Q.Alcohols cannot be used as a solvent for Grignard reagent. Give reason.

Grignard reagents are powerful carbanion-like nucleophiles/bases that react instantly with any active hydrogen; the $-OH$ hydrogen of an alcohol is active, so an alcohol solvent would consume the Grignard reagent before it ever meets the desired substrate.

Reason: The Grignard reagent, $RMgX$, has a highly polar $R^{\delta-}-Mg^{\delta+}X$ bond, giving the carbon a strong carbanion-like (basic/nucleophilic) character. It reacts violently and instantaneously with any compound containing an active (i.e. sufficiently acidic) hydrogen atom, such as the hydrogen of $-OH$ (alcohols, water), $-COOH$, $-NH_2$/$-NH-$, or terminal alkyne $\equiv C-H$.

If an alcohol, $R'OH$, were used as the solvent, the Grignard reagent would react with the solvent itself as fast as it formed:

$RMgX + R'OH \rightarrow R-H\uparrow + R'-O-MgX$

This protonates the carbanion-like carbon, converting the valuable Grignard reagent into a simple alkane (wasting it) and an alkoxymagnesium halide — leaving no active Grignard reagent to carry out the desired addition reaction with, say, an aldehyde, ketone, ester, or $CO_2$.

Why dry ether is used instead: Diethyl ether ($C_2H_5-O-C_2H_5$) is chosen as the solvent because:

• It has no active/acidic hydrogen, so it does not react with the Grignard reagent. …