Esters lactates

Reaction of a metal lactate (such as silver lactate) with an alkyl haUde is a classic method of preparation of the ester, but it is too expensive to be of commercial relevance. Lactamide [2043-43-8] is another high yielding condensation product from lactic acid. It can be produced by aminolysis of dilactide or lactate ester such as methyl or ethyl lactate. 

Commercial chromatography silica gel promotes effectual Diels-Alder cycloaddition of optically active pyrone lactate ester (5) with benzyl vinyl ether (6), affording the endo adduct 7 in an approximately 4 1 mixture of diastereoisomers [16] (Equation 4.1). 

Mandelate and lactate esters have been found to generate diastereoselectivity in reactions of hydroxy-substituted quinodimethanes generated by thermolysis of benzo-cyclobutenols.88 The reactions are thought to proceed by an exo TS with a crucial hydrogen bond between the hydroxy group and a dienophile carbonyl. The phenyl (or methyl in the case of lactate) group promotes facial selectivity. 

Allylic methyl group hydroxylation and oxidation to carboxylic acid Beauveria bassiana) Allylic methyl group hydroxylation and lactate ester formation glucosidation Cunninghamella echinulata)... 

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). 

Most studies on the effect of storage on -lactam residues have been directed toward penicillin G. Kidney tissue samples containing penicillin G showed some loss of microbiological activity when stored at 4 C (1), whereas incurred tissues held in a walk-in cooler at 4 C for about 2 weeks or stored in freezer at 20 C over the same period were also found to contain lower penicillin G levels than were present initially (20). The lactate ester of penicilloic acid has been identified as the major decomposition product of penicillin G formed during the storage of incurred beef and chicken samples at 2 C or room temperature (21). 

Various degradation products of penicillin G have been demonstrated in the cooked meat (21). The major product formed after cooking was identified as the lactate ester of penicilloic acid. Moreover, formation of bound residues was also suggested. 

Owing to the high thermal and long-term stability, amide phases bonded to polysiloxane are regarded as sensitive materials for the sensoric approach to enantiomeric separation. An important factor for the resolution of the stationary material is the number of dimethylpolysiloxane units between the chiral moieties. More than 200 different amide phases have been synthesised and applied for the discrimination of amino acids, lactate esters and many other substances [10]. 

The enantiomeric composition of methyl lactate ester mixtures was measured by an array of S- and it-sensors and the data were evaluated by chemo-metric tools (multiple line regression, partial component analysis and principal component regression). The ability to distinguish the enantiomeric composition of various mixtures of N-TFA-Ala-OMe or lactates quantitatively with octyl-Chirasil-Val was demonstrated [18]. 

Both enantiomers of methyl and ethyl lactate ester and several amino acid derivatives were successfully discriminated by both optical transduction principles. In Fig. 8 the results of SPR measurements of both enantiomers of the valine esters with L-Chirasil-Calix are shown. In accordance with gas chromatographic investigations, the L-enantiomer of the amino acid derivatives shows stronger interaction with an L-Chirasil-Calix sensitive layer. This leads... 

Regarding the response signals of the lactate esters, the D-enantiomers showed stronger interaction with the L-polymer of Chirasil-Calix. This is in agreement with the elution sequence in GC. 

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. 

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... 

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). 

However, benzyl alcohols can be converted to benzaldehydes even in the dark.208 It has been reported that catalytic amounts of HBr may be used for this reaction.209 Primary aliphatic alcohols give rise to carboxylic esters. Catalytic amounts of bromine itself have been used, instead of HBr in the oxidation of lactate esters to pyruvates.210... 

It was prepd by duPont Co by, presumably, standard nitration of the lactate ester and found, on examination, to be an explosive stable at 75° but decomposing at 105° with evoln, after 17 hours, of 30cc of gas, vs 120cc for NG. Its impact sensitivity with 20kg wt was 40 inches for 1/10 shots and 37 inches for 0/10 shots Refs 1) Beil, not found 2) CA, not found... 

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. 

Asymmetric reactions of oc-keto esters of ( —)-l. Reduction of the a-keto ester (2) of (- )-8-phenylmenthol (1) with potassium triisopropoxyborohydride proceeds in 90% de to give the lactate ester (R)-3 with chirality opposite to that obtained by reaction of... 

Scheme 2-5. Molecular basis of enterococcal vanA/B- and vanC-glycopeptide resistance. Interaction of vancomycin with D-Ala-D-Lac. The lactate ester bond leads to a lowered ligand binding affinity by loss of one hydrogen bond and electronic repulsion (solid arrow).

Argonne National Laboratory received a 1998 Presidential Green Chemistry Challenge Award for the development of a novel membrane based process for producing lactate esters.The process uses pervaporation membranes and... 

Reduction of 8-phenylmenthyl pyruvate with Potassium Triiso-propoxyborohydride in THF gives 90% de of the (R)-lactate ester (eq 2), but other reducing reagents show little selectivity. The stereochemical outcome of this reduction is explained as occurring in the s-trans conformation of the pyruvate. 

Clary JJ, Feron VJ, van Velthuijsen JA. Safety assessment of lactate esters. Regul Toxicol Pharmacol 1998 27(2) 88—97. 

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 generation of the enediolate intermediate of the free lactate ester 5 a is even slower than that of the benzyl ether and requires a reaction time at —78 °C of 1 hour and warming before addition of chlorotrimethylsilane to give a 30% yield of 6a and 7a in a 4 1 ratio. 

Among other surface active esters, polyglycol esters of fatty acids, alkanoyl glycerol acetates and lactates, alkyl lactates, esters of fatty acids and pentaerythritol, glucose, methylglucose, mannose, sucrose, and, especially, sorbitol are often exploited. The latter, sorbitan acylates, are particularly known as Spans , Arlacels , and Arlamol ISML - all of ICI production. These mild and low-toxic emulsifiers are widely applied in food, pharmaceutical, personal care and other consumer and industrial products. 

Alternatively, 689 is available from lactate esters 401 or 402 by partial reduction with diisobutylaluminum hydride at —78 °C [117,129,148]. Yields for this process typically range from 76-100%. 

Figure 2 Schematic representation of the formation and degrad-tion for dex(lactate)HEMA hydrogels. Gels are formed by radical polymerization of the methacrylate groups using KPS and TEMED as initiator system. Degradation occurs by hydrolysis of the carbonate and lactate ester.

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