d
\((d)\) The Grignard reagent is a very powerful base ; in effect it contains a  carbanion. Thus, it is not possible to prepare a Grignard reagent from an  organic group that contains an acidic hydrogen ; by an acidic hydrogen, we  mean any hydrogen more acidic than the hydrogen atoms of an alkane or  alkene. We cannot, for example, prepare a Grignard reagent from a compound containing an \(- OH\) group, an \(- NH -\)  group, an \(- SH\) group, a \(- CO_2H\) group, or an \(- SO_3H\) group. If we were to attempt to prepare a  Grignard reagent from an organic halide containing any of these groups, the  formation of the Grignard reagent would simply fail to take place. (Even if a  Grignard reagent were to form, it would immediately react with the acidic  group.) 

Since Grignard reagents are powerful nucleophiles, we cannot prepare a  Grignard reagent from any organic halide that contains a carbonyl, epoxy, nitro,  or cyano \((- CN)\) group. If we were to attempt to carry out this kind of  reaction, any Grignard reagent that formed would only react with the unreacted  starting material 

 

This means that when we prepare Grignard reagents, we are effectively limited  to alkyl halides or to analogous organic halides containing carbon -  carbon double bonds, internal triple bonds, ether linkages, and -\(NR_2\) groups