Methyl lactate

Meth/I lactate is a water-white liquid, completely miscible with water and most organic liquids. It is a solvent for nitrocellulose, cellulose acetate, cellulose ocetobutyrate ond cellulose acetoprapionate. It is used in the manufacture of locquers and dopes where it contributes high tolerance for diluents, good flaw and blush resistance. 

Between 141 C and 14S C Above 15S C Flash point Heat of eombiutlon Freaiing point Non.volatlle matter Purity 

No turbidity when mixed with 19 volumae of 00 B4 gasoline 9.09 lbs 

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This mixture can be purified by adding methanol to form methyl lactate [547-64-8] which is separated from the ammonium bisulfate. The methyl lactate is distilled, then hydroly2ed back to the aqueous acid. Removal of most of the water yields 90% lactic acid (29). 

This method of preparation is suitable for producing primary alkyl lactates but is unsatisfactory for /3-methallyl lactate because the strong mineral acid catalyzes the rearrangement of methallyl alcohol to isobutyraldehyde. Methyl lactate can be made conveniently (80-85% yield) by heating 1 mole of lactic acid condensation polymer with 2.5-5 moles of methanol and a small quantity of sulfuric acid at 100 for 1-4 hours in a heavy-walled bottle, such as is used for catalytic hydrogenation with a platinum catalyst. 

Hydrazoic acid Hydrides, volatile Hydrogen cyanide (unstabilized) Hydrogen (low pressure) Hydrogen peroxide (> 35% water) Magnesium peroxide Mercurous azide Methyl acetylene Methyl lactate Nickel hypophosphite Nitriles > ethyl Nitrogen bromide... 

We ll see in Section 21.3 that carboxylic acids (RCO2H) react with alcohols (R OH) to form esters (RC02R )- Suppose that ( )-lactic acid reacts with CH3OH to form the ester, methyl lactate. What stereochemistry would you expect the product(s) to have What is the relationship of the products ... 

Figure 4. Side and top views of the energetically most favorable complexes formed between protonated cinchonidine and methyl pyruvate which would yield (R)-methyl lactate (left) and (S)-methyl lactate (right), respectively, upon hydrogenation. The complexes have been accomodated on a space filling model of platinum (111) surface in order to illustrate the space requirements of the adsorbed complexes. For the sake of clarity, in the side views the carbon atoms of the reactant are marked with a white square and the oxygen atoms with an o. Data taken from ref. [41].

Deuterium distributions in methyl pyruvate and methyl lactate (X = H or D) ... 

Figure 2. Mechanism for exchange in methyl pyruvate and for its hydrogenation to methyl lactate via an enol intermediate. R = COOCH3...

The enantiomeric excess (ee) of the hydrogenated products was determined either by polarimetry, GLC equipped with a chiral column or H-NMR with a chiral shift reagent. Methyl lactate and methyl 3-hydroxybutanoate, obtained from 1 and 2, respectively, were analized polarimetry using a Perkin-Elmer 243B instrument. The reference values of [a]o(neat) were +8.4° for (R)-methyl pyruvate and -22.95° for methyl 3-hydroxybutcinoate. Before GLC analysis, i-butyl 5-hydroxyhexanoate, methyl 5-hydroxyhexanoate, and n-butyl 5-hydroxyhexanoate, obtained from 1, 5, and 6, respectively, were converted to the pentanoyl esters, methyl 3-hydroxybutanoate was converted to the acetyl ester, and methyl 4-methyl-3-hydroxybutanoate obtained from 2 was converted the ester of (+)-a-methyl-a-(trifluoromethyl)phenyl acetic acid (MTPA). 

One of the most interesting side reactions taking place during the enantioselective hydrogenation is the transesterification of the substrate or the reaction product. If the enantioselective hydrogenation of ethyl pyruvate was performed in methanol as a solvent the formation of methyl pyruvate and methyl lactate was observed. CD appeared to be an effective catalyst for the above transesterification reaction. 

Choi and Won (1999) have reported a very u.seful strategy of recovering relatively nonvolatile lactic acid (e.g. from fermentation of carbohydrates) as volatile methyl lactate using a cationic ion-exchange resin as the catalyst. In another column reactor the methyl lactate is hydrolysed, using a cationic ion-exchange resin as the catalyst, to lactic acid and methanol, and the latter is recycled. 

Methyl acrylate is also produced by the carboxylation of acetylene in aqueous methanol, by the dehydration of methyl lactate and by the methanolysis of p-propiolactone or acrylic acid. 

One may use the stronger term chirality discrimination when a substantial suppression of one intermolecular diastereomer with respect to the other occurs. This requires multiple strong interactions between the two molecular units and therefore more than simple monofunctional alcohols. Some examples where one of the molecules involved is a chiral alkanol are reported in Refs. 112 and 119 121. Pronounced cases of higher-order chirality discrimination have been observed in clusters of hydroxy esters such as methyl lactate tetramers [122] and in protonated serine octamers [15,123,124]. The presence of an alcohol functionality appears to be favorable for accentuated chirality discrimination phenomena even in these complex systems [113,123,125,126]. Because the border between chirality recognition and discrimination is quite undefined, it is suggested that the two may be used synonymously whenever both molecular partners are permanently chiral [127]. 

T. B. Adler, N. Borho, M. Reiher, and M. A. Suhm, Chirality induced switch in hydrogen bond topology Tetrameric methyl lactate clusters in the gas phase. Angew. Chem. Int. Ed. 45, 3440 3445 (2006). 

Chiacchio et al. (43,44) investigated the synthesis of isoxazolidinylthymines by the use of various C-functionalized chiral nitrones in order to enforce enantioselec-tion in their cycloaddition reactions with vinyl acetate (Scheme 1.3). They found, as in the work of Merino et al. (40), that asymmetric induction is at best partial with dipoles whose chiral auxiliary does not maintain a fixed geometry and so cannot completely direct the addition to the nitrone. After poor results with menthol ester-and methyl lactate-based nitrones, they were able to prepare and separate isoxazo-lidine 8a and its diastereomer 8b in near quantitative yield using the A-glycosyl... 

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

For the Pt/cinchona catalysts only preliminary adsorption studies have been reported [30]. From the fact that in situ modification is possible and that under preparative conditions a constant optical yield is observed we conclude that in this case there is a dynamic equilibrium between cinchona molecules in solution and adsorbed modifier. This is supported by an interesting experiment by Margitfalvi [63] When cinchonine is added to the reaction solution of ethyl pyruvate and a catalyst pre-modified with cinchonidine, the enantiomeric excess changes within a few minutes from (R)- to (S)-methyl lactate, suggesting that the cinchonidine has been replaced on the platinum surface by the excess cinchonine. 

If we convert (+)-lactic acid into its methyl ester, we can be reasonably certain that the ester will be related in configuration to the acid, because esterification should not affect the configuration about the chiral carbon atom. It happens that the methyl ester so obtained is levorotatory, so we know that (+)-lactic acid and (—)-methyl lactate have the same relative configuration at the asymmetric carbon, even if they possess opposite signs of optical rotation. However, we still do not know the absolute configuration that is, we are unable to tell which of the two possible configurations of lactic acid, 2a or 2b,... 

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