Malonic acid, 290 Table

Acetic, succinic and malonic acids (Table 1) are reported (4) to derive from Ar-CHa, Ar(CH2)2Ar (including hydroaromatic) and Ar-CH2 Ar (Ar - aromatic ring) units respectively. Examination of the concentrations of these major aliphatic products suggests that the medium lithotypes contain the highest concentrations of aryl methyl and Ar(CH2)2Ar structures. Diaryl methane units are proposed to be most significant in the pale lithotype possibly reflecting a resin input. 

Giordano (1990) calculated concentrations of Ca, Mg, Na, Pb, Zn, Fe, and Al as acetate, oxalate, malonate, succinate, and catechol complexes in three reconstructed MVT ore solutions and a model oil-field brine at 100 °C. In Table 5, results are presented for revised speciation calculations for the three MVT ore fluids and calculated speciation results for a model RBRBM ore fluid. These model results are based in part on recently published data at elevated temperatures for Ca, Mg, and Al complexes and high-temperature constants for ionization reactions of oxalic and malonic acids (Table 4). In the MVT model proposed by Anderson (1975 model 1, Table 5), the ore fluid is moderately oxidized and falls well above the sulfide-sulfate boundary in logao2 - pH space at 100°C. It is slightly acid and contains 10 molal... 

The physical properties of cyanoacetic acid [372-09-8] and two of its ester derivatives are Hsted ia Table 11 (82). The parent acid is a strong organic acid with a dissociation constant at 25°C of 3.36 x 10. It is prepared by the reaction of chloroacetic acid with sodium cyanide. It is hygroscopic and highly soluble ia alcohols and diethyl ether but iasoluble ia both aromatic and aUphatic hydrocarbons. It undergoes typical nitrile and acid reactions but the presence of the nitrile and the carboxyUc acid on the same carbon cause the hydrogens on C-2 to be readily replaced. The resulting malonic acid derivative decarboxylates to a substituted acrylonitrile ... 

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. 

Order of thermal stabiUty as determined by differential thermal analysis is sebacic (330°C) > a2elaic = pimelic (320°C) > suberic = adipic = glutaric (290°C) > succinic (255°C) > oxahc (200°C) > malonic (185°C) (19). This order is somewhat different than that in Table 2, and is the result of differences in test conditions. The energy of activation for decarboxylation has been estimated to be 251 kj/mol (60 kcal/mol) for higher members of the series and 126 kJ/mol (30 kcal/mol) for malonic acid (1). 

Examination of the effect of pH on the rates of protodeboronation of the 2,6-dimethoxy compound at 90 °C in malonic acid-sodium malonate buffer solutions of ionic strength 0.14 gave the data in Table 199. A plot of these data revealed the curve shown in Fig. 3 (one of the points was misplotted on the original) and the linear portions of the plot were attributed to acid and base catalysis as shown on Fig. 3, and since the rates in the region of pH 4-5 are higher than would be... 

The effect of metal-ion catalysis (especially that of cadmium ion) in the above reaction has been studied628, and in Table 201 are listed the first-order rate coefficients for protodeboronation of 2,6-dimethoxybenzeneboronic acid in malonic acid-sodium malonate buffer or perchloric acid, observed in the absence ( ) or presence ( ) of cadmium ion, together with the second-order rate coefficients (k2) obtained by dividing the difference of these values by the cadmium ion concentration. The data of the first ten rows of Table 201 are plotted in Fig. 4 and the... 

Charney et al. (2001), Harvey (1985), Matthew (1971), and Wesson and Smith (1977) have discussed the pharmacology of barbiturates. Barbiturates are derived from barbituric acid, which is the product of the fusion of malonic acid and urea. Barbituric acid lacks CNS activity. The two main classes of barbiturates are the highly lipid-soluble thiobarbiturates, in which sulfur replaces oxygen at the second carbon atom of the barbituric acid ring, and the less soluble oxybarbiturates, with oxygen at the second carbon atom (Table 3-3). Highly lipid-soluble barbiturates have a more rapid onset, a short duration of action, and greater potency than those with lower lipid solubility. 

Table 20 Ring closures to [1,2,4]triazolo[1,5-a]pyrimidines by reaction of 3-amino[1,2,4]triazoles with /3-oxo ketones, esters, nitriles, or malonic acid derivatives...

V-(3-trifluoromethylphenyl)aminomethylenemalonate (749, R = 3-CF3) proved unsuccessful in boiling phosphoryl chloride. The thermal cycliza-tion of ZV-ethyl-N-arylaminomethylenemalonates (749) and their ring closure in acetic acid, in acetic anhydride with zinc chloride, or in a melt of aluminium chloride were likewise unsuccessful (71JHC357). The corresponding quinoline was not obtained in a one-pot version when N-ethylani-line and EMME were reacted in polyphosphoric acid. Table V shows the yields of quinoline-3-carboxylic acid derivatives obtained from /V-ethyl-N-phenyl- and iV-ethyl-7V-(3,4-methylenedioxyphenyl)aminomethylene-malonates (749, R = H and 3,4-0CH20) under various acidic cyclization conditions. 

Table II summarizes a temperature jump study (14) of the reaction of hydroxide ion with various intramolecularly hydrogen bonded malonic acid monoanions and points up the fact that, as the steric hindrance increases, a considerable strengthening in the hydrogen bond occurs with a concomitant slowing down of the rate at which the reaction proceeds (generalization number 4). At the time the authors did not foresee that it would be possible to distinguish between whether the hydrogen bond was broken directly by the attacking base or whether, in fact, there first had to be a collapse of the hydrogen bond into an open form of the anion that would subsequently react with the base. Thus, they simply postulated the former mechanism (direct attack). ...

