Aromatic Aldehydes Ketones and Acids - Result Question 6
####7. In the following reactions, the product $S$ is
(2019 Main, 12 Jan I) (a)
(c)
(b)
(d)
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Answer:
Correct Answer: 7. $(b, c)$
Solution:
- Key Idea Grignard reagent usually attacks on $>C=O$ group as :
$C=O+RMgX \longrightarrow$
$$
\underset{\substack{\text { (Ionic salt) } \ C}}{OMg X} \underset{-Mg(OH) X}{\text { Hydration }}>C\rangle _R^{OH} $$
The question is related to above reaction only with the condition that the consumption of $R \operatorname{Mg} X$ will be more than 1 equivalent in some of the given cases.
Among the given compounds $B$, i.e.
contain additional groups which can give active hydrogens. Grignard reagents produce alkanes whenever come in contact with any group or compound which can give active hydrogen as:
$$ R OH+R^{\prime} Mg X \underset{\text { ether }}{\text { Dry }} R^{\prime} H+Mg _{\backslash}{ }^{OR} $$
These reactions are equivalent to acid-base reactions. So, in both of these compounds more than one equivalent will be required to form Grignard products. Remember these compounds will give 2 type of products as:
(i) from the $>C=O$ group
(ii) from the group which release active hydrogen
The additional reactions involved are:
