction. In case of formation of two isomers of alkenes, explain which is formed in greater proportion CH3 -Br H3C+E CH3 EtOH

(1) Predict the outcome of the addition of HBr to (a) trans-2-pentene, (b) 2-methyl-2-butene, and (c) 4-methylcyclohexene. How many isomers can be formed in each case? (2) Addition of HBr to 3,3-dimethyl-1-butene gives a mixture of two isomeric alkyl bromide products. Draw structures for the two products, and give a mechanistic explanation for their formation.

3. Please draw the most important (stable) resonance form of the carbonation that mediates the following reaction: OH H3O+ O 4. Draw the structure of the alkene isomer (with the molecular formula of C5H10) that is most reactive one in the addition reaction with Br₂.

Only one of the chlorine atoms in the molecule, 3,4-dichloronitrobenzene, will undergo nucleophilic substitution. Indicate which position will react and provide the expected product for the given reaction using reaction intermediates (resonance structures).