- Dicarboxylic acids are crystalline solids, their melting points being much higher than the corresponding monocarboxylic acid.
- The lower member dissolve readily in water but the solubility falls with the increase of molecular weight.
- The melting points of dicarboxylic acids show ‘alternation’ or ‘oscillation’ from one member to the other. The melting point of an ‘even acid’ (having even number of carbon atoms) is always higher than that of the ‘odd acid’ lying immediately above and below it.
Dicarboxylic acids give the same reactions as those of monocarboxylic acids in duplicate. Thus they give mono- and di-derivatives such as salts, esters, amides and acid halides. However, in the lower members in which the two COOH groups are closer together , the possibilities of mutual interactions increases. From this point, the action of heat on Dicarboxylic Acids is very interesting and needs a special mention.