Showing papers on "Malonic acid published in 2006"

Pharmaceutical Cocrystal and Salts of Norfloxacin

Abstract: The aim of this study was to investigate the structural and pharmaceutical properties of norfloxacin (a poorly soluble antibacterial drug), its cocrystal, and salts. Norfloxacin in the anhydrous form (form A, 1) was crystallized. It was cocrystallized with isonicotinamide (2), and organic salts were prepared with succinic acid, malonic acid, and maleic acid (3−5, respectively). These phases were characterized by differential scanning calorimetry (DSC), infrared (IR) and Raman spectroscopy, and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction data were obtained, and crystal structures were solved. The apparent solubility of these phases was determined. Robust O−H···O, O−H···O-, O−H···N, N−H···O, N+−H···O-, and N−H···N interactions were present in all these structures. Quinolone moieties in these structures stack with π···π interactions and form channels to include CHCl3 or H2O. Herein we report a new cocrystal and salts of norfloxacin with improved aqueous solubility.

Ionic liquid as catalyst and reaction medium – a simple, efficient and green procedure for Knoevenagel condensation of aliphatic and aromatic carbonyl compounds using a task-specific basic ionic liquid

Abstract: The basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, [bmIm]OH, efficiently catalyzes Knoevenagel condensation without requirement of any organic solvent. A wide range of aliphatic and aromatic aldehydes and ketones easily undergo condensations with diethyl malonate, malononitrile, ethyl cyanoacetate, malonic acid and ethyl acetoacetate. The reactions proceed at room temperature and are very fast (10-30 min). However, the most significant feature of this methodology is the condensation of aliphatic aldehyde with diethyl malonate, which is not very easy to achieve by conventional reagents, and was not addressed adequately in literature providing a general and convenient procedure.

Ionic Liquid of Choline Chloride/Malonic Acid as a Solvent in the Synthesis of Open-Framework Iron Oxalatophosphates

Abstract: Two new iron(III) oxalatophosphates, Cs2Fe(C2O4)0.5(HPO4)2 (1) and CsFe(C2O4)0.5(H2PO4)(HPO4) (2), have been synthesized by using a low melting point eutectic mixture of choline chloride and malonic acid as a solvent and characterized by single-crystal X-ray diffraction and magnetic susceptibility. Crystal data are as follows: compound 1, monoclinic, P21/c (No. 14), a = 8.5085(4) A, b = 12.7251(6) A, c = 9.8961(4) A, β = 107.117(1)°, V = 1024.01(8) A3, Z = 4, and R1 = 0.0264; compound 2, monoclinic, P21/n (No. 14), a = 8.0038(3) A, b = 10.2923(3) A, c = 11.4755(4) A, β = 100.507(1)°, V = 929.47(5) A3, Z = 4, and R1 = 0.0311. The structure of 1 comprises FeO6 octahedra connected by HPO42- tetrahedra and bisbidentate oxalate anions to form a 3D framework containing intersecting 12-ring channels, with the charge-compensating Cs+ cations being located at the intersections of these channels. The structure of 2 consists of 2D layers of octahedral FeO6, tetrahedral H2PO4- and HPO42- moieties, and bisbidentate o...

Crystallization of Aqueous Inorganic−Malonic Acid Particles: Nucleation Rates, Dependence on Size, and Dependence on the Ammonium-to-Sulfate Ratio

Abstract: Using an electrodynamic balance, we determined the relative humidity (RH) at which aqueous inorganic−malonic acid particles crystallized, with ammonium sulfate ((NH4)2SO4), letovicite ((NH4)3H(SO4)2), or ammonium bisulfate (NH4HSO4) as the inorganic component The results for (NH4)2SO4−malonic acid particles and (NH4)3H(SO4)2−malonic acid particles show that malonic acid decreases the crystallization RH of the inorganic particles by less than 7% RH when the dry malonic acid mole fraction is less than 025 At a dry malonic acid mole fraction of about 05, the presence of malonic acid can decrease the crystallization RH of the inorganic particles by up to 35% RH For the NH4HSO4−malonic acid particles, the presence of malonic acid does not significantly modify the crystallization RH of the inorganic particles for the entire range of dry malonic acid mole fractions studied; in all cases, either the particles did not crystallize or the crystallization RH was close to 0% RH Size dependent measurements show t

Photoassisted decomposition of malonic acid on TiO2 studied by in situ attenuated total reflection infrared spectroscopy.

