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Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are common in organic chemistry and biological materials, and often have a pleasant characteristic, fruity odor. This leads to their extensive use in the fragrance and flavor industry.
If the alcohol produced by the reaction can be separated from the reactants by distillation this will drive the equilibrium toward the products. This means that esters with larger alkoxy groups can be made from methyl or ethyl esters in high purity by heating the mixture of ester, acid/base, and large alcohol.
The reaction is often carried out without a solvent (particularly when a large reagent excess of the alcohol reagent is used) or in a non-polar solvent (e.g. toluene, hexane) that can facilitate Dean–Stark distillation to remove the water byproduct. [4] Typical reaction times vary from 1–10 hours at temperatures of 60–110 °C.
[4] [6] Alcohol dehydrogenase and aldehyde dehydrogenase are present at their highest concentrations (in liver mitochondria). [98] [107] But these enzymes are widely expressed throughout the body, such as in the stomach and small intestine. [2] Some alcohol undergoes a first pass of metabolism in these areas, before it ever enters the ...
The reaction usually requires a catalyst, such as concentrated sulfuric acid: R−OH + R'−CO 2 H → R'−CO 2 R + H 2 O. Other types of ester are prepared in a similar manner−for example, tosyl (tosylate) esters are made by reaction of the alcohol with 4-toluenesulfonyl chloride in pyridine.
In biochemistry, an esterase is a class of enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis (and as such, it is a type of hydrolase). A wide range of different esterases exist that differ in their substrate specificity, their protein structure, and their biological function.
An example of an ester formation is the substitution reaction between a carboxylic acid (R−C(=O)−OH) and an alcohol (R'OH), forming an ester (R−C(=O)−O−R'), where R and R′ are organyl groups, or H in the case of esters of formic acid.
Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. [1] [2] It is an important type of alkaline hydrolysis. When the carboxylate is long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate ...