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Alkaline hydrolysis of esters is also known as saponification. A base such as sodium hydroxide is required in stochiometric amounts. Unlike acid-catalyzed ester hydrolysis, it is not an equilibrium reaction and proceeds to completion. Hydroxide ion attacks the carbonyl carbon to give a tetrahedral intermediate, which then expels an alkoxide ion.
This reaction is important in the history of organic chemistry because it helped prove the structure of ethers. The general reaction mechanism is as follows: [3] An example is the reaction of sodium ethoxide with chloroethane to form diethyl ether and sodium chloride: C 2 H 5 Cl + C 2 H 5 ONa → C 2 H 5 OC 2 H 5 + NaCl
This would be a reversal of the standard esterification mechanism. An example of this method is the acylation of 3-phenylpropanol using glacial acetic acid and TBATB. The reaction generates the ester in 15 minutes in a 95% yield without the need to remove water.
In these reactions, the conjugate acid of the carbonyl group is a better electrophile than the neutral carbonyl group itself. Depending on the chemical species that act as the acid or base, catalytic mechanisms can be classified as either specific catalysis and general catalysis. Many enzymes operate by general catalysis.
Ethyl sulfate can be produced in a laboratory setting by reacting ethanol with sulfuric acid under a gentle boil, while keeping the reaction below 140 °C. The sulfuric acid must be added dropwise or the reaction must be actively cooled because the reaction itself is highly exothermic. CH 3 CH 2 OH + H 2 SO 4 → CH 3 CH 2 OSO 3 H + H 2 O
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H 2 O 2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H 2 O 2 is reduced.
Acetoacetic ester synthesis is a chemical reaction where ethyl acetoacetate is alkylated at the α-carbon to both carbonyl groups and then converted into a ketone, or more specifically an α-substituted acetone. This is very similar to malonic ester synthesis. Acetoacetic ester synthesis equation
The Barton decarboxylation is a radical reaction in which a carboxylic acid is converted to a thiohydroxamate ester (commonly referred to as a Barton ester). The product is then heated in the presence of a radical initiator and a suitable hydrogen donor to afford the decarboxylated product.