Showing papers on "Carboxylic acid published in 1987"

Fast and selective oxidation of primary alcohols to aldehydes or to carboxylic acids and of secondary alcohols to ketones mediated by oxoammonium salts under two-phase conditions

Abstract: General Oxygenation Procedure. An apparently heterogeneous mixture of an olefin (cyclohexene, 1-pentene, or styrene, 1 g), NaBH, (300 mg, 7.9 mmol), (OEP)RhnxCl (4.0 mg, 6 pmol; [Rh] = 0.6 mM), and an internal standard (p-xylene, mesitylene, or durene, appropriate amount) in dry THF (10 mL) exposed to dry air was stirred a t 20-25 \"C. The oxygenation of 1-methylcyclohexene was carried out by using the rhodium catalyst in an amount 2 or 20 times as much as that used above ([Rh] = 1.2 or 12 mM). The electronic spectra of the reaction mixture underwent no significant change even after 100 h. The formation of oxygenation products was monitored by gas chromatography. Similarly was carried out the oxygenation of 1,5-cyclooctadiene and acetylenes (1-heptyne and 3-heptyne) by using substrate (300 mg), NaBH, (300 mg), and (OEP)RhmC1 or (TPP)RhInC1 (4.0 mg) in THF (20 mL). Reaction products, after conversion if necessary to silylated derivatives, were identified by gas chromatography on the basis of coinjection with authentic samples, and their yields determined also by gas chromatography. 2-Methylcyclohexanol as a mixture of stereoisomers arising from the oxygenation of 1-methylcyclohexene was purified by preparative gas chromatography. The stereoisomer distribution was determined by 'H NMR spectroscopy by taking advantage of the characteristic signals for hydroxymethine protons a t 6 3.1 (for E isomer) and 3.75 (for 2 isomer). The following control runs were carried out by using cyclohexene as substrate: (1) without rhodium porphyrin catalyst, (2) without 02, (3) without NaBH,, and (4) with NaBH(OCHJ3 in place of NaBH,. In neither case was detected oxygenation of substrate to any significant extent. Another control run using cyclohexene oxide in place of cyclohexene under otherwise identical oxygenation conditions did not give cyclohexanol. Borane Transfer. A mixture of (0EP)Rh\"'Cl (40 mg, 0.06 mmol), NaBH4 (100 mg, 2.64 mmol), and 1-pentene (70 mg, 1.0 mmol) in T H F (2 mL) in a vessel sealed with a rubber septum was degassed by freezepumpthaw cycles and was stirred a t room temperature for 19 h. The electronic spectrum of the mixture showed A, a t 395,514, and 545 nm, indicating the formation of (OEP)RhH? Following the standard procedure for the analysis of organoboranes,28 the mixture was then subjected to gas chromatography at 170 OC on a column of silicone SE-30 (2 m), which had been treated with Silyl-8 (Pierce Chemical Co.) to mask protic sites with trimethylsilyl groups. The product was readily identified as tripentylborane on the basis of coinjection with the authentic sample prepared by hydroboration of olefin with diborane under standard conditions. The mixture was exposed to air, stirred for 20 min, and then analyzed by gas chromatography to show the formation of 1-pentanol and 2-pentanol (94:6, in a total yield of 45% based on mol of Rh complex used). Oxidation of Alkylborane. A T H F solution of (E)-bis(2methy1cyclohexyl)borane\" was prepared by the hydroboration of 1-methylcyclohexene (96 mg, 1.0 mmol) with borane-THF (1 M) (0.5 mL, 0.5 mmol) in THF (1 mL) under nitrogen. To this was added 1 N aqueous NaOH (0.5 mL), and the mixture was stirred under air atmosphere for 20 h. Gas chromatographic analysis using silicone DCQF-1 showed the formation of 2methylcyclohexanol with the stereoisomer ratio of E / Z = 7624. Another control run for the oxidation of alkylborane with O2 was carried out in the presence of NaBH, (38 mg, 1.0 mmol) instead of aqueous NaOH under otherwise identical conditions and gave the isomer ratio of E / Z = 81:19. A solution of (E)-bis(2-methylcyclohexyl)borane in THF (0.21 mL) was prepared as above starting from the olefin (15.4 mg, 0.16 mmol). This solution was added to (OEP)RhH15 (100 mg, 0.16 mmol) under nitrogen. The mixture was then allowed to contact with a gentle stream of THF-saturated air for 20 h. Gas chromatography coupled with 'H NMR analysis indicated almost exclusive formation of (E)-2-methylcyclohexanol.

