Cerate oxidimetry: Oxidation of carbohydrates

It has been shown that glucose and xylose are oxidized completely to formic acid with ceric sulphate and require respectively 12 and 10 equivalents of oxygen per gram mole of the sugar.Under the same conditions, fructose requires 14 equivalents of oxygen per and mole and in this case, the ketonic group is furtlicr oxidixecl to carbon dioxide.The disaceharides can be estimated by the above procedure after hydrolysis.     

Cerate oxidimetry : Oxidation of formic,glycolic, malic,malonic and tartaric acids

1. Contrary to the observations of earlier workers, it has been shown that formic acid can be quantitatively oxidixed by ceric sulphate in the presence of concentrated sulphuric acid. 2. Tartaric, malonic, malic and glycolic acids can also be oxidized completely to carbon dioxide and water by the following general procedure : to a known amount of the organic acid is added ceric sulphate (excess) solution in dilute sulphuric acid and the mixed solution refluxed for ten to fifteen minutes. Concentrated sulphuric acid (double the volume of the reaction mixture) is then added taking care that formic acid is not lost during the addition, and the mixture again refluxed for 45 to 50 minutes. The excess ceric sulphate is determined by titrating against ferrous ammonium sulphate. 3. The complete oxidation of the above acids provides satisfactory methods for their quantitative estimation.     

Cerate oxidimetry: Oxidation of glycerol,glycol and other organic compounds

1. Oxidation ot tartronic acid has been studied and it has been shown that the oxidation of glycerol by ceric sulphate does not proceed via this acid by was presumed by earlier workers. 2. It has been shown that the oxidation of formic acid by pure ceric sulphate is negligible, but using chromium sulphate as catalyst, formic acid can be quantitatively oxidized. 3. Oxidation of glycol and glycerol can be carried out quantitatively either to the -formic acid stage or completely to carbon dioxide and water. A combination of the above provides a method for the estimation of the two compounds when present together in a mixture.     

Cerate oxidimetry of alpha-hydroxy and alpha-keto carboxylic acids in acetic acid

Methods for the preparation and use of a solution of ammonium hexanitratocerate(IV) in acetic acid as a titrant for the oxidation of alpha-hydroxy and alpha-keto carboxylic acids in acetic acid are presented. The applicability of this reagent with respect to the stoichiometry, products and reaction times obtained is discussed.     

Cotton-Mouton constants for benzoic and phthalic acids

The Cotton-Mouton effect was used to investigate benzoic, phthalic, isophthalic, and terephthalic acids. The additive tensor characteristics of the magnetic susceptibility ellipsoid were obtained for the C_ar-COOH fragment. Magnetic and electric double refraction, dipole moment, and quantum chemistry methods were used to study the spatial structure of phthalic acid in solution.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1568–1571, September, 1993.     

Correlation of observed and model vibrational frequencies for aqueous organic acids: UV resonance Raman spectra and molecular orbital calculations of benzoic, salicylic, and phthalic acids

The aromatic carboxylic acids benzoic, salicylic and phthalic acid were used to study the interaction of soluble organics compounds with metal cations. To accomplish this, we have developed methods for studying the carboxylic acids using UV resonance Raman (UVRR) combined with molecular orbital density functional theory calculations. The pH values of the acid solutions were based on the pK(a)'s for the different acids to examine the neutral and charged species. Deprotonation of the organic acids was detectable down to 10(-4)M using UVRR (two orders of magnitude lower than previous vibrational spectroscopy studies). Limitations to decreasing the concentration lower using the current UVRR facilities are discussed. Two methods were used to calculate the optimized geometry and frequencies of the acids: explicit and continuum solvation. The frequencies from the experimental spectra were then compared to the theoretical results obtained from the two methods.     

The heat effects of dissociation of maleic and fumaric acids

The heat effects of dissociation of maleic and fumaric acids at 298.15 K and several ionic strength values were determined calorimetrically in the presence of NaNO₃. The thermodynamic characteristics of dissociation at fixed ionic strengths and under standard conditions were calculated.     

