Showing papers on "Carboxylic acid published in 1994"

Organization of Organic Molecules with Inorganic Molecular Species into Nanocomposite Biphase Arrays

Abstract: The organization of cationic or anionic organic and inorganic molecular species to produce three-dimensional periodic biphase arrays is described. The approach uses cooperative nucleation of molecular inorganic solution species with surfactant molecules and their assembly a t low temperatures into liquid-crystal-like arrays. The organic/inorganic interface chemistry makes use of four synthesis routes with @+I-), @-I+), (S+X-I+), and (S-M+I-) direct and mediated combinations of surfactant (cationic S+, anionic S-) and soluble inorganic (cationic I+, anionic I-) molecular species. The concepts can be widely applied to generate inorganic oxide, phosphate or sulfide framework compositions. Distinct lamellar, cubic silica mesophases were synthesized in a concentrated acidic medium (S+X-I+), with the hexagonal and the cubic phases showing good thermal stability. For the hexagonal mesostructured silica materials high BET surface areas (>lo00 m2/g) are found. Hexagonal tungsten(V1) oxide materials were prepared in the presence of quaternary ammonium surfactants in the pH range 4-8. Cubic (Iu3d) and hexagonal antimony(V) oxides were obtained by acidifying (pH = 6-7) homogeneous solutions of soluble Sb(V) anions and quaternary ammonium surfactants a t room temperature @+I-). Using anionic surfactants, hexagonal and lamellar lead oxide mesostructures were found (S-I+). Crystalline zinc phosphate lamellar phases were obtained a t low synthesis temperatures (4 \"C) and lamellar sulfide phases could be also readily generated a t room temperature. The synthesis procedure presented is relevant to the coorganization of organic and inorganic phases in biomineralization processes, and some of the biomimetic implications are discussed.

Anti-AIDS agents, 11. Betulinic acid and platanic acid as anti-HIV principles from Syzigium claviflorum, and the anti-HIV activity of structurally related triterpenoids.

Abstract: Betulinic acid [1] and platanic acid [2], isolated from the leaves of Syzigium claviflorum, were found to be inhibitors of HIV replication in H9 lymphocyte cells. Evaluation of anti-HIV activity wich eight derivatives of 1 revealed that dihydrobetulinic acid [3] was also a potent inhibitor of HIV replication. The C-3 hydroxy group and C-17 carboxylic acid group, as well as the C-19 substituents, contribute to enhanced anti-HIV activity. The inhibitory activity of these compounds against protein kinase C (PKC) was also examined, since a correlation between anti-HIV and anti-PKC activities has been suggested. However, there was no apparent correlation between anti-HIV activity and the inhibition of PKC among these compounds

Influence of low-molecular-weight organic acids on the solubilization of phosphates.

Abstract: A range of low-molecular-weight organic acids were identified in rhizosphere soil, leaf litter, and poultry manure compost. Laboratory and greenhouse experiments were carried out to examine the effects of seven low-molecular-weight organic acids on phosphate adsorption by soils, and the solubilization and plant uptake of P from soil pre-incubated with monocalcium phosphate and North Carolina phosphate rock. Acetic, formic, lactic (monocarboxylic), malic, tartaric, oxalic (dicarboxylic), and citric (tricarboxylic) acids were used in the study. The addition of organic acids decreased the adsorption of P by soils in the order tricarboxylic acid>dicarboxylic acid>monocarboxylic acid. The decreases in P adsorption with organic acid addition increased with an increase in the stability constant of the organic acid for Al (logK Al). Organic acids extracted greater amounts of P from soils meubated with both monocalcium phosphate and phosphate rock than water did. Although more phosphate was extracted by the organic acids from monocalcium phosphate — than from phosphate rock — treated soils in absolute terms, when the results were expressed as a percentage of dissolved phosphate there was little difference between the two fertilizers. The amount of P extracted by the organic acids from both fertilizers increased with an increase in logK Al values. The addition of oxalic and citric acids increased the dry matter yield of ryegrass and the uptake of P in soils treated with both fertilizers. The agronomic effectiveness of both fertilizers increased in the presence of organic acids and the increase was greater with the phosphate rock than with the monocalcium phosphate. The results indicated that organic acids increase the availability of P in soils mainly through both decreased adsorption of P and increased solubilization of P compounds.

