What reactions can esters undergo?
Esters can react with ammonia to form amides. For example, people make tributyl citrate acetylated to form CAS No 77 90 7 acetyl tributyl citrate.
Acetyl tributyl citrate can react with water to form the corresponding carboxylic acids and alcohols. For example, tributyl citrate is hydrolyzed to form citric acid and n-butanol.
The hydrolysis ability of CAS No 77 90 7
The hydrolysis ability of esters is less than that of acyl halides and anhydrides, but greater than that of amides. People regard these reactions as the replacement of H in the HOH molecule by acyl groups. Acyl halides and anhydrides have the strongest acylating ability, so we often use them as acylating agents in organic synthesis.
Why esters have strong hydrolysis ability in alkaline and acidic solutions
CAS No 77 90 7 acetyl tributyl citrate is more easily hydrolyzed in acidic or alkaline solutions than in neutral solutions. Because acidic solutions provide hydrogen ions, they can bind to polar carbonyl oxygen, making oxygen positively charged, so the π electron cloud is more transferred to oxygen, making the carbonyl carbon positively charged and more prone to nucleophilic addition reactions. Even weaker nucleophiles, such as water, can undergo nucleophilic addition reactions.
The hydrolysis characteristics of CAS No 77 90 7 in alkaline solutions
Under alkaline conditions, ester hydrolysis generally reacts with sodium hydroxide, which also requires heating. This reaction is irreversible and complete. People call the hydrolysis of esters in alkaline solutions as saponification, because the higher fatty acid salts obtained by alkaline hydrolysis of oils and fats are soaps.
The hydrolysis characteristics of esters in acidic solutions
Take CAS No 77 90 7 acetyl triethyl citrate as an example. The alcohol generated after the reaction is still ethanol, but due to the presence of sodium hydroxide, finally we obtained sodium citrate. These two conditions are the main ways in which ester hydrolysis occurs. The hydrolysis under acidic conditions is incomplete and reversible, while the hydrolysis under alkaline conditions is complete and irreversible.
Related Links: CAS No 77 89 4, High Purity Tributyl Citrate Plasticizer, CAS No 77 94 1, Tributyl Citrate (TBC)
