Dicarboxylic Acid Physical As Well As Chemic Properties

Physical Properties:

1. Dicarboxylic acids are crystalline solids, their melting points beingness much higher than the corresponding monocarboxylic acid.
2. The lower fellow member dissolve readily inwards H2O only the solubility falls alongside the increment of molecular weight.
3. The melting points of dicarboxylic acids demonstrate ‘alternation’ or ‘oscillation’ from ane fellow member to the other. The melting signal of an ‘even acid’ (having fifty-fifty seat out of carbon atoms) is ever higher than that of the ‘odd acid’ lying directly higher upwards too below it.
   

Acidity. The dicarboxylic acids ionise inwards 2 steps:

The electron-withdrawing lawsuit of the instant COOH grouping enhances the acidity of the root COOH. Therefore, the value of the dissociation constant K1 is higher than that of acetic acid (Ka=1.5x10-5). The inductive lawsuit becomes weaker equally the 2 COOH groups are farther separated past times CH2 grouping and K1 decreases equally nosotros ascend the series.

As evident from the Table 21.2 the value of K2 is smaller than Ka of acetic acid (with the exception of oxalic acid) because the removal of proton from the instant COOH is to a greater extent than difficult. This is too then because the electrostatic repulsion due to negative charges inwards the dianion, ōOC-COō, destabilizes the dianion. That is why the value of K2 is much less than K1.

Chemical Properties:

Dicarboxylic acids reach the same reactions equally those of monocarboxylic acids inwards duplicate. Thus they reach mono- too di-derivatives such equally salts, esters, amides too acid halides. However, inwards the lower members inwards which the 2 COOH groups are closer together , the possibilities of usual interactions increases. From this point, the activity of rut on Dicarboxylic Acids is rattling interesting too needs a exceptional mention.