Action Of HCl Research Articles

English

The chemical analysis of CaCO3 contents of soils provide information about not only efficiency of soil for supplying plant with nutrients but also identification of factors affecting this efficiency in the soil. The aim of the current experiment was to develop new methods based on sensors and compare with conventional Scheibler method. The CO2 liberated by the action of HCl on CaCO3 content of the soil in a reaction bottle and an accumulation chamber was determined by pressure sensor and CO2 sensor, respectively. The CaCO3 contents of soils were estimated using the regression equation of standard curves. The CaCO3 contents of soils obtained using Scheibler calcimetric, pressure and CO2 sensor methods ranged from 0.20 to 54.74%, 0.25 to 54.10% and 0.55 to 53.05%, respectively. On the basis of linearity of calibration curve and high correlation with Scheibler calcimetric method it can be said that developed pressure and CO2 sensor methods appears to be very useful for quantification of CaCO3 contents of soils. The pressure sensor has provided the opportunity in developing a simple and handy device with an affordable cost to measure CaCO3 contents of soils as accurately as Scheibler calcimeter when compared with CO2 sensor method. Even if there is a good relationship between Scheibler calcimetric method and CO2 sensor method the cost of CO2 sensor method may limit the use in determination of CaCO3 contents of soils. However, CO2 sensor method can be used to monitor CO2 evolved in biochemical process such as respiration and fermentation

Micro-spectrophotometric determination of nickel in Gentiana rigescens after switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction

In this work, switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction (SHS-UA-LPME) was combined with micro-volume UV-vis spectrophotometry for the determination of trace nickel in the medicinal plant Gentiana rigescens Franch. ex Hemsl. (G. rigescens) samples for the first time. Micro-volume spectrophotometry has the characteristics of microanalysis, economy and low operation cost, which is feasible to be combined with miniaturized enrichment method. Dipropylamine (DPA) as a switchable solvent completed the extraction during the phase conversion process. It was changed from hydrophobic to hydrophilic under the action of HCl, and then completed phase transition under the action of NaOH. The parameters influencing the extraction efficiency were investigated. Under the optimal conditions, the enhancement factor (EF), the limit of detection (LOD), the limit of quantitation (LOQ) and relative standard deviation (RSD, n = 7) were 28, 0.02 µg/L, 0.067 µg/L and 1.4%, respectively. The established method was applied to the determination of G. rigescens samples collected from the local field with satisfactory results.

Synthesis of Hybrid Compounds on the Basis of 4-[(1-Oxo-3,4-dihydro-2H-naphthalen-2-ylidene)methyl]benzoic acid

The reactions of 4-[(1-oxo-3,4-dihydro-2H-naphmalen-2-ylidene)methyl]benzoic acid with 3-(1,3-dioxobutane-1-yl)-2H-chromen-2-one in the presence of nitrogenous bases (piperidine, triethylamine or pyridine) were used to synthesize for the first time hybrid systems containing the pharmacophoric fragments of the reagents. The reaction scheme involves formation of a condensed dihydropyran structure and its subsequent aromatization into a benzodihydrochromenilium salt under the action of HCl. The process may be accompanied by the competing addition of an azanucleophile by the double bond of the chalcone.

Rapid Boulton–Katritzky rearrangement of 5-aryl-3-[2-(piperidin-1-yl)ethyl]-1,2,4-oxadiazoles upon exposure to water and HCl

Сhemical stability of 3-(2-aminoethyl)-5-substituted 1,2,4-oxadiazoles was studied with respect to Boulton–Katritzky rearrangement, which is known to produce planar pyrazolines and pyrazoles upon heating in DMF at 150°C or without solvent at 240°C. The reactivity of 5-aryl-3[2(piperidin-1-yl)ethyl]-1,2,4-oxadiazoles in one type of Boulton–Katritzky rearrangement was observed at room temperature in H 2 O, DMF + H 2 O, and in the presence of HCl. Hydrolysis of 3,5-disubstituted 1,2,4-oxadiazoles under the first two conditions gave 2-amino-1,5-diazaspiro[4.5]dec-1-en-5-ium benzoates, while the action of HCl on 3,5-disubstituted 1,2,4-oxadiazoles produced their hydrochlorides along with 2-amino-1,5-diazaspiro[4.5]dec-1-en-5-ium chloride hydrate. Thus, the reaction afforded spiropyrazoline compounds instead of products with a planar structure.

