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Manganese nodules from ocean bed are potential resources of Cu, Ni, and Co for which land-based deposits are scarce in India. The present work describes a novel approach of using glycerol, a nontoxic biomass-derived reductant, for the reductive acid leaching of manganese nodules. Parameters such as acid concentration, time, temperature, and pulp density were optimized for leaching. The optimal leaching conditions were found to be 10% (w/v) pulp density and 10% (v/v) H2SO4 at 80 °C with 1% (v/v) glycerol yielding >95% of Ni and >98% Cu, Co, and Mn extraction within an hour. Kinetic analysis of the data based on the initial rate method showed that the leaching process was chemical reaction-controlled with an apparent activation energy of 55.47 kJ/mol. Various oxidation intermediates of glycerol formed during leaching were identified using mass spectrometry and Raman spectroscopy, and a probable oxidation pathway of glycerol during the leaching process has been elucidated based on the analysis. Glycerol was oxidized to glyceraldehyde, glyceric acid, tartronic acid, dihydroxyacetone, hydroxy pyruvic acid, glyoxalic acid, oxalic acid, and finally converted to CO2 during leaching. The fast reaction kinetics, near-complete dissolution of manganese, and other associated metals in the nodule can be attributed to the participation of all intermediate products of glycerol oxidation in redox reactions with MnO2, enhancing the overall reduction leaching efficiency.

In this work, glycerol valorization into tartronic acid – one of the most valuable derivatives of glycerol – was reported over platinum supported on multi-walled carbon nanotubes (Pt/CNT) electroca...

Isoprothiolane (IPT) was one of the most commonly used pesticides around the world. It was reported to be the highest concentration and frequency of detection of 13 most commonly used pesticides in Mekong Delta recently. The oxidation degradation kinetic of ozone and chlorine with IPT and the identification of the degradation products was investigated in this research. The results showed that both ozone and chlorine oxidized IPT rapidly under typical water treatment condition, and that both reactions followed second order reaction kinetics. The ozone reaction rates exhibited no pH dependence with the rate constant of 247.1 (±11.0) M−1s−1 at 25 °C, whereas chlorine reaction rates increased dramatically with decreasing pH. The rate constant for hypochloric acid was 73.3 (±3.1) M−1s−1 at 25 °C, while the reaction of hypochlorite was negligible. The degradation products by chlorine and ozone were identified by LC-MS/MS and the reaction pathways were proposed. The thioether and the carbon-carbon double bond in IPT were the reactive sites during chlorine and ozone oxidation. The thioether group was oxidized into sulfoxide and further sulfone group, and the carbon-carbon double bone were cleaved to form diisopropyl ester of malonic acid, diisopropyl ester of tartronic acid and diisopropyl ester of ketomalonic acid monohydrate. Compared to ozone reaction, it was more complicated for chlorine reaction, which yielded chlorine substituted, hydroxylated and dithiolane ring-opening products.

A screening study of the chromatographic separation of Glyceric Acid (GCA) and Tartronic Acid (TTA) was performed using three different polystyrene-divinylbenzene ion-exchange resins in hydrogen form (Dowex® 50WX-8, Dowex® 50WX-4, Dowex® 50WX-2). The experiments were described by the axial dispersion flow model with the LDF approximation incorporated into the software gPROMS. From the three investigated adsorbents differing by the crosslinking, Dowex® 50WX-2 has presented the higher adsorption capacity, as well as the highest bed efficiency expressed by the number of theoretical plates. The adsorption equilibrium constants were determined from single breakthrough experiments, and a very good agreement between experimental and simulated data was achieved for both single components and binary mixtures. Therefore, the fundamental data determined within this work represents a key contribution to the design of continuous chromatographic processes for the purification of GCA and TTA.

