Showing papers on "Carboxylic acid published in 1985"

Acid-base behavior of carboxylic acid groups covalently attached at the surface of polyethylene: The usefulness of contact angle in following the ionization of surface functionality

Abstract: : Oxidation of polyethylene with chromic acid/sulfuric acid generates a material (PE-CO2H) having a high density of carboxylic acid and ketone functionalities in a thin surface layer on the polymer. This paper determines the extent of ionization of the surface and near-surface carboxylic acid groups of these materials in contact with water as a function of pH using three experimental techniques: measurement of attenuated total reflectance infrared (ATR-IR) spectra, measurement of contact angles, and direct potentiometric titration. On the basis of correlations between results obtained using these three techniques, we propose an equation relating the contact angles an aqueous solution having a given value of pH and the extent of ionization (a subscript i) of those carboxylic acid groups that are directly exposed to the solution. These carboxylic acid groups have broad titration curves, and have CO2H groups that are less acidic than soluble carboxylic acids. The initial ionization of these carboxylic acid groups occurs when the solution is approximately pH = 6. The detailed structures of these oxidized polymer surface layers and the nature of the interactions between the carboxylic acid and carboxylate ions in them are still not completely defined. Salt effects on the extent of ionization a subscript i at a particular value of pH are unexpectedly small, and suggest that charge-charge interactions between carboxylate ions may not dominate the titration curves. This work demonstrates the usefulness of contact angle in following chemical changes occurring in organic functional groups of surfaces.

Non-peptide polyamino acid bioerodible polymers

Abstract: A novel bioerodible polymeric composition is provided comprising a plurality of monomer units of two or three amino acids which are polymerized via hydrolytically labile bonds at their respective side chains rather than at the amino or carboxylic acid terminals by amide bonds. Such polymers are useful for controlled release applications in vivo and in vitro for delivery of a wide variety of biologically and pharmacologically active ligands.

Synergistic scale and corrosion inhibiting admixtures containing carboxylic acid/sulfonic acid polymers

Abstract: The instant invention is directed to an admixture, and its use in inhibiting scale and corrosion in aqueous systems, comprising: (a) a water-soluble polymer having a weight average molecular weight of less than 25,000, as determined by low angle laser light scattering, comprising an unsaturated carboxylic acid and an unsaturated sulfonic acid, or their salts, having a ratio of 1:20 to 20:1, and (b) at least one compound selected from the group consisting of water-soluble polycarboxylates, phosphonates, phosphates, polyphosphates, metal salts and sulfonates. The instant invention is also directed to a method of inhibiting the formation of insoluble alluvial, metal oxide and metal hydroxide deposits in an aqueous system, comprising adding to the system at least 0.1 mg/l of a water-soluble polymer having a weight average molecular weight of less than 25,000, as determined by low angle laser light scattering, comprising an unsaturated carboxylic acid and an unsaturated sulfonic acid, or their salts, having a ratio of 1:20 to 20:1 and a phosphonate.

Conformation of mono- and dicarboxylic acids adsorbed on silver surfaces

Abstract: Deduction, a partir des spectres de diffusion Raman augmentee en surface, de la geometrie et de la conformation d'une serie d'ions d'acides mono- et dicarboxyliques adsorbes a la surface d'argent colloidal

Biogeochemistry of aquatic humic substances in Thoreau's Bog, Concord, Massachusetts

Abstract: Thoreau's Bog is an ombrotrophic floating-mat Sphagnum bog developed in a glacial kettlehole and surrounded by a red maple swamp. Concentrations of dissolved organic carbon in the porewater of the bog average 36 mg/L and are greatest near the surface, especially during late summer. This distribution suggests that the upper layer of living and dead Sphagnum and moderately humified peat is the major site of dissolved organic material production in the bog. The dissolved organic material consists mainly of aquatic fulvic acid (67%) and hydrophilic acids (20%); these organic acids control the pH (typically 4 or somewhat lower) of the bogwater. The elemental, amino acid, carbo- hydrate, and carboxylic acid contents of fulvic acid from the bog are similar to those of aquatic fulvic acid from the nearby Shawsheen River, although the phenolic hydroxyl content of fulvic acid from Thoreau's Bog is higher. The hydrophilic acids have greater amino acid, carbohydrate, and carboxylic acid contents than the fulvic acid, consistent with the hypothesis that hydrophilic acids are more labile intermediate compounds in the formation of fulvic acid.

Stereocontrolled total synthesis of lipoxins A

Abstract: Synthese de la lipoxine A (acide trihydroxy-5,6,15 eicosatetraene-7,9,11,13oique) et de ses isomeres tout-trans

Process for the vapor phase hydrogenation of carboxylic acids to esters and alcohols

Abstract: The vapor phase formation of carboxylic acid alcohols and/or esters such as ethanol and ethyl acetate from the corresponding mono and di-functional carboxylic acid, such as acetic acid, in the presence of a copper oxide-metal oxide supported catalyst, such as CuO/ZnAl 2 O 4 .

Direct Alkylation of 2′-Deoxynucleosides and DNA following in Vitro Reaction with Acrylamide

Abstract: Reaction of the rodent carcinogen acrylamide (AM) at pH 7.0 and 37°C for 10 and 40 days with 2′-deoxyadenosine (dAdo), 2′-deoxycytidine (dCyd), 2′-deoxyguanosine (dGuo), and thymidine (dThd) resulted in the formation of 2-formamidoethyl and 2-carboxyethyl adducts via Michael addition. The alkylated 2′-deoxynucleoside adducts isolated (% yield after 40 days) were 1-(2-carboxyethyl)-dAdo (1-CE-dAdo) (8%), N6-CE-dAdo (21%) (via Dimroth rearrangement of 1-CE-dAdo), 1-CE-dGuo (4%), 7-(2-formamidoethyl)-Gua (7-FAE-Gua) (6%), 7,9-bis-FAE-Gua (1%) (formed by reaction of AM with depurinated 7-FAE-Gua during the course of the reaction), and 3-FAE-dThd (4%). The products isolated following in vitro reaction of AM with calf thymus DNA at pH 7.0 and 37°C for 40 days were (nmol/mg DNA) 1-CE-dAdo (5.5), N6-CE-dAdo (1.4), 3-CE-dCyd (2.8), 1-CE-dGuo (0.3), and 7-FAe-Gua (1.6). Compound 3-FAE-dThd was not detected. Structures were assigned on the basis of chemical properties, UV spectra, and electron impact, chemical ionization, desorption chemical ionization, Californium-252 fission fragment ionization, and fast atom bombardment mass spectra. A facile hydrolysis of the amide group to a carboxylic acid was observed when AM alkylated a ring nitrogen adjacent to an exocyclic nitrogen atom. In previous studies, we had observed an analogous phenomenon when studying the in vitro reactions of acrylonitrile with DNA, i.e., a facile hydrolysis of nitrile to carboxylic acid when acrylonitrile alkylated (via Michael addition) a ring nitrogen adjacent to an exocyclic nitrogen. Since the nitrile group hydrolyzes to a carboxylic acid via an amide intermediate, we had hypothesized in the present study that the same facile hydrolysis of amide to carboxylic acid would occur under identical stereochemical conditions as had occurred with the nitrile group. Thus, in vitro alkylation of calf thymus DNA by both acrylonitrile and, in the present study, AM, resulted in mixed adduct formation.

Viscosity index improver - dispersant additive useful in oil compositions

Abstract: Hydrocarbon polymers such as ethylene copolymers may be reacted with unsaturated nitrogen-containing monomers or unsaturated carboxylic acids in the presence of a free radical catalyst such as a peroxide or azo free radical initiator and a chain stopping agent, e.g. a mercaptan to inhibit excessive cross-linking and branching. The copolymer grafted directly with the nitrogen-containing monomers may be utilized as an additive for oil and fuel compositions, particularly lubricating oil compositions as a V.I.-dispersant additive. The polymer reacted with carboxylic acid may be further reacted with amines, polyols, amino-alcohols, etc. to also form a V.I.-dispersant additive.

Organic-inorganic reactions during progressive burial: key to porosity and permeability enhancement and preservation

