Esters condensation reactions

The usual base or acid catalyzed aldol addition or ester condensation reactions can only be applied as a useful synthetic reaction, if both carbonyl components are identical. Otherwise complicated mixtures of products are formed. If two different aldehydes or esters are to be combined, it is essential that one of the components is transformed quantitatively into an enol whereas the other component remains as a carbonyl compound in the reaction mixture. 

Acid added to an alcohol produces an ester (condensation reaction). 

Acetoacetic Ester can be prepared by the condensation of ethyl acetate, called the Acetoacetic Ester Condensation Reaction, a Claisen Condensation-. 

Conversely, ester condensation reactions join acyl groups from CoA derivatives to Schiff bases derived from glycine or serine. Succinyl-CoA is the acyl donor... 

Intramolecular ester condensation reactions are called Dieckmann condensations and are very useful ring-forming reactions. Examples are shown in the following equations. In the second equation the yield is only 54% if sodium ethoxide is used as the base. 

Show how ester condensation reactions could be used to synthesize these compounds ... 

There are currently two proposed mechanisms for the acyloin ester condensation reaction. In mechanism A the sodium reacts with the ester in a single electron transfer (SET) process to give a radical anion species, which can dimerize to a dialkoxy dianion. Elimination of two alkoxide anions gives a diketone. Further reduction (electron transfer from the sodium metal to the diketone) leads to a new dianion, which upon acidic work-up yields an enediol that tautomerizes to an acyloin. In mechanism B an epoxide intermediate is proposed. ... 

Other Studies. - The P NMR chemical shifts of alcohols, carboxylic acids and phenols phosphitylated with 2-chloro-4,4,5,5-tetramethyl-dioxaphospholane have been correlated with substituent effects of phenols. P NMR spectroscopy has also been used to study activation pathways of aryl H-phosphonate ester condensation reactions, the conversion of allenyl and divinyl phosphines to 1- and 2-phosphadienes, the reaction of tetraphosphorus decasulfide with dialkyl disulfides, the reaction of phosphine with cyclic olefins, the chemical shift tensors of powder samples of phosphole derivatives, the reactions of alcohols and mercaptans with tetraphosphorus trichalcogen diiodides, the structure of aminomethanebisphosphonic acids, and reactions of 00-di-(2-ethylhexyl)dithiophosphoric acids. ... 

Inoue T, Nagase T, Hasegawa Y, Kiyozumi Y, Sato K, Nishioka M, Hamakawa S and Mizukami F (2007), Stoichiometric ester condensation reaction processes by pervaporative water removal via acid-tolerant zeolite membranes , Ind Eng Chem Res, 46,3743-3750. 

This section will describe reactions of ester enolates that are generated using "modem enolate anion technology. The use of lithium diisopropylamide and related "non-nucleophilic bases allows a measure of control in ester condensation reactions that is unmatched by the more traditional techniques described in previous sections. 

A hafnium catalyst suitable for fluorous biphasic system, which attracts attention from the viewpoint of green chemistry, was reported. In ester condensation reaction shown in Equation 69, hafnium (IV) perfluorooctane sulfonylamide (158) showed high activity to give the corresponding ester (159) in excellent yield from carboxylate (157) and octanol in 1 1 molar ratio [75]. The catalyst is recyclable by simple phase separation in the two phase system after the reaction. 

Esterification In 2000, Tanabe et al. reported that diphenylammonium triflate ([Ph2NH3] [OTf 1 10mol%) catalyzed the ester condensation reaction of... 

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