( ii ) Reaction involving cleavage of C-O bond in alcohols In these reactions , the reactivity order of different alcohols :
Alkyl group due to + 1 effect increases the electron density on the carbon and oxygen atom of C-OH bond . As a result , the bond cleavage becomes easy . Greater the number of alkyl groups present , more will be the reactivity of alcohol . Thus , the relative order of reactivity of the alcohols is justified .
Reaction with halogen acids
Alcohols can be converted into haloalkanes by the action of halogen acids .
R – OH + HX ( HCI , HBr , HI ) → R-X + H2O
For a given alcohol order of reactivity of HX is
H-1 > H-Br > H-Cl
For a given halogen acid order of reactivity of alcohols
Tertiary > Secondary > Primary