Esterification kinetics

Determination of water removal rate. This technique is usually applied to the continuous following of esterification kinetics. 

Before studying esterification kinetics, it must be kept in mind that side reactions can interfere with the main reaction. They must either be avoided by changing experimental conditions or taken into account in kinetic calculations. Three types of phenomena can occur ... 

Malek et al.49-190 often use.the terms metal ion catalysis and consider that metal ions play a very important role. According to our knowledge of esterification kinetics, this is only an assumption although these authors provided interesting arguments on esterification kinetics49 ... 

Keywords esterification, kinetics, catalysis, diffusion, microstructure. 

Reimschuessel, H. K. and Debona, B. T., Terephthalic acid esterification kinetics 2-(2-methoxyethoxy)ethyl terephthalates, J. Polym. Sci., Polym. Chem. Ed, 17, 3241-3254 (1979). 

In the literature concerning solid-catalysed esterifications, kinetic studies of other ester-forming reactions are scarcely reported. Reactions of... 

Bromlield-Lee, D. and M. T. Oliver-Hoyo (2009) An esterification kinetics experiment that relies on the sense of smell. Journal of Chemical Education 56(1), 82-84. 

Upases [bmim][BF4], [bmim][PF6], other ILs esterifications, trans-esterifications, kinetic resolution of secondary and allyUc alcohols... 

Maury S, Buisson P, Perrad A, Pierre AC (2(X)5) Compared esterification kinetics of the lipase from Burkholderia cepacia either free or encapsulated in a silica aerogel. J Mol Catal B Enzymatic 32 (5-6) 193-203... 

Esters have played a significant role in daily living and chemical industry, such as plasticizers, fragrance, adhesive and lubricants (Joseph et al., 2005 Mbaraka Shanks, 2006 Krause et al., 2009 Martinez et al., 2011). The vast majority of esters can be prepared using esterification reaction in the chemical engineering industry. Esterification has acquired further improvement from the engineering side this mainly depends on the research of esterification kinetics. On the other hand, the need to control chemical reactions at the molecular level, which depends critically on the catalytic mechanism, is rapidly increasing (Salciccioli et al, 2011). 

Herein, we review the mechanisms of esterification catalyzed by inorganic acid, Lewis acid, metallic compounds, solid acids, ion-exchange resin, respectively. Meanwhile, the kinetics for each esterification is also conducted in detail. The study on the mechanism of various catalysts is not only useful in the present applications but it is required to enhance the scope of their applications. Therefore, it is desired to research and develop more efficient catalysts for high yield ester production, under mild reaction conditions. The esterification kinetics is important for simulation and design of a reactor. 

A literature survey more than 90 relevant references has been done in this chapter. The studies on esterification are mainly focused on the following aspects (1) establishing the adequate reaction mechanism according to the research papers, and (2) evaluating the available esterification kinetics. 

Based on the above mechanism pa-op)osed by Streitweiser, Ronnback, et al. developed a esterification kinetic model of carboxylic add with methanol in the presence of hydrogen iodide though isothermal batch experiments at 30-60°C. The catalyst concentration varied from 0.05 to 10.0 wt%. Because the proton-donation step (1) as well as the subsequent steps (3)-(5) is assumed to be rapid, the simplified mechanism shown in Figure 3 ... 

Along with the scientific and technological progress and social development, more and more researchers have concerned about this issue, including the kinds of catalysts, the mechanism and kinetics of reaction. Thus, the contents containing the reaction mechanism and esterification kinetics have been significantly reviewed according to the type of catalysts as follows. 

The esterification kinetics of acetic acid with iso-butanol catalyzed by Dowex 50 Wx2 was studied (Izci Bodur, 2007). ft is considered to be reversible reactions and can be described by pseudo-homogeneous (PH) model. The general reaction rate expression can be written as follows. 

Sanz, M., R. Murga, S. Beltran, J. Cabezas J. Coca (2002) Autocatalyzed and ion-exchange-resin-catalyzed esterification kinetics of lactic acid with methanol. Industrial Engineering Chemistry Research, 41,512-517,1SSN 0888-5885. 

Homogeneously and heterogeneously catalyzed esterification kinetics butyl acetate esterification—online H NMR spectroscopy monitoring of rapidly changing compositions offered a fast and reliable analysis of all reaction components. 

Maki-Arvela (1999) has developed a new polyolefin supported sulphonic acid catalyst for esterification of acetic acid with methanol. The esterification kinetics (pseudo-homogeneous) was modeled with a mechanistic rate equation, the parameters of which were determined by non-linear regression. The esterification rate constant of the most active modification of the new catalyst was 9.6 x 10 ° dm /(mol g min) at 328 K, which clearly exceeds the corresponding value obtained with a traditional (Amberlyst 15) polyvinyl benzene supported catalyst, 1.5 x 10 ° dm /(moP g min). 

Mazzotti et al. (1996) studied the esterification of acetic acid with ethanol on a highly cross-linked sulphonic ion exchange resin (Amberlyst-15) in a continuous simulated moving bed reactor. The resin acted as catalyst as well as a selective sorbent simultaneously. They have studied the multicomponent sorption equilibria and swelling of the resin, as well as esterification kinetics with appropriate models. The thermodynamic and kinetic descriptions of the system have been combined to develop a fully predictive mathematical model of the chromatographic reactor. 

The catalyst content was found to have an impact on the esterification kinetics. Fradet and co-workers [90] confirmed Deleens observation [64] that there exists an optimal catalyst concentration. Actually, a low catalyst content would not result in a process faster than that carried out without catalyst. This phenomenon has been attributed to the formation of catalyst condensates. However, once a threshold concentration is reached, the polymerization rate will increase with the catalyst concentration, although a too high amount of catalyst can lead to side reactions, which may involve the esterification of the diacid with the catalyst itself. 

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