Fibrous glass binders

Abstract: A fibrous glass binder comprises a polycarboxy polymer, a β-hydroxyalkylamide, and an at least trifunctional monomeric carboxylic acid.

Use of polyurethanes with carboxylate functionality for hair fixative applications

Abstract: A soluble polyurethane prepared from an organic diisocyante, a diol, and a 2,2-hydroxymethyl-substituted carboxylic acid is neutralized with a cosmetically acceptable organic or inorganic base and formulated into a hair fixative composition containing low amounts of volatile organic solvent.

Mechanism of lactide polymerization in the presence of stannous octoate: The effect of hydroxy and carboxylic acid substances

Abstract: The effect of hydroxy and carboxylic acid substances on lactide polymerization in the presence of stannous octoate was investigated. A polymerization mechanism was postulated to attempt to explain the controversies existing in the literature and also to explain our experimental observations. Stannous alkoxide, a reaction product between stannous octoate and alcohol, is proposed as the substance initiating the polymerization through coordinative insertion of lactide. Alcohol can affect the polymerization through the reactions of initiator formation, chain transfer, and transesterfication. Carboxylic acid affects the polymerization through a deactivation reaction. Experiments showed that alcohol increased PLLA production rate while carboxylic acid decreased it. Both alcohol and carboxylic acid reduced PLLA final molecular weight. The higher the alcohol concentration, the lower the polymer molecular weight. However, the final molecular weight of PLLA was not sensitive to the carboxylic acid concentration. A polymerization induction period was observed at high carboxylic acid concentration, due to the deactivation reaction caused by carboxylic acid. © 1994 John Wiley & Sons, Inc.

Hyperbranched Aromatic Polyesters with Carboxylic Acid Terminal Groups

Abstract: Melt condensation of 6-acetoxyisophtalic acid (1) and 5-(2-hydroxyethoxy)isophthalic acid (4) yielded hyperbranched aromatic polyesters with carboxylic acid terminal groups. The polymer of 1 has a T g of 289°C and thus required melt acidolysis polymerization temperatures of 240-260°C to obtain M w s in the 20000 to 80000 range. The polyesters based on 4, with a lower T g , was obtained at around 190°C standard polycondensation techniques. NMR studies revealed the degree of branching to be about 50%, similar to what has been observed in other hyperbranched polyester systems

Aminoxyl-containing radical spin labeling in polymers and copolymers

Abstract: Aminoxyl-containing radical is provided in polymers and copolymers by replacing a hydroxyl moiety in a carboxyl group at a chain end of a starting material biodegradable polymer or copolymer with imino or oxy linked to aminoxyl-containing radical to form an amide linkage or an oxycarbonyl linkage at the chain end of biocompatible polymers or copolymers to the aminoxyl-containing radical. Preferred starting material polymers and copolymers are prepared from the hydroxy alkyl carboxylic acid monomers glycolic acid and lactic acid. Preferred aminoxyl-containing radical is 2,2,6,6-tetramethylpiperidine-1-oxy. Product polymers are useful for aminoxyl-containing radical treatment of tumors, and to increase the efficiency of chemotherapy and ionizing radiation therapy of tumors and for the reconstruction of injured, diseased, or aged human blood vessels.

Infrared identification of carboxylic acids formed in polymer photooxidation

Abstract: Several low molecular weight carboxylic acids with different substitutions were introduced into various polymer matrices: polypropylene, polystyrene, poly(butylene terephthalate), MDI-based polyurethane, and poly(vinyl chloride). These acids were then submitted to chemical treatments by sulfur tetrafluoride and ammonia. Derivatization reactions by SF4 and NH3 gave, respectively, acyl fluorides and carboxylate ions. The wavenumbers corresponding to the vco maxima of the carboxylic acids, acyl fluorides, and carboxylate ions were determined. For each one of these species, noticeable shifts were recorded that depended on the nature of the substitutents as well as on the nature of the polymer matrix. In addition, samples of the chosen polymers were exposed to photoaging. Photooxidized samples were reacted with SF4 and NH3. Their IR characteristics were determined before and after the treatments. Comparison with the results obtained with the molecular acids permitted us to specify the chemical structure of the acids formed by photooxidation and then to determine the oxidation sites on the macromolecular chains of the different polymers. © 1994 John Wiley & Sons, Inc.