Methylene chloride chemical ionization of fumaric and maleic acids and their esters

The chemical ionization (CI) mass spectrometry of fumaric and maleic acids and their esters with methylene chloride as reagent gas is described. The introduction of methylene chloride to the CI(CH₄) plasma led to the formation of new characteristic ions in addition to the protonation and the subsequent fragmentation, revealing diagnostic information on the configuration of geometrical isomers. The new characteristic ions have been found to arise from the addition of the reactant ion of methylene chloride, [CH₂Cl]⁺, to the substrates and, for higher dialkyl esters, from the further McLafferty rearrangement of the adduct ion [M + CH₂Cl]⁺.     

Nucleophilic and electrophilic radical attack on maleic and fumaric acids in aqueous solution

Rate coefficients (k) of CH₂OH, , and radical addition to maleic and fumaric acids were investigated between pH 1 and 8. Strong pH dependences observed were attributed to changes in protonation states of acids: H₂X, HX⁻ and X²⁻. k of CH₂OH, , addition to fumaric acid decreased in the order k_H2F>k_HF^->k_F^2- in agreement with the nucleophilic character of reaction. The electrophilic radical showed opposite tendency. With maleic acid the monoanion had the highest reactivity towards nucleophilic and the lowest one towards electrophilic radicals. This is attributed to a prevalence of steric over polar effects for HM⁻.     

Thermal studies on mixtures of benzoic and salicylic acids with cyclodextrins

The thermal behaviour of benzoic and salicylic acids is compared with the behaviour of 1:1 molar ratio physical and kneaded mixtures of these acids with each of three different cyclodextrins (b-, hydroxypropyl-b-, and g-cyclodextrin). Differential scanning calorimetry and thermogravimetry coupled with evolved gas analysis by Fourier transform infrared spectroscopy were used for the thermal studies and X-ray powder diffraction and infrared spectroscopy provided complementary information. Thermal studies of benzoic acid with the cyclodextrins showed significant interactions in both physical and kneaded mixtures of benzoic acid/b-cyclodextrin and benzoic acid/hydroxypropyl-b-cyclodextrin. Interactions in the kneaded benzoic acid/g-cyclodextrin mixtures were the most extensive as might be expected for the cyclodextrin with the largest molecular cavity. The results for the salicylic acid/b-cyclodextrin and salicylic acid/hydroxypropyl-b-cyclodextrin mixtures were similar to those for benzoic acid/b-cyclodextrin and benzoic acid/hydroxypropyl-b-cyclodextrin. Again, the kneaded salicylic acid/g-cyclodextrin mixture showed the most interaction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radiation copolymerization of vinyl acetate with the diethyl esters of maleic and fumaric acids

The radiation-induced copolymerization of vinyl acetate with diethyl maleate and with diethyl fumarate was investigated in the temperature range from ?40 to 90°C over a wide range of comonomer compositions. Both the rates of copolymerization and the molecular weights of the resulting copolymers were found to depend strongly on the initial comonomer compositions. The apparent activation energy was found to change at 13°C with an increase in temperature from a value of 1.76 kcal/mole to a value of 4.31 kcal/mole in the copolymerization with diethyl maleate, while in the case of the copolymerization with diethyl fumarate the apparent activation energy changed at 21°C from a value of 1.76 kcal/mole to a value of 5.98 kcal/mole. Scavenger studies indicate that a free-radical mechanism prevails over the entire temperature range investigated in the case of both copolymerizations.     

Salts of maleic and fumaric acids with oxine: the role of isomeric acids in hydrogen‐bonding patterns

Both maleic and fumaric acid readily form adducts or complexes with other organic molecules. The 1:1 adduct formed by quinolin‐8‐ol (oxine) with maleic and fumaric acid are salts, namely 8‐hydroxyquinolinium hydrogen maleate, C₉H₈NO⁺·C₄H₃O₄⁻, (I), and 8‐hydroxyquinolinium hydrogen fumarate, C₉H₈NO⁺·C₄H₃O₄⁻, (II). The cations and anions of both salts are linked by ionic N⁺—H...O⁻ hydrogen bonds. The maleate salt crystallizes in the space group P2₁2₁2₁, while the fumarate salt crystallizes in P. The maleic and fumaric acids in their complex forms exist as semimaleate and semifumarate ions (mono‐ionized state), respectively. Classical N—H...O and O—H...O hydrogen bonds, together with short C—H...O contacts, generate an extensive hydrogen‐bonding network. The crystal structures of the maleate and fumarate salts of oxine have been elucidated to study the importance of noncovalent interactions in the aggregation and interaction patterns of biological molecules. The structures of the salts of the Z and E isomers of butenedioic acid (maleic and fumaric acid, respectively) with quinolin‐8‐ol are compared.     