Photooxidation of organic impurities in water using thin films of titanium dioxide

Abstract: Results of the destruction of organic solutes in a simple, thin film TiO2 reactor are described. The reactor was illuminated with a 20-W blacklight UV fluorescent tube and the aqueous stream containing the organic solute flowed past the stationary photocatalyst. In the continuous recirculation mode, the destructive rate of each solute obeyed approximately first-order kinetics. The reaction rate constant decreased with increasing solute concentration. The times for 50% destruction of 500 cmT of 10 M solutions of each of the solutes salicylic acid, phenol, 2-chlorophenol, 4-chlorophenol, benzoic acid, 2-naphthol, naphthalene, and fluorescein were 7.1, 7.2, 8.2, 8.7, 6.9, 8.5, 4.3, and 6.4 min, respectively. It was found that the observed apparent first-order dependence and the change in rate constant with concentration could by explained in terms of the integrated form of the Langmuir adsorption isotherm. A marked dependence of the destruction rate on flow rate was observed and an expression developed which allows the calculation of the destruction curve with good precision at any solute concentration and flow rate. A corresponding curve was observed for the formation of carbon dioxide from salicylic acid solution. It was shown that hydroxylation of the aromatic ring to give salicylic acid is a minormore » reaction path in the destruction of benzoic acid. The maximum quantum yield for the destruction of salicyclic acid at 25C was found to be 0.022. The activation energy for the photooxidation of salicyclic acid was determined to be 11.0 +/- 0.8 kJ mol .« less

Barriers to rotation adjacent to double bonds. 3. The carbon-oxygen barrier in formic acid, methyl formate, acetic acid, and methyl acetate. The origin of ester and amide resonance

Abstract: The structures of the rotamers about the C-O bonds of formic acid, methyl formate, acetic acid, and methyl acetate were calculated by using the 6-31G* basis set and complete geometrical relaxation Large basis sets (6-311+G**) and correction for electron correlation were needed in order to obtain calculated barriers that were in good agreement with the available experimental data The factors that control the geometry at a carbonyl group are considered, and it is shown that an analysis in terms of bond path angles leads to a direct connection with electronegativity The nature of the interaction between an amino group and a carbonyl, as in an amide, is examined and shown not to involve charge transfer from the nitrogen to the carbonyl oxygen, but rather it involves charge transfer between carbon and nitrogen The origin of the rotational barrier in esters and of the difference in energy between the E and Z conformers is discussed

Organic Chemistry: Structure and Function

Abstract: Structure and Bonding in Organic Molecules - Structure and Reactivity: Acids and Bases, Polar and Nonpolar Molecules - Reactions of Alkanes: Bond-Dissociation Energies, Radical Halogenation, and Relative Reactivity - Cyclic Alkanes - Stereoisomers - Properties and Reactions of Haloalkanes: Bimolecular Nucleophilic Substitution - Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination - Hydroxy Functional Group: Alcohols: Properties, Preparation, and Strategy of Synthesis - Further Reactions of Alcohols and the Chemistry of Ethers - Using Nuclear Magnetic Resonance Spectroscopy to Deduce Structure--Extensively revised and updated with 300-MHz spectra - Alkenes and Infrared Spectroscopy - Reactions of Alkenes - Alkynes: The Carbon-Carbon Triple Bond - Delocalized Pi Systems: Investigation by Ultraviolet and Visible Spectroscopy - Benzene and Aromaticity: Electrophilic Aromatic Substitution - Electrophilic Attack on Derivatives of Benzene: Substituents Control Regioselectivity - Aldehydes and Ketones: The Carbonyl Group - Enols, Enolates, and the Aldol Condensation: - Carboxylic Acids - Carboxylic Acid Derivatives and Mass Spectrometry - Amines and their Derivatives: Functional Groups Containing Nitrogen - Chemistry of Benzene Substituents: Alkylbenzenes, Phenols, and Benzenamines - Enolates and the Claisen Condensation: Synthesis of b-Dicarbonyl Compounds Acyl Anion Equivalents - Carbohydrates: Polyfunctional Compounds in Nature - Heterocycles: Heteroatoms in Cyclic Organic Compounds--Updated - Amino Acids, Peptides, Proteins, and Nucleic Acids: Nitrogen-Containing Polymers in Nature - Chapter Integration Problems / Important Concepts / Problems / Team Problems / Preprofessional

Asymmetric hydrogenation of unsaturated carboxylic acids catalyzed by BINAP-ruthenium(II) complexes

Abstract: Hydrogenation d'acides, d'hydroxyacides, et de diacides vinyliques. Application a la synthese du naproxene a partir de l'acide [methoxy-6 naphtyl-2]-2 acrylique

Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite

Abstract: Much effort has been directed to analyses of organic compounds in carbonaceous chondrites because of their implications for organic chemical evolution and the origin of life We have determined the isotopic composition of hydrogen, nitrogen and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite The unusually high D/H and ^(15)N/^(14)N ratios in the amino acid fraction (δD = 1,370‰, after correction for isotope exchange; δ^(15)N = 90) are uniquely characteristic of known interstellar organic materials The δD value of the monocarboxylic acid fraction is lower (377‰), but still consistent with an interstellar origin These results confirm the extraterrestrial origin of both classes of compound, and provide the first evidence suggesting a direct relationship between the massive organo-synthesis occurring in interstellar clouds and the presence of pre-biotic compounds in primitive planetary bodies The isotope data also bear on the historical problem of distinguishing indigenous material from terrestrial contaminants

Metal-mediated approach to enynes

Abstract: Dimerisation d'octyne-1, methyl-2 butyne-3ol-2 et butyne-3 dicarboxylate-1,1 de dimethyle et codimerisation entre le butyne-2oate de methyle ou la (phenyl propynyl) sulfone et des composes acetyleniques en presence d'acetate de Pd(II)-triphenylphosphine

Anion and cation permeability of a chloride channel in rat hippocampal neurons.

Abstract: The ionic permeability of a voltage-dependent Cl channel of rat hippocampal neurons was studied with the patch-clamp method. The unitary conductance of this channel was approximately 30 pS in symmetrical 150 mM NaCl saline. Reversal potentials interpreted in terms of the Goldman-Hodgkin-Katz voltage equation indicate a Cl:Na permeability ratio of approximately 5:1 for conditions where there is a salt gradient. Many anions are permeant; permeability generally follows a lyotropic sequence. Permeant cations include Li, Na, K, and Cs. The unitary conductance does not saturate for NaCl concentrations up to 1 M. No Na current is observed when the anion Cl is replaced by the impermeant anion SO4. Unitary conductance depends on the cation species present. The channel is reversibly blocked by extracellular Zn or 9-anthracene carboxylic acid. Physiological concentrations of Ca or Mg do not affect the Na:Cl permeability ratio. The permeability properties of the channel are consistent with a permeation mechanism that involves an activated complex of an anionic site, an extrinsic cation, and an extrinsic anion.

Immobilization of DNA via oligonucleotides containing an aldehyde or carboxylic acid group at the 5' terminus.

Abstract: A general method for the immobilization of DNA through its 5'-end has been developed. A synthetic oligonucleotide, modified at its 5'-end with an aldehyde or carboxylic acid, was attached to latex microspheres containing hydrazide residues. Using T4 polynucleotide ligase and an oligonucleotide splint, a single stranded 98mer was efficiently joined to the immobilized synthetic fragment. After impregnation of the latex microspheres with the fluorescent dye, Nile Red and attachment of an aldehyde 16mer, 5 X 10(5) bead-DNA conjugates could be detected with a conventional fluorimeter.

Monomeric phthalocyanine reagents

Abstract: Fluorescent and/or chronogenic reagents in which a phthalocyanine derivative is monomerically conjugated whith an antigen, antibody, or oligonucleotide. For use as fluorophores, the free base phthalocyanine may be metallated with aluminium, silicon, phosphorous, gallium, germanium, cadmium, magnesium, tin, or zinc. For use as chromogens, the phthalocyanine may or may not be metallated. For use in aqueous solution, the phthalocyanine macrocycle should be derivatized with water-solubilizing substituents such as sulfonic acid, sulfonate, carboxylic acid, carboxylate, phosphoric acid, phosphate, phosphonate, hydroxy, phenoxy, amino, ammonium, and pyridinium substituents. To further promote disaggregation, metallation with an atom of +3 valence or higher is recommended, so that the monomer will take on an axial ligand in aqueous solution. Useful as detectable markers in immunuassays. For use in enzymatic immunoassays and cDNA assays, the monomeric phthalocyanine derivative is conjugated via an enzyme-cleavable linkage with the antigen, antibody, or oligonucleotide. Reversibly quenched embodiments are also provided, in which a cleavable linkage joins a fluorescent phthalocyanine monomer with another phthalocyanine, a heavy metal, or a paramagnetic species. Also useful as monoclonal antibody reagents provide reagents in fluorescence microscopy, flow cytometry, and photodynamic therapy.

Oxo carboxylate tin ladder clusters. A new structural class of organotin compounds

Abstract: The hexameric n-butyloxotin benzoate, [n-BuSn(O)O2CC6H4NO2.2]6.3C6H6, 1, and the dimeric methyloxotin cyclohexanoate, [(MeSn(O)O2CC6H11)2MeSn(O2CC6H11)3]2, 4, were prepared by condensing the stannoic acid with the respective carboxylic acid. Reaction of n-butyltin. trichloride with the silver salt of the respective carboxylic acid gave the dimeric n-butyloxotin carboxylate compositions, [(n-BuSn(O)O2CR)2-n-BuSn(O2CR)3]2, 2 (R = Ph) and 3 (R = Me). These represent new substances and, as found by X-ray analysis, form a new structural class of organotin compounds for 2-4 having “unfolded drum” or “ladder” structures. The hexamer composition 1 exists in “drum” form. 119Sn NMR data show that the drum and ladder structures interconvert reversibly. 1 crystallizes in the rhombohedral/space group R3 with a H = 15.283 (4) A, cH, = 34.683 (9) A, and Z = 3. 2 crystallizes in the triclinic space group P1 with a = 13.657 (6) A, b = 14.104 (2) A, c = 14.559 (4) A, a = 99.14 (2)°, β = 111.73 (3)°, γ = 101.57 (3)...