Non-aqueous thixotroped paint and method of producing multilayer coatings with this paint

Abstract: The invention concerns non-aqueous paints containing a polyacrylate resin and a urea-group-containing thixotroping agent. The paints are characterized in that the polyacrylate resin can be prepared by polymerizing (a) 16 to 51 % by wt. of a hydroxy-group-containing ester of acrylic or methacrylic acid or a mixture of these monomers, (b) 32 to 84 % by wt. of an aliphatic or cycloaliphatic ester of acrylic or methacrylic acid, but different from (a), with at least 4 C-atoms in the alcohol group, or a mixture of such monomers, (c) 0 to 2 % by wt. of an ethylenically unsaturated carboxylic acid or a mixture of ethylenically unsaturated carboxylic acids and (d) 0 to 30 % by wt. of an ethylenically unsaturated monomer different from (a), (b), or (c) or a mixture of such monomers. The polyacrylate resin produced has an acid number between 0 and 15, a hydroxy number between 80 and 140 and a mean molecular weight between 1,500 and 10,000, the sum of the proportions of components (a), (b), (c) and (d) always giving 100 % by wt.

Syntheses and structures of bismuth(III) complexes with nitrilotriacetic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid

Abstract: The reactions of bismuth subcarbonate with nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA) were used to synthesize the respective bismuth complexes: (nitrilotriacetato)bismuth(III) dihydrate (1), (hydrogen ethylenediaminetetraacetato)bismuth(III) dihydrate (2), and bis(guanidinium) (diethylenetriaminepentaacetato)bismuthate(III) tetrahydrate (3). The structures of all three complexes were determined by single-crystal X-ray studies. In 1 the ligand is completely deprotonated, so that the resulting complex is neutral

(Cyanomethylene)phosphoranes as Novel Carbonyl 1,1-Dipole Synthons: An Efficient Synthesis of .alpha.-Keto Acids, Esters, and Amides

Abstract: Carboxylic acids react with (cyanomethylene)triphenylphosphorane in the presence of EDCI to form cyano keto phosphoranes. The resulting ylides may then be oxidatively cleaved with ozone to form α,β-diketo nitriles. These highly electrophilic products may then be converted in situ to α-keto acids, esters, and amides

Sorption and extraction of lactic and succinic acids at pH > pKa1. I. Factors governing equilibria

Abstract: Many fermentation to produce carboxylic acid operate most effectively at pH above pK[sub a1] of the acid product, under which conditions the acid is largely in the carboxylate form. One approach to acid recovery from such solutions is to use solid sorbents or liquid extractants that are strongly enough basic to provide substantial capacity even at moderately high values of pH. Data are presented for sorption of lactic and succinic acids by several commercially available basic polymeric sorbents. Performance at pH > pK[sub a1] is a function of sorbent basicity, and apparent pK[sub a] or monomer pK[sub a] can be used to predict sorbent performance. Data are also presented for the extraction of the acids by two commercial amine extractants, Alamine 336 and Amberlite LA-2, in various diluents. The extractants sustain capacity to higher pH in diluents that stabilize the acid-amine complex. Secondary amines provide higher capacities than do tertiary amines in diluents that solvate the additional proton. Competitive uptakes of sulfate, phosphate, and carboxylate were also measured.