Effect of phthalic and salicylic acids on the synthesis and properties of polyaniline films

Effects of phthalic and salicylic acids on the kinetics of the synthesis of polyaniline (PAN) at platinum and on the PAN doping and degradation are studied, along with the adsorption behavior of these acids during the synthesis and degradation of PAN. Effect of additives on the PAN properties is determined by the interaction between additives and PAN. The acids make no impact on the PAN synthesis kinetics and affect only the PAN doping and degradation.     

Polarizability anisotropy of maleic and phthalic anhydrides

Conclusions The polarizability ellipsoids of the maleic and phthalic anhydride molecules are characterized by substantial nonadditivity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2154–2156, September, 1977.     

Interaction model for the antiinflammatory action of benzoic and salicylic acids and phenols

Ab initio, quantum chemical methods have been used to develop an interaction model for the binding of benzoic and salicylic acids and phenols to cyclooxygenase, leading to their antiinflammatory action. The model is based on a regression analysis of the energy of the highest occupied molecular orbital with the potency of the active substances to inhibit prostaglandin production in mouse macrophages and on an analysis of the frontier orbital charge distributions and electrostatic potentials of active and inactive compounds. The model suggests that binding is controlled by an electrostatic orientational factor and a charge transfer or polarization contribution. The observed relative potencies of the phenols and acids can be rationalized with the help of the proposed interaction model.     

Crystal engineering approach to forming cocrystals of amine hydrochlorides with organic acids. Molecular complexes of fluoxetine hydrochloride with benzoic, succinic, and fumaric acids

A crystal engineering strategy for designing cocrystals of pharmaceuticals is presented. The strategy increases the probability of discovering useful cocrystals and decreases the number of experiments that are needed by selecting API:guest combinations that have the greatest potential of forming energetically and structurally robust interactions. Our approach involves multicomponent cocrystallization of hydrochloride salts, wherein strong hydrogen bond donors are introduced to interact with chloride ions that are underutilized as hydrogen bond acceptors. The strategy is particularly effective in producing cocrystals of amine hydrochlorides with neutral organic acid guests. As an example of the approach, we report the discovery of three cocrystals containing fluoxetine hydrochloride (1), which is the active ingredient in the popular antidepressant Prozac. A 1:1 cocrystal was prepared with 1 and benzoic acid (2), while succinic acid and fumaric acid were each cocrystallized with 1 to provide 2:1 cocrystals of fluoxetine hydrochloride:succinic acid (3) and fluoxetine hydrochloride:fumaric acid (4). The presence of a guest molecule along with fluoxetine hydrochloride in the same crystal structure results in a solid phase with altered physical properties when compared to the known crystalline form of fluoxetine hydrochloride. On the basis of intrinsic dissolution rate experiments, cocrystals 2 and 4 dissolve more slowly than 1, and 3 dissolves more quickly than 1. Powder dissolution experiments demonstrated that the solid present at equilibrium corresponds to the cocrystal for 2 and 4, while 3 completely converted to 1 upon prolonged slurry in water.     

The mass spectra of carboxylic acids—I: Fragmentation mechanisms in maleic and fumaric acids and related compounds

The mass spectra of maleic acid, maleic acid-2,3-d, fumaric acid and fumaric acid-2,3-d have been examined and fragmentation mechanisms are proposed for these compounds. The molecular ion of the cis-acid fragments via H atom transfer from one carboxyl group to the other followed by loss of CO₂. The trans acid does not fragment significantly by this route and the former effect may be characteristic of molecules containing two carboxyl groups cis-oriented to each other. This hypothesis was successfully tested by examining the mass spectra of citraconic, itaconic and phthalic acids. Itaconic and mesaconic acids show some of the fragmentation characteristics of fumaric acid.