Give reasons for the following:
(i) Grignard reagent should be prepared under anhydrous conditions.
(ii) Neo-pentyl bromide undergoes nucleophilic substituting reactions very slowly.
(iii) p-Methoxybenzyl bromide reacts faster than p-nitrobenzyl bromide with ethanol to form an ether product.
(i) Grignard reagent reacts with water and gets decomposed, so it is produced in anhydrous conditions.
(ii) Neo-pentyl bromide being a primary halide reacts slowly through SN1, and being a sterically hindered halide reacts slowly even through SN2 mechanism.
(iii) Methoxy (-OCH3) group being an electron releasing group stabilizes the intermediate carbocation. On the other hand nitro group (-NO2) is an electron withdrawing group and hence it destabalises the intermediate carbocation. Thus p-methoxy benzyl bromide reacts faster than p-nitrobenzyl bromide because the reaction proceeds via more stable intermediate carbocation.