Malonic acid reduction

Properties. — It is soluble m water and alcohol, but not in ether. On heating, it loses water and is converted into fumaiic and maleic acids (see p. 125). On o.xidation it gives malonic acid and on reduction succinic acid. 

Catalytic reduction of the nitrile 79 in the presence of semicarbazide affords initially the semicarbazone of 80. Hydrolysis-interchange, for example in the presence of pyruvic acid, gives the aldehyde 80. Condensation with the half ester of malonic acid leads to the acrylic ester 81 the double bond is then removed by means of catalytic reduction (82). Base catalyzed reaction of the... 

Amino acids can be synthesized in racemic form by several methods, including ammonolysis of an a-bromo acid, alkylation of diethyl acetamido-malonate, and reductive amination of an cv-keto acid. Alternatively, an enantio-selective synthesis of amino acids can be carried out using a chiral hydrogenation catalyst. 

Sengupta and Aditya ° find the usual reactivity sequence for Ce(IV) salts, viz. CIO4" > NOj" > S04 , but note that plots of log (Ce(lV)] versus time are linear even when equal molar concentrations of Ce(IV) and malonic acid are taken. This implies a first-order dependence on [Ce(IV)] and zero-order dependence on malonic acid concentration. Kemp , however, has found a clear first-order dependence on malonic acid concentration for the Ce(IV) sulphate oxidation, using an excess of reductant and making a four-fold variation in reductant concentration. Moreover, consumption of Ce(lV) was intermediate between first- and second-order. Further work is needed to resolve this discrepancy. 

Malonic acid allylic esters undergo intramolecular cyclization reaction under solid-liquid phase transfer catalytic conditions in the presence of Aliquat 336, potassium carbonate, and iodine (Eq. 60) [84]. Application of microwave irradiation to this procedure enabled 2-3-fold reduction in the reaction time compared with conventional conditions. It was found that use of microwaves affected the exo/endo diastereoi-somers ratio - a linear correlation between microwave power and exo isomer concentration was observed [85]. 

When solution contains sufficient amount of Br", reduction of BrOj and bromination of malonic acid (HMa) take place by HOBr or Br2 as follows ... 

The acid chlorides have served as useful synthetic intermediates leading to ketones via the malonic acid synthesis and Friedel rafts reaction, thiadiazole acetic acid derivatives, and halo ketones via the Arndt Eistert synthesis and carbinols by hydride reduction <68AHC(9)107>. The dialkylcadmium conversion of acid chlorides into ketones fails in the 1,2,5-thiadiazole series. The major product is either a tertiary carbinol or the corresponding dehydration product, by virtue of the high reactivity of the intermediate ketone. 

Japanese workers have also displaced a methyl sulfone group with a variety of nucleophiles. Thus they were able to introduce, ethoxy, thiophenyl, aniline, and malonic acid groups in to the pyridine A -oxide derivative (105). Acid hydrolysis produced the 2-one compound, while reduction with sodium borohydride cleaved off the methylsulfone group <87CPB1030>. 

Malonic acid CH2(C02H)2 (H2mal) (209) has a coordination chemistry with chrommm(III) closely resembling that of oxalate. Malonic acid is a slightly weaker acid than oxalic acid and slightly more labile complexes are formed. The tris complex is the most extensively studied, prepared by the reduction of chromate solutions or the reaction of chromium(III) hydroxide with malonate.917,918 919 The cis and trans diaqua complexes may be prepared by the reduction of chromate with malonate the isomers are separated by fractional crystallization. The electronic spectrum of the tris complex is similar to that of the tris oxalate and a detailed analysis of these spectra has appeared.889... 

In peroxyl radical reactions the formation of carbonyl functions generally dominates over a reduction (Chap. 8). This would lead to the formation malonic acid aldehyde [reactions (34) and (35)]. Being an aldehyde, it should be very easy to detect (Lipari and Swarin 1982), but the corresponding experiments seem not yet to have been carried out. 

Prior to our systematically designed oscillators, the inorganic oscillator most intensively studied was the BZ reaction. Examination of this reaction and the FKN mechanism reveals several features helpful to achieving an appreciation for the construction of a chemical oscillator. The driving force for the BZ reaction is the reduction of bromate and the associated oxidation of malonic acid (MA) to carbon dioxide. The stoichiometry is not that simple, however, since bromomalonic acid is also produced in the reaction, and can be oxidized to formic acid. A possible stoichiometry is... 

