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Addition of Grignard reagents to dry ice followed by hydrolysis gives carboxylic acids whereas that of organolithium compounds under similar conditions give ketones. Explain. |
Answer» SOLUTION :The electronegativity of Li (E.N. = 1.0) is LOWER than that of Mg (E.N. = 1.2) so that organolithium compounds are more nucleophilic than Grignard reagents. Therefore, organolithium compounds not only add to the more reactive `CO_2` but also to LESS reactive resonance stabilized lithium salts of carboxylic ACIDS forming ketones.  On the other hand, Grignard reagents are less nucleophilic and add only to CO, but not to less reactive resonance stabilized magnesium salts of carboxylic acids from which the carboxylic acid can be generated by hydrolysis with mineral acids. 
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