Presence Of Hydrochloric Acid Research Articles

Preparation of Primary-Amine Functionalized Poly(2,5-benzimidazole) Membrane for Fuel Cells

Acid doped polybenzimidazole membrane has been prepared for proton exchange membrane fuel cell. The present work aims at improving the proton conductivity without losing mechanical properties at high doping level by modifying poly (2,5-benzimidazole) (ABPBI). The nitration of ABPBI has been carried out with acid mixture of HNO3 and H2SO4 at 30oC. This nitro compound has been reduced successfully by stannous chloride/dimethylacetamide in presence of hydrochloric acid. Fourier transform infrared (FT-IR) spectra confirm the presence of primary amine groups in the ABPBI structure. The primary amine functionalized ABPBI has been cross-linked by hexamethylene diisocyanate and casted onto glass Petridis using dimethyl sulfoxide as solvent. Membrane doped with phosphoric acid shows comparatively higher proton conductivity, but lower tensile strength.

The first synthesis of 3‐hydroxy‐2‐(polyfluoroalkyl)chromones and their ammonium salts. 3‐hydroxychromone in the Mannich reaction

Abstract magnified image 3‐Hydroxy‐2‐(polyfluoroalkyl)chromones were obtained in good yields via the nitrozation reaction of 2‐(polyfluoroalkyl)chroman‐4‐ones with isopropyl nitrite in the presence of hydrochloric acid. Treatment of 3‐acetoxy‐2‐(trifluoromethyl)chromone with primary amines and hydrazine gave the corresponding ammonium salts. Reaction of 3‐hydroxychromone, prepared by this method, with formaldehyde and α‐aminoacids has been studied. J. Heterocyclic Chem., (2010).

Some condensations of methyl 4-acetylphenylcarbamate

Condensation of methyl 4-acetylphenylcarbamate with isatin in the presence of diethylamine afforded methyl 4-[(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)acetyl]phenylcarbamate which was converted into the corresponding chalcone on heating in glacial acetic acid in the presence of hydrochloric acid. 1,3-Dipolar cycloaddition to that chalcone of azomethine ylide generated from 2-phenacylisoquinolinium bromide by the action of triethylamine gave methyl 4-(3′-benzoyl-2-oxo-1′,2,2′,3,3′,10b′-hexahydro-1H-spiro-[indole-3,1′-pyrrolo[1,2-a]isoquinolin]-2′-ylcarbonyl)phenylcarbamate. Condensation of 2-hydroxy- and 2,4-dihydroxybenzaldehydes with methyl 4-acetylphenylcarbamate in the presence of gaseous hydrogen chloride resulted in the formation of chromenium salts with a methoxycarbonylaminophenyl fragment on the C2 atom in the heteroring.

Preparation of free-standing films with sulfonyl group from 3-mercaptopropyl(trimethoxy)silane/1,2-bis(triethoxysilyl)ethane copolymer

3-Mercaptopropyl(trimethoxy)silane (MTMS)/1,2-bis(triethoxysilyl)ethane copolymer was synthesized by the hydrolytic polycondensation of the two alkoxysilanes in the presence of hydrochloric acid as a catalyst under nitrogen flow. Free-standing films were prepared by heating the copolymer at 80 °C for 4 days. The films were dipped in a 30% hydrogen peroxide solution at room temperature for 4 days. The sulfonated films were stable against hydrolysis and maintained their form at 150 °C. The sulfonyl group content of the film at 150 °C was 1.20 mmol g−1 when the composition of MTMS/1,2-bis(trimethoxysilyl)ethane was 1:2. Sulfonated free-standing films were prepared by sulfonation of the free-standing films of 3-mercaptopropyl(trimethoxy)silane (MTMS)/1,2-bis(triethoxysilyl)ethane (BTESE) copolymers. The sulfonyl group content was 1.23 mmol g−1 when the composition of MTMS/BTESE was 1:2, which sulfonyl group content at 150 °C was 1.20 mmol g−1.

