Alkyl Lactates Research Articles

Lipase-catalyzed enantioselective synthesis of (R,R)-lactide from alkyl lactate to produce PDLA (poly D-lactic acid) and stereocomplex PLA (poly lactic acid)

R-lactide, a pivotal monomer for the production of poly (D-lactic acid) (PDLA) or stereocomplex poly (lactic acid) (PLA) was synthesized from alkyl (R)-lactate through a lipase-catalyzed reaction without racemization. From among several types of lipase, only lipase B from Candida antarctica (Novozym 435; CAL-B) was effective in the reaction that synthesized (R,R)-lactide. Enantiopure (R,R)-lactide, which consisted of over 99% enantiomeric excess, was synthesized from methyl (R)-lactate through CAL-B catalysis. Removal of the methanol by-product was critical to obtain a high level of lactide conversion. The (R,R)-lactide yield was 56% in a reaction containing 100mg of Novozym 435, 10mM methyl (R)-lactate and 1500mg of molecular sieve 5A in methyl tert-butyl ether (MTBE). The important monomer (R,R)-lactide that is required for the production of the widely recognized bio-plastic PDLA and the PLA stereocomplex can be obtained using this novel synthetic method.

Synthesis of titanium alkoxide complexes with alkyl lactate ligands. Asymmetric epoxidation of cinnamyl alcohol

A family of titanium (IV) alkoxide compounds [{Ti(OPri)3(OLact)}2], and [Ti(OPri)2(OLact)2] (1–6) have been prepared by alcohol exchange of Ti(OPri)4 and the corresponding alkyl-2-hydroxy-alkylpropionate or alkyl lactate (LactOH = Benzyl-(S)-lactate, methyl-(S)-3-phenyllactate and menthyl-(S)-lactate. These alkoxide titanium (IV) compounds have been characterized by spectroscopic and electrochemical techniques. In addition, these chiral Lewis acid titanium compounds have been studied in the asymmetric epoxidation of cynnamyl alcohol, the obtained results show that these complexes with dynamic behaviour in solution exert low control of the enantioselectivity. Electronic and sterical effects of the ligands in the catalytic results have been studied.

Fast and Selective Sugar Conversion to Alkyl Lactate and Lactic Acid with Bifunctional Carbon–Silica Catalysts

A novel catalyst design for the conversion of mono- and disaccharides to lactic acid and its alkyl esters was developed. The design uses a mesoporous silica, here represented by MCM-41, which is filled with a polyaromatic to graphite-like carbon network. The particular structure of the carbon-silica composite allows the accommodation of a broad variety of catalytically active functions, useful to attain cascade reactions, in a readily tunable pore texture. The significance of a joint action of Lewis and weak Brønsted acid sites was studied here to realize fast and selective sugar conversion. Lewis acidity is provided by grafting the silica component with Sn(IV), while weak Brønsted acidity originates from oxygen-containing functional groups in the carbon part. The weak Brønsted acid content was varied by changing the amount of carbon loading, the pyrolysis temperature, and the post-treatment procedure. As both catalytic functions can be tuned independently, their individual role and optimal balance can be searched for. It was thus demonstrated for the first time that the presence of weak Brønsted acid sites is crucial in accelerating the rate-determining (dehydration) reaction, that is, the first step in the reaction network from triose to lactate. Composite catalysts with well-balanced Lewis/Brønsted acidity are able to convert the trioses, glyceraldehyde and dihydroxyacetone, quantitatively into ethyl lactate in ethanol with an order of magnitude higher reaction rate when compared to the Sn grafted MCM-41 reference catalyst. Interestingly, the ability to tailor the pore architecture further allows the synthesis of a variety of amphiphilic alkyl lactates from trioses and long chain alcohols in moderate to high yields. Finally, direct lactate formation from hexoses, glucose and fructose, and disaccharides composed thereof, sucrose, was also attempted. For instance, conversion of sucrose with the bifunctional composite catalyst yields 45% methyl lactate in methanol at slightly elevated reaction temperature. The hybrid catalyst proved to be recyclable in various successive runs when used in alcohol solvent.

Recovery of alkyl lactate from ammonium lactate by an advanced precipitation process

The recovery of lactic acid from ammonium lactate solution is impossible by the conventional acidification process because of the high solubility and lack of precipitation of ammonium sulfate. We found that only the addition of methanol to the solution during acidification of ammonium lactate was very effective in decreasing the solubility of the produced ammonium sulfate. This product could then be separated from the solution by simple filtration. With this advanced acidification process, the lactic acid filtrate was transformed into methyl lactate rapidly by an esterification reaction with methanol even at room temperature. The methyl lactate produced from the fermentation broth of ammonium lactate by this technique could be separated by simple distillation without change in the optical purity of lactic acid. This approach is simple and cost effective because all processes can be carried out at room temperature without complicated equipment. It is also regenerative because the ammonium sulfate byproduct can be utilized for production of sulfuric acid and ammonia.

