Esterification of lactic acid

Two methods of prepn are listed in Ref 3 a)By esterification of lactic acid with ethanol and b)By combining acetaldehyde with hydrocyanic. acid to form acetaldehyde cyanohydrin, and this is treated wi th ethanol HC1 to ethyl lactate. Used as a solvent for cellulose acetate and nitrate, other cellulose esters, resins, lacquers, paints and enamels Refs l)Beil 3, 264, 267, 280,(102,109) ... 

Problem 5.9 Esterification of ( + )-lactic acid with methyl alcohol gives (-)-methyl lactate. Has the configuration changed ... 

Tanaka K, Yoshikawa R, Ying V, Kita H, and Okamoto K. Application of zeolite T membrane to vapor-permeation-aided esterification of lactic acid with ethanol. Chem Eng Sci 2002 57 1577-1584. 

Ethyl lactate is produced by the esterification of lactic acid with ethanol in the presence of a little mineral oil, or by combination of acetaldehyde with hydrocyanic acid to form acetaldehyde cyanhydrin. This is followed by treatment with ethanol (95%) and hydrochloric or sulfuric acid. Purification is achieved using fractional distillation. The commercial product is a racemic mixture. 

Derivation (a) By the esterification of lactic acid with ethanol (b) by combining acetaldehyde with hydrogen cyanide to form acetaldehyde cyanohydrin, which is converted into ethyl lactate by treatment with ethanol and an inorganic acid. 

Gas residence time 0.5 to 1.3 s gas velocity 3 to 10 m/s Re > 10, L/D > 100. To eliminate backmixing, Pe > 100. Liquid residence time 1 to 6 s liquid velocity 1 to 2 m/s Re > 10, L/D > 100. PFTR is smaller and less expensive than CSTR. PFTR is more efhcient/volume than CSTR if the reaction order is positive with simple kinetics. For fast reactions, nse small-diameter empty tube in turbulent flow. For slow reactions, use large-diameter empty tubes in laminar flow. If reaction is complex and a spread in RTD is harmful, consider adding motionless mixer (Section 16.11.6.10). Examples hydrolysis of corn starch to dextrose polymerization of styrene hydrolysis of chlorobenzene to phenol esterification of lactic acid. Gas-liquid see transfer line. Section 16.11.6.9, or bubble reactors. Section 16.11.6.11. Liquid-liquid see transfer line. Section 16.11.6.9, or bubble reactors. Section 16.11.6.11. 

Examples hydrolysis of com starch to dextrose polymerization of styrene hydrolysis of chlorobenzene to phenol esterification of lactic acid. 

Budd et al. (2004) prepared multilayer membranes by altering the adsorption of cationic polyelectrolyte, chitosan, and an anionic polyelectrolyte, poly(4-styrene sulfonate) onto zeolite. The films were formed on porous supports in sheet and tube forms. The multilayer membranes were shown to exhibit high selectivity for water over alcohols associated with zeolite A but to be considerably more stable under acidic conditions than the pure zeolite A membrane. The membranes were successfully applied to the selective removal of water by PV in the esterification of lactic acid with EtOH, catalyzed by p-toluenesulfonic acid. For esterification at 70°C, yields of... 

Benedict D J, Parulekar S J and Tsai S-P (2003), Esterification of lactic acid and ethanol with/without pervaporation , Ind Eng Chem Res, 42,2282-2291. 

Delgado P, Sanz M T, Beltrdn S and Niinez L A (2010), Ethyl lactate production via esterification of lactic acid with ethanol combined with pervaporation , Chem g 7,165, 693-700. 

The commercial PVA membranes GFT-1005 and Tl-b (PVA-based) were used by Bendict et al. (2003, 2006) in a stirred batch reactor coupled with an ESU pervaporation cell for the esterification of lactic acid/succinic acid and ethanol. In these two studies, two solid catalysts Amberlyst XN-1010 and Nation NR50 were used. The kinetics of pervaporation were studied to obtain a correlation for the flux of water... 

Kumar, R., Mahajani, S. M. (2007). Esterification of lactic acid with n-butanol by reactive distillation. Industrial Engineering Chemistry Research, 46, 6873—6882. 

Wasewar, K., Patidar, S., Agarwal, V. K. (2009). Esterification of lactic acid with ethanol in a pervaporation reactor modeUng and performance study. Desalination, 243, 305—313. 

The kinetic behavior of esterification of lactic acid with isopropanol over Amberlyst 15 was investigated (Toor et al., 2011 Kirbaslar et al., 2001), at different temperatures from 323K to 353K The ER model was used to describe the reaction mechanism that takes place between adsorbed molecules of isopropanol and the molecules of lactic acid in bulk. The adsorption of ester is reported to be negligible. Hence the rate equation can be described as follows. 