With diketene, intermediates of type (III) were isolated and subsequently cyclized under basic conditions following step (b). In the case of 3-oxo-carboxylic acid esters or 3-acyl Meldrum s acids, cyclization step (b) immediately follows reaction step (a), if a slight excess of amine is employed (85TH1 87TH1). Note that conversion of (III) to (V) involves the (IH)-enol (Table I cf. 75BSF2731). The relatively low yield in the case of malonic acid ester, as well as the failure of the reaction with the non-enolizable diphenyl phosphinylacetic ester and cyanoacetate, points to the participation of an enol structure of (III). 

From retrosynthetic Scheme 1 follows a synthesis of4-amino-3-carboxy-1,5-dihydro-2-pyrrolones (type Y R4 = OH or OR) that needs malonic acid or malonate as starting material. Such reaction is expected to give low yields due to the limited tendency of malonate to undergo enolization (see Table I) yet it is frequently the only solution at hand. 

Table VIII. Elution Performance of Malonic Acid vs.

Table 3.6.1 Malonic acid needed for solvent extraction of urine...

Che and Kustin studied complexation 438 results for oxalic and malonic acids are in Table 27. From previous relaxation data 07 and their own results, they concluded that the rate constants are more consistent with a normal dissociative pathway if VOL formation from [VO(OH)]+ is assumed. 

Many formation constants involve polycarboxylates Table 28 summarizes the data. Nagyp l and Fabian s report on the oxalic and malonic systems seems the most complete as hydrolysis of both metal ion and complexes has been included.584 A concentration distribution of the complexes in the malonic system is shown in Figure 25. The order of basicities is succinic > citraconic > itaconic > maleic > malonic acid and log /3U0 should follow the same order. However, from Table 28, the order of stabilities is citraconic > malonic > maleic > itaconic > succinic acid.608... 

The effect of exchange of lactic, mandelic and sulfosalicylic acids on the relaxation of solvent protons gave rate constants (k) of exchange from 1.73 to 0.701 mol-1 s-1.642 Kinetics of complex formation with mandelic (HMDA) and vanillomandelic acids (HVMDA) gave rate constants (1.09 x 103 and 1.13 x 103 mol-1 s 1 for MDA- and VMDA ) consistent with a dissociative (Eigen) mechanism.438 As in the case of oxalic and malonic acids (Section 33.5.5.5.ii Table 27), species with coordinated hydroxyl are labilized. 

The computation was improved by Westheimer and Kirkwood, who assumed a dielectric constant of 2.0 within the molecule. By approximating the molecule as an ellipsoid of revolution, they were able to make reasonably accurate calculations of electrostatic effects on pKa values.15 Thus, for malonic acid Westheimer and Shookhoff16 predicted r = 0.41 nm for malonic acid dianion. Recently more sophisticated calculations17 have been used to predict pKa values for the compounds in Table 7-1 and others.18... 

Esterification of resin-bound alcohols with 3-oxo carboxylic acids (which readily undergo decarboxylation) or with malonic acid is best performed using the corresponding ketenes, which can be generated in situ by thermolysis of dioxinones or other precursors (Entries 6-9, Table 13.12). PEG can also be acetoacetylated with acetyl ketene generated by thermolysis [171]. 

Following electrophilic attack on benzene, the carbenium-carboxonium dication 94 is generated, which then gives the product 95. There have been several studies of the chemistry of malonic acid (80) and its esters in superacidic media. It has been shown that diprotonated products (i.e., 81) are formed (Table 1, entry 5).36... 

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. 

Previous work on this reaction has included the use of triethanolamine as catalyst, as well as triethylamine as catalyst and solvent. [21-24] The use of elevated temperatures (>75°C) can lead to uncontrolled decarboxylation of malonic acid before condensation, giving acetic acid, which is then too weak a carbon acid to condense. This difficulty means that often up to 3 equivalents of the malonic acid need to be used to achieve good conversion. Our aim in this work was therefore to find a catalyst which would cause the condensation to occur efficiently, but at low enough temperatures to avoid decomposition of the malonic acid. Using THF as solvent and a 1 1 ratio of malonic acid to aldehyde, with 15g of catalyst per mole of reagent, we obtained high levels of conversion of aldehyde in a reasonable time (Table 3). 

Table 4.4 Elementary transformations at the Belousov-Zhabotinsky reaction with malonic acid as the oxidized substrate...

A few comments on the values of r and (r+ - - r ) (cf. Table VIII) are necessary. Increasing hydrocarbon content decreases the hydrophilic property of the anion (cf. formic, acitic, propanoic, butanoic, 3-methyl-butanoic, and benzoic acids) resulting in the decrease of hydration the trend eventually levels off. Hydrophilic substitution increases hydration (cf. acetic, chloroacetic, cyanoacetic, glycolic acids cf. glutaric, succinic, and malonic acids cf. benzoic and salicyclic acids). Also note that r is smallest for benzoic acid and largest for malonic acid. These trends cannot be fortuitous. 

A greater contrast is provided by the first-order rate of decarboxylation of malonic acid. In Table XV.4 are gathered some data from a compilation of Clark (Zoc. dt) on the effect of different solvents. The data in H2O of Hall (Zoc. cit.) are included for comparison purposes. Here, over a range... 

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