Master Organic Chemistry Reaction Guide

Addition of Grignard reagents to ketones to give tertiary alcohols

Description: When a ketone is treated with a Grignard reagent, a new C–C bond is formed at the carbonyl carbon. Subsequent addition of acid will then give the alcohol.
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Comment section

4 thoughts on “Addition of Grignard reagents to ketones to give tertiary alcohols

  1. Hi James,
    Is there a rule for stereochemistry when adding a grignard? For instance, in example 1 and 2, would the stereocenter default to R or S?

    1. “Conservation of optical inactivity”. If there’s no chiral influence on a reaction, the product of an achiral starting material with an achiral reagent will result in an optically inactive product. A racemic mixture of enantiomers, in other words.

    1. That’s because #4 is a trick question! Acid base reactions are fast, relative to Grignard addition – the Grignard reacts with the carboxylic acid in an acid-base reaction, and the carboxylic acid is later protonated with acid workup. Very common trick question!

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