MATHEMATICAL AND QUANTUM CHEMICAL STUDIES FOR THE CORROSION INHIBITION OF STEEL IN HCL ACID

The application of empirical and quantum chemical models on the corrosion inhibition of steel in hydrochloric acid in presence of phenylthiourea (PTU) as corrosion inhibitor have been modeled. Two mathematical models were used, third order polynomial model and Arrhenius type equation model. Levenberg-Marquardt method was used to evaluate the coefficients of two Models. Two models were suitable to represent the corrosion rate data at different conditions. The correlation coefficient of third order model was 0.973, while for the Arrhenius type model was 0.919. The structure of inhibitor was optimized by ArgusLab 4.0.1 package. The quantum chemical parameters (EHOMO, ELUMO, ΔE, and dipole moment µ) were estimated by PM3-SCF method

Synthesis of hollow polyaniline nanoparticles with reactive template

γ-Fe 2O 3 nanoparticles were used as the reactive templates for the fabrication of the hollow polyaniline nanoparticles via the chemical oxidative polymerization of aniline in the presence of hydrochloric acid. The particle size of the doped hollow polyaniline nanoparticles in the emeraldine form was determined by the reactive template. It was found that the reacting temperature played an important role in the formation of the hollow nanoparticles because of the low redox potential of Fe(III) ion. However, the kind of the protonic acids used had no influence on the fabrication of the hollow nanostructure. The formation mechanism of the hollow polyaniline nanoparticles was also proposed.

Octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes via 4-trimethylsilylphenyl derivatives

Pure octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes were obtained by regio-selective 4-nitration of octa, deca, and dodeca(4-trimethylsilylphenyl) cage silsesquioxanes via ipso-substitution of trimethylsilyl-phenyl bonds by fuming nitric acid. 3-Nitration of octa(4-methylphenyl)octasilesquioxane was also described. The starting octa(4-methyl-, 4-isopropyl- and 4-trimethylsilylphenyl)octasilsesquioxanes were selectively formed in 9-21% isolated yield in the presence of hydrochloric acid. Mixtures of octa, deca and dodecasilsesquioxanes, with decasilsesquioxane as the main component, were formed in the presence of tetrabutylammmonium fluoride as a catalyst. All the cage compounds could be separated mainly by crystallization.

Synthesis of a succinate–dihydrotestosterone–dihydropyrimidine conjugate

In this work a new steroid-dihydropyrimidine derivative was synthesized. The route involved preparation of a dihydrotestosterone-dihydropyrimidine derivative using dihydrotestosterone, benzaldehyde, and thiourea in the presence of hydrochloric acid, followed by esterification of the dihydrotestosterone-dihydropyrimidine derivative with succinic acid to form a succinate-dihydrotestosterone-dihydropyrimidine conjugate.

Esterification of Self-Assembled Carboxylic-Acid-Terminated Thiol Monolayers in Acid Environment: A Time-Dependent Study

This contribution reports on the influence of acids on the quality of carboxylic-acid-terminated self-assembled monolayers (SAMs) on gold prepared from ethanolic solution of HS-(CH(2))(15)-COOH and HS-(CH(2))(11)CONH-(EG)(6)CH(2)-COOH. Null ellipsometry, contact angle goniometry, and infrared reflection-absorption spectroscopy are used to monitor the physical and chemical changes occurring within the SAMs upon acid post treatment; after incubation with acids present in the solution; and after incubation in aged acid containing solutions. The presence of acid has a positive effect on the crystallinity, packing, and orientation of the supporting alkyl and ethylene glycol subunits of the SAM. Our studies also confirm previous findings stating that the carboxylic groups are rapidly converted into ethyl ester groups in the presence of hydrochloric acid in the incubation solution. It is also evident that the conversion occurs in the presence of the weaker acid, acetic acid, although at a much slower rate than that for hydrochloric acid. This is a new observation that has not been reported on before. The physical and chemical characterization is also complemented with a functional bioaffinity study. The functional evaluation revealed that the present model system was surprisingly insensitive to the degree of esterification of the carboxylic acid groups, but that 4 weeks of storage of the two investigated thiols in hydrochloric acid containing ethanol resulted in SAMs that were completely inactive with respect to immobilization and subsequent binding of the antigen. It was encouraging to note that the nonspecific binding of both antigen and antibody was extremely low on the two SAMs, regardless of the relative amount of ethyl esters on the surface.

