Esters acid-catalyzed

An important application of the Reformatsky reaction is the conversion of P-hydroxy esters to a, P-unsaturated esters. Acid-catalyzed dehydration usually leads to a mixture of a, P- and P, y-unsaturated esters. However, conversion of the initially formed p-hydroxy esters to their corresponding acetates by treatment with acetyl chloride, followed by base-catalyzed dehydration with NaOEt, produces conjugated esters in high purity. This sequence of reactions provides an alternative route to the Homer-Wads worth-Emmons olefmation of ketones (see Chapter 8). 

The preparation of esters can be classified into two main categories (1) carboxylate activation with a good leaving group and (2) nucleophilic displacement of a carboxylate on an alkyl halide or sulfonate. For simple esters, acid-catalyzed esterification with azeotropic removal of water is also very effective, but limited to simple systems for the most part. The nucleophilic approach is generally not suitable for the preparation of esters if the halide or tosylate is sterically hindered, but there has been some success with simple secondary halides and tosylates (ROTs, DMF, K2CO3, 69-93% yield). The section on transesterification should also be consulted, since this technology can be quite useful for the preparation of esters from other esters. 

Chem. Descrip. Zinc phosphate pigment CAS 7779-90-0 EINECS/ELINCS 231-143-9 Uses Corrosion inhibitor, pigment for aikyds, water reducible epoxies and aikyds, latex emulsions, epoxy esters, acid catalyzed systems, acrylic lacquer emulsions, vinyiidene chloride systems, polyesters, thin film applies., high gloss systems... 

Carbon-Carbon Bond Formation. Various types of Bronsted and Lewis acids and superacids may be applied to perform the reaction of alkanes or arenes with different alkylating agents (alkenes, alkynes, alkyl halides, alcohols, ethers, esters). Acid-catalyzed alkylations, particularly alkane-alkene reactions, are of great practical importance in upgrading motor fuels. Acid-catalyzed alkylation produces alkylaromatics for manufacture of plastics (styrenes), detergents, and chemicals. 

Now let s draw the forward scheme. Baeyer-Villiger oxidation of the starting ketone achieves the insertion of an oxygen atom between the carbonyl group and the more substituted aUcyl group, thereby giving an ester. Acid-catalyzed hydrolysis of the ester gives butyric acid, which is then converted to the acid chloride upon treatment with thionyl chloride. The acid chloride is then converted into the desired product upon treatment with excess dimethyl amine (via a nucleophilic acyl substitution reaction). 

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