© 2020 by the authors., Gold nanoparticles supported on various oxides (CeO2, CeO2/TiO2, MgO, MgO/TiO2, La2O3, La2O3/TiO2) (with 4 wt.% Au loading) were investigated in the liquid (aqueous) phase oxidation of glycerol by molecular oxygen under mild conditions, in the presence of alkaline earth (CaO, SrO and MgO) or alkaline (NaOH) bases. Full conversion and selectivity between 38 and 68% to sodium glycerate were observed on different Au supported catalysts (Au/MgO/TiO2, Au/La2O3/TiO2, Au/CeO2 and Au/CeO2/TiO2). The combined effect of Au particle size and basicity of the support was suggested as the determining factor of the activity. Agglomeration of gold nanoparticles, found after the reaction, led to the deactivation of the catalysts, which prevents the further oxidation of sodium glycerate into sodium tartronate. Promising results were obtained with the use of alkaline earth bases (CaO, SrO, MgO), leading to the formation of free carboxylic acids instead of salts, which are formed in the presence of the more usual base, NaOH., This work was partially supported by the Associate Laboratory for Green Chemistry (LAQV), financed by national funds from FCT/MCTES (UIDB/50006/2020) (Portugal), the Tomsk Polytechnic University Competitiveness Enhancement Program project VIU-RSCBMT-197/2020, and the Russian Foundation of Basic Research, project 18-29-24037.

Palladium-bismuth nanoparticles were supported into strongly basic anion-exchange resin of gel-type and tested as catalysts for the selective oxidation of glycerol with molecular oxygen at atmospheric pressure. Detailed study of the precursors preparation and reduction were undertaken. The catalyst 3%Pd-1%Bi where the bismuth was deposited on the palladium particles (3.4 nm) exhibited at 95% glycerol conversion more than 63% yield toward glyceric acid and tartronic acid after 3 h of reaction. The catalyst maintains practically similar catalytic performance as in fresh state for at least five consecutive catalytic cycles without extra catalyst treatment and reactivation.

N-Doped mesoporous carbons (NMCs) with extra framework magnesium were prepared by a one-pot method and used as supports for Pt catalysts. The surface basicity of NMC improved in the presence of extra framework magnesium (e.g., -Ph-O-Mg), meanwhile, the electron density of Pt was enriched by the electron transfer from graphitic N in NMC to Pt. As a result, the catalytic activity of the supported Pt catalyst was improved to be able to selectively oxidize glycerol (GLY) to tartronic acid (TA) under base-free conditions.

The coordination chemistry of tartronic acid 1 with copper(II) has been investigated. Structures of two complexes are reported containing respectively the complex [Cu(1 2H)2Cl]3 where 1 acts as a bidentate ligand through carboxylates and [Cu3(1 3H)3]3 where the alcohol function is deprotonated to bridge two coppers in a triangular trinuclear complex. The latter species undergoes facile oxidation leading to carbon carbon bond formation. The magnetic and EPR properties of the trinuclear complex have been studied in detail.

Bi has been widely employed as a modifier for Pd and Pt based catalyst mainly in order to improve selectivity. We found that when Bi was added to the bimetallic system AuPd, the effect on activity in alcohol oxidation mainly depends on the amount of Bi regardless its position, being negligible when Bi was 0.1 wt% and detectably negative when the amount was increased to 3 wt%. However, the selectivity of the reactions notably varied only when Bi was deposited on the surface of metal nanoparticles suppressing parallel reaction in both benzyl alcohol and glycerol oxidation. After a careful characterization of all the catalysts and additional catalytic tests, we concluded that the Bi influence on the activity of the catalysts could be ascribed to electronic effect whereas the one on selectivity mainly to a geometric modification. Moreover, the Bi-modified AuPd/AC catalyst showed possible application in the production of tartronic acid, a useful intermediate, from glycerol.

The selective oxidation of glycerol and 5-hydroxymethylfurfural (HMF) to diacids over supported gold catalysts (Au/C and Au/TiO2) in liquid water at mild temperatures was a strong function of the added base such as NaOH. Use of hydrotalcite as a solid base in place of NaOH in the HMF reaction medium facilitated the production of diacid over Au/TiO2, but extensive leaching of magnesium suggested that hydrotalcite was consumed stoichiometrically in the reaction. Production of diacids from glycerol oxidation over supported Au catalysts was promoted by operating in a continuous flow reactor and by increasing the catalyst loading in a semi-batch reactor. Trace inhibitors formed by conversion of the product monoacid are proposed to account for the generally low selectivity to diacids over gold catalysts.