Synthesis of Lactide from Alkyl Lactate via a Prepolymer Route

Poly(lactic acid) is a biodegradable polymer that has enormous potential for use as a replacement for some petroleum-based materials. However, the properties of this polymer depend strongly on the quality of the lactide monomer from which it is often synthesized. In this work, lactide was synthesized from alkyl lactate via a prepolymer route, and the reaction kinetics was compared with lactide synthesis from lactic acid. A number of different parameters were investigated in order to obtain the highest possible yield of lactide, as well as to achieve l-isomer selectivity. Among the various acid catalysts tested, Sn(Oct)2 was found to be the most effective for L-lactide selectivity as well as for producing a high oligomer yield from the alkyl lactate. The effect of the alkyl group length of the starting materials was investigated with the highest lactide yield being obtained from ethyl lactate, over methyl and butyl lactate. The deoligomerization reaction was also studied in detail. It was found that an oligomer with a molecular weight of 600–800 g/mol gave the highest lactide yield. The optimum depolymerization temperature for the oligomer with a molecular weight of 1274 g/mol was shown to be 180 °C, as above this temperature, the reaction rate of oligomerization for heavy residue was much faster than that of deoligomerization for crude lactide, which resulted in a lower lactide yield.

Highly selective catalytic propylene glycol synthesis from alkyl lactate over copper on silica: Performance and mechanism

Catalytic alkyl lactate hydrogenolysis over silica-supported copper at atmospheric hydrogen pressure and temperature range 433–493K provides an eco-friendly green alternative to the petroleum-based process for propylene glycol synthesis. It was shown that catalytic activity strongly depends on copper loading and the most active catalyst contains ca. 45wt.% Cu. General peculiarities of methyl and butyl lactate hydrogenolysis were studied demonstrating that an overall reaction rate increases with reaction temperature increase but a selectivity to propylene glycol decreases due to enhanced concurrent dehydrogenation of propylene glycol to a by-product hydroxyacetone. It was found that the amount of propylene glycol formed during the reaction is determined by thermodynamic equilibrium between propylene glycol and hydroxyacetone that results in propylene glycol selectivity of 96% at full butyl lactate conversion at 453K. Overall mechanism of alkyl lactate transformation involving formation of intermediate hemiacetal over bifunctional Cu/SiO2 catalyst was proposed.

Protease-Catalyzed Oligomerization and Hydrolysis of Alkyl Lactates Involving l-Enantioselective Deacylation Step

ADVERTISEMENT RETURN TO ISSUEPREVNoteProtease-Catalyzed Oligomerization and Hydrolysis of Alkyl Lactates Involving l-Enantioselective Deacylation StepHitomi Ohara*†, Emiko Nishioka†, Syuhei Yamaguchi†, Fusako Kawai‡, and Shiro Kobayashi*‡View Author Information† Department of Biobased Materials Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan‡ Center for Nanomaterials and Devices, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, JapanE-mail: [email protected] (H.O.); [email protected] (S. K.).Cite this: Biomacromolecules 2011, 12, 10, 3833–3837Publication Date (Web):August 26, 2011Publication History Received20 July 2011Revised22 August 2011Published online9 September 2011Published inissue 10 October 2011https://doi.org/10.1021/bm201004gCopyright © 2011 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views464Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (770 KB) Get e-AlertsSUBJECTS:Catalysts,Hydrolysis,Monomers,Oligomerization,Peptides and proteins Get e-Alerts

Conversion of triose sugars with alcohols to alkyl lactates catalyzed by Brønsted acid tin ion-exchanged montmorillonite

We describe the Brønsted acid catalysis of tin ion-exchanged montmorillonite (Sn-Mont), which is easily prepared by the ion-exchange of naturally occurring sodium montmorillonite (Na-Mont) with an aqueous tin tetrachloride solution, for the conversion of two trioses, i.e., dihydroxyacetone (DHA) and glyceraldehyde (GLA), in alcohols to afford the corresponding alkyl lactates. For the conversion of DHA with methanol, the product distribution closely depends on the substrate concentrations, reaction temperatures, and reaction times. Under the optimized reaction conditions, an almost quantitative yield of methyl lactate is obtained with the production of water as the exclusive side-product. Additionally, the montmorillonite catalyst is easily recovered from the reaction mixture by filtration, and reused without any loss in activity. Sn-Mont also demonstrates a high activity for the conversion of DHA with higher alcohols, such as EtOH, nPrOH, and nBuOH, to the corresponding alkyl lactates in 89–93% yields.