C") Chlorite-iodine-reductant. These systems, which include systems 8 b, 9 b and 10b of Table 8 appear to be only minor variants of type C ) in which (M 9) replaces (M 8). C ") Chlorite-iodide-reductant. The only known example of this type is the chlorite-iodide-malonic acid system, which is of special interest because it supports both batch oscillations and spatial wave patterns. The slow decomposition of iodinated malonic acid species apparently provides a long lasting, indirect flux of iodide (via (M2) + (M9)) in this system. 

An aqueous solution of sodium nitrite that is treated with HC1 contains nitrosyl cations 0=N . These can react with the enol E of the malonic acid diethyl ester (cf. Figure 12.9, bottom). First, a nitroso compound (F) is formed, which then undergoes acid-catalyzed isomerization to give the oxime A. Usually, the oxime is reduced by zinc, which is dissolved in acetic acid, to yield an amine that normally undergoes in situ acetylation in acetic acid. In this way the (acetamido)malonic acid diethyl ester B is obtained as the reduction/acetylation product, which can be employed, for example, in the synthesis of amino acids (Figure 13.39). 

The phenanthrenequinone oxime 54 was built in four steps from the two benzenoid precursors 52 and 53. Beckmann rearrangement of 54 furnished the cyano-acid 55. The latter, after reduction to the corresponding cyano-aldehyde, was homologated by Knoevenagel condensation with malonic acid to give, after reduction, hydrolysis and esterification, the diester 56. This compound underwent Dieckmann condensation, installing the seven-membered C-7 ketone 57 in 69% yield after hydrolysis and decarboxylation of the intermediate (3-ketoester. 

The synthesis of 6a-methyldigitoxigenin acetate (394) has been reported according to Scheme 19.198 Pregn-4-en-21-ol-3,20-dione was converted into its 6a-methyl derivative (387) using a previously described five-step reaction sequence biological hydroxylation furnished the 14a,12-diol (388) and reduction of the derived 21-acetate gave the 5/3-dihydro-steroid (389). Dehydration furnished the A14-olefin (390) which was converted into the 21-mesylate and thence into the lactone (391) by reaction with the monoethyl ester of malonic acid. The crude lactone was decarbox-ylated, reduced to the 3/3-alcohol (392), and converted into the bromohydrin (393) via its 3/3-acetate and thence by debromination into 6a-methyldigitoxigen 3-acetate... 

On the other heuid,if this were the correct forr..ula the con.pound should readily add bromine and reduce potassium penuangante the first reaction it gave only in the sunlight,the other not at all. These facts,its stability towards reduction with sodium aiualgam, the value of its magnetic rotation and the fact that it behaved like a disubstituted malonic acid settled the dispute in favor of Perkin. 

Substituted malonic acids are obtained by alkaline hydrolysis of alkyl-cyano esters prepared either by direct alkylation or by reduction of unsaturated cyano esters from the Knoevenagel reaction. ... 

An oscillatory cycle can be qualitatively described in the following way. Suppose that a high enough ceric ion concentration is present in the system. Then, bromide ion will be produced rapidly, and its concentration will also be high. As a result, autocatalytic oxidation is completely inhibited, and the ceric ion concentration decreases owing to the reduction of ceric ion by malonic acid. The bromide ion concentration decreases along with that of ceric ion. When the ceric ion concentration reaches its lower threshold, the bromide ion concentration drops abruptly. The rapid autocatalytic oxidation starts and raises the ceric ion concentration. When this concentration reaches its upper threshold, the bromide concentration increases sharply, completely inhibiting the autocatalytic oxidation. The cycle then repeats. Pulse injections of Br, Ag, and Ce " result in phase shifts in oscillations of the Ce " " concentration (Fig. 3), which confirm the mechanism. 

However, because malonic acid has only one methylene group, it is obvious that no oxidation-reduction can take place. Only association of the enzyme and inhibitor, and dissociation of the I complex, can occur. Another classical example of a competitive inhibitor is the sulfa drug sulfanilamide, which interferes with the biosynthesis of folic acid from the precursor -aminobenzoic acid (PABA). 

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