Chemical reaction entropically favored

We have seen that when the products are at a lower enthalpy than the reactants (AH° < 0), a chemical reaction is energetically favored. We have also seen that when the products are more disordered than the reactants (AS > 0), a chemical reaction is entropically favored. 

During a chemical reaction there is a change in the identity of substances as reactants transform to products. If the sum of the standard entropies of the products is gre-ater than the sum of the standard entropic s of the reactants, then there is a net incrc-ase in entropy and the reaction is favored. The difference in entropies can be calculated using data such as is given in Table 9.2 by the same... 

Such esterifications and acetal formations are achieved through enzyme catalyses. However, such reactions are relatively rare in aqueous conditions chemically. This is because the reversed reactions, hydrolysis, are much more favorable entropically. Kobayashi and co-workers found that the same surfactant (DBSA) that can catalyze the ether formation in water (5.2 above) can also catalyze the esterification and acetal formations reactions in water.52 Thus, various alkanecarboxylic acids can be converted to the esters with alcohols under the DBSA-catalyzed conditions in water (Eq. 5.6). Carboxylic acid with a longer alkyl chain afforded the corresponding ester better than one with a shorter chain at equilibrium. Selective esterification between two carboxylic acids with different alkyl chain lengths is therefore possible. 

---