Grignard Synthesis of Carbinols

Introduction. The general formula for carbinols is ROH. If the radical is aliphatic, they are called alcohols, if aromatic, and the functional group (OH) is attached directly to the benzene nucleus, they are called phenols. The student already knows that one method of preparation is the hydrolysis of halogen compounds. One way to summarize the preparation of alcohols is to consider the progressive oxidation of the methane carbon atom  

The direct oxidation of the hydrocarbon to alcohol is difiicult because the oxidation proceeds to the acid stage, thus giving rise to mixtures. In only a very few cases is it possible to develop a practical method. Aside from the hydrolysis of the halogen compoxmds, the reduction of aldehydes or acids can, according to the above diagram, be used for the preparation of alcohols. Reductions of this type are possible under certain conditions for the.se the student should refer to the text. 

The Grignard reagent reacts with the carbonyl group (CO) of the aldehydes and ketones to give addition compounds, which upon hydrolysis yield alcohols  

In the reaction with aldehydes (equation 1) the product is a secondary alcohol, except with formaldehyde, when a primary alcohol is formed. 

Equation 2 shows that ketones form tertiary alcohols with the Grignard reagent. The objective of the present experiment is to provide an illustration of the use of the Grignard reagent for the synthesis of alcx)hols. 

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