Abstract: The photoassisted mineralization, i.e., conversion to CO2 and water, of malonic acid over P25 TiO2 was investigated by in situ attenuated total reflection infrared (ATR-IR) spectroscopy in a small volume flow-through cell. Reassignment of the vibrational bands of adsorbed malonic acid, assisted by deuterium labeling, reveals two dissimilar carboxylate groups within the molecule. This indicates adsorption via both carboxylate groups, one in a bridging or bidentate and the other in monodentate coordination. During irradiation the coverage of malonic acid strongly decreases, and oxalate is observed on the surface in at least two different adsorption modes. The major oxalate species observed during irradiation is characterized by monodentate coordination of both carboxylate groups. In the dark, however, part of these species adopts another adsorption mode, possibly interacting only with one carboxylate group. During band gap illumination a large fraction of the surface is not covered by acid. Oxalate is a maj...

Electrical property improvement of electrically conductive adhesives through in-situ replacement by short-chain difunctional acids

Abstract: To improve the electrical properties of electrically conductive adhesives (ECAs), short-chain difunctional acids, such as malonic acid (acid M), adipic acid (acid A), and terephthalic acid (acid T) were introduced into a typical isotropic conductive adhesive formulation. By in-situ replacement of the commonly used surfactant-stearic acid in silver(Ag) flakes, such difunctional acids can increase the conductivity of ECAs. With the addition of malonic acid and adipic acid, which only have short chain single-bond hydrocarbon between the dicarboxylic groups, the conductivity of the typical conductive adhesives was improved significantly. Terephthalic acid, however, deteriorates the conductivity due to the rigid aromatic structure in the molecule. Dynamic mechanical analysis and thermomechanical study indicated the improved electrical properties with malonic and adipic acids were achieved without negatively affecting the mechanical and physical properties of ECAs.

Versatile supramolecular self-assembly. Part I. Network formation and magnetic behaviour of the alkaline salts of the bis(malonate)cuprate(II) anion

Abstract: Five malonate-containing copper(II) compounds of formula {[A(H2O)n]2 [Cu(mal)2(H2O)m]} [A = Li (1), Na (2), K (3), Rb (4) and Cs (5); H2mal = malonic acid] have been synthetized and characterized by X-ray diffraction. The structure of these compounds consists of bis(malonate)cuprate(II) anions and alkaline cations that are held together by means of carboxylate bridges and water molecules leading to 3D networks. A study of the self-assembling of the bis(malonate)cuprate(II) and the alkaline cations is carried out, the size of the alkaline metal ion playing an important role in the control of the resulting malonate-bridged copper(II) structure. A regular alternation of layers of anionic malonate–copper(II) and cationic alkaline metal atoms occurs compounds 2–5. The alkaline metal ions are connected through μ-oxo bridges affording thus, different cationic motifs: dimers (1), single (2 and 3) and double helical chains (4) and layers (5). Depending on the alkaline cation, the bis(malonate)cuprate(II) units can be linked to each other through malonate carboxylate bridges giving rise to anionic networks which exhibit different topologies: monomers (1 and 5), chains (4) and layers (2 and 3). Variable-temperature (1.9–290 K) magnetic susceptibility measurements show the occurrence of ferromagnetic interactions [ranging from +0.77(1) to +0.90(1) cm−1] between the copper(II) ions through the caboxylate–malonate bridge in the out-of-plane anti-anti conformation.

