Ester Alcoholysis

Acidic Cation-Exchange Resins. Brmnsted acid catalytic activity is responsible for the successful use of acidic cation-exchange resins, which are also soHd acids. Cation-exchange catalysts are used in esterification, acetal synthesis, ester alcoholysis, acetal alcoholysis, alcohol dehydration, ester hydrolysis, and sucrose inversion. The soHd acid type permits simplified procedures when high boiling and viscous compounds are involved because the catalyst can be separated from the products by simple filtration. Unsaturated acids and alcohols that can polymerise in the presence of proton acids can thus be esterified directiy and without polymerisation. 

H-Chromene, 2-ethyl-3-phenyl-synthesis, 3, 764 4H-Chromene, 2-phenyl-synthesis, 3, 763 4H-Chromene, 2,4,4-trimethyl-addition reactions, 3, 669 2 H-Chromene-3-carboxamide reduction, 3, 675 2H-Chromene-3-carboxylic acid methyl ester alcoholysis, 3, 668... 

Conversion of Acid Halides into Esters Alcoholysis Acid chlorides react with alcohols to yield esters in a process analogous to their reaction with water to yield acids. In fact, this reaction is probably the most common method for preparing esters in the laboratory. As with hydrolysis, alcoholysis reactions are usually carried out in the presence of pyridine or NaOH to react with the HC1 formed. 

Ester alcoholysis (transesterification) in organic media is an equilibrium reaction and must be shifted in the desired direction. For example, Bornscheuer and coworkers [61] reported the resolution of ibuprofen vinyl ester by transesterification tvith n-hexanol in the presence of CAL-B. The vinyl alcohol generated during the reaction tautomerizes to acetaldehyde, thus making the reaction irreversible, as illustrated in Figure 6.14. 

Camel through the eye of a needle" syntheses, in zeolites, 231, 232/ Carboxylate esters, alcoholysis of, with transition metal ion and Ln3 + catalysts, 288-294... 

Organic Titanium Compounds as Mery lie Ester Alcoholysis Catalysts, Titanium Intermediates, Ltd., London, 1967. 

Transesterification (also known as ester exchange, ester interchange, or ester alcoholysis) is the most important of the esterification reactions. Polyesters of relatively low molecular weight (around 2000) prepared from aliphatic dicarboxylic acids and glycols are most commonly made by direct esterification (Section 5.2) with or without addition of an external acidic catalyst. Phosphoric acid, p-toluenesulphonic acid, and antimony pentafluoride have been used as catalysts. The preparation of PET by the direct esterification of TA with ethylene glycol was not practical until the... 

O hIb r CXnR2 Aminolysis of oxygen esters, alcoholysis of amides. 

Sucrose ester alcoholysis of 14 labelled fatty acid and sucrose... 

During heating and long storage of foods, esters may also be formed in small quantities as secondary odour-active compounds. For example, esters are formed during aging of wines and spirits by esterihcation of carboxylic acids with alcohols (ethanol or fusel oil alcohols, but the non-enzymatic esterification is a very slow reaction), acidolysis (reaction of acids with esters), alcoholysis (reaction of alcohols with esters) or ester exchange (reaction of esters with other esters). 

The most common reactions of carboxylic acid derivatives are substitution by water to yield an acid (hydrolysis), by an alcohol to yield an ester (alcoholysis), by an amine to yield an amide (aminolysis), by hydride ion to yield an alcohol (reduction), and by an organomagnesium halide to yield an alcohol (Grignard reaction). 

---