Further Reactions of Active Hydrogen Compounds

The malonic ester synthesis is a tool for synthesizing substituted acetic acids. 

Direct formation of such anions is possible (Section 18.4), but it is often more convenient to use diethyl malonate as a synthetic equivalent because its a hydrogens are more easily removed. 

In Special Topic E we shall see biosynthetic equivalents of these anions. 

Because of the acidity of their methylene hydrogens malonic esters, acetoacetic esters, and similar compounds are often called active hydrogen compounds or active methylene compounds. Generally speaking, active hydrogen compounds have two electron-withdrawing groups attached to the same carbon atom  

Active hydrogen compound (Z and Z are electron-withdrawing groups.) 

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