Malonic acid

About: Malonic acid is a research topic. Over the lifetime, 3129 publications have been published within this topic receiving 41686 citations. The topic is also known as: Malonate & Propanedioic acid.

Radiation Damage in Organic Crystals. II. Electron Spin Resonance of (CO2H)CH2CH(CO2H) in β-Succinic Acid

Abstract: An analysis of the electron spin resonance of x‐irradiated single crystals of β‐succinic acid shows that: (a) the principal long‐lived paramagnetic species produced by the radiation damage is (CO2H)CH2–ĊH(CO2H); (b) the radical is oriented in the crystal lattice in nearly the same way that the parent succinic acid molecule is oriented in the undamaged lattice; (c) the strongly anisotropic hyperfine interaction due to the σ proton is very nearly the same as that previously found for the σ proton in the malonic acid radical, (CO2H)ĊH(CO2H). In these molecules the σ proton is directly bonded to the carbon atom on which the odd electron is largely localized. The two methylene protons in the radical are not equivalent, and their hyperfine interactions are nearly isotropic, and in the range 80–100 Mc.

Highly efficient and mild copper-catalyzed N- and C-arylations with aryl bromides and iodides.

Abstract: Mild, efficient, copper-catalyzed N-arylation procedures for nitrogen heterocycles, amides, carbamates, and C-arylation procedures for malonic acid derivatives have been developed that afford high yields of arylated products with excellent selectivity. The N-arylation of imidazole with aryl bromides or iodides was found to be greatly accelerated by inexpensive, air-stable catalyst systems, combining catalytic copper salts or oxides with a set of structurally simple chelating ligands. The reaction was shown to be compatible with a broad range of aryl halides, encompassing sterically hindered, electron-poor, and electron-rich ones, providing the arylated products under particularly mild conditions (50-82 degrees C). The lower limit in ligand and catalyst loading and the scope of Ullmann-type condensations catalyzed by complexes bearing those ligands with respect to the nucleophile class have also been investigated. Chelating Schiff base Chxn-Py-Al (1c) generates a remarkably general copper catalyst for N-arylation of pyrrole, indole, 1,2,4-triazole, amides, and carbamates; and C-arylation of diethyl malonate, ethyl cyanoacetate, and malononitrile with aryl iodides under mild conditions (50-82 degrees C). The new method reported here is the most successful to date with regard to Ullmann-type arylation of some of these nucleophiles.

The hygroscopic properties of dicarboxylic and multifunctional acids: measurements and UNIFAC predictions.

Abstract: The role of water-soluble organic compounds on the hygroscopic properties of atmospheric aerosols has recently been the subject of many studies. In particular, low molecular weight dicarboxylic acids and some multifunctional organic acids have been found or are expected to exist in atmospheric aerosols in urban, semiurban, rural, and remote sites. Unlike for their inorganic counterparts, the hygroscopic properties of organic acids have not been well characterized. In this study, the hygroscopic properties of selected water-soluble dicarboxylic acids (oxalic acid, malonic acid, succinic acid, and glutaric acid) and multifunctional acids (citric acid, DL-malic acid, and L-(+)-tartaric acid) were studied using single droplets levitated in an electrodynamic balance at 25 degrees C. The water activities of bulk samples of dilute solutions were also measured. Solute evaporation was observed in the dicarboxylic acids but not in the multifunctional acids. Oxalic acid, succinic acid, and glutaric acid droplets crystallize upon evaporation of water, but, except for glutaric acid droplets, do not deliquesce even at 90% relative humidity (RH). Mass transfer limitation of the deliquescence process was observed in glutaric acid. Neither crystallization nor deliquescence was observed in malonic acid, citric acid, DL-malic acid, or L-(+)-tartaric acid. Malonic acid and these three hydroxy-carboxylic acids absorb water even at RH much lower than their respective deliquescence RH. The growth factor (Gf), defined as the ratio of the particle diameter at RH = 10% to that at RH = 90%, of oxalic acid and succinic acid was close to unity, indicating no hygroscopicity in this range. The remaining acids (malonic acid, glutaric acid, citric acid, malic acid, and tartaric acid) showed roughly similar hygroscopicity of a Gf of 1.30-1.53, which is similar to that of "more hygroscopic" aerosols in field measurements reported in the literature. A generalized equation for these four acids, Gf = (1-aw)-0.163, was developed to represent the hygroscopicity of these acids. Water activity predictions from calculations using the UNIFAC model were found to agree with the measured water activity data to within 40% for most of the acids but the deviations were as large as about 100% for malic acid and tartaric acid. We modified the functional group interaction parameters of the COOH(-H20, OH-H20, and OH-COOH pairs by fitting the UNIFAC model with the measured data. The modified UNIFAC model improves the agreement of predictions and measurements to within 38% for all the acids studied.

Catalytic oxidation of carbohydrates into organic acids and furan chemicals

Abstract: A wide variety of commodity chemicals can be produced from the catalytic oxidation of carbohydrates or carbohydrate derived molecules including formic acid, acetic acid, glycolic acid, gluconic acid, glucaric acid, malonic acid, oxalic acid, 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furancarboxylic acid (HFCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-furandicarboxylic acid (FDCA). This review will highlight the recent research progress in the development of new routes for the production of organic acids and furan compounds via catalytic oxidation reactions. Particular attention will be paid to these one-pot reactions with the requirements of an acidic site and a metal site. For the one-pot transformation of cellobiose or lignocellulose into gluconic acid, these reactions were performed via a one-step strategy using a single catalyst containing an acidic site and a metal site. However, a two-step strategy was adopted for the oxidative transformation of carbohydrates into DFF or FDCA in order to avoid the oxidation of the carbohydrates. The first step was performed for the dehydration of carbohydrates into 5-hydroxylmethylfuran (HMF) in the presence of an acid catalyst, and the second step was performed for the oxidation of HMF into DFF or FDCA with a metal catalyst.