The liquid-phase oxidation of glycerol has been studied on gold nanoparticles supported on different carbon materials: activated carbon (AC), graphite (G) and carbon ribbon-type nanofibers (CNF-R). Catalysts were prepared by two different methods: impregnation (-IMP) and gold-sol (-SGT). The influence of the operating conditions (e.g. pressure, temperature, NaOH/glycerol molar ratio and glycerol/Au molar ratio) on the catalytic activity and product selectivity was studied in detail. The oxygen pressure was found to have a very small influence on the reaction rates, with the reaction being zero order with respect to oxygen. The selectivity to glyceric acid was significantly enhanced on increasing both the oxygen pressure and reaction temperature, which simultaneously led to a decrease in both glycolic and tartronic acid selectivities. Glycerol conversion and glyceric acid selectivity increased on increasing the NaOH/glycerol molar ratio in the range from 1 to 2. At higher values of this molar ratio, these two parameters remained approximately constant. A linear correlation was observed between glycerol conversion and the amount of catalyst (up to 0.5 g) and this indicates that the reaction was kinetically controlled. However, along with the increase in the catalytic activity with the amount of catalyst, a substantial decrease in the selectivity to glyceric acid was also observed. Finally, a kinetic model to describe the reaction mechanism was proposed and good agreement between the experimental and predicted values was achieved.

Oxidation of glycerol to form various types of short chain oxygenated derivative compounds became an important reaction to support biodiesel industries. In this study, bimetallic Au–Pd catalysts supported on TiO2 with different Au/Pd atomic ratios have been successfully prepared by deposition-precipitation method with urea decomposition. The catalysts were tested in the glycerol oxidation reactions in order to examine the effect of Au–Pd ratio on the conversion and selectivity. Catalytic activity of all the catalysts were as follow: Au7Pd3/TiO2 > Au5Pd5/TiO2 > Au8Pd2/TiO2 > Au9Pd1/TiO2 > Au6Pd4/TiO2 . Analysis by XRD revealed the presence of metallic Au and gold-enriched Au–Pd alloy phase which were located between the [111] and [200] peaks of Au and Pd in the Au–Pd bimetallic catalysts. XPS analysis ascertained the formation of Au0 , Au3+ , Pd0 and PdO species together with Au–Pd alloy phase in the bimetallic Au–Pd catalysts. This shows that the catalytic activity of the catalysts was depended to the formation of mixture of active species namely Au0 , Au3+ , Pd0 dan PdO together with the presence of "synergisti" effect in the Au–Pd alloy. The reactions were performed at low and high temperatures (50°C and 100°C) and it was found that the selectivity to tartronic acid was enhanced at lower reaction temperature. The highest selectivity to tartronic acid (55% at 99% conversion) was obtained by using Au9Pd1/TiO2 at 50°C and after 8 h of reaction time.

Glycerol was oxidized catalytically under aerobic conditions in the presence of monometallic nanoclusters of gold on poly(1-vinylpyrrolidin-2-one) (PVP) to give hydroxymalonic acid (tartronic acid) as the major product, together with 2,3-dihydroxypropanoic acid (glyceric acid) and hydroxyacetic acid (glycolic acid) as minor products. In contrast, oxalic acid was selectively obtained when bimetallic Au–Pd:PVP nanoclusters were used as the catalyst.

Oxidation of gycerol to form various types of important short chain oxygenated derivatives became an important reaction to support biodiesel industries. In this study, a series of AuPd nanoparticles at different metal mole ratios which were 9:1 and 8:2 supported on titania (TiO2) were successfully prepared, characterized and tested for its activity and selectivity in liquid phase oxidation reaction of glycerol. All the catalysts were prepared by deposition-precipitation method with decomposition of urea. AuxPdy/TiO2 catalysts were characterized using XRD, TEM and XPS. The formation of alloy Au-Pd phase was ascertained by XRD and XPS analysis. TEM analyses have shown that the Au and Pd metal particles in the range of 10-30 nm in size were uniformly dispersed on the TiO2 support with narrower size distribution. Higher catalytic activity observed for the catalysts was attributed to the presence of metallic Au0 and PdO phases together with the ‘synergistic’ effect of Au-Pd alloy. The highest selectivity to tartronic acid (55%) was obtained by using Au9Pd1/TiO2 catalyst after 8 h of reaction time at 50oC reaction temperature.

Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO3) produced an exceptionally high tartronic acid yield. LaMnO3 produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology.

A HO2 mass accommodation coefficient of α = 0.23 ± 0.07 was measured onto submicron copper(II)-doped ammonium sulfate aerosols at a relative humidity of 60 ± 3%, at 293 ± 2 K and at an initial HO2 concentration of ∼1 × 109 molecules cm−3 by using an aerosol flow tube coupled to a sensitive fluorescence assay by gas expansion (FAGE) HO2 detection system. The effect upon the HO2 uptake coefficient γ of adding different organic species (malonic acid, citric acid, 1,2-diaminoethane, tartronic acid, ethylenediaminetetraacetic acid (EDTA), and oxalic acid) into the copper(II)-doped aerosols was investigated. The HO2 uptake coefficient decreased steadily from the mass accommodation value to γ = 0.008 ± 0.009 when EDTA was added in a one-to-one molar ratio with the copper(II) ions, and to γ = 0.003 ± 0.004 when oxalic acid was added into the aerosol in a ten-to-one molar ratio with the copper(II). EDTA binds strongly to copper(II) ions, potentially making them unavailable for catalytic destruction of HO2, and could also be acting as a surfactant or changing the viscosity of the aerosol. The addition of oxalic acid to the aerosol potentially forms low-volatility copper−oxalate complexes that reduce the uptake of HO2 either by changing the viscosity of the aerosol or by causing precipitation out of the aerosol forming a coating. It is likely that there is a high enough oxalate to copper(II) ion ratio in many types of atmospheric aerosols to decrease the HO2 uptake coefficient. No observable change in the HO2 uptake coefficient was measured when the other organic species (malonic acid, citric acid, 1,2-diaminoethane, and tartronic acid) were added in a ten-to-one molar ratio with the copper(II) ions.

Monometallic and bimetallic catalysts based on Au and Pt metal supported on carbon, were synthesized by varying the nature of Pt precursor and the reducing agent. It was found that the nature of Pt precursor in combination with reducing agent, significantly affected the process of reduction and particle growth. The catalytic performance of the synthesized Pt/C catalysts in the liquid phase oxidation of glycerol was considerably affected in terms of activity and distribution of products. Reduction by H2 and NaBH4 depending on the nature of the Pt precursor resulted in the most active and selective catalysts. Improvement of activity was found by addition of Au. © 2006 Elsevier B.V. All rights reserved.

The influence of metal particle size of monometallic and bimetallic supported catalysts (Au, Pd, Au-Pd)/C was studied using as a model reaction the liquid phase oxidation of glycerol. By tuning the metal particle size from 2 to 16 nm a progressive decrease of activity and simultaneously an increase in the selectivity to sodium glycerate was observed. Moreover, the influence of the temperature was studied and it was found that by increasing the temperature, only with a large particle size the formed glycerate was retained and not over-oxidized to tartronate. © 2006 Springer Sdence+Business Media, Inc.

