Lactic Acid In Water Research Articles

Selective Conversion of Glycerol to Lactic Acid in Water via Acceptorless Dehydrogenation Catalyzed by a Water-Soluble Metal-Ligand Bifunctional Iridium Catalyst.

An efficient method for the selective conversion of glycerol, the major byproduct of the biodiesel manufacturing process, to lactic acid in water via acceptorless dehydrogenation has been developed. In the presence of a water-soluble [Cp*Ir(6,6'-(OH)2-2,2'-bpy)(H2O)][OTf]2 (0.1 mol %) and KOH (1.1 equiv), the reaction proceeded at 120 °C for 24 h to afford the desired product in >99% yield with >99% selectivity. It was confirmed that OH functional groups in the ligand were crucial for the activity of the iridium complex. Furthermore, density functional theory calculations and mechanistic experiments were also undertaken.

Safety and efficacy of a feed additive consisting of lactic acid produced by Weizmannia coagulans (synonym Bacillus coagulans) DSM 32789 for all animal species except for fish (Jungbunzlauer SA).

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of lactic acid produced by a non‐genetically modified strain of Weizmannia coagulans (synonym of Bacillus coagulans) (DSM 32789) for all animal species except for fish. The production strain qualifies for the QPS approach for safety assessment. Although uncertainty remains concerning the possible presence of viable cells and/or spores of the production strain in the final product, this does not raise safety concerns for the target species, humans and the environment. The lactic acid is safe at 50,000 mg/kg complete feed for functional ruminants and pigs and at 20,000 mg/kg feed for all the other animal species and categories except for pre‐ruminants for which a safe level cannot be established. The corresponding safe levels in water for drinking would be 15,000 mg/L water for pigs and 8,000 mg/L for other non‐ruminant species. Although no safe concentration of lactic acid in water for drinking for ruminants can be derived, the Panel considers that the use in water for drinking is safe in ruminants when the total daily intake of the additive does not exceed the daily amount that is considered safe when consumed via feed. The use of the additive under assessment in animal nutrition is considered safe for the consumers and for the environment. It is considered corrosive to the skin, eyes and mucous membranes. Lactic acid is used in food as a preservative. It is reasonable to expect that the effect seen in food will be observed in feed when it is used at comparable concentrations and conditions. However, the FEEDAP Panel has reservations about its effectiveness as a preservative in complete feed with a moisture content of ≤ 12%.

Visible-light-driven prompt and quantitative production of lactic acid from biomass sugars over a N-TiO2 photothermal catalyst

Biomass sugars can be quantitatively upgraded to lactic acid in water over a visible-light-activated N-TiO2 photothermal catalyst under mild conditions (60 °C, 0.5–2 h).

Continuous Conversion of Glucose into Methyl Lactate over the Sn-Beta Zeolite: Catalytic Performance and Activity Insight

In this study, we developed an efficient technology for the continuous conversion of glucose into methyl lactate over the Sn-Beta zeolite with a trickle bed reactor. The catalyst exhibited a high yield of 59.7% for lactic acid in water, and the total yield of methyl lactate and xylitol reached 59.8% (37.3% for methyl lactate) in methanol. The continuous evaluation of Sn-Beta demonstrated a maximum yield of 45.0% for methyl lactate along with 99% conversion of glucose in methanol, and the catalyst was continuously operated for over 434 h at 165 °C. The changes in Sn coordination and fouling stand as the dominant reason for the activity loss of Sn-Beta. Compared with the rapid decline of activity in water, reaction in methanol exhibited much less carbon deposition, structural changes, and Sn leaching after a long-term operation. The promising result indicated the potential application of Sn-Beta as an industrial catalyst for biomass utilization.

Lewis Acid and Base Catalysis of YNbO4 Toward Aqueous‐Phase Conversion of Hexose and Triose Sugars to Lactic Acid in Water

AbstractAmphoteric YNbO4 was synthesized by the simple coprecipitation using (NH4)3[Nb(O2)4] and Y(NO3)3, and examined as a new solid acid‐base bifunctional catalyst for various reactions including aqueous‐phase conversion of glucose to lactic acid. After drying the white precipitate at 353 K for 3 h, the resultant oxide is an amorphous YNbO4 with high densities of Lewis acid sites (0.18 mmol g−1) and base sites (0.38 mmol g−1). Negatively‐charged lattice oxygen of amorphous YNbO4 functioned as Lewis base sites that promote a Claisen‐Schmidt‐type condensation reaction with acetylacetone and benzaldehyde with comparable activity to reference catalysts. Amorphous YNbO4 can also be applicable to the production of lactic acid from glucose in water, which gives relatively high yields (19.6 %) compared with other reference catalysts. Mechanistic studies using glucose‐1‐d and 2H nuclear magnetic resonance spectroscopy (NMR) revealed that YNbO4 first converts glucose to two carbohydrates (glyceraldehyde and pyruvaldehyde) through dehydration via the formation of 3‐deoxyglucosone and subsequent retro‐aldolization, and these intermediates are then converted to lactic acid by both dehydration and isomerization through hydride transfer.

