Ad
related to: reagents and conditions for esterification
Search results
Results From The WOW.Com Content Network
Reagents are known that drive the dehydration of mixtures of alcohols and carboxylic acids. One example is the Steglich esterification , which is a method of forming esters under mild conditions. The method is popular in peptide synthesis , where the substrates are sensitive to harsh conditions like high heat.
If conditions are acidic enough, the acetic acid can be further reacted via the Fischer esterification pathway, but at a much slower pace. However, in many carefully designed syntheses, reagents can be designed such that acid anhydrides are generated in situ and carboxylic acid byproducts are reactivated, and Fischer esterification routes are ...
If the esterification is slow, a side-reaction occurs, diminishing the final yield or complicating purification of the product. This side-reaction is a 1,3-rearrangement of the O-acyl intermediate to an N-acylurea which is unable to further react with the alcohol. DMAP suppresses this side reaction, acting as an acyl transfer-reagent in the ...
The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester RCO 2 H + R′OH ⇌ RCO 2 R′ + H 2 O. Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water.
The Yamaguchi esterification is the chemical reaction of an aliphatic carboxylic acid and 2,4,6-trichlorobenzoyl chloride (TCBC, Yamaguchi reagent) to form a mixed anhydride which, upon reaction with an alcohol in the presence of stoichiometric amount of DMAP, produces the desired ester. It was first reported by Masaru Yamaguchi et al. in 1979 ...
HATU was first reported by Louis A. Carpino in 1993 as an efficient means of preparing active esters derived from 1-hydroxy-7-azabenzotriazole (HOAt). [2] HATU is commonly prepared from HOAt and TCFH under basic conditions [3] and can exist as either the uronium salt (O-form) or the less reactive iminium salt (N-form).
The order of addition of the reagents of the Mitsunobu reaction can be important. Typically, one dissolves the alcohol, the carboxylic acid, and triphenylphosphine in tetrahydrofuran or other suitable solvent (e.g. diethyl ether), cool to 0 °C using an ice-bath, slowly add the DEAD dissolved in THF, then stir at room temperature for several hours.
The mechanism of acid-catalyzed hydrolysis of esters is the reverse of Fischer esterification. Acid is only required in catalytic amounts, as in Fischer esterification, and an excess of water drives the equilibrium towards carboxylic acid and alcohol. [1]