Versatile supramolecular self-assembly : Part II. Network formation and magnetic behaviour of copper(ii) malonate anions in ammonium derivatives

Abstract: Five new metal–organic compounds of formula An[Cu(mal)2(H2O)m] (A being an amine cation and H2mal = malonic acid) have been structurally and magnetically characterized. The crystal structure of these compounds consists of an alternation of malonate-containing copper(II) anionic and amine cationic layers. Depending on the amine cation, the bis(malonate)cuprate(II) units can be connected to other units through carboxylate bridges resulting in anionic networks which exhibit different topologies: monomers (2 and 5), layers (3 and 4) and three-dimensional structures (1). Hydrogen bonding plays an important role in the self-assembling of metal–organic compounds and how the size of the amine cation, in this case, can control the malonate-bridged copper(II) structure and moreover can tune the magnetic properties of these compounds. Variable-temperature (1.9–290 K) magnetic susceptibility measurements indicate the occurrence of weak ferromagnetic interactions [+0.263(5) and +0.755(1) cm−1] between the copper(II) ions through the anti–anti caboxylate–malonate bridges.

Mild Conversion of β-Diketones and β-Ketoesters to Carboxylic Acids

Abstract: A mild protocol for the conversion of β-ketoesters and β-diketones to carboxylic acids with use of CAN in CH3CN is described. The method is compatible with a number of functional groups, and can generate carboxylic acids under neutral conditions at room temperature. The reaction is fast and general, providing an alternative method to the commonly used malonic ester acid preparation. Initial mechanistic studies show that initial oxidation of the enol form of the β-dicarbonyl initiates the reaction. The presence of nitrate as an oxidant ligand or as an additive is critical for success of the reaction.

Cluster phase chemistry: gas-phase reactions of anionic sodium salts of dicarboxylic acid clusters with water molecules.

Abstract: A homologous series of anionic gas-phase clusters of dicarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) generated via electrospray ionization (ESI) are investigated using collision-induced dissociation (CID). Sodiated clusters with the composition (Na+)2n+1(dicarboxylate2-)n+1 for singly charged anionic clusters, where n = 1−4, are observed as major gas-phase species. Isolation of the clusters followed by CID results mainly in sequential loss of disodium dicarboxylate moieties for the clusters of succinic acid, glutaric acid, and adipic acid (C4−C6). However, all oxalate (C2) and malonate (C3) clusters and dimers (n = 1) of succinate (C4) and glutarate (C5) exhibit more complex chemistry initiated by collision of the activated cluster with water molecules. For example, with water addition, malonate clusters dissociate to yield sodium acetate, carbon dioxide, and sodium hydroxide. More generally, water molecules serve as proton donors for reacting dicarboxylate an...

One-pot Preparation of Caffeic Acid Esters from 3, 4-Dihydroxybenzaldehyde:

Abstract: A convenient one-pot process for preparing various esters of caffeic acid from 3,4-dihydroxybenzaldehyde has been developed. The alcohols or phenols react with Meldrum's acid to form malonic acid m...

Synthesis and biological activity of new 1,3,4-thiadiazole derivatives

Abstract: The aminothiadiazole (II) on treatment with aromatic aldehydes yielded Schiff bases, which cyclized to thiazolidinone derivatives by reaction with thioglycolic acid. Reaction of II with phenyl isocyanate and phenyl isothiocyanate afforded the carbamide and carbothiamide derivatives, respectively, which on reaction with malonic acid in acetyl chloride gave barbituric and thiobarbituric acid derivatives. However, reaction of carbon disulfide and methyl iodide with II gave dithiocarbamidate derivative which on treatment with ethylenediamine or o-phenylenediamine gave the condensed N-imidazolylthiadiazolylamine derivatives.

Contribution to the chemistry of the Belousov-Zhabotinsky reaction. Products of the Ferriin-Bromomalonic acid and the Ferriin-Malonic acid reactions.