Antimicrobial activity of native and esterified legume proteins against Gram-negative and Gram-positive bacteria

Three legume proteins (broad bean, soybean and chick pea proteins) were isolated and esterified with methanol in the presence of hydrochloric acid (50 mol acid/mole carboxylic group) for 10 h at 4 °C to give yields of 75%, 80% and 83%, respectively. The SDS–PAGE molecular weight distribution of proteins showed slight increments after esterification. Esterification raised the pIs (iso-electric points) of legume proteins from pH 4.5 for the native legume proteins, to pH 6 in the case of broad bean protein and pH 8 in the case of soybean and chick pea proteins. Applying methylated proteins at three different concentrations (0.1, 1.0 and 10 mg/ml) to Petri dishes containing nutrient agar infected with two pathogenic Gram-positive ( Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria ( Pseudomonas aeroginosa and Escherichia coli) gave rise to concentration-dependent inhibition zones. Applying native or methylated proteins at low or medium concentrations (0.1% and 0.5%) to 100 ml nutrient broth infected with 200 μl of either Gram-positive or Gram-negative bacteria resulted in lower media turbidity (OD 600) values, when compared to control and referring to lower bacterial growth.

Synthesis and Characterisation of Polyaniline/Montmorillonite Nanocomposites

A series of polyaniline / montmorillonite clay (PANI-MMT) composites has been synthesised by solution polymerisation in the presence of hydrochloric acid and a substoichiometric amount of ammonium persulfate (APS). For a preferred molar ratio of monomer to oxidant of 2:1, the aniline was polymerised and largely incorporated into the MMT. The PANI-MMT composites were characterised and compared by Fourier-transform infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction and scanning electron microscopy (SEM). The effect of loading with the conducting polymer on the nanocomposites’ DC electrical conductivity was studied, and the maximum conductivity (pressed powder compact) was found to be 4.73 × 10 1 S.cm-1, comparable with that of pure polyaniline in the same form. The conductivity followed quite well the temperature-dependence relationship □(T) = □0.exp[-To/T)1/2], characteristic of one-dimensional variable-range hopping (1-D VRH).

Enaminones as building blocks in organic syntheses: on the reaction of 3-dimethylamino-2-propenones with malononitrile

An X-ray crystal structure for the product of reacting enaminones and malononitrile in ethanol with piperidine conclusively established its structure as dienamides 4a,b that cyclize to 1,2dihydropyridine-3-carbonitriles 5 on treatment with acetic anhydride in the presence of hydrochloric acid. Reaction of 4a with a second mol equivalent of malononitrile afforded 2-[3(dimethylamino)-3-phenyl-2-propenylidene]malononitrile 7 that was also converted into 5, and to 5-phenyl-1H-pyrazole 9 via treatment with hydrazine hydrate. Reaction of enaminone 1a with ethyl cyanoacetate in the presence of piperidine afforded the pyranone derivative 12.

Stereoselective hydrogenation of 4-alkylphenols over carbon-supported rhodium catalyst in supercritical carbon dioxide solvent

Hydrogenation of 4-alkylphenols was studied over a carbon-supported rhodium catalyst in supercritical carbon dioxide (scCO2) solvent, and the results were compared with those in 2-propanol. Higher selectivities to cis-4-alkylcyclohexanols were obtained in scCO2 than in 2-propanol for the hydrogenation of all 4-alkylphenols tested. In addition, the formation of alkylcyclohexane (dehydroxylated product) was suppressed in scCO2. Stereoselectivities to cis forms were further improved in the presence of hydrochloric acid.

Facile synthesis of polyaniline nanofibers using pseudo-high dilution technique

A new approach for the synthesis of polyaniline nanofibers under pseudo-high dilute conditions in aqueous system has been developed. High yield nanoscale polyaniline fibers with 18–110 nm in diameter are readily prepared by a high aniline concentration 0.4 M oxidation polymerization using ammonium persulfate (APS) as an oxidant in the presence of hydrochloric acid (HCl), perchloric acid (HClO 4), (1S)-(+)-10-camphorsulfonic acid (CSA), acidic phosphate PAEG120 (PA120) and sulfuric acid (H 2SO 4) as the dopants. The novel pathway always produces polyaniline nanofibers of tunable diameters, high conductivity (from 10 0 to 10 1 S/cm) and crystallinity.

Escherichia coli and Salmonella enterica are protected against acetic acid, but not hydrochloric acid, by hypertonicity.

