1.

Give structure of the products you would expect when each of the following alcohol reacts with (a) HCl-ZnCl_(2) (b) HBr and (c) SOCl_(2), (i) Butan-1-ol (ii) 2-Methylbutan-2-ol.

Answer»

Solution :(a) With `HCL-ZnCl_(2)` (Lucas reagent). 2-methylbutan-2-ol
(ii) being a `3^(@)` alcohol, reacts with Lucas reagent to produce turbidity IMMEDIATELY due to the formation of insoluble tert-alkyl chloride while butan-1-ol (i) being a `1^(@)` alcohol does not react with Lucas reagennt at ROOM temperature
`underset("2-Methylbutan-2-ol "(3^(@)))(CH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+HCl(conc.) overset("Anhyd. "ZnCl_(2))to underset("2-Chloro-2-methylbutane (White turbidity)")(CH_(3)-underset(CL)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+H_(2)O`
`underset("Butan-1-ol "(1^(@)))(CH_(3)CH_(2)CH_(2)CH_(2)-OH)+HCl(conc.)overset("Anhyd. "ZnCl_(2))to` No reaction at room temperature
(b) Both the alcohols react to produce the corresponding alkyl bromides.
`underset("Butan-1-ol "(1^(@)))(CH_(3)CH_(2)CH_(2)CH_(2)OH)+HB r overset(Delta)to underset("1-Bromobutane")(CH_(3)CH_(2)CH_(2)CH_(2)Br)+H_(2)O`
`underset("2-Methylbutan-2-ol "(3^(@)))(CH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+HB r overset(Delta)to underset("2-Bromo-2-methylbutane")(CH_(3)-underset(Br)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+H_(2)O`
(c) Both the alcohols react to form the corresponding alkyl chlorides.
`underset("Butan-1-ol "(1^(@)))(CH_(3)CH_(2)CH_(2)CH_(2)OH)+SOCl_(2) overset(Delta)to underset("1-CHlorobutane")(CH_(3)CH_(2)CH_(2)CH_(2)Cl)+SO_(2)uarr+HCl uarr`
`underset("2-Methylbutan-2-ol")(CH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+SOCl_(2)overset(Delta)to underset("2-Chloro-2-methylbutane")(CH_(3)-underset(Cl)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3))+SO_(2)uarr+HCl uarr`


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