Comparison of the photocatalytic efficiency of TiO2, iron oxides and mixed Ti(IV)Fe(III) oxides: photodegradation of oligocarboxylic acids

Abstract: Comparative photo-oxidations of three oligocarboxylic acids, i.e. oxalic acid, EDTA and malonic acid, were performed with different catalysts, i.e. TiO 2 (Degussa P-25), α-Fe 2 O 3 , γ-Fe 3 O 4 and two samples of mixed Fe(III)Ti(IV) oxides containing 0.5 wt.% and 5 wt.% Fe respectively. Different irradiation wavelengths were used. It was found that the photocatalytic efficiency depends mainly on the physicochemical properties of the catalyst, the irradiation wavelength, and the redox potential and adsorption ability of the substrate. The effect of surface complexes formed between the oxide and the organic compound was analysed. TiO 2 was found to be the best catalyst. The relative utility and stability of iron oxides and mixed FeTi oxides is discussed.

A recombinant phenobarbital-inducible rat liver UDP-glucuronosyltransferase (UDP-glucuronosyltransferase 2B1) stably expressed in V79 cells catalyzes the glucuronidation of morphine, phenols, and carboxylic acids.

Abstract: V79 (Chinese hamster lung fibroblast) cell lines expressing a functional recombinant phenobarbital-inducible rat liver UDP-glucuronosyltransferase (UGT), i.e., UGT2B1, were established. Western blot analysis of positive colonies, using anti-rat liver UGT antibodies, revealed the presence of an immunoreactive polypeptide of the expected molecular mass of 52 kDa. The substrate specificity of the recombinant enzyme toward > 100 compounds was determined. Phenolic and alcoholic substrates included 4-methylumbelliferone, 4-hydroxybiphenyl, chloramphenicol, and testosterone, but a range of carboxylic acids of both endogenous (medium-chain saturated fatty acids, long-chain polyunsaturated fatty acids, and bile acids) and exogenous (profen nonsteroidal anti-inflammatory drugs, fibrate hypolipidemic agents, and sodium valproate) origin were also accepted, indicating that the enzyme was capable of forming both ether- and ester-type glucuronides from various structurally unrelated compounds. Determination of apparent kinetic constants for the glucuronidation by UGT2B1 of selected aglycones revealed a high maximal velocity toward the 3-position of morphine (49.3 +/- 2.2 nmol/min/mg of protein), compared with other known substrates such as 4-methylumbelliferone (2.67 +/- 0.11 nmol/min/mg of protein) or clofibric acid (0.06 +/- 0.02 nmol/min/mg of protein). To gain a better insight into the mechanisms underlying the apparently wide substrate specificity of UGT2B1, series of structurally related compounds were tested as potential substrates. The rate of glucuronidation of unbranched saturated fatty acids and omega,omega,omega-triphenylalkanoic acids increased progressively with increasing alkyl chain length and then declined, with the best substrates in these two homologous series being decanoic acid and 4,4,4-triphenylbutanoic acid, respectively. Glucuronidation of para-substituted phenols always proceeded at a higher rate than that of the corresponding para-substituted benzoic acids. This could mean that the aglycon hydroxyl group was better positioned in the enzyme active site in the case of phenols. Alternatively, if the initial interaction with the enzyme required the aglycon to be in the protonated uncharged form, then the observation could be explained by the difference in ionization between phenols and benzoic acids at the incubation pH used. The introduction of a bulky alkyl group into the para-position led to increases of up to 300-fold in the rate of glucuronidation, probably as a result of the increased aglycon lipophilicity. Finally, the enzyme showed a degree of stereo- and regiospecificity, preferring (S)-ibuprofen to the R-enantiomer (Vmax/Km, 3.06 and 1.10 microliters/min/mg of protein, respectively) and glucuronidating lithocholic acid but not hyodeoxycholic acid, which differs by only a single hydroxyl group.(ABSTRACT TRUNCATED AT 400 WORDS)