Chapman et al. (B. Chapman, N. Jensen, T Ross, and M. B. Cole, Appl. Environ. Microbiol. 72:5165-5172, 2006) demonstrated that an increased NaCl concentration prolongs survival of Escherichia coli O157 SERL 2 in a broth model simulating the aqueous phase of a food dressing or sauce containing acetic acid. We examined the responses of five other E. coli strains and four Salmonella enterica strains to increasing concentrations of NaCl under conditions of lethal acidity and observed that the average "lag" time prior to inactivation decreases in the presence of hydrochloric acid but not in the presence of acetic acid. For E. coli in the presence of acetic acid, the lag time increased with increasing NaCl concentrations up to 2 to 4% at pH 4.0, up to 4 to 6% at pH 3.8, and up to 4 to 7% (wt/wt of water) NaCl at pH 3.6. Salmonella was inactivated more rapidly by combined acetic acid and NaCl stresses than E. coli, but increasing NaCl concentrations still decreased the lag time prior to inactivation in the presence of acetic acid; at pH 4.0 up to 1 to 4% NaCl was protective, and at pH 3.8 up to 1 to 2% NaCl delayed the onset of inactivation. Sublethal injury kinetics suggest that this complex response is a balance between the lethal effects of acetic acid, against which NaCl is apparently protective, and the lethal effects of the NaCl itself. Compared against 3% NaCl, 10% (wt/wt of water) sucrose with 0.5% NaCl (which has similar osmotic potential) was found to be equally protective against adverse acetic acid conditions. We propose that hypertonicity may directly affect the rate of diffusion of acetic acid into cells and hence cell survival.

A New Method of Halogenation of Aromatic Compounds

: A halogenation of eleven aromatic compounds using a new method for iodination of activated aromatic compounds is presented. The reaction of one mole of aromatic compound with a mixture of one mole Potassium iodide and two moles Potassium sulfate in the presence of hydrochloric acid gives mono iodo aromatic compounds in high yields. The products have been identified by (I.R) spectrally and also by quantitative elemental analysis. In conclusion, a convenient and versatile procedure for iodination of activated aromatic compounds has been reported. In this method, neither harmful reagents are used nor toxic residues are left after completion of the reaction. Thus, these iodination reactions are indeed, environmentally benign. In each case, mono iodination was identified with high yields.

Synthesis of 5-aryl-1-methyl-1,2,3,4-tetrahydrobenzo[a]phenanthridines

5-Aryl-1-methyl-1,2,3,4-tetrahydrobenzo[a]phenanthridines were synthesized by cascade heterocyclization of the corresponding substituted benzaldehydes with 2-methylcyclohexanone and naphthalen-2-amine in a polar solvent in the presence of hydrochloric acid.

Cyclic Tetrasiloxanetetraols: Formation, Isolation, and Characterization

Abstract Hydrolysis of trialkoxysilanes having various substituents gave cyclic tetrasiloxanetetraols with all-cis isomer as the major fraction in the presence of equimolar amounts of water and sodium hydroxide. All stereoisomers of phenyl derivative were produced by isomerization of the all-cis isomer in the presence of hydrochloric acid, and isolated and identified.

Shape and Size Control of Oriented Polyaniline Microstructure by a Self-Assembly Method

Oriented polyaniline (PANI) microstructures (e.g., bulks, spheres, flakes, and fibers) were prepared without a template by polymerization at 80 degrees C and crystal growth at 0 degrees C and using a self-assembly method in the presence of hydrochloric acid (HCl) as the dopant. It was found that the shape and size of the resulting PANI microstructures depended on the HCl dosage and aniline concentration. Polyanilinium salt precipitates, as a templete, drive the formation of highly oriented PANI microstructures. The infrared and UV-vis absorption spectra and X-ray diffraction were used to characterize the molecular structures of the PANI microstructures. The results showed that their main structure was identical to those of the emeraldine salt form of PANI.

Synthesis and characterization of some polyacrylate/montmorillonite nanocomposites by in situ emulsion polymerization using redox initiation system

AbstractIntercalated modification of Montmorillonite clay (MMT) with three different amino acids—Alanine, Leucine, and Phenylalanine—in the presence of hydrochloric acid followed by surface modification by methyl triethoxy silane coupling agent to produce double modified Montmorillonite clay which is characterized by X‐ray diffraction (XRD) and Thermogravimetric analysis (TGA). The data shows an increase in d‐spacing of modified clay as a result of cationic exchange. Double modified MMT clay was used in the preparation of Polyacrylate/clay nanocomposites by using an in situ redox emulsion polymerization of polyglycidylmethacrylate (PGMA) and polymethylmethacrylate (PMMA). The structure and properties of the prepared nanocomposites were achieved by XRD, TGA, and SEM. The results show that all weight loses temperatures for the nanocomposite samples are higher than that of pure polymer in both PGMA and PMMA. It is also obvious that the increasing in the clay content plays an effective role in the increasing of thermal stability of these materials. SEM shows that the clay is more homogenously dispersed in PMMA than in PGMA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009