Hydroxyapatite Supported Lewis Acid Catalysts for the Transformation of Trioses in Alcohols

We prepared hydroxyapatite-supported tin(II) chloride and tin(IV) chloride Lewis acid catalysts. These catalysts showed catalytic activity for the transformation of trioses in alcohols to yield alkyl lactates. Under optimal conditions, n-butyl lactate was obtained in 73.5% yield when dihydroxyacetone and n-butanol were treated with hydroxyapatite-supported tin(II) chloride. ： 采用浸渍法制备了羟基磷灰石 (HAP) 负载的路易斯酸 SnCl2 和 SnCl4 催化剂. 它们在三糖在醇溶液中转化为乳酸酯反应中表现出一定的催化活性. 在最佳的反应条件下, SnCl2/HAP 催化 1,3-二羟丙酮在正丁醇溶液中转化为乳酸正丁酯, 收率高达 73.5%.

Lipase-Catalyzed Oligomerization and Hydrolysis of Alkyl Lactates: Direct Evidence in the Catalysis Mechanism That Enantioselection Is Governed by a Deacylation Step

Lipase-catalyzed oligomerization of alkyl d- and l-lactate monomers (RDLa and RLLa, respectively) was studied for the first time. It has been found that the oligomerization occurs enantioselectively only for d-lactates to give oligomers up to heptamers of lactic acid (LA) in good to high yields by using primary C1 to C8 alkyl groups and sec-butyl group for d-lactate monomers. No reaction happened for all l-lactates in similar conditions. Lipase-catalyzed hydrolysis of alkyl d- and l-lactates was also examined, revealing that the hydrolysis took place for both d- and l-lactates, although l-lactates proceeded a couple of times slower. The hydrolysis results clearly demonstrate that the lipase catalysis mechanism involves an acyl-enzyme intermediate (EM) formation via the acylation step from both d- and l-lactates as a rate-determining step, and the subsequent deacylation step, a nucleophilic attack of water to the EM, takes place to produce free LA. On the other hand, in the oligomerization of d-lactates, the deacylation step, in which a sec-alcohol group of the monomer or of the propagating chain-end attacks to the EM, is only allowed for the sec-d-alcohol group to give a one-LA-unit-elongated oligomer. l-Lactates form the EM; however, the subsequent deacylation reaction with both the sec-l- and sec-d-alcohol groups does not take place, failing in the oligomerization to occur. These results provide with the first direct evidence in the lipase catalysis that the enantioselection is governed by the deacylation step. In the co-oligomerization between l- and d-lactates, the l-isomer retarded the reaction rate of the d-isomer, which was found due to the function of the former as a competitive inhibitor in the acylation step toward the latter.

Principles into Practice Setting the Bar for Green Chemistry

Recent years have seen a disheartening string of revelations in which everyday items once considered safe—food packaging, toys, clothes, furniture, electronic components, and many more products—are found to contain carcinogens, endocrine disruptors, and other harmful chemicals.1 Growing demand for healthier alternatives, already seen in food production and housing construction,2 is also happening at the building-block level of manufacturing, where so-called green chemistry represents a revolutionary change in preventing pollution and health problems starting at the chemical design stage. Many industry and government entities are beginning to espouse the principles of green chemistry on their websites and in public statements. Now comes the task of crafting policy to put those principles into action. The U.S. Environmental Protection Agency (EPA) defines green chemistry as “the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, and use.”3 Green chemistry also aims to mitigate the type of uncertainty Alan Gold-berg, a professor of toxicology at the Johns Hopkins Bloomberg School of Public Health, recently described to The New York Times: “I can get [toxicity] information on only 20 percent of chemicals we interact with on a daily basis.”4 Of that 20%, he now says, he may be able to find information on overt toxicity for about half, but for details on specific effects such as developmental neurotoxicity, the figure shrinks toward zero. So what does green chemistry look like? Consider the example of pregabalin, the active ingredient in the neuropathic pain drug Lyrica®. Pfizer developed an alternative green-chemistry process that converted several steps of pregabalin synthesis from use of organic solvents to water. That reduced both health hazards and production heating requirements. With the new synthesis, waste from the process dropped from 86 kg of waste per kg product to 17 kg, and energy use dropped by 82%.5 Proponents say that’s how the field can offer a win–win–win solution: good performance, lower cost, and less environmental impact—what Richard Engler, program manager of the EPA Green Chemistry Program, calls the “triple bottom line.” For many, a standard is a logical next step. “At some point you have to go beyond a definition and principles,” says Engler. “I think that’s something the standard will enable.”

Enzyme-catalyzed synthesis of enantiospecific RR-lactide from alkyl lactate using Novozym 435

Enzyme-catalyzed synthesis of enantiospecific RR-lactide from alkyl lactate using Novozym 435

Tin‐Catalyzed Conversion of Trioses to Alkyl Lactates in Alcohol Solution.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly Enantioselective Acylation of rac‐Alkyl Lactates Using Candida antarctica Lipase B.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tin-catalyzed conversion of trioses to alkyl lactates in alcohol solution

Tin chlorides, SnCl2 and SnCl4.5H2O are excellent catalysts for the reactions of trioses, dihydroxyacetone and glyceraldehyde with alcohols (MeOH, EtOH and nBuOH) to give alkyl lactates, whose reaction mechanism involves the intermediary formation of pyruvic aldehyde followed by its esterification, which is distinctively promoted by tin halides.

