Malonic acid complexes

In order to gain better insight into this phenomenon, several X-ray analyses of 0-cyd clathrates have been undertaken. The first results of the crystal structure determination of the 3-cyd benzil complex were previously reported (1). Since then, this structure has been refined and those of benzophenone, biphenyl and phenyl-ethyl malonic acid complexes have been solved. We report herein the main features of these crystallographic studies. 

The kinetics of the oxidation of malonic acid in the presence and absence of Mn(II) have been reinvestigated.The rate law for the uncatalyzed reaction differs from that when Mn(II) is present and where the principal pathway is via reaction of a Mn(II)-malonic acid complex with HCr04T. 

The intense reddish-brown color of the acetylacetone titanium complexes impart a yellow discoloration to white inks. This discoloration is accentuated when the inks are used to print substrates that contain phenol-based antioxidants. The phenoHc compounds react with the organic titanate to form a highly colored titanium phenolate. Replacement of 0.25 to 0.75 moles of acetylacetone with a malonic acid dialkyl ester, such as diethyl malonate, gives a titanium complex that maintains the performance advantages of the acetyl acetone titanium complexes, but which is only slightly yellow in color (505). These complexes still form highly colored titanium phenolates. 

Beryllium, calcium, boron, and aluminum act in a similar manner. Malonic acid is made from monochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. The acid and the intermediate cyanoacetic acid are used for the synthesis of polymethine dyes, synthetic caffeine, and for the manufacture of diethyl malonate, which is used in the synthesis of barbiturates. Most metals dissolve in aqueous potassium cyanide solutions in the presence of oxygen to form complex cyanides (see Coordination compounds). 

Calcium-binding proteins, 6, 564, 572, 596 intestinal, 6, 576 structure, 6, 573 Calcium carbonate calcium deposition as, 6, 597 Calcium complexes acetylacetone, 2, 372 amides, 2,164 amino acids, 3, 33 arsine oxides, 3, 9 biology, 6, 549 bipyridyl, 3, 13 crown ethers, 3, 39 dimethylphthalate, 3, 16 enzyme stabilization, 6, 549 hydrates, 3, 7 ionophores, 3, 66 malonic acid, 2, 444 peptides, 3, 33 phosphines, 3, 9 phthalocyanines, 2,863 porphyrins, 2, 820 proteins, 2, 770 pyridine oxide, 3,9 Schiff bases, 3, 29 urea, 3, 9... 

Oxidation of malonic acid by Cr(VI) has been noted briefly by Snethlage and later by Kemp and Waters . The kinetics are simple second-order but the acidity dependence is complex. Heckner et a/. find the alkaline permanganate oxidation of malonic acid (and also of o- and p-toluic acids and of p-toluene-sulphonic acid) to be retarded by added Mn(VI), viz. 

For the catalytic oxidation of malonic acid by bromate (the Belousov-Zhabotinskii reaction), fimdamental studies on the interplay of flow and reaction were made. By means of capillary-flow investigations, spatio-temporal concentration patterns were monitored which stem from the interaction of a specific complex reaction and transport of reaction species by molecular diffusion [68]. One prominent class of these patterns is propagating reaction fronts. By external electrical stimulus, electromigration of ionic species can be investigated. 

The aromatic spacer group of the model receptors prevent the formation of intramolecular hydrogen bonds between the opposing carboxyls yet these functions are ideally positioned for intermolecular hydrogen bonds of the sort indicated in 32. The acridine derivatives do indeed form stoichiometric complexes with oxalic, malonic (and C-substituted malonic acids) as well as maleic and phthalic acids, Fumaric, succinic or glutaric acids did not form such complexes. Though protonation appears to be a necessary element in the recognition of these diacids, the receptor has more to... 

One of the most recent developments in the field of Ni-catalyzed reactions of alkyl halides with organozinc derivatives is a study of Terao et al.411 They reported the use of three additives in the couplings 1,3-butadiene, N,N-bis(penta-2,4-dienyl)benzylamine 308a, and 2,2-bis(penta-2,4-dienyl)malonic acid dimethyl ester 308b. Addition of tetraene 308b to the reaction mixtures significantly increased the product yields (Scheme 157). The remarkable effect of these additives was explained by the formation of the bis-7r-allylic complex 309 as the key intermediate (Scheme 158). 

Copper complexes of substituted malonic acids had no influence on the acute toxicity towards adult zebra fish [227], possibly due to stronger chelating groups at the gill epithelia. In contrast, hatching of zebra fish, which is already very sensitive to Cu2+ alone, was delayed in the presence of hydrophobic ra-hexade-cyl malonate, and was not influenced by the less hydrophobic benzyl malonate [227], Overall, it appeared that the toxicity of free Cu2+ and the Cu-hexadecyl malonate complex was additive [227],... 

