Show how would you synthesisse the following alcohols form approprite alkenes.
i. ii.
iii. iv.

Explanation

Since addition and elimination are opposite to each other, the general strategy is to first dehydrate alcohol to give either a single alkene or a mixture of alkenes. If a mixture of alkanes is possible, find out wich of the alkenes will give the desired alcohol. The acid-catalyded addition of `H_(2)O` to alkenes occurs in accordance with Markovnikov's rule.
i.
Addition of `H_(2)O` to both these alkenes gives the desired alcohol.

ii.
Addition of `H_(2)O` to 4-methylhept-3-ene in the presence of an acid gives the desired alcohol.

iii.
Now, the addition of `H_(2)O` to pent-1-ene gives the desired alcohol.

However, the addition of `H_(2)O` to pents-2-ene gives a mixture of two alcohols, i.e., pentan-2-ol and pentan-2-ol and pentan-3-ol.

Thus, the desired alkene is pent-1-ene and not pent-2-ene.
iv.
Now, addition of `H_(2)O` to both 2-cyclohexylbut-2-ene and 2-cyclohexlidenebutane in the presence of an acid gives the desired alcohol.