Abstract: The development of porosity and permeability enhancement and preservation or both in many sandstones is a function of aluminosilicate or carbonate mineral stability. The dissolution of aluminosilicate minerals and subsequent porosity and permeability enhancement is a problem of aluminium mobility. Our experimental data demonstrate that it is possible to increase the mobility of aluminium significantly and to transport it as an organic complex in organic acid solutions. These organic acids, primarily carboxylic and phenolic acids, also have the ability to dissolve carbonate grains and cements. W. W. Carothers & Y. K. Kharaka (Geochim. cosmochim. Acta 44, 323-332 (1980)) have shown that concentrations of carboxylic acid anions range up to 5000/10$^{6}$ (by mass) over a temperature range of 80-100 degrees C in some oil-field formation waters. Our experiments show that acetic acid solutions at the same concentration and over the same temperature range can increase the solubility of aluminium by one order of magnitude, whereas oxalic acid solutions increase the solubility by three orders of magnitude. Phenols such as hydroquinone and catechol are almost as effective as oxalate. The textural relations observed in the experiments are identical to those in sandstones containing porosity enhancement as a result of aluminosilicate dissolution. A natural consequence of the burial of sedimentary prisms is the maturation of organic material. Nuclear magnetic resonance (n.m.r.) studies have shown that carbonyl and phenol groups are removed from the kerogen molecule before the generation of hydrocarbons. Thermal degradation or the action of mineral oxidants, or both (the reduction of Fe$^{3+}$ released from clay diagenesis and the reduction of polysulphides are two examples) may be the mechanisms by which the peripheral groups containing the phenols and carboxylic acids are released from the kerogen molecule. The experiments suggest that the enhancement of porosity in a sandstone as the result of aluminosilicate or carbonate dissolution is the natural consequence of the interaction of organic and inorganic reactions during progressive diagenesis. Because of the time and temperature dependence of these reactions, the actual reaction sequences will be sensitive to the thermal and stratigraphic history of the source reservoir sediments.

Camphorsulfonamide-Shielded, Asymmetric 1,4-Additions and Enolate Alkylations; Synthesis of a Southern Corn Rootworm Pheromone. Preliminary Communication

Abstract: Using readily accessible 10-sulfonamido-isoborneols as regenerable, chiral auxiliaries, highly face-selective C–C-bond formations at Cα and Cβ of carboxylates could be conveniently achieved. Thus, conjugated additions of RCu to enoates (12) furnished, after saponification, β-substituted carboxylic acids 3 in 94–98% e.e. Similarly, propionates 12 yielded after deprotonation, enolate alkylation, and reductive ester cleavage the (R)-alcohols 15 in 78–98% e.e. The acid (+)-3e was converted to the pheromone (–)-11.

Acylation of albumin by 1-O-acyl glucuronides.

Abstract: Representative examples of drug metabolites containing a carboxylic acid group conjugated to glucuronic acid are shown to be active chemical electrophiles, which acylate albumin in vitro through transesterification reactions. Based on these and other observations, we propose that this acylating reactivity is characteristic of 1-O-acyl glucuronides as a class, and that albumin is representative of many susceptible biopolymers. The hypothesis is advanced that this reaction can occur in vivo as well, and that it may offer a molecular mechanism for the physiological activity or toxicity of some xenobiotic and lipophilic compounds.

Synthesis of the Metabolites and Degradation Products of 2-Amino-7-isopropyl-5-oxo-5H-[1] benzopyrano [2, 3-b] pyridine-3-carboxylic Acid (Amoxanox)

Abstract: The metabolites and degradation products of 2-amino-7-isopropyl-5-oxo-5H-[1] benzopyrano-[2, 3-b] pyridine-3-carboxylic acid (Amoxanox, AA-673, 1), a promising drug for the treatment of bronchial asthma, were synthesized to confirm the proposed structures and to determine their activity in the rat passive cutaneous anaphylaxis test.

O‐nitrobenzyl photochemistry: Solution vs. solid‐state behavior

Abstract: The efficiency of various 2-nitrobenzyl groups in the photogeneration of carboxylic acid from nitrobenzyl esters has been determined, and the solution vs. solid polymer matrix photochemistry is compared. Generally, the quantum yield for photoreaction is lower in the solid state, probably due to decreased conformational mobility. The substitution that affords the largest increase in quantum yield (ϕ) is at the α-carbon atom. The value of ϕ for α-methyl-2-nitrobenzyl trimethylacetate in solution is 0.65 vs. 0.13 for the parent 2-nitrobenzyl ester.

Polymeric phthalocyanines and their precursors, 7. Synthesis and analytical characterization of polymers from 1,2,4,5‐benzenetetracarboxylic acid derivatives

Abstract: Structurally uniform polymeric phthalocyanines 5a–e, containing imido end groups, were synthesized by reaction of different derivatives of 1,2,4,5-benzenetetracarboxylic acid, 2a–d, with metal salts, urea and a catalyst. 5a–e were converted into polymers 3, 4 and 6, containing anhydride, carboxylic acid and amido end groups, respectively. IR and UV/VIS spectroscopy were used as appropriate methods for describing end groups and structural uniformity. It could be shown that the octasubstituted phthalocyanines 7–10 and not the phthalocyanine 1 must be considered as the low-molecular-weight analogues. The number of phthalocyanine units in the polymers was found to be ⩾ 9. The determination of the real molecular weights is not possible, due to the low solubility of the polymers.