Esterification
From Wikipedia, the free encyclopedia
Esterification is the general name for a chemical reaction in which two chemicals (typically an alcohol and an acid) form an ester as the reaction product. These are commonly used as fragrance or flavour agents. Esterification is a reversible reaction. Hydrolysis- literally "water splitting" involves adding water and a catalyst (commonly NaOH) to a carboxylic acid to get the sodium salt of the carboxylic acid and alcohol.
Examples of esterification reactions include:
- Heating to reflux an acid (usually, but not always a carboxylic acid) and an alcohol in the presence of a catalyst (commonly H2SO4) forms the ester and water byproduct which can be removed to force the equibilibrium across to the desired products. This method is called Fischer esterification
- For example, esterification of acetic acid in excess ethanol in the presence of sulfuric acid results in an ester (ethyl acetate).
H3C-COOH + HO-CH2-CH3 → H3C-COO-CH2-CH3 + H2O (with the presence of conc. sulfuric acid)
- the reaction of an alkali carboxylate and an alcohol. For example, the reaction of sodium acetate with ethanol.
H3C-COO- Na+ + HO-CH2-CH3 + H+ → H3C-COO-CH2-CH3 + H2O + Na+
- The reaction of a silver carboxylate with a halogenoalkane (presumably driven by the insolubility of the silver halide).
H3C-CO2-Ag+ + Cl-CH2-CH3 → H3C-COO-CH2-CH3 + AgCl
- The reaction of a carboxylic acid halogenide (which is also called acyl halide) with an alcohol/phenol.
H3C-COCl + HO-CH2-CH3 → H3C-COO-CH2-CH3 + H-Cl
- The reaction of a carboxylic acid anhydride with an alcohol. (This method is used to synthesize aspirin)
H3C-CO-O-CO-CH3 + HO-CH2-CH3 → H3C-COO-CH2-CH3 + H3C-COOH
[edit] See also
- Transesterification, a reaction to transform one ester into a different ester.
- Hydrolysis, the cleavage of an ester with water back to a carboxylic acid and alcohol.
- acetylation
- acylation