Palmer, F. B., Butler, C. A., Timperley, M. H. and Evans, C. W. (1998). Toxicity to embryo and adult zebrafish of copper complexes with two malonic acids as models for dissolved organic matter, Environ. Toxicol. Chem., 17, 1538-1545. 

RhClCO(dppp) 2] for the sequential construction of an enyne precursor, starting from a malonic acid derivative and allylic acetate, which was converted in situ to the cycloaddition product with excellent yields. Obviously, the Pd complex catalyzes the allylic substitution reaction, while the rhodium catalyst is responsible for the PKR (Eq. 6). 

While much attention has been paid to the chemistry of cyclodextrin complexes in solution, there have been relatively few studies of their solid-state reactions. One such reaction is the decarboxylation of phenylethylmalonic acid, 155. In solution this is catalyzed by fj-cyclodextrin, and yields racemic 2-phenylbutyric acid, 156 (230). The malonic acid forms a crystalline 1 1 complex with p-cyclodextrin in which decarboxylation occurs at a much lower temperature than in the crystalline diacid. Interestingly, the product formed in the clathrate reaction is nonracemic, the optical yield being 7%. 

Both CO2 activation and enolate formation are combined in the preparation of malonic acid derivatives. The reaction of CO2 with methacrylic esters or methacry-lonitrile and under visible light irradiation produced the corresponding aluminum porphyrin malonate complex. When diethylzinc was added to this system, Al(TPP)Et could be regenerated by axial ligand exchange reactions, and the malonic acid derivatives were formed catalytically with respect to the aluminum porphyrins in a one-pot photosynthetic route (Scheme 1). The first step in this... 

The enthalpies and entropies of formation of mono-mandelato-complexes have been determined and, in comparison with other hydroxycarboxylic acid complexes, the enthalpy order of stabilization is lactate > a-hydroxyiso-butyrate mandelate > glycolate, whereas the entropy order of stabilization is glycolate > a-hydroxyisobutyrate > mandelate > lactate. The stability constants and enthalpy of formation of mono- and di-malonate complexes have also been measured.The mono-1,1-cyclopentanedicarboxylato-complexes are less stable than the corresponding malonate species. 

Lenhart, J.J. Bargar, J.R. Davis, J.A. (2001) Spectroscopic evidence for ternary surface complexes in the lead(ll)-malonic acid-hematite system. J. Coll. Int. Sci. 234 448-452 Lenhart, J.L. Honeyman, B.D. (1999) Uranium (VI) sorption to hematite in the presence of humic acid. Geochim. Cosmochim. Acta 63(19/20) 2891-2901 Leussing, D.L. Kolthoff, I.M. (1953) Iron-thio-glycolate complexes. J. Am. Chem. Soc. 75 3904-3911... 

Moran et al. recently reported receptor 20 that contains two pyridazine-2,4-dione units as polar anchor groups anellated to an aromatic framework [28] as well as the xanthone compound 21 where one of the binding sites is a ben-zoylamido group [29]. Compound 20 fits the binding pattern required for malonic acids, whereas 21 forms complexes with aromatic carboxylic acids like p-ethoxybenzoic add in CDCI3. 

Problem 16.18 (a) Suggest a mechanism for a ready decarboxylation of malonic acid, HOOCCH,COOH, that proceeds through an activated, intramolecular H-bonded, intermediate complex, (b) Give the decarboxylation products of (i) oxalic acid. HOOC—COOH, and (ii) pyruvic acid, CHjCOCOOH. 

A typical chemical system is the oxidative decarboxylation of malonic acid catalyzed by cerium ions and bromine, the so-called Zhabotinsky reaction this reaction in a given domain leads to the evolution of sustained oscillations and chemical waves. Furthermore, these states have been observed in a number of enzyme systems. The simplest case is the reaction catalyzed by the enzyme peroxidase. The reaction kinetics display either steady states, bistability, or oscillations. A more complex system is the ubiquitous process of glycolysis catalyzed by a sequence of coordinated enzyme reactions. In a given domain the process readily exhibits continuous oscillations of chemical concentrations and fluxes, which can be recorded by spectroscopic and electrometric techniques. The source of the periodicity is the enzyme phosphofructokinase, which catalyzes the phosphorylation of fructose-6-phosphate by ATP, resulting in the formation of fructose-1,6 biphosphate and ADP. The overall activity of the octameric enzyme is described by an allosteric model with fructose-6-phosphate, ATP, and AMP as controlling ligands. 

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. 

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