Ester solvents ethyl lactate

Another reactive separation processes studied for ethyl lactate production is the catalytic extractive reaction (Figure 20.4.7). In this case, the esterification is performed in a biphasic liquid solvent system composed by a reactive polar liquid phase which contains the esterification constituents lactic acid, eflianol and catalyst, and an extractive organic solvent selective of the ester. Therefore, ethyl lactate should preferably be dissolved in the extractive organic phase shifting, in this way, the reaction equilibrium to ester formation. The immiscible extractive solvent is an aromatic or other solvent like toluene, benzene or diethyl ether, among others. Nevertheless, it has also been used an immiscible solvent based on fatty acid methyl ester, but in this case, the procedure represents a method to produce an organic biosolvent and not just ethyl lactate as solvent. 

Medium Boiling Esters. Esterificatioa of ethyl and propyl alcohols, ethylene glycol, and glycerol with various acids, eg, chloro- or bromoacetic, or pymvic, by the use of a third component such as bensene, toluene, hexane, cyclohexane, or carbon tetrachloride to remove the water produced is quite common. Bensene has been used as a co-solvent ia the preparatioa of methyl pymvate from pymvic acid (101). The preparatioa of ethyl lactate is described as an example of the general procedure (102). A mixture of 1 mol 80% lactic acid and 2.3 mol 95% ethyl alcohol is added to a volume of benzene equal to half that of the alcohol (ca 43 mL), and the resulting mixture is refluxed for several hours. When distilled, the overhead condensate separates iato layers. The lower layer is extracted to recover the benzene and alcohol, and the water is discarded. The upper layer is returned to the column for reflux. After all the water is removed from the reaction mixture, the excess of alcohol and benzene is removed by distillation, and the ester is fractionated to isolate the pure ester. 

Much work [42] has been devoted to cinchona alkaloid modified Pd and Pt catalysts in the enantioselective hydrogenation of a-keto esters such as ethyl pyruvate (Scheme 5.11). Optimal formulation and conditions include supported Pt, the inexpensive (—)-cinchonidine, acetic acid as solvent, 25 °C and 10-70 bar H2. Presently, the highest e.e. is 97.6% [to (R)-ethyl lactate]. 

The solvents most commonly employed are water, ethyl and methyl alcohol, ether, benzene, petroleum ether, acetone, glacial acetic acid also two or three solvents may be mixed to get the desired effect as described later. If you still cannot dissolve the compound, try some of these chloroform, carbon disulfide, carbon tetrachloride, ethyl acetate, pyridine, hydrochloric acid, sulfuric acid (acids are usually diluted first), nitrobenzene, aniline, phenol, dioxan, ethylene dichloride, di, tri, tetrachloroethylene, tetrachloroethane, dichloroethyl ether, cyclohexane, cyclohexanol, tetralin, decalin, triacetin, ethylene glycol and its esters and ethers, butyl alcohol, diacetone alcohol, ethyl lactate, isopropyl ether, etc. 

In Illinois, engineers have devised a new way of halving the cost of mannfactnring ethyl lactate. The new process uses a fine membrane to efficiently remove water, which is prodnced as a reaction byproduct, and allows the production of lactate esters that are almost pnre. This method of prodnction will make the environmentally benign ethyl lactate a cheap replacement for the harmfnl solvents nsed for paints, glues, inks, and dyes (Knight, 1998). 

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) ... 

The ethyl lactate should be of good quality, as its impurities tend to appear in the final product. The submitter used a good commercial grade supplied by British Industrial Solvents, Ltd. Its specification included an ester content of not less than 99% (calculated as ethyl lactate). 

Solubility in the solvent selected for application Currently the organic solvent are replaced with water as a suspension system, although certain types of film coatings may require organic solvents to be used. Commonly used solvents include alcohols (methanol, ethanol, and isopropanol), esters (ethyl acetate and ethyl lactate), ketones (acetone), and chlorinated hydrocarbons (dichlo-romethane and trichloroethane). 

