589-75-3Relevant articles and documents
Kinetic Study of Liquid-Phase Esterification with Sulfonic Acid Cation-Exchange Resin of the Macroreticular Type. II. Solvent Effects on Resin Catalysis
Shimizu, Shoichi,Hirai, Choichiro
, p. 1975 - 1980 (1987)
The rates of the esterification of octanoic acid with 1-butanol catalyzed by macroreticular sulfonated ion-exchange resin in the presence of various organic solvents and water were measured by the use of a batch reactor.The solvent effects on the rate were investigated by applying the heterogeneous-pseudohomogeneous reaction mechanism.From these results, it was found that the effects can be quantitatively estimated by means of the magnitude of the equilibrium constants, K(S)sol, for the solvent-separated ion-pair formations, which are due to the interaction of the sulfo groups in the resin with the solvents.The correlations of the K(S)sol value with the physical properties, μ end ε; the solvatochromic parameters ?*, α, and β, and Gutmann's parameters, ANE and DNB, have been examined by using linear regession analysis methods.The results of the correlations in which the protic solvents have been excluded suggest that the positions of the equilibria of solvent-separated ion-pair formations depend mainly on the electron-donor property of the solvents; that is to say, the solvents with a strong donor property diminish the number of un-ionized sulfo groups which act as catalytic species for the heterogeneous reaction.
Immobilization of lipase in organic solvent in the presence of fatty acid additives
Ozturk, Taylan K.,Kilinc, Ali
, p. 214 - 218 (2010)
In this study porcine pancreatic lipase (PPL) was covalently immobilized on cross-linked polyvinyl alcohol (PVA) in organic media in the presence of fatty acid additives in order to improve its immobilized activity. The effects of fatty acid additions to the immobilization media were investigated choosing tributyrin hydrolysis in water and ester synthesis by immobilized PPL in n-hexane. Various fatty acids which are also the substrates of lipases in esterification reactions were used as active site protecting agents during the immobilization process in an organic solvent. The obtained results showed that covalent immobilization carried out in the presence of fatty acids as protective ligands improved the hydrolytic and esterification activity of immobilized enzyme. A remarkable increase in activity of the immobilized PPL was obtained when octanoic acid was used as an additive and the hydrolytic activity was increased from 5.2 to 19.2 μmol min-1 mg-1 as compared to the non-additive immobilization method. With the increase of hydrolytic activity of immobilized lipase in the presence of octanoic acid, in an analogous manner, the rate of esterification for the synthesis of butyl octanoate was also increased from 7.3 to 26.3 μmol min-1 g-1 immobilized protein using controlled thermodynamic water activities with saturated salt solutions. In addition, the immobilized PPL activity was maintained at levels representing 63% of its original activity value after 5 repeated uses. The proposed method could be adopted for a wide variety of other enzymes which have highly soluble substrates in organic solvent such as other lipases and esterases.
1,3-Dibromo-5,5-dimethylhydantoin as a Precatalyst for Activation of Carbonyl Functionality
?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
, (2019/08/01)
Activation of carbonyl moiety is one of the most rudimentary approaches in organic synthesis and is crucial for a plethora of industrial-scale condensation reactions. In esterification and aldol condensation, which represent two of the most important reactions, the susceptibility of the carbonyl group to nucleophile attack allows the construction of a variety of useful organic compounds. In this context, there is a constant need for development of and improvement in the methods for addition-elimination reactions via activation of carbonyl functionality. In this paper, an advanced methodology for the direct esterification of carboxylic acids and alcohols, and for aldol condensation of aldehydes using widely available, inexpensive, and metal-free 1,3-dibromo-5,5-dimethylhydantoin under neat reaction conditions is reported. The method is air- and moisture-tolerant, allowing simple synthetic and isolation procedures for both reactions presented in this paper. The reaction pathway for esterification is proposed and a scale-up of certain industrially important derivatives is performed.
Esterification of aryl/alkyl acids catalysed by n-bromosuccinimide under mild reaction conditions
?ebular, Klara,Bo?i?, Bojan ?.,Stavber, Stojan
, (2018/09/10)
N-halosuccinimides (NXSs) are well-known to be convenient, easily manipulable and low-priced halogenation reagents in organic synthesis. In the present work, N-bromosuccinimide (NBS) has been promoted as the most efficient and selective catalyst among the NXSs in the reaction of direct esterification of aryl and alkyl carboxylic acids. Comprehensive esterification of substituted benzoic acids, mono-, di- and tri-carboxy alkyl derivatives has been performed under neat reaction conditions. The method is metal-free, air- and moisture-tolerant, allowing for a simple synthetic and isolation procedure as well as the large-scale synthesis of aromatic and alkyl esters with yields up to 100%. Protocol for the recycling of the catalyst has been proposed.