A Combined Catalyst of Pt Nanoparticles and TiO2 with Water‐Tolerant Lewis Acid Sites for One‐Pot Conversion of Glycerol to Lactic Acid

AbstractCatalytic conversion of glycerol to valuable chemicals has been recognized as an attractive and challenging reaction in biorefinery. In this paper, we demonstrated that a combined catalyst of Pt nanoparticles and TiO2 worked as a highly active catalyst for the one‐pot conversion of glycerol to lactic acid in water. The yield of lactic acid reached 63 % under oxygen atmosphere without the use of any additives such as strong bases, and the catalyst could be reused without significant loss of the catalytic performance. The mechanistic studies revealed that Pt nanoparticles on TiO2 selectively oxidized glycerol to C3 aldehyde/ketone, and Lewis acid sites on TiO2 smoothly promoted the dehydration and rehydration/rearrangement reactions of the intermediates to produce lactic acid efficiently.

Synthesis of Pb(OH)2/rGO Catalyst for Conversion of Sugar to Lactic Acid in Water

Conversion of sugars from biomass to platform chemicals or fuels is an attracting topic for the utilization of biomass. Pb2+ ion is an efficient catalyst for the degradation of sugar to lactic acid, and it will be better to fix lead on a solid catalyst to reduce the risk of exposure of Pb2+ to environment. Here, a simple method has been developed to prepare a composite catalyst of Pb(OH)2/rGO, where the nanoparticles of Pb(OH)2 in size of 2–5 nm were prepared and fixed over the as-prepared reduced graphene oxide (rGO) nanosheets. The as-obtained catalyst showed an efficient catalytic activity to degrade glucose, fructose, and cellulose in aqueous solution, and the major product is lactic acid. The yield of lactic acid reached 58.7% when fructose was used as the feedstock (433 K and 2.5 MPa N2), and the catalyst can be recycled with high activity. Cellulose can also be directly converted into lactic acid in aqueous solution over the catalyst without extra acid or alkali, and the maximum yield of lactic acid is 31.7%.

Enaminone-Based Three-Component Reactions for the Diastereoselective Synthesis of Fused Tetrahydropyridines

An environmentally benign multicomponent synthetic method has been realized for the diastereoselective construction of fused tetrahydropyridines. Structurally diverse products have been acquired with generally good yields via the assembly of simple starting materials, enaminones or nitroenamines, o-aminophenols, and cinnamaldehydes, in the presence of lactic acid in water–ethanol media.

Lactic acid production from glucose over polymer catalysts in aqueous alkaline solution under mild conditions

Polymerizates of imidazole and epichlorohydrin ([IMEP]Cl) were used to convert simple sugars to lactic acid in water at low temperatures.

Efficient Conversion of Pyruvic Aldehyde into Lactic Acid by Lewis Acid Catalyst in Water

Abstract Homogeneous and heterogeneous catalysts with water-tolerant Lewis acids, such as Sc(OTf)3 and Nb2O5·nH2O, effectively promote the hydride transfer of pyruvic aldehyde into lactic acid in water at 383 K, whereas Brønsted acid catalysts cannot function as effective catalysts under mild conditions. NMR measurement in the presence of D2O suggests that the reaction on a Lewis acid catalyst proceeds via the Meerwein–Ponndorf–Verley (MPV) reduction.

Biopropionic acid production via molybdenum-catalyzed deoxygenation of lactic acid

As the search for non-fossil based building blocks for the chemical industry increases, new methods for the deoxygenation of biomass-derived substrates are required. Here we present the deoxygenation of lactic acid to propionic acid, using a catalyst based on the non-noble and abundant metal molybdenum under relatively mild reactive distillation conditions (200–270 °C). Good yields of sodium propionate (up to 41%) can be obtained with either triethylene glycol dimethyl ether or water as the solvent in the presence of one equivalent of sodium hydroxide, without an external reductant, and using an industrially relevant feedstock of 44% lactic acid in water. Mechanistic studies show that several reactions occur simultaneously, including decarboxylation and decarbonylation of lactic acid, dehydration, and deoxygenation. The major pathway of propionic acid formation was determined with isotopic labeling studies to proceed via direct C–O cleavage, and to a lesser extent via the dehydration/hydrogenation pathway involving acrylic acid.

