Lactate ester solvents

Fermentation-derived organic acids and their esters are potentially important chemical feedstocks for polymers and specialty polymers, but most significantly as alternative solvents for industrial and consumer applications. For example, lactate esters are derived from renewable carbohydrate raw materials such as cornstarch. They exhibit much lower toxicity compared with halogenated hydrocarbons and ethylene glycol ethers and are environmentally benign. Some studies suggested that lactate ester solvents have the potential of replacing petroleum-based solvents... 

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). 

Lactic acid is an important chemical that has wide applications in food, pharmaceutical, cosmetic, and chemical industries. There are increasing interests in production of lactate esters and biodegradable polylactic acid (PLA) from lactic acid. Lactate esters are a relatively new family of solvents with specific properties. They are considered safe and are biodegradable (1). In many situations they can replace toxic solvents. Their functions vary from that of intermediates in chemical reactions to solvents in ink formulations and cleaning applications (2). PLA has been widely used in medical implants, sutures, and drug-delivery systems because of its capacity to dissolve over time (3-5). PLA also can be used in products such as plant pots, disposable diapers, and textile fabrics. 

The levels of selectivity achieved in these reactions are amongst the highest reported for non-enzymatic acylative KR, and the scope of the method has been reviewed by Vedejs [40], as has its application in PKR [43]. The PBO catalysts 2a-c are prepared by a multi-step enantioselective synthesis from lactate esters [42, 44] and are air-sensitive hence, the reactions are generally run in de-oxygenated solvents. However, the air-stable tetrafluoroboric acid salts of these catalysts can also be employed with in-situ deprotonation by EtsN these conditions give results comparable with those obtained using the original protocol [45]. (For experimental details see Chapter 14.17.1). 

VOC Requirements — The minimization of VOC s (Volatile Organic Compoimds) in the workplace is another trend which has emerged in recent years. Choice of solvent mixture can again benefit this requirement, with additions of solvents such as Acetone and higher boiling point Lactate Esters. 

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. 

Within certain industrial applications like gas and oil industry and ink and printing industry there is a need for cleaning when the remaining surface should be water-wet. A neutral microemulsion system based on a surfactant, a lactate ester as co-surfactant and an organic solvent like limonene is suggested by Harrison for this purpose. Butyl lactate is shown to enlarge the one-phase (Winsor IV) area in the phase diagram, for instance SDS and limonene in water [94, 95]. 

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. ... 

Classification Lactate ester Definition 2-Ethylhexyl ester of lactic acid Uses Solvent... 

Novel Membrane-Based Process for Producing Lactate Esters— Nontoxic Replacements for Halogenated and Toxic Solvents... 

Amyl lactate CH3CH(OH)COOC5Hn. Water white to pale yellow colored liquid used as an ester solvent. It plasticizes in lacquers and has a bp of 210°C. 

Substituting formic, propionic, or butyric acid for acetic acid in the esterification reaction yields the corresponding formate, propionate, and butyrate esters. Lactic acid and oxalic acid (a difunctional acid) can also be reacted with alcohols to give the lactate and oxalate ester solvents. A versatile series of esters formed from the reaction of methanol with difunctional adipic, glutaric, and succinic acids yield the dibasic esters which are commonly referred to as DBE solvents. Reaction of lower aliphatic alcohols with t)-phthalic acid or phosphoric acid yield the corresponding phthalate and phosphate esters. Another important group of esters are obtained from the... 

ANL s novel process uses pervaporation membranes and catalysts. In the process, ammonium lactate is thermally and catalytically cracked to produce the acid, which with the addition of alcohol is converted to the ester. The selective membranes pass the ammonia and water with high efficiency while retaining the alcohol, acid, and ester. The ammonia is recovered and reused in the fermentation to make ammonium lactate, eliminating the formation of waste salt. The innovation overcomes major technical hurdles that had made current production processes for lactate esters technically and economically noncompetitive. The iimovation will enable the replacement of toxic solvents widely used by industry and consumers, expand the use of renewable carbohydrate feedstocks, and reduce pollution and emissions. 

More than 80% of the applications—requiring the use of over 7.6 billion pounds of solvents—in the United States each year are suitable for reformulation with environmentally friendly lactate esters. 

Although LA production by LAB is very efficient, further improvements in the process can help make it more cost competitive with petroleum-based polymers for PL A production. Environmentally friendly, green solvents are another potential area for lactic acid derivatives, particularly lactate esters of low-molecular-weight alcohols such as ethyl, propyl and butyl lactate (John et al. 2007 Delgado et al. 2010). From that perspective the lactate esters have also further applications in order to run alternative downstream technology (Kamble et al. 2012) and PLA polymerization process (Marques et al. 2012). 

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]. 

However, morpholine-4-carboxylic acid 2-hydroxy-1-methyl-ethyl ester is formed by the reaction of PC and the substrate morpholine in an undesired side reaction. By use of 1.4-dioxane or the pyrrolidones as mediator s3 about 30 to 45% of the morphoUne is consumed by this side reaction. The by-product is contained in the PC phase and can not be extracted to the non-polar product phase. The selectivity to the desired amines is lowered, because of the consiunption of the morphoUne. Thus, PC has to be substituted by another polar solvent (e.g. water, methanol or ethylene glycol) in future experiments. The lactates react with the morphoUne, too resulting in the corresponding amide. Overall, the hydroaminomethylation in the TMS systems PC/dodecane/lactate results in a conversion of 1-octene of about 80%, but in selectivities to the amines of only 50 to 60%. 

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. 

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