UV–Vis spectra and structure of acid-base forms of dimethylamino- and aminoazobenzene

The changes in the UV–Vis absorption spectra of dimethylaminoazobenzene (DAB) in the cellulose triacetate (CTA) matrix during the absorption of gaseous hydrogen chloride and protonation of DAB in weakly and strongly acid solutions of hydrochloric and sulfuric acids were studied. The yellow-orange color of DAB and its analog aminoazobenzene (AAB) was shown to be due to the dimers, whose structure involves phenylaminyl type cations formed due to the promotion of the sp 2 electrons of the azo groups to the Rydberg R 3s orbitals of the azo groups and possessing Vis bands at 400–417 nm. The cations exist immanently as the dimers due to the Rydberg intermonomer bonds; the Vis bands of the dimers shifted toward 500–520 nm under the action of HCl (in CTA) and weakly acid media as a result of the formation of phenyl aminyl type pair cations, whose π* levels are split by Simpson’s mechanism, during the protonation of interrelated monomers. In the concentrated sulfuric acid, the Vis bands at 500–520 nm vanished because of the decomposition of the dimers into diprotonated monomers possessing Vis bands at 400–417 nm. The mechanism of transformations of chromogens responsible for the spectral transformation was given.

Spectrophotometric determination of alogliptin in bulk and tablet dosage form using bromate–bromide mixture as brominating agent

Two simple and sensitive visible spectrophotometric methods (A and B) have been developed and validated for the determination of alogliptin in bulk and tablet dosage forms. The methods are based on the bromination of alogliptin using bromine produced by the action of HCl on the bromate–bromide mixture. The residual bromine is determined with a fixed amount of either methyl orange and measuring the absorbance at 505 nm (method A) or methylene blue and measuring the absorbance at 720 nm (method B). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 1–10 μg mL−1 and 2.5–12.5 μg mL−1 for method A and method B, respectively. The detection limits were 0.115 μg mL−1 and 0.210 μg mL−1 for method A and method B, respectively. The accuracy of the proposed methods was assessed by recovery studies and the percent recoveries of aloglitpin were found to be 99.91 ± 0.126%–99.99 ± 0.168% for method A and 99.86 ± 0.170%–99.98 ± 0.193% for method B. The methods were successfully applied to the determination of alogliptin in tablets with percentage recovery of 99.84 ± 0.139%–100.20 ± 0.625% (method A) and 99.96 ± 0.351%–10.320 ± 0.422% (method B). The optimized methods were fully validated and proved to be specific, robust, precise and accurate for the quality control of the alogliptin in their pharmaceutical formulations.

N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XI. Some Substitution Reactions of Pyrazolo[1,5-b][1,2,4,6]thiatriazine 1,1-Dioxides

The recently discovered pyrazolo[1,5-b][1,2,4,6]thiatriazine template was shown to possess four nucleophilic sites (N2, N4, C5, N7) that underwent a range of substitution reactions. Methylation occurred at both N4 and N7. Alkylation with benzylic halides occurred preferentially at N7, regardless of the solvent, but also occurred at C5, N4, and N2. Similar alkylation with α-halo esters occurred at both N4 and N7, but the latter derivatives underwent a novel pyrazole ring expansion to afford pyrimido[1,6-b][1,2,4,6]thiatriazine derivatives. Bromination of pyrazolo[1,5-b][1,2,4,6]thiatriazines afforded unstable 5-bromo derivatives. Tosylation occurred selectively at C5, but in modest yield; catalysis with 1-methylimidazole also led to a low yield of the 5,5′-dimer. The action of HCl on N7-benzylated pyrazolo[1,5-b][1,2,4,6]thiatriazines readily caused extrusion of sulfur dioxide to produce pyrazolo-guanidines.

The influence of acid treatment of carbon nanofibers on the activity of palladium catalysts in the liquid-phase hydrodechlorination of dichlorobenzene

Palladium catalysts on the basis of acid treated carbon nanofibers (CNF) were studied. Using physico-chemical methods of investigation (low-temperature nitrogen adsorption–desorption, FTIR spectroscopy and Boehm titration) it has been shown that under the action of HCl and HNO3 there take place a reduction in the specific surface area and the volume of pores and an increase of the concentration of surface functional groups. This has a substantial influence on the adsorptive properties of CNF, the dispersion of palladium and the catalytic activity in the liquid-phase hydrodechlorination of 1,2-dichlorobenzene. The reaction rate was observed to be the highest in the presence of Pd/CNF-HCl. Treatment of CNF by HCl gives the highest dispersion of palladium on the external surface of CNF. There is also an increase in the adsorption capacity for 1,2-dichlorobenzene and a decreased adsorption of the solvents on the surface of the acid-modified CNF.