Toor, A. P., M. Sharma, S. Thakur R. K Wanchoo (2011) Ion-exchange Resin Catalyzed Esterification of Lactic Acid with Isopropanol a Kinetic Study. Bulletin of Chemical Reaction Engineering Catalysis, 6,39-45, ISSN 1978-2993. 

Kavcic S, Knez Z, Leitgeb M. Antimicrobial activity of n-butyl lactate obtained via enzymatic esterification of lactic acid with n-butanol in supercritical trifluoromethane. Supercrit Fluids 2014 85 143-50. 

Esterification/Saponification. Esterification of lactic acid with methanol/ethanol yields systems with good separation characteristics to separate many impurities with different boiling points [60]. However, the energy demand of a full reaction/distillation route from crude acid to pure acid is high. 

The synthesis of lactide was first described by Pelouze in 1845 [71]. He investigated the self-esterification of lactic acid by heating and driving off water and obtained a prepolymer that was no longer fully miscible with water. Upon continued heating of the prepolymer, he noticed that in a certain distillate fraction nice crystals were formed. He was able to deduce the chemical formula and gave the name lactid to the substance. An improved procedure was... 

Ethyl lactate (ethyl 2-hydroxypropionate) is a nontoxic biodegradable compoxmd naturally found in a variety of food and industrially produced via esterification of lactic acid with ethanol [149]. Both of the components for the production of ethyl lactate are derived from renewable raw material (including low-cost agricultural waste) mainly by the fermentation process. This environmentally benign solvent with high boiling point (154 °C) and low volatility has properties superior to many conventional petroleum-based solvents and can substitute them as an eco-friendly alternative in many reactions [150,151]. The applications of ethyl lactate as a medium for the multicomponent heterocyclic synthesis are exemplified below. 

Yadav and Kulkami (2000) have studied the esterification of lactic acid with isopropanol in presence of various ion exchange resin catalysts (Indion-130, Amberlyst-36, Amberlyst-15, Amberlite-120, Dowex 50W, Filtrol-44, 20% DTPA/K-10 and 20% DTPA/Filtrol-44) A theoretical kinetic model was developed for evaluation of this slurry reaction. The effects of various parameters on the rate of reaction were evaluated. The reaction was found to be kinetically controlled and there were no intraparticle as well as interparticle mass transfer limitations on the rate of reactions. 

Kamble SP, Barve PP, Joshi JB, Rahman I, Kulkarni BD (2012) Purification of lactic acid via esterification of lactic acid using a packed column, followed by hydrolysis of methyl lactate... 

From, M., Adlercreutz, P. and Mattiasson, B. (1997) Lipase catalyzed esterification of lactic acid. Biotechnol. Lett., 19, 315-317. 

Ethyl lactate is produced by esterification of lactic acid with ethanol and this process can be done in biorefineries. In these plants, biomass as raw material is transformed into biobased products such as proteins, acids, alcohols, fibers or energy (biogas). In the case of ethyl lactate, both ethanol and lactic acid can be produced in biorefineries from a variety of biomass crops, such as sugar, starch or cellulosic feedstocks, particularly from wastes, resulting also in an economic revaluation for by-products. 

Ethyl lactate is commercially produced by esterification of lactic acid with ethanol with water as by-product (Figure 20.4.3). This esterification process is important not only to produce the solvent, but also as a step in the purification of lactic acid itself Lactic acid formed via fermentation from agroindustrial by-products needs purification since the fermented broth contains residual sugar compounds, organic acids, and other impurities, together with materials added during the production process such as calcium carbonate to neutralize the lactic acid. ° In this regard, lactic acid molecules are reacted with ethanol and other alcohols such as methanol and butanol to form lactic acid esters and, once they... 

Figure 20.4.3. Esterification of lactic acid with ethanol.

Figure 20.4.5. Lactic acid oligomerization (a), esterification of lactic acid oligomer (b) and hydrolysis equilibrium.

Several authors have reported kinetic studies on the esterification of lactic acid with ethanol, carried out with different catalysts (mainly heterogeneous catalysis), at different temperatures, lactic acid/ethanol ratio and different eoneentrations of aqueous lactic acid. " In most studies, the presence of oligomers has not been considered, since their amount is irrelevant at equilibrium. ... 

VLB measurements of the quaternary system involved in the esterification of lactic acid with ethanol at 101.3 kPa was presented by Delgado et al The esterification reaction is equilibrium-limited and usually does not reach completion. Lactic acid esters are used as powerful high-boiling solvents, and are produced by conventional esterification of lactic acid with the corresponding alcohol. 

Pereira, C.S.M., Pinho, S.P., Silva, V.M.T.M., et al., 2008. Thermodynamic equilibrium and reaction kinetics for the esterification of lactic acid with ethanol catalyzed by acid ion-exchange resin. Industrial Engineering Chemistry Research 47,1453-1463. 

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