Highly Enantioselective Acylation of rac-Alkyl Lactates Using Candida antarctica Lipase B

By using Candida antarctica lipase B under mild conditions, the highly enantioselective acylation of alkyl (R)-lactate from racemic mixture with vinyl alkanoate has been accomplished. In this research effects of the organic solvent, the alkyl chain length of the alkyl lactates and of the vinyl alkanoates, and the reaction temperature on the enantiomeric excess as well as the reaction rate, were investigated. In all cases, only alkyl (R)-lactate was stereoselectively acylated at >99.5% ee. The lipase-catalyzed acylation rate of the alkyl lactates was affected by the nature of the organic solvents, but showed no correlation to log P of the solvent. The lipase-catalyzed acylation rate of the alkyl lactates was enhanced by increasing the chain length of the vinyl alkanoate from acetyl to butanoyl and by raising the reaction temperature to 65 °C. Finally, the lipase-catalyzed acylation and subsequent vacuum distillation successfully provided both butyl (R)-O-butanoyllactate and butyl (S)-lactate in excellent yields (48%) and enantioselectivities (>99.5% ee) on a large scale. It is expected that the present method will prove to be more efficient in achieving the chiral resolution of racemic alkyl lactate than other conventional methods in terms of environmental friendliness and simplicity.

Preparation of o-palmitoyl alkyl lactates through lipase catalysis.

Preparation of o-palmitoyl alkyl lactates with methyl, ethyl, propyl, isopropyl and butyl lactates were attempted in a complex esterification reaction using lipases as catalysts. Compared to lactic acid, alkyl lactates were found to be less inhibitory in nature as they resulted in slightly better yields at shake-flask level. Of the alkyl lactates tested, butyl lactate showed better esterification. Porcine pancreas lipase gave higher yields of esters than Rhizomucor miehei lipase (Lipozyme IM20).

The ecotoxicity and the biodegradability of lactic acid, alkyl lactate esters and lactate salts

The ecotoxicity of lactic acid, its alkyl esters and selected metal salts was studied experimentally with the micro alga Selenastrum capricornutum, the crustacean Daphnia magna and the fish species Brachydanio rerio and Pimephales promelas. In addition, the biodegradation of lactate esters was also studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. The ecotoxicity data are evaluated by means of Structure Activity Relations (SAR), using literature data on a nonpolar narcotic mechanism of toxicity as a baseline for comparison. Lactate salts were evaluated by comparison to the toxicity of the metal ion. For the fish and D. magna, it was evident that methyl, ethyl, propyl and to a lesser extent butyl lactate were slightly more toxic in comparison to baseline non-polar narcotic toxicity data. The toxicity tests carried out with lactate-salts demonstrated clearly that the toxicity in standard tests is only determined by the associated cation and not by the lactate part. Lactic acid and its alkyl esters were degraded for more than 60% in the ready biodegradability tests and from the data presented, it is evident that the majority of alkyl lactates are readily biodegradable. The results presented in this study indicate that alkyl lactate esters show some differences in their ecotoxicity when compared to non polar narcotic compounds in but that these differences are generally small. When aquatic toxicity is considered together with their rapid tendency to biodegrade, it is concluded that lactate esters show generally favourable environmental characteristics.

High-resolution GC separation of alkyl lactate enantiomers and the determination of the enantiomeric excess of the optical isomers of alkyl lactates

In this paper, the recently reported chiral stationary phase [1,2] was applied to the chiral resolution of alkyl lactates in the investigation of the effect of a new asymmetric heterogeneous catalyst system (cinchonidine-modified finely dispersed polyvinylpyrrolidone-stabilized platinum clusters) in the enantioselective hydrogenation of α-ketoesters. The enantiomers of methyl, ethyl, isopropyl, n-propyl and n-butyl lactates were successfully resolved while the enantiomers of isobutyl lactate could not be resolved, at all. The separation of the enantiomers of isopropyl, n-propyl and n-butyl lactates are reported for the first time. The results show that the new asymmetric heterogeneous catalyst system is effective in the enantioselective hydrogenation of α-ketoesters.

Mono‐branched alkyl lactate as a rheological improver for body and personal care formulations

The use of mono-branched alkyl lactate, in aqueous anionic surfactant mixtures, as a viscosity improver and cold storage stability enhancer in personal care formulations is examined, and compared with the results given by similar mixtures containing cocamide DKA. A detailed evaluation of the results is given.