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Cleaning of Organic Objects and Materials
Published in Radko Tiňo, Katarina Vizárová, František Krčma, Milena Reháková, Viera Jančovičová, Zdenka Kozáková, Plasma Technology in the Preservation and Cleaning of Cultural Heritage Objects, 2021
Radko Tiňo, Katarina Vizárová, František Krčma, Milena Reháková, Viera Jančovičová, Zdenka Kozáková
Esters are derived from carboxylic acids. The general formula of esters is RCOOR1. Unpaired electron pairs on oxygens cause polarity but do not bind hydrogen bonds. Esters are very good solvents for nitrocellulose and some are good solvents for polyvinyl acetate adhesives.
Atmospheric Pollution and Pollutants
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
Esters are organic compounds produced by the reaction of alcohols with organic acids. They are widely used as solvents and industrial feedstock. Emissions to the atmosphere are relatively limited, and esters have negligible atmospheric significance.
Basic Chemical Hazards to Human Health and Safety — I
Published in Jack Daugherty, Assessment of Chemical Exposures, 2020
Ester. An ester is an organic compound formed from an alcohol by dehydrating an acid in a process called esterification. The breaking down of the ester to reform an alcohol and an acid is a hydrolysis reaction. Contact with water breaks esters down into their component acids and alcohols. The reaction rate of esterification is greatly enhanced by the presence of acids. The ester “ethyl acetate” becomes acetic acid and ethyl alcohol. The reaction between an ester and a metallic base is saponification. Since the hydroxyl ions attack electrophilic carbons, hydrolysis of esters is favored under alkaline conditions. This ester linkage is called a carboxylester and is found in common drugs, such as aspirin, but also in pesticides, such as malathion and pyrethrum. Such chemicals are easily hydrolyzed in the body, whereas chemicals that do not have a carboxylester branch will accumulate in fat, if they are lipophilic.
Ion exchange resin catalyzed synthesis of methyl butyrate: batch reactor and packed bed reactor studies
Published in Journal of the Chinese Institute of Engineers, 2022
Rajendra B. Bhandare, Amit Katariya, Yogesh. S. Mahajan
Esters of carboxylic acids are important chemicals and are useful in several applications. Typically, esters are used as solvents and plasticizers in bio-related applications and in the flavor and fragrance industry. Esters are generally formed by the reaction of acid and alcohol, mostly in the presence of an acid catalyst. For a given acid, as the alcohol chain length increases, the reaction rate decreases. Similarly, when a branched alcohol is used, the rate decreases. Esterification reactions are reversible and so, to achieve more conversion than that obtained at equilibrium, one or more of the following ways can be used: increase the mole ratio of reactants, increase the temperature of the reaction, use additional quantity of catalyst or continuously remove one of the products of reaction. Due to the formation of water during the reaction, the conversion is restricted, if it is not removed (Chakrabarti and Sharma 1993; Yadav and Thathagar 2002; Ali et al. 2007; Otera and Nishikido 2010). Different catalysts like homogenous (H2SO4, PTSA, MTSA etc.), heterogeneous (ion exchange resins IER, zeolites etc.) and other specialized catalysts (e.g. ionic liquids) can be used for the purpose to enhance reaction rate (Gandi, Silva, and Rodrigues 2005; Mahajan et al. 2008a; Pereira, Silva, and Rodrigues 2009; Talnikar and Mahajan 2014; Constantino et al. 2015; Talnikar et al. 2017, 2018). Reactive separation (RS), which employs reaction and separation in the same vessel, can be employed (Mahajan et al. 2008b; Shinde et al. 2015).
Physico-mechanical properties of jute fiber-reinforced LDPE-based composite: effect of disaccharide (sucrose) and gamma radiation
Published in Radiation Effects and Defects in Solids, 2020
Md. Sahadat Hossain, Md. Razzak, Muhammad B. Uddin, A. M. Sarwaruddin Chowdhury, Ruhul A. Khan
When composites were irradiated under gamma radiation, there was some free radical due to high energy radiation. The produced free radical reacted with each other and also with one another. Thus some new functional group was produced. In FT-IR analysis the new functional group was observed. Figure 11 shows the FT-IR analysis of gamma-irradiated sucrose-treated Jute/LDPE-based composite. At the wavenumber 1700 cm–1 peak was observed for the stretch of C=O group and at 3600 cm–1 for overtone of C=O group. Stretch band of C–O was observed at 1300 cm–1. The C–O, C=O, and O–H all together indicated the carboxyl group. The presence of C–O and C=O also indicated the ester group.
Modeling and optimizing the synthesis of isopropyl acetate over niobium pentoxide using experimental design methodology coupled with artificial neural network
Published in Chemical Engineering Communications, 2023
Aline C. M. Trindade, Heveline Enzweiler, Nina P. G. Salau
The main route for the synthesis of esters is the Fischer esterification (Fischer and Speier 1895), where a carboxylic acid reacts with an alcohol to produce an ester and water. Thermodynamic equilibrium controls this reaction, and the water produced causes hydrolysis of the ester, making the reaction reversible. Thus, to shift the balance toward product formation, the water is removed by pervaporation or reactive distillation. Another option is the use of excess alcohol (Knozowska et al. 2020; Martínez et al. 2020; Salt et al. 2020; Q. Zhang et al. 2019).