Abstract: In the present mechanistic schemes of the ferroin-catalyzed oscillatory Belousov-Zhabotinsky (BZ) reaction the oxidation of the organic substrates (bromomalonic or malonic acid) by ferriin (the oxidized form of the catalyst) plays an important role. As the organic products of these reactions were not yet identified experimentally, they were studied here by an HPLC technique. It was found that the main organic oxidation product of bromomalonic acid is bromo-ethene-tricarboxylic acid (BrEETRA), the same compound that is formed when bromomalonic acid is oxidized by Ce4+ (another catalyst of the BZ reaction). Formation of BrEETRA is explained here by a new mechanism that is more realistic than the one suggested earlier. To find any oxidation product of malonic acid in the ferriin-malonic acid reaction was not successful, however. Neither ethane-tetracarboxylic acid (ETA) nor malonyl malonate (MAMA), the usual products of the Ce4+- malonic acid reaction, nor any other organic acid, not even CO2, was found as a product of the reaction. We propose that malonic acid is not oxidized in the ferriin-malonic acid reaction, and it plays only the role of a complex forming catalyst in a process where Fe3+ oxidizes mostly its phenantroline ligand.

Ionic Liquid as Catalyst and Reaction Medium — A Simple, Efficient and Green Procedure for Knoevenagel Condensation of Aliphatic and Aromatic Carbonyl Compounds Using a Task-Specific Basic Ionic Liquid.

Abstract: The basic ionic liquid 1-butyl-3-methylimidazolium hydroxide, [bmIm]OH, efficiently catalyzes Knoevenagel condensation without requirement of any organic solvent. A wide range of aliphatic and aromatic aldehydes and ketones easily undergo condensations with diethyl malonate, malononitrile, ethyl cyanoacetate, malonic acid and ethyl acetoacetate. The reactions proceed at room temperature and are very fast (10-30 min). However, the most significant feature of this methodology is the condensation of aliphatic aldehyde with diethyl malonate, which is not very easy to achieve by conventional reagents, and was not addressed adequately in literature providing a general and convenient procedure.

Polyisocyanates blocked with diisopropyl malonate and their use in one-component coating compositions

Abstract: The present invention relates to a blocked polyisocyanate composition containing A) a blocked polyisocyanate which is the reaction product of i) a polyisocyanate prepared from an aliphatic and/or alicyclic diisocyanate and ii) a malonic acid diester blocking agent containing at least 90 equivalent %, based on the total equivalents of blocking agent, of diisopropyl malonate, and B) a mono-functional active hydrogen-containing compound. The present invention also relates to a one-component coating composition containing these blocked polyisocyanate compositions and a polyhydroxyl compound.

Micelle formation of a diblock copolymer having pyridine as pendant groups by carboxylic acids in nonselective solvents

Abstract: The micelle formation of a poly(4-pyridinemethoxymethylstyrene)-block-polystyrene diblock copolymer (PPySt-b-PSt) was investigated in nonselective solvents using bifunctional and trifunctional carboxylic acids. The copolymer showed no self-assembly in 1,4-dioxane and tetrahydrofuran (THF) because the PPySt and PSt blocks were solvophilic to the solvents. Dynamic light scattering studies demonstrated that the copolymer formed micelles in the nonselective solvents in the presence of bifunctional carboxylic acids. Oxalic acid, maleic acid, citric acid, and phospholic acid promoted the micellization, while malonic acid, succinic acid, and glutalic acid had no effect on the micellization. The micellar size, aggregation number, and critical micelle concentration were dependent not only on the acid strength but also on the type of acid and the functionality. The micellization was also affected by the solvent quality. The micellization proceeded more effectively in 1,4-dioxane than in THF. It was found that the micellization occurred by hydrogen bonding between the pyridine moiety and the carboxylic acid and by the interaction among the carboxylic acids. This is because the copolymer needed over an equivalent of the acid to the PySt unit to complete the micellization. Furthermore, monofunctional carboxylic acid such as trichloroacetic acid and trifluoroacetic acid promoted the micellization, although dichloroacetic acid had no effect on the micellization.