Dehydration of glucose to organic acids in microporous pillared clay catalysts

Abstract: Glucose is an abundant and renewable feedstock for chemicals production The objective of this study was to determine if microporous pillared-clay catalysts could promote the shape-selective, partial dehydration of glucose to organic acids Iron-, chromium-, and aluminum-pillared montmorillonite catalyst powders were prepared The iron-pillared montmorillonite had the most open pore structure in the > 10Arange Pore slit widths of at least 10Aallowed the 86Aglucose molecule to diffuse and react directly within the catalyst micro- and meso-pores Each catalyst powder was reacted with 075 M glucose solution (4 g catalyst/150 ml) within a well-mixed Parr autoclave reactor for 0–24 h at temperatures ranging from 130–170°C All of the catalysts tested promoted four acid-catalyzed reactions: isomerization of glucose to fructose, partial dehydration of glucose to 5-hydroxymethylfurfural (HMF), rehydration and cleavage of HMF to formic acid and 4-oxopentanoic acid, and coke formation The Fe-pillared montmorillonite provided the highest glucose conversion rate, with 100% glucose conversion attained within 12 h at 150°C This catalyst also provided the lowest selectivity of the HMF (the reaction intermediate) and the highest selectivity of formic acid (the final product) in the bulk phase at an optimum temperature of 150°C Apparently, the fraction of pores in the 10–25Arange allowed glucose to diffuse into the microporous matrix, but also trapped the bulky HMF molecule within the micropores, thus directing the reaction scheme to the final organic acid products However, 4-oxopentanoic acid selectivities were low ( < 20%), and coke formation was as high as 04 g coke/g catalyst, implying carbonization of final reaction products

Kinetics of Wet Air Oxidation of Glyoxalic Acid and Oxalic Acid

Abstract: Oxidation of lower molecular weight monobasic and dibasic acids such as formic acid, acetic acid, glyoxalic acid, and oxalic acid is often the rate-controlling step during wet air oxidation (WAO) of an aqueous waste stream exhibiting very high chemical oxygen demand (COD). The kinetics of WAO of glyoxalic acid and oxalic acid was studied in absence and presence of a cupric sulfate catalyst in the temperature range of 120--245 C and oxygen partial pressure of 0.345--1.380 MPa. The wet oxidation of oxalic acid was found to require more severe conditions as compared to glyoxalic acid. The reaction mechanism and kinetic model have been discussed.

Study of the sequential conversion of citric to itaconic to methacrylic acid in near-critical and supercritical water

Abstract: Between 200 and 400 million lb of citric acid are produced annually in the USA by fermentation of molasses and other sugars using the microorganism Aspergillus niger. A lesser quantity of itaconic acid is manufactured by a similar technology using Aspergillus terreus. The recovery of citric acid from its fermentation broth via calcium salt precipitation is a costly, highly complex, sophisticated operation. USDOE estimates the cost of dry citric acid produced from a new plant to be about $0.59/lb, whereas the estimated cost of wet citric acid (in its fermentation broth) from a new plant is about $0.19/lb and from an old plant is about $0.15/lb. Citric acid rapidly reacts in hot (250 C), compressed (34.5 MPa) liquid water to form itaconic and citraconic acids with a combined selectivity that exceeds 90%. At higher temperatures (360 C), in the absence and presence of NaOH, itaconic acid decarboxylates to form methacrylic acid. The yield of methacrylic acid depends on the temperature, pH, and buffer strength of the medium, reaching a maximum of about 70% (by mole) of the itaconic acid feed. Conditions which favor the production of methacrylic acid also lead to the formation of its hydration product: hydroxyisobutyric acid. Undermore » optimum conditions the combined yield of methacrylic acid and hydroxyisobutyric acid from itaconic acid exceeds 80%. Results are consistent with well-established dehydration and decarboxylation mechanisms.« less

Catalyst for direct reduction of carboxylic acid, process for preparation thereof and process for preparation of alcohol compound using the catalyst

Abstract: Disclosed are a catalyst for directly reducing a carboxylic acid, the catalyst comprising a tin compound and a ruthenium compound supported on a carrier, the catalyst being prepared by the steps of calcining the tin compound in the presence of oxygen after deposition of the tin compound alone on the carrier, and activating the obtained product after deposition of the ruthenium compound on said carrier, a process for preparing the catalyst, and a process for preparing an alcohol compound using the catalyst.