Simple Synthesis of α,ω-Diarylpolyynes Part 1: Diphenylpolyynes

A series of α,ω -diphenylpolyynes were synthesized through the Cadiot Chodkiewicz reaction starting from Cu(I)-phenylacetylide and diiodoacetylene. The complete series of diphenylpolyynes Φ -(C≡C)n-Φ with n = 2,3,4 and 5 was obtained and analyzed by electronic absorption spectroscopy, liquid chromatography (HPLC-diode array) and FT-IR spectroscopy. The diphenylpolyynes when treated with nascent hydrogen produced by the action of HCl on Zn dust are changed into a mixture of diphenylpolyenes as shown by UV spectroscopy and HPLC.

Kinetic Isotope Effects on the Photolysis of C60H18 and C60D18

Fullerane C60H18 and its deuterated analogous C60D18 were synthesized in n‐hexane solution by a reduction reaction of C60 under the action of HCl or DCl on Zn dust. The resulting solutions were subjected to UV irradiation at 245 nm from a low pressure mercury lamp under He. It was found that at 212 nm the photolysis rate constant of C60H18 molecule Hk212 = 8.68 × 10−4 s−1 was significantly higher than that of its deuterated analogous C60D18: Dk212 = 5.93 × 10−4 s−1. Similarly, at 256 nm it was confirmed the result that C60D18 was photolyzed more slowly than C60H18. Also in this case, Hk256 = 6.83 × 10−4 s−1 is significantly higher than that of its deuterated analogous C60D18: Dk212 = 3.74 × 10−4 s−1. Kinetic isotope effect involving the C‐H and C‐D bond activation has been advocated to explain the differences in photodecomposition speed of C60H18 in comparison to C60D18. On the basis of solubility in alkanes and unique electronic absorption spectrum C60H18 with C3ν symmetry prepared under high hydrogen pressure can be easily distinguished from the C60H18 and its deuterated analogous C60D18 synthesized in n‐hexane from Zn/HCl or Zn/DCl. The C3ν ‐ C60H18 displayed also a different evolution of the electronic absorption spectrum under photolysis in comparison to C60H18 and its deuterated analogous C60D18. The pseudofirst rate constant of C3ν ‐C60H18 is k217 = 4.04 × 10−4 s−1 and k255 = 2.25 × 10−4 s−1.

Simultaneous phase- and morphology-controlled synthesis of MnO2 crystals through controlled release of cuprous ions in hydrothermal condition

The α-, β-, and δ-MnO2 with various morphologies have been synthesized by a novel redox system of KMnO4 and CuCl with HCl added under a hydrothermal condition. The resultant MnO2 products have been characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Upon control of reaction temperature and duration, it was observed that MnO2 polymorphs of different morphology (e.g., flowery δ-MnO2, β-MnO2 nanowires and octahedrons, α-MnO2 nanowires) can be prepared in an adjustable manner. The phenomenon is mainly attributed to the effect of cuprous ions controllably released from CuCl by the action of HCl at different experimental conditions. The corresponding formation mechanism for the MnO2 crystals will also be proposed and discussed.

Mechanism of the catalytic action of the mechanoactivated salt K2PTCL4 in the gas-phase hydrochlorination of acetylene

A heterogeneous catalyst for the hydrochlorination of acetylene by gaseous HCl is formed as a result of mechanical treatment of the solid salt K2PtCl4 in an atmosphere of acetylene, ethylene, or propylene by the formation of π complexes of platinum(II) as active centers in the surface layer under these conditions. The controlling stage of the catalytic reaction is chloroplatination of the π-coordinated acetylene by the HCl molecule. The reaction takes place as a concerted process, in which an intermediate β-chlorovinyl derivative of platinum(II), a complex of platinum with a coordination vacancy[PtCl3*]−, and a new molecule of HCl are formed simultaneously with cleavage of the H—Cl and Pt—Cl bonds in the metal complex adjacent to the π-acetylene complex. The catalytic cycle closes with rapid dissociation of the organoplatinum intermediate by the action of HCl, giving the final product and the initial complex [PtCl4]2−.

