In the presence of a proton source, the product can either revert back into the starting ketone or aldehyde or can form a new product, the enol. The equilibrium reaction between the ketone or aldehyde and the enol form is commonly referred to as "keto-enol tautomerism". The ketone or aldehyde is generally strongly favored in this reaction. Of the two resonance structures of the enolate ion the one which places the negative charge on the oxygen is the most stable.
The electronegativity of oxygen is greater than that of carbon, so oxygen is capably negatively charged. The equilibrium on the first one is skewed far to the left , whereas that on the second one is skewed enough to the right. Related questions What functional groups are found in proteins? What functional groups are found in the structure of melatonin? What functional groups are present in carbohydrates? What is the structure of the functional group and the condensed formula for 4,4,5-triethyl Certain other strong bases, such as alkyl lithium and Grignard reagents, cannot be used to make enolate anions because they rapidly and irreversibly add to carbonyl groups.
Nevertheless, these very strong bases are useful in making soluble amide bases. In the preparation of lithium diisopropylamide LDA , for example, the only other product is the gaseous alkane butane.
In this application, one equivalent of diisopropylamine is produced along with the lithium enolate, but this normally does not interfere with the enolate reactions and is easily removed from the products by washing with aqueous acid.
Although the reaction of carbonyl compounds with sodium hydride is heterogeneous and slow, sodium enolates are formed with the loss of hydrogen, and no other organic compounds are produced. Asked 4 years, 7 months ago. Active 2 months ago.
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