The formation of lactic acid and its role as a food preservative were already discussed in connection with food fermentations, where it is produced in small concentrations. It is also possible to isolate it as a neat acid to convert the acid to the corresponding esters. Ethyl and butyl esters are good solvents for polymers and resins. Ethyl lactate, for instance, is used in the electronics industry to remove salts and fat from circuit boards it is also a component in paint strippers. Ethyl and butyl esters are approved food additives. This illustrates their low toxicity. 

Following the key finding of Helmchen [23], the bis-(S)-ethyl lactate ester of fumaric acid was prepared from fumaryl chloride, as illustrated in Scheme 2. Cycloaddition of this dienophile with cyclopentadiene to give (3) required some experimental modification in order to eliminate halogenated solvents. A survey of solvents and reaction conditions revealed that triethylamine as solvent allows both a reasonable reaction rate and high diastereomeric excess (d.e. = 93%) when the reaction is conveniently conducted at room temperature. 

The most popular solvents used in the formulation of DNQ/novolac resists are propylene glycol monomethylether acetate, ethylene glycol monomethyl or monoethyl ether (cellosolve or methyl cellosolve), and ethyl lactate. For more hydrophobic resins, celloslove acetate (ethylene glycol monoethyl ether acetate) is employed. Ester solvents, particularly acetates such as butyl acetate, are used as diluents, as are aromatic hydrocarbons, such as xylenes. ... 

Ethyl lactate is the ethyl ester of lactic acid and is used today in food, pharmaceuticals, cosmetics, and in the manufacture of semiconductors. The global production of ethyl lactate is estimated to be 14—18000 tonnes per year at a selling price of 2.30-3.00 EUR kg" [26]. This price has been a hurdle in the expansion of ethyl lactate beyond its use as a specialty solvent and kept sales volumes low. 

Ethyl lactate is a colorless and olmost odorless liquid, which, upon evaporotion, will sometimes develop a disagreeable odor. This is owing to the iactides, or inner anhydrides, contained in the lactic acid mode by fermentation. It is miscible with water, alcohols, ketones, esters, hydrocarbons and oils. Ethyl lactate will dissolve cellulose acetate ond nitrate ond many of the ethers of Cellulose. It is also a solvent for basic dyes, alkyd resins, kauri, manila, pontionac, rosin, shellac and vinyl resins. Ethyl lactate has high solvent power and equally high tolerance far nonsolvents and diluents. These exceptional properties are accounted for by the existence of both an alcohol and an ester group in its molecule. 

Imparts typical acetic acid ester aroma (high ethyl acetate fruity-solvent notes). Produce large quantities of acids lactic and consequently ethyl lactate, and acetic acid. 4-ethylphenol and 4-ethylguaiacol also associated with Brett heers (see text). 

In the main esterification process for acetic acid ethyl ester (ethyl acetate) a mixture of acetic acid and ethanol with a small amount of sulphuric acid is preheated and fed to an esterifying column where it is refluxed. The mixture removed goes to a second refluxing column where a ternary azeotrope containing 85% ethyl acetate is removed. Water is mixed with the distillate after which it separates into two layers. The top layer is fed to a refluxing column from which the residue containing 95% ethyl acetate is distilled to remove any impurities. Ethyl acetate and ethyl lactate are used as solvents. Some ethyl esters of carboxylic acids are used as flavor and aroma substances. 

Ethyl lactate is a nontoxic and biodegradable solvent derived from renewable carbohydrates. Its use and acceptance can be increased only if it is competitively priced to replace traditional organic solvents such as methylene chloride and chloroform. Argoime s National Lab developed a selective membrane technology for synthesizing ethyl lactate that eliminates the production of an equimolar amount of salt waste. The process uses pervaporation membranes and catalysts to directly convert the salts to esters, thereby eliminating the problem of salt waste. This approach reduces the product cost by half. The concept of pervaporation consists of the use of a membrane that selectively accepts one compound from a mixture of compounds it is explained in Chapter 6. 

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