During the last decade, biodiesel has become a viable fuel as an alternative or supplement energy source. This biomass-derived energy is obtained by a transesterification reaction between triglycerides and alcohol, which produces glycerol (GlOH) concomitantly as a co-product. Nowadays, the amount of GlOH produced is greater than commercial demand, leading to a cheapening on the worldwide market. It is therefore an opportune moment to find alternative applications for this abundant and cheap compound. One possibility would be to apply GlOH as raw material for fine chemical industries. In this context, the partial electrocatalytic oxidation of GlOH on metallic surfaces seems to be a promising route for producing valuable compounds from this alcohol. Based on chromatographic analysis, Roquet et al. proposed a mechanism for the GlOH electrooxidation reaction (GEOR) on platinum catalyst, with the formation of glyceraldehyde, glyceric acid, formic acid, oxalic acid, and tartronic acid. Similar results were found by Kwon et al. with platinum and platinum-modified surface with bismuth as catalysts. 7] One of the main practical difficulties is to selectively produce tartronic acid or any other specific chemical from GlOH electrooxidation. Before this goal can be accomplished, much effort needs to be focused on understanding the GEOR in detail. Recently, spectroscopic studies in situ have shed some light on the mechanism of GEOR. By using isotopically labeled GlOH, Fernandez et al. showed that the substrate generates CO2 from both types of carbon atoms, which implies that, at least to some extent, GlOH is able to completely dissociate on platinum surfaces. 9] From previous fundamental work by our group, we know that GEOR is highly dependent on the orientation of the surface sites. At low potentials, Pt(111) is more active for GEOR than Pt(100) and Pt(110) and, as seen by FTIR spectroscopy in situ, the reason for that can be related to the fact that carbon monoxide, a common adsorbed intermediate of organic molecules oxidation on Pt, is more easily removed from Pt(111) than from Pt(100) and Pt(110). However, for practical systems, the GEOR process requires a highly dispersed catalyst, which increases considerably the variables that could influence the reaction. In this sense, it is crucial to understand how the GEOR proceeds in less complex systems so that the weight of each variable can be estimated. In this work, we focused our attention on GEOR sensitivity to the catalyst surface structure and we present new results We investigate the electrooxidation of glycerol (GlOH) on polycrystalline Pt. The results obtained in the presence of GlOH were compared with those of fresh and disturbed low-index Pt single crystals [(111), (100) and (110)] . Monitoring of the oxidation currents of GlOH by cyclic voltammetry on the different surfaces revealed that the electrooxidation of GlOH is highly sensitive to the order of the polycrystalline Pt atoms. Interestingly, after being disturbed by the application of voltammetric cycles, the combined responses of the disordered single crystals become similar to that of polycrystalline Pt. The changes in the current values associated with the specific potentials at which each oxidation peak takes place suggest that different ordered domains of Pt oxidize GlOH independently. This simple approach can clearly assist in our understanding of the effect of the order of surface atoms in a given reaction, not only in electrochemical reactions.

The effect of oxygen on the Ce4+−malonic acid reaction was studied in a semibatch reactor. That effect is important for the Belousov−Zhabotinsky (BZ) chemical oscillator. The Ce4+ reagent inflow and consequently the rate of the reaction itself was controlled by a peristaltic pump. The reaction products were analyzed by HPLC. With this technique two major oxidation pathways were identified. One is significant at high Ce4+ inflow rates only; the product of this channel is tartronic acid. The other pathway leading to oxalic acid is active at all flow rates but dominant when the feed is slow. A great part of oxalic acid is oxidized further to carbon dioxide and water. A reaction mechanism compatible with these findings is presented. A key step of this mechanism is the fate of the peroxymalonyl radical which is the first intermediate for both channels. It is proposed that at high Ce4+ concentrations a fast reaction of this intermediate with Ce4+ leads to tartronic acid. At low Ce4+ concentrations, however, the...

We investigate the kinetics of bromination of malonic acid, bromomalonic acid, tartronic acid, and ethanetetracarboxylic acid in 1 M sulfuric acid with bromine and hypobromous acid as brominating agents. In all cases the reaction occurs via the enol form of the acid, and the reaction products are brominated species. The possibility of bromide production in the reaction of malonic acid or bromomalonic acid with hypobromous acid can be ruled out. These results are important for the negative feedback loop in the Belousov−Zhabotinsky reaction.

A novel Cerium(IV) mediated oxygenation of dialkyl malonates leading to a direct synthesis of tartronic acid derivatives is described.

The stoichiometry of CO2 production during the ceric oxidation of various organic acids is measured under conditions with organic acid excess. Measurements utilize a photo- metric methodology. For anaerobic conditions stoichiometries (CO2)produced : (Ce(IV))reduced of about 0 (malonic acid), 0.5 (e.g., glyoxylic acid), and 1.0 (oxalic acid) are found. Oxalic acid showed an oxygen-induced decrease of CO2 production, while other compounds such as ma- lonic acid increased the amount of produced CO2 or showed no changes (e.g., tartronic acid). In the case of mesoxalic acid the stoichiometry is increased from about 0.5 to 2.0 due to the presence of molecular oxygen. The results are discussed on the basis of simple reaction mech- anisms demonstrating that useful information on reaction pathways and intermediates can be extracted from these simple measurements. q 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 899- 902, 1998

A novel synthesis of hydroxyglycine retropeptidic derivatives was achieved through a Passerini 3-component reaction of glyoxyl amides or esters, followed by an unprecedented environmentally benign zinc catalysed solvolysis.

Tartronic acid forms the title salt, C3H5N2+·C3H3O5−, with imidazole. Hydro­gen bonds in the crystal link the anions, forming a hydrogen-bonded layer. The cations cross-link the layers, leading to a three-dimensional hydrogen-bonded network.

Due to its three hydroxyl groups, glycerol is a potential starting material for various high value fine chemicals such as dihydroxyacetone, tartronic acid and mesoxalic acid. The corresponding oxidation reactions are catalysed by various metals such as palladium, platinum, bismuth or gold. Nevertheless, the selectivity not only depends on the type of the active phase, but is also influenced by numerous parameters such as the metal particles size, the pore size of the support and the pH of the reaction medium. This review not only describes the recent developments in the field of research for new catalysts but also spotlights the role of the reaction conditions as well as the possible transport limitations in this tri-phasic system. Furthermore, an economical analysis of some processes is given, which shows that this is realistic to envision sustainable production of, e.g., dihydroxyacetone.

A novel Cerium(IV) mediated oxygenation of dialkyl malonates leading to a direct synthesis of tartronic acid derivatives is described.

The liquid phase oxidation of glycerol with oxygen has been studied using a series of monometallic and bimetallic catalysts based on Au, Pd and Pt metals supported on carbon, in order to study the effect of the metal on the distribution of the products. It was found that by using bimetallic catalysts (Au-Pd, Au-Pt) the distribution of the products could be controlled. Moreover, bimetallic catalysts were by far more active than monometallic catalysts. Selectivity could be tuned by using different preparation method. © 2005 Elsevier B.V. All rights reserved.

Tartronic acid forms a hydrogen-bonded complex, C 5 H 5 NO.-C 3 H 4 O 5 , (I), with 2-pyridone, while it forms acid salts, namely 3-hydroxypyridinium hydrogen tartronate, (II), and 4-hydroxypyridinium hydrogen tartronate, (III), both C 5 H 6 NO + .-C 3 H 3 O 5 - , with 3-hydroxypyridine and 4-hydroxypyridine, respectively. In (I), the pyridone molecules and the acid molecules form R 2 2 (8) and R 2 2 (10) hydrogen-bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N-H...O and O-H...O hydrogen bonds to form a hydrogen-bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxylate groups in (II) and (III).

Publisher Summary This chapter describes the use of Ti-MCM-41 materials in the oxidation of the model mono- and disaccharides methyl α-D-glucopyranoside, sucrose and α, α-trehalose, and discusses the effect of the zeolite synthesis on the effectiveness in these reactions. Several preparative approaches of Ti-MCM-41 have been compared in the oxidation of these model carbohydrates. In aqueous medium in the presence of hydrogen peroxide the titanium leaches easily out of Ti-MCM-41 synthesized by impregnation by bis-cyclopentadienyl titanium dichloride of an all silica MCM-41. The dissolved titanium catalyzes the oxidation of methyl α-D-glucopyranoside to 1- O -methyl glucuronic acid. This product is sensitive to further oxidation to formic, glycolic, and tartronic acid. In the oxidation of sucrose and trehalose monocarboxylate are probably formed beside C 1 – C 4 monoand dicarboxylates.

Bimetallic platinum-bismuth catalysts, supported on active carbon, were employed to oxidise aqueous solutions of glyceric and tartronic acid with air, in a batch reactor. High selectivities for the corresponding keto-acids were obtained under acidic conditions. Glyceric acid was selectively oxidised to hydroxypyruvic acid and maximum yields were obtained at pH 5 (74% at 77% conversion). Tartronic acid was selectively oxidised to mesoxalic acid with highest yields also being obtained at pH 5 (39% at 79% conversion). Analysis of the reaction mixture after 22 hours indicated that leaching of the platinum component of the catalyst was negligible but significant quantities of the bismuth promoter were present (10–17 mg/l).

Platinum metal catalysts, promoted or not with bismuth, have been designed to favour oxidation of either the primary or the secondary alcohol functions of glycerol in aqueous solution. Thus, on palladium catalyst oxidation of the primary function of glycerol predominates and glyceric acid is the chief product (70% yield at 90% conversion, pH=11) whereas on bismuth-promoted platinum catalyst oxidation of the secondary function prevails to give dihydroxyacetone (37% yield at 75% conversion, pH=2). Subsequent oxidation of glyceric acid on platinum gives the tartronate (61% yield at 94% conversion, pH=10–11); improved yields were obtained with the bismuth-promoted catalyst (83% yield at 90% conversion, pH=10–11). On bismuth-promoted platinum oxidation of glyceric acid gives hydroxypyruvic acid as the main product (64% yield at 75% conversion, pH=3–4) and under the same conditions tartronic acid is oxidised to mesoxalic acid (29% yield at 53% conversion, pH=1.5) bismuth adatoms have two roles: they prevent over-oxidation by strongly adsorbed acids and orientate the selectivity towards oxidation of the secondary alcohol function.

Due to its three hydroxyl groups, glycerol is a potential starting material for various high value fine chemicals such as dihydroxyacetone, tartronic acid and mesoxalic acid. The corresponding oxidation reactions are catalysed by various metals such as palladium, platinum, bismuth or gold. Nevertheless, the selectivity not only depends on the type of the active phase, but is also influenced by numerous parameters such as the metal particles size, the pore size of the support and the pH of the reaction medium. This review not only describes the recent developments in the field of research for new catalysts but also spotlights the role of the reaction conditions as well as the possible transport limitations in this tri-phasic system. Furthermore, an economical analysis of some processes is given, which shows that this is realistic to envision sustainable production of, e.g., dihydroxyacetone.

The addition of small amounts of tartronic acid was found to improve the perpendicular magnetic anisotropy of Co-Ni-Re-Mn-P alloy films, and the increased anisotropy energy Ku was explained by the constant Hk with decreasing Ms. The addition of tartronic acid up to 0.05mol dm-3, was observed to bring about an increase in the Ni and P content, accompanied by a decrease in Co content. Differences in magnetic properties were not observed between electroless Ni-P and activated copper substrates at various tartronic acid concentrations; but differences were observed in the lower NiSO4 concentration region. Read/write characteristics were tested using 8-inch disks plated with Co-Ni-Re-Mn-P alloy under optimum conditions in combination with ring head having a 0.33μm head gap. Dipulse waveforms, which are characteristics of perpendicular magnetic recording, were observed in the long wavelength and recording density D50=58kFRPI was obtained at 0.20μm head-to-medium spacing.

1. Contrary to the observations of earlier workers, it has been shown that formic acid can be quantitatively oxidixed by ceric sulphate in the presence of concentrated sulphuric acid. 2. Tartaric, malonic, malic and glycolic acids can also be oxidized completely to carbon dioxide and water by the following general procedure : to a known amount of the organic acid is added ceric sulphate (excess) solution in dilute sulphuric acid and the mixed solution refluxed for ten to fifteen minutes. Concentrated sulphuric acid (double the volume of the reaction mixture) is then added taking care that formic acid is not lost during the addition, and the mixture again refluxed for 45 to 50 minutes. The excess ceric sulphate is determined by titrating against ferrous ammonium sulphate. 3. The complete oxidation of the above acids provides satisfactory methods for their quantitative estimation.