Extraction of pentachlorophenol from soils using environmentally benign lactic acid solutions

Soil contamination with pentachlorophenol (PCP) is widespread across the globe. Soil washing/extraction is a common technique to remove this compound. Several soil washing/extraction solutions have been used but a majority of them have the problem of persistence in the environment due to their low biodegradability. Our aim was to investigate mixed solutions of lactic acid and water as potential alternatives to surfactant solutions or organic solvent systems used for the removal of PCP from three soils: montmorillonite, a natural sediment (with organic matter), and the same sediment without organic matter (ignited sediment). This study included the optimization of the concentration of lactic acid in water for maximum extraction efficiency and the determination of linear desorption constants for removal of PCP from the three soils with lactic acid. The effect of soil/sediment organic matter on the extraction efficiency was also studied. Initial experiments showed that 24 h was the optimum extraction time. High extraction efficiencies were obtained for montmorillonite (40–80%) and ignited sediment (∼90%). The natural sediment exhibited low PCP extraction due to presence of organic matter, while high desorption coefficient values (∼23 L/kg) were obtained for the ignited sediment. For all soils, a decrease in extraction was observed at higher concentrations of lactic acid. The specific surface area of soil/sediment was also found to be an important factor affecting the extraction of PCP.

Photocatalytic Decomposition of Lactic Acid in Water on a Photoelectrochemical Circuit System Consisting of a Rod-type TiO2 Electrode and Silicon Solar Cell

Lactic acid, a well-known substance causing dental caries, was dissolved in water and completely oxidized into CO2 and H2O on a powdered TiO2 photocatalyst under UV light irradiation. Furthermore, a unique photoelectrochemical circuit system consisting of a rod-type TiO2 electrode and counter electrode connected through a silicon solar cell was constructed and its photocatalytic activity for the decomposition of lactic acid was investigated. The photoelectrochemical circuit system was found to effectively mineralize the lactic acid in water into CO2 while the negative bias applied on the rod-type TiO2 electrode enhanced the photocatalytic decomposition rate of the lactic acid.

Temperature‐Induced Chiroptical Changes in a Helical Poly(phenylacetylene) Bearing N,N‐Diisopropylaminomethyl Groups with Chiral Acids in Water

A stereoregular poly(phenylacetylene) bearing an N,N-diisopropylaminomethyl group as the pendant (poly-1) changed its structure into the prevailing one-handed helical conformation upon complexation with optically active acids in water. The complexes exhibited induced circular dichroism (ICD) in the UV/Vis region of the polymer backbone. Poly-1 is highly sensitive to the chirality of chiral acids and can detect a small enantiomeric imbalance in these acids, in particular, phenyl lactic acid in water. For example, a 0.005% enantiomeric excess of phenyl lactic acid can be detected by CD spectroscopy. The observed ICD intensity and pattern of poly-1 were dependent on the temperature and concentration of poly-1, probably due to aggregations of the polymer at high temperature as revealed by dynamic light scattering and AFM. On the basis of the temperature-dependent ICD changes, the preferred chiral helical sense of poly-1 was found to be controlled by noncovalent bonding interactions by using structurally different enantiomeric acids.

Comparison of isotopic fractionation in lactic acid and ethanol fermentations

Pure d(−) and l(+) enantiomers of lactic acid were prepared by fermentation reactions with specific bacteria. In addition, naturally deuterated ethanol was prepared and converted into diastereoisomers using mandelic acid. Various sugars and nutrients were fermented into lactic acid in water having different deuterium contents and ethanol samples were obtained from yeast fermentation of sugars from different botanical origins. The methine and methylene groups in lactic acid and ethanol respectively show similar deuterium contents which are related to that found in the fermentation water. However, the methyl groups of both molecules are significantly different whatever the botanical origin of the carbon source in the fermentation medium.

The effect of applied strain on the degradation of absorbable suture in vitro

The influence of applied strain on the degradation of a copolymer of glycolic acid and lactic acid in water and hydrogen peroxide solution has been studied. Hydrogen peroxide, simulating the environment around activated cells, produces a greater rate of hydrolysis than water. In both cases, 4% applied strain increased the rate of degradation compared to unstrained samples.

The Treatment of Stingray Injuries

ABSTRACT To the Editor:— In tropical climates stingray wounds may not heal for months (195:708, 1966), leaving bad scars. Since 1940 a treatment has been used which yields rapid healing without unbearable pains. There is no scarring of significance and a minimum incapacitation during recovery.The sting of the stingray is a bone, like a double-toothed saw, which lies in a small canal over the tail of the fish. This canal contains glands which secrete a sticky liquid, which is strongly alkaline and is highly destructive to soft tissues.The treatment I have followed consists of immersing the affected member in a warm solution of lactic acid in water, 0.5% to 1.0% depending upon the size of the wounds. This is continued for three to five days. Secondary infection is prevented by the administration of antibiotics.Under this regimen analgesics are needed in minimal amount, if at all. In four