Malic acid, oxidation

Physical Properties. Malonic acid, HOOC—CH2—COOH (1), was discovered and isolated in 1858 as a product of malic acid oxidation. The physical properties of malonic acid are Hsted in Table 1. 

Kumar and Saxena studied the oxidation of malic acid (in the absence of silver ions) and found approximately first-order kinetics with respect to peroxodisulphate, and an order varying from zero to first with respect to malic acid. Similar results are reported by Venkatasubramanian and Sabesan . Saxena and Singhal ° studied the oxidation of tartaric acid (in absence of silver ions) and found features very similar to those reported for the malic acid oxidation. 

The grapes are left on the vine for as long as possible with this natural drying method—sometimes even after grape cluster peduncle twist. The berries progressively shrivel, losing their water composition. They produce a naturally concentrated must, richer in sugar and aromatic substances. Acidity does not increase in the same proportions and can even decrease by malic acid oxidation. Other biochemical maturation phenomena also occur notably, the skin cell walls deteriorate. This methods should therefore be used only with relatively thick-skinned varieties to limit the risk of B. cinerea development. 

Colourless prisms m.p. 130 C. Manufactured by treating maleic anhydride with water. It is converted to the anhydride by heating at By prolonged heating at 150 "C or by heating with water under pressure at 200 C, it is converted to the isomeric (trans) fumaric acid. Reduced by hydrogen to succinic acid. Oxidized by alkaline solutions of potassium permanganate to mesotartaric acid. When heated with solutions of sodium hydroxide at 100 C, sodium( )-malate is formed. Used in the preparation of ( )-malic acid and in some polymer formulations. 

Alkyl hahdes in the presence of silver oxide react with alkyl malates to yield alkoxy derivatives of succinic acid, eg, 2-ethoxysuccinic acid, H00CCH2CH(0C2H )C00H (12,13). A synthetic approach to produce ethers of malic acid is the reaction of malic esters and sodium alkoxides which affords 2-alkoxysuccinic esters (14). 

Make acid yields coumaUc acid when treated with fuming sulfuric acid (19). Similar treatment of malic acid in the presence of phenol and substituted phenols is a facile method of synthesi2ing coumarins that are substituted in the aromatic nucleus (20,21) (see Coumarin). Similar reactions take place with thiophenol and substituted thiophenols, yielding, among other compounds, a red dye (22) (see Dyes and dye intermediates). Oxidation of an aqueous solution of malic acid with hydrogen peroxide (qv) cataly2ed by ferrous ions yields oxalacetic acid (23). If this oxidation is performed in the presence of chromium, ferric, or titanium ions, or mixtures of these, the product is tartaric acid (24). Chlorals react with malic acid in the presence of sulfuric acid or other acidic catalysts to produce 4-ketodioxolones (25,26). 

Other Acids. Ascorbic acid (3) is used primarily as an antioxidant and to a lesser extent as an added nutrient ia beverages. It oxidizes readily, preventing the oxidation of certain flavoting compounds. Tartaric (4) and adipic acids are used to a lesser extent ia grape flavored beverages. Malic acid can be used as an alternative to citric acid ia some fmit flavored beverages. 

The best direct synthetic route to uracil is probably the classical procedure from malic acid and urea in concentrated sulfuric acid (26JA2379), despite efforts to use maleic acid, urea and polyphosphoric acid (71S154) or propiolic acid, urea and a little concentrated sulfuric acid (77JOC2185) to achieve the same result. However, the most convenient source (apart from purchase) is to convert 2-thiouracil (937 X = S) into uracil by boiling with aqueous chloroacetic acid (52MI21300) or perhaps by oxidation with DMSO in strong sulfuric acid (74S491). 

Oxy-aldehyd, n, hydroxy aldehyde, -ammo-niak, n, oxyammonia (hydroxylamine), -azoverbindung, /. hydroxyazo compound, -benzol, n, hydroxybenzene (phenol), -bem-steinsaure. /, hydroxysuccinic acid (malic acid). -biazol, n. oxadiazole, oxdiazole. -bitumen, n, oxidized bitumen, -carbon-s ure, /, hydroxycarboxylic acid, -chlnoltn, n. hydroxyquinoline, -clunon, n. hydroxy-quinone. -chlorid, n. oxychloride, -chlor-kupfer, n. copper oxychloride, -cyan, n. oxycyanogen. 

The student may wonder just what the mechanism is in cases where retention of configuration is involved since it certainly is not simple Sn2. As we shall see later, the reaction between malic acid and thionyl chloride is an SNi process (p. 420), while a neighhoring-group mechanism (p. 404) is involved in the treatment of chlorosuccinic acid with silver oxide. 

Catalytic combustion of diesel soot particulates over LaMnOs perovskite-type oxides prepared by malic acid method has been studied. In the LaMn03 catalyst, the partial substitution of alkali metal ions into A site enhanced the catalytic activity in the combustion of diesel soot particulates and the activity was shown in following order Cs>K>Na. In the LarxCs MnOj catalyst, the catalytic activity increased with an increase of X value and showed constant activity at the substitution of x>0.3... 

In this paper, we prepared LaMnOa perovskite-type oxides using the malic acid method and investigated their physical properties. It has been also investigated the effect of partial substitution of metal iorrs into La and Mn sites and the reaction conditions on the activity for the combustion of soot particulates. 

The preparation method of perovskite-type oxides was taken from the previous paper[4]. Malic acid was added into mixed aqueous solution of metal nitrates in a desired proportion so as for the molar ratio of malic... 

Table 1. Perovskite-type oxides prepared by malic acid method and their catalytic performances...

It was observed by Gopala Rao and Sastri that the reaction between hydro-quinone and chromic acid leads to the induced oxidation of oxalic acid, glycerol, lactic acid, glucose, citric acid, and malic acid. If the concentrations of the above acceptors are cen times that of that of the hydroquinone inductor, the values of F found are, respectively, 0.51,0.46,0.35,0.27 and 0.17. The numerical values of the induction factor do not permit us to discuss the nature of coupling intermediate. 

Copper(II) oxide and cobalt(II) hydroxide form cements with solutions of many multifunctional organic acids propanetricarboxylic acid, tartaric acid, malic acid, pyruvic acid, mellitic acid, gallic acid, tannic acid and phytic acid (Allen et al., 1984 Prosser et al., 1986). These have been used mainly in cement devices for the sustained release of copper and cobalt (Manston et al., 1985 Mansion Gleed, 1985). Little is known about... 

Magnesium oxide, 33, 84 Maleic anhydride, 30, 93 31, 85 Malic acid, 31, 23... 

The enantiomerically pure indolizidine (—)-422 has been synthesized starting from L-malic acid diethyl ester 407. The hydroxyl function of L-malic acid diethyl ester 407 has been protected as dihydropyranyl ether 408 with 2/7-dihydropyran and Amberlyst 15 in pentane at room temperature. The diethyl ester 408 was then reduced with lithium aluminium hydride in diethyl ether under reflux and the newly generated hydroxyl functions then protected with mesyl chloride in the presence of triethylamine in dichloromethane at 0°C. This was converted into newly protected pyrroline nitrone 409 in 44% overall yield through a well-established method (Scheme 90). The regio-isomeric 5-pyrroline-iV-oxide 410 formed in 4% overall yield was easily separated by column chromatography <20000L2475>. 

The laevo-rotatory form is the ordinary malic acid while the dextrorotatory form is an ethylene oxide resulting from the migration of the hydrogen of the hydroxyl on the asymmetric carbon to the carbonyl oxygen of the carboxyl group. 

Aside from the multifaceted chemical conversions, there are sources to develop into industrially viable microbial conversions. 1,2,4-Butanetriol, for example, used as an intermediate chemical for alkyd resins and rocket fuels, is currently prepared commercially from malic acid by high-pressure hydrogenation or hydride reduction of its methyl ester. In a novel environmentally benign approach to this chemical, wood-derived D-xylose is microbially oxidized to D-xylonic acid, followed by a multistep conversion to the product effected by a biocatalyst specially engineered by inserting Pseudomonas putida plasmids into E. coli ... 

Since the formation of optically active, dioxolanone-based di-enolates was not successful, a consecutive alkylation strategy was developed for a short synthesis of (-)-wikstromol (ent-3) from (-)-malic acid (99) (Scheme 25). The first alkylation reaction was analogous to that reported for the enantioselective total synthesis of (-)-meridinol (97). In order to avoid a reduction/re-oxidation sequence and an almost unselective second alkylation, two disadvantages of the synthesis of meridinol (97) [55], we planned to use a different strategy for the second alkylation. Therefore, we have focused our strategy on two stereoselective alkylation reactions, one of dialkyl malates and one of a dioxolanone prepared thereof. Both alkylation reactions were previously described by Seebach and coworker [56, 63, 64]. The... 

CCM is formed by neutralization of an alkaline Ca source with citric and malic acids. The alkaline Ca source can be Ca hydroxide (Ca(OH)2), Ca carbonate (CaCOa), or Ca oxide (CaO). The neutralization reactions involved in the formation of the neutral 6 2 3 molar ratio CCM salt from Ca(OH)2 and CaCOa are as follows ... 

Similarly the mechanism of the Cu(II) catalyzed oxidation of malic acid by S2Og (173) was reinterpreted on the basis of the properties of CuII-CR1R2R3 and CuIII-CR1R2R3 complexes. The following catalytic Scheme 6 was proposed (174). 

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