Consider the following reactions:
(i) (CH3)2CH−CH2BrC2H5OH−−−−−−−−−−−−−→(CH3)2CH−CH2OC2H5+HBr
(ii) (CH3)2CH−CH2BrC2H5O−−−−−−−−−−−−−−→(CH3)2CH−CH2OC2H5+Br−
The mechanism of reactions (i) and (ii) are respectively: