Chapter 19, Problem 49P

Interpretation Introduction

Interpretation:

Products A–E and queen substance for the given reaction chain are to be provided.

Concept introduction:

Grignard reagent reactions with carbonyl groups are treated as acid–base reactions.

The reaction of Grignard reagents with carbonyl groups yields secondary and tertiary alcohols. These reactions are two-step reactions. In the first step, nucleophilic addition of carbonyl group takes place because the Grignard reagent, being nucleophilic, uses its lone pair of electrons to form a bond with a carbon atom. This results in the formation of an alkoxide ion which remains associated with $M{g}^{2+}$ and $X^{-}$.

In the second step, addition of aqueous HX causes the protonation of the alkoxide ion, which leads to the formation of the alcohol and $Mg{X}_2$.

Hydrogenation of unsaturated compounds, such as alkenes and alkynes, is done with hydrogen and in the presence of a pure metal, like Platinum or Palladium.

Secondary and tertiary alcohols undergo elimination reactions, when they are treated with mineral acids and heat. Dehydration of alcohols via E1 elimination reaction.

Ozonolysis cleaves the cyclic bond of ring hydrocarbons and converts the ring structure to a straight chain. Dimethyl sulfide reduces the intermediate to form a final compound with two carbonyl groups.

Aldehydes react with dicarboxylic acids in the presence of weak bases like pyridine to give unsaturated carboxylic acids.

When methyl ketones react with halogen in excess of base, multiple halogenation occurs at the methyl group. The methyl trihalide groups become excessively acidic and leave the ketone to give carboxylate ion and a haloform. The reaction is called haloform reaction.