Ozonation degradation of p-nitrochlorobenzene in aqueous solution: kinetics and mechanism

Abstract: The kinetics and mechanism of ozonation degradation of p-nitrochlorobenzene(pCNB)were investigated.The reaction rate constant of pCNB with O_3 was 1.6 L·mol~ -1 ·s~ -1 by direct determination.With nitrobenzene and chlorobenzene as the reference compounds, the reaction rate constant of pCNB with ·OH that was determined by means of competition kinetics was 2.6×10~ 9 L·mol~ -1 ·s~ -1 .During the pCNB ozonation degradation, organic nitrogen and organic chlorine were almost completely converted to nitrate and chloride.Ozonation could not reduce TOC obviously.The results of LC-MS and GC-MS showed that the main intermediate products were aromatic substances such as p-chlorophenol, p-nitrophenol, 2-chloro-5-nitrophenol, etc., and non-aromatic substances such as oxalic acid, malonic acid, maleic acid, muconic acid etc.Finally, a possible reaction pathway of ozonation degradation of pCNB was proposed according to these intermediate products.

Process of preparing malonic ester

Abstract: This invention relates to a method to synthesize malonate from chloroacetic acid, which includes neutralization, cyanidation, acidification, dehydration and esterification. It has the characteristics that dilute sulphuric acid is added after dehydration so that cyanoacetic acid is hydrolyzed into malonic acid which is then esterified to obtain malonate. This invention has the advantages of low cost, easily-controlled technique and high yield.

Ligand-assisted inhibition in cytochrome P450 158A2 from Streptomyces coelicolor A3(2).

Abstract: Cytochrome P450 158A2 (CYP158A2) can polymerize flaviolin to red-brown pigments, which may afford physical protection to the organism, possibly against the deleterious effects of UV radiation. We have found that the small molecule malonic acid enables cocrystallization of this mixed function oxidase with the azole inhibitor 4-phenylimidazole. The presence of malonate molecules affects the behavior of the binding of 4-phenylimidazole to CYP158A2 and increases inhibition potency up to 2-fold compared to 4-phenylimidazole alone. We report here the crystal structure of the 4-phenylimidazole/malonate complex of CYP158A2 at 1.5 A. Two molecules of malonate used in crystallization are found above the single inhibitor molecule in the active site. Those two molecules are linked between the BC loop and beta 1-4/beta 6-1 strands via hydrogen bond interactions to stabilize the conformational changes of the BC loop and beta strands that take place upon inhibitor binding compared to the ligand-free structure we have reported previously. 4-Phenylimidazole can launch an extensive hydrogen-bonding network in the region of the F/G helices which may stabilize the conformational changes. Our findings clearly show that two molecules of malonate assist the inhibitor 4-phenylimidazole to assume a specific location producing more inhibition in the enzyme catalytic activity.

Process for preparing 4-[(1,6-dihydro-6-oxo-2-pyrimidinyl)-amino]benzonitrile

Abstract: This invention relates to a process for preparing 4-[(1,6-dihydro-6-oxo-2-pyrimidinyl)-amino]benzonitrile (I) starting from a 4-oxo-1,6-dihydro-pyrimidinylcarboxylic acid ester (II) or starting from a guanidine derivative which is reacted with an alkoxy-methylene malonic acid ester to an ester (II) which is converted to (I), which reaction sequence may be a one-pot procedure.

Aminoacetic acid as complexing agent in baths for electroless deposition of Ni–W–P coatings

Abstract: Ni–W–P alloy coatings were deposited from a bath containing, nickel sulphate (VI), sodium tungstate (VI), sodium hypophosphite, sodium formate, and a complexing agent. The complexing agents were formic acid, acetic acid, lactic acid, succinic acid, malic acid, malonic acid, aminoacetic acid and triethanoloamine. It is shown that Ni–W–P coatings are deposited the slowest when complexing agents with the highest stability constants are used. As the deposition rate increases, i.e. in the presence of less stable complexing compounds, the amount of tungsten in the coating decreases. When aminoacetic acid and citric acid were used, the tungsten content in the coating amounted to ∼2 wt-%, depending on the complexing agent concentration and the pH of the bath.