General Method for the Synthesis of Phospholipid Derivatives of 1,2-O-Diacyl-sn-Glycerols

Abstract: An efficient phosphite coupling protocol is described for the syntheses of the major classes of phospholipids that are derived from 1,2-O-diacyl-sn-glycerols and analogues thereof. The symmetrical diacyl glycerols 10c,d were prepared by straightforward acylation of 3-O-benzyl-sn-glycerol (7) with the appropriate carboxylic acid in the presence of dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino)pyridine (DMAP). A simple method for preparing saturated and unstaturated mixed 1,2-O-diacyl-sn-glycerols was then devised that involved stepwise acylation of 7 with different alkyl carboxylic acids and debenzylation; this procedure is exemplified by the preparation of 10a,b. The 1,2-O-diacyl-sn-glycerols 10a-d were then coupled with suitable protected lipid head groups employing reactive alkyl or aryl dichlorophosphites to give intermediate phosphite triesters in high overall yields. Oxidation or sulfurization of these phosphites smoothly to give the corresponding phosphate or phosphorothioate triesters, deprotection of which then provided the phosphatidylcholines 16 and 17, the phosphatidylethanolamine 20, the phosphatidylserine 28, and the phosphatidylinositols 37 and 38. Preparation of 37 and 38 requireed the invention of an improved method for resolving the isopropylidene-protected D-myo-inositol derivative 33; This phosphite coupling procedure was modified to assemble phospholipids bearing polyunsaturated acyl side chains at the sn-2-position as exemplified by the preparation of the phosphatidylethanolamine 26. The one-pot phosphite coupling procedure is also applicable to the syntheses of a variety of other biologically interesting phospholipid analogues. For example, the phosphatidylinositol analogues 49-51, in which the hydroxyl group at C(2) of the inositol ring has been modified, were prepared in excellent overall yields by conjoining the 1,2-O-diacyl-sn-glycerol 10c with the protected inositol derivatives 44,45, and 48. Phospholipid analogues that contain other replacements of the phosphate group including phosphoramidates and thiophosphates may be prepared as evidenced by the syntheses of 56 and 61 in which the sn-3 oxygen atom of the 1,2-O-diacyl-sn-glycerol moiety is replaced with an N-benzyl group or a sulfur atom, respectively

Phosphazene polyelectrolytes as immunoadjuvants

Abstract: An immunoadjuvant soluble polyphosphazene polyelectrolyte is disclosed. In one embodiment, the polymeric adjuvant is a poly(organophosphazene) with (i) ionized or ionizable pendant groups that contain, for example, carboxylic acid, sulfonic acid, or hydroxyl moieties, and (ii) pendant groups that are susceptible to hydrolysis under the conditions of use, to impart biodegradability to the polymer.

Synthesis and characterization of epoxyphilic' montmorillonites

Abstract: ‘Epoxyphilic’ montmorillonites were prepared containing various functional groups which can react with one or both of the components in amine-cured epoxy formulations. The preparation involves the ion exchange of six organic ammonium compounds containing either carboxylic acid, anhydride, phenolic hydroxyl, alcoholic hydroxyl, amide or amine functional groups. X-ray diffraction, elemental analysis and FTIR studies confirm the intercalation of the organic cations to form epoxyphilic montmorillonites. The adsorption behaviour of the modified montmorillonites are compared with the unmodified montmorillonite in an epoxy resin before and after the curing process.

Microbial transformation of Ibuprofen by a nocardia species.

Abstract: The carboxylic acid functional group of ibuprofen [α-methyl-4-(2-methylpropyl) benzene acetic acid] is reduced to the corresponding alcohol and subsequently esterified to the acetate derivative by cultures of Nocardia species strain NRRL 5646. The alcohol and ester microbial transformation products were isolated, and their structures were determined by 1H and 13C nuclear magnetic resonance spectroscopy and mass spectrometry. By derivatization of synthetic and microbiologically produced ibuprofen alcohols with S(+)-O-acetylmandelic acid, nuclear magnetic resonance analysis indicated that the carboxylic acid reductase of Nocardia sp. is R enantioselective, giving alcohol products with an enantiomeric excess of 61.2%. The R enantioselectivity of the carboxylic acid reductase enzyme system was confirmed by using cell extracts together with ATP and NADPH in the reduction of isomeric ibuprofens.