Synthesis and beta-lactamase inhibitory properties of 2 beta-[(1,2,3-triazol-1-yl)methyl]-2 alpha-methylpenam-3 alpha-carboxylic acid 1,1-dioxide and related triazolyl derivatives.

Abstract: Benzhydryl 2 beta-[(1,2,3-triazol-1-yl)methyl]-2 alpha-methylpenam- 3 alpha-carboxylate 1,1-dioxide was prepared by heating benzhydryl 2 beta-(azidomethyl)-2 alpha-methylpenam-3 alpha-carboxylate 1,1-dioxide with (trimethylsilyl)acetylene. The ester group was removed by hydrogenolysis to give sodium 2 beta-[(1,2,3-triazol-1-yl)methyl]-2 alpha-methylpenam-3 alpha-carboxylate 1,1-dioxide (3i, YTR-830), which was found to be a potent inhibitor of various bacterial beta-lactamases. A series of related compounds was prepared in a similar way, and all of these compounds show excellent beta-lactamase inhibitory properties.

Revised structure for the phenazine antibiotic from Pseudomonas fluorescens 2-79 (NRRL B-15132).

Abstract: A phenazine antibiotic (mp, 243 to 244 degrees C), isolated in a yield of 134 micrograms/ml from cultures of Pseudomonas fluorescens 2-79 (NRRL B-15132), was indistinguishable in all of its measured physicochemical (melting point, UV and infrared spectra, and gas chromatography-mass spectrometry data) and biological properties from synthetic phenazine-1-carboxylic acid. Gurusiddaiah et al. (S. Gurusiddaiah, D. M. Weller, A. Sarkar, and R. J. Cook, Antimicrob. Agents Chemother. 29:488-495, 1986) attributed a dimeric phenazine structure to an antibiotic with demonstrably similar properties obtained from the same bacterial strain. Direct comparison of the physicochemical properties of the authentic antibiotic obtained from D. M. Weller with synthetic phenazine-1-carboxylic acid and with the natural product from the present study established that all three samples were indistinguishable within the experimental error of each method. No evidence to support the existence of a biologically active dimeric species was obtained. Phenazine-1-carboxylic acid has a pKa of 4.24 +/- 0.01 (25 degrees C; I = 0.09), and its carboxylate anion shows no detectable antimicrobial activity compared with the active uncharged carboxylic acid species. These data suggest that phenazine-1-carboxylic acid is probably not an effective biological control agent for phytopathogens in environments with a pH greater than 7. Images

Prodrug derivatives of carboxylic acid drugs

Abstract: Novel ester derivatives of carboxylic acid medicaments of formula (I), wherein R-COO - represents the acyloxy residue of a carboxylic acid drug or medicament, n is an integer from 1 to 3, and R1 and R2 are the same or different and are selected from a group consisting of an alkyl, an alkenyl, an aryl, an aralkyl, a cycloalkyl and which group may be unsubstituted or substituted, or R1 and R2 together with the N forms a 4-, 5-, 6- or 7-membered heterocyclic ring, which in addition to the nitrogen atom may contain one or two further heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur and which heterocyclic group may be substituted. These compounds are highly biolabile prodrug forms of the corresponding carboxylic acid compounds and are highly susceptible to undergoing enzymatic hydrolysis in vivo whereas they are highly stable in aqueous solution. The novel derivatives are less irritating to mucosa than the parent carboxylic acids and may provide an improved bioavailability of the drugs.

Process for production of ethylene glycol and dimethyl carbonate

Abstract: A process is disclosed for the preparation of ethylene glycol and dimethyl carbonate by reacting methanol and ethylene carbonate in the presence of a series of heterogenous catalyst systems including ion exchange resins with tertiary amine, quaternary ammonium, sulfonic acid and carboxylic acid functional groups, alkali and alkaline earth silicates impregnated into silica and ammonium exchanged zeolites.

Palladium-Catalyzed Vinylation of Acetylenic Iodides under Solid-Liquid Please-Transfer Conditions

Abstract: Vinylation a l'aide de butene-3one-2 ou d'acrylate de methyle. Formation des trans-enynones et enynoates correspondants