Polyfunctional Derivatives of Isocytosine: I. Intramolecular Rearrangement of 6-Methyl-4-oxo-2-[2-(phenylcarbamoyloxy)ethyl]aminodihydro-3H-pyrimidine

The reaction of 2-(2-hydroxyethyl)amino-6-methyl-4-oxodihydro-3H-pyrimidine with phenyl isocyanate yields 6-methyl-4-oxo-2-[2-(phenylcarbamoyloxy)ethyl]dihydro-3H-pyrimidine, which rearranges into 2-(2-hydroxyethyl)amino-6-methyl-4-oxo-5-phenylcarbamoyldihydro-3H-pyrimidine under the action of HCl.

Action of HCl on 3-hydroxypyrazolo(iso)quinolines to give 1-chloropyrazoles: evidence for an addition-elimination mechanism by ab initio calculations in gas phase and water

Addition–elimination reactions involving a nucleophile and a remote leaving group [SHN(AE)tele] are well-known under basic conditions, especially amongst electron-poor six-membered heterocycles, but are less commonly encountered for five-membered heterocycles and are rare under acidic conditions. Concentrated HCl converts 1-hydroxy-1H-pyrazolo[3,4-c] isoquinoline and 1-hydroxy-1H-pyrazolo[3,4-c]quinoline into 3-chloro-1H-pyrazolo[3,4-c]isoquinoline and 3-chloro-1H-pyrazolo[3,4-c]quinoline, respectively. However, apparently neither the isomeric 1-hydroxy-1H-pyrazolo[4,3-c](iso)-quinolines nor the parent 1-hydroxypyrazole undergo this reaction. Additionally, all these systems are refractory under basic conditions. We present a plausible mechanism for the reaction, involving the 3-addition of Cl- to the diprotonated heterocycle, followed by the elimination of water. Calculations of the initial transition states and intermediates, using optimisation at B3LYP/6-311+G(d,p), including thermochemistry [HF/6-31+G(d)], and single-point Poisson–Boltzmann self-consistent reaction field determination of the free energy of solvation (Jaguar Poisson–Boltzmann self-consistent reaction field), support this mechanism and reproduce the observed order of reactivity, the addition step being 2–4 kcal less favourable for the isomeric 1-hydroxy-1H-pyrazolo[4,3-c](iso)quinolines and provide a rationalisation for the role of strong acid.

Synthesis of New Anionic Perhalophenylplatinate(II) Complexes

Action of HCl on dichlorobis(pentafluorophenyl)platinate(II) complexes results on the cleavage of one of the Pt–C bonds and coordination of a Cl ligand. If the reaction takes place in the presence of a neutral ligand, L, it is incorporated instead of Cl to the coordination sphere of the metal. AgC6X5 (X = F, Cl) has been used as an arylating agent towards platinum derivatives with Cl ligands, which has allowed the preparation of new complexes with both C6F5 and C6Cl5 groups bonded to the same metal center. Analytical data, conductance measurements and spectroscopic methods (IR, 1H and 19F NMR) have been used to characterize the new complexes. The structure of complex (n‐Bu4N)2[Pt(C6Cl5)(C6F5)3] also has been determined by single crystal X‐ray analysis.

A New Route for Preparation of 5‐Deoxy‐5‐(hydroxyphosphinyl)‐D‐mannopyranose and ‐L‐gulopyranose Derivatives.

Starting from methyl 2,3-O-isopropylidene-α-D-mannofuranoside (5), methyl 6-O-benzyl-2,3-O-isopropylidene-α-D-lyxo-hexofuranosid-5-ulose (12) was prepared in three steps. The addition reaction of dimethyl phosphonate to 12, followed by deoxygenation of 5-OH group, provided the 5-deoxy-5-dimethoxyphosphinyl-α-D-mannofuranoside derivative 15a and the β-L-gulofuranoside isomer 15b. Reduction of 15a and 15b with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by the action of HCl and then H2O2, afforded the D-mannopyranose (17) and L-gulopyranose analog 21, each having a phosphinyl group in the hemiacetal ring. These were converted to the corresponding 1,2,3,4,6-penta-O-acetyl-5-methoxyphosphinyl derivatives 19 and 23, respectively, structures and conformations (4C1 or 1C4, resp.) of which were established by 1H-NMR spectroscopy.

A New Route for Preparation of 5-Deoxy-5-(hydroxyphosphinyl)- D-mannopyranose and -L-gulopyranose Derivatives

Starting from methyl 2,3-O-isopropylidene-α-D-mannofuranoside (5), methyl 6-O-benzyl-2,3-O-isopropylidene-α-D-lyxo-hexofuranosid-