A polyuronide, main component of the water extract of achine of Ficus awkeotsang MAKINO (on-gyo-tye), was purified by ion-exchange chromatography on DEAE-cellulose. The polyuronide (Fraction IB) is homogeneous electrophoretically and consists mainly of galacturonic acid. Optical rotation of Fraction IB is [α]26D=+294.7 and content of methoxyl group is trace. In periodate oxidation of Fraction IB, molar ratio of galacturonic acid residue and periodate consumption was 1, and formic acid formation was very small. Periodate oxidation product of Fraction IB was oxidized further with bromine and the resulted substance was hydrolyzed. In the hydrolyzate, presence of large amount of tartaric and glyoxylic acids and small amount of tartronic acid were detected by paper chromatography. Reduced viscosity of aquous solution of Fraction IB increased with decreasing of the concentration of Fraction IB solution. From these results, it was deduced that Fraction IB has a linear structure of 1→4 linkage of D-galacturonic acid, probably α-linkage.

A new method for the microdetermination of acetoin and tartronic acid was described. This was done by an oxidation-reduction reaction. Oxidation of acetoin and tartronic acid were effected by means of an excess of Cu(III) solution on heating, the remaining excess of Cu(III) was titrated back by acidifying and adding a known excess of arseneous oxide solution against a standard iodine solution with the use of starch as an indicator.

Dehydroascorbic acid is shown to be converted to 2-(threo-1,2,3-trihydroxypropyl)tartronic acid in aqueous alkaline solutions. The structure of the acid was determined by mass spectrometry of its acyclic Me3Si derivative. Mass spectrometric and chromatographic data are compared with those of related compounds. The acid is formed by a benzilic acid rearrangement of the intermediate 2,3-hexodiulosonic acid. The rate of formation at 38°C was studied quantitatively by glc. It increases at increased alkalinity but is significant even at physiological pH. The presence of oxygen does not substantially influence the reaction.

FROM an analysis of X-ray data on carboxylic acids1 we have established the stability of the approximately coplanar arrangement of the non-hydrogen atoms of the acetic acid group (C–COOH) with the α-substituent in α-substituted carboxylic acids (Fig. 1). In the crystal structures of tartronic acid (X = OH) (ref. 2), aminomalonic acid (X = NH2) (ref. 3) and fluoroacetic acid (X = F) (ref. 4) the coplanar cis conformation has been found. In crystals of unsubstituted monocarboxylic acids the acetic acid group has been found to be coplanar with the β-carbon atom1.

C-(2-Hydroxyethyl)tartronic acid is predominant among the dicarboxylic acids and its formation in 12 % yield makes it a major product from xylan. The structure indicates that it is formed from terminal, oxidized xylose units by beta-elimination at C-4 and subsequent benzilic acid rearrangement. It is proposed that 2-ulosonic acid end-groups or ulosono-1,5-lactone end-groups, related in structure to ascorbic acid, are formed as precursors.

The effect of sodium tartronate was studied in experiments on mice and rats on the basis of data on the inhibition of the transfer of carbohydrates into fats by tartronic acid presented by Wesson. Sodium tartronate was administered in doses of 0.025 to 0.09 g and its effect on body weight, fat and liver glycogen was studied. If 0.09 g of sodium tartronate is introduced subcutaneously to adult rats weighing from 254 to 364 g for 10 days, reduction of weight, increase of glycogen content and a certain decrease of fat content is noted in the liver. If 0.025 g of this substance is introduced subcutaneously to adult mice weighing 31 to 33 g, there is an increase of glycogen and decrease of fat in the liver. However, with mice there is no reduction of weight.

The production of 2-keto-D-gluconic acid from glucose and also from gluconic acid by Pseudomonas species was at one time considered to be a feature which differentiated these organisms from Acetobacter species. Bernhauer and co-workers1–3 showed, however, that twelve species of Acetobacter produced from glucose a strongly reducing acid which formed a soluble calcium salt. They assumed that this substance was either 2-ketogluconic acid, or aldehydogluconic acid, or a mixture of both, because they were able, from cultures of A. gluconicum and of A. suboxydans, to isolate and to characterize 2-ketogluconic acid, and because aldehydo-gluconic acid was isolated from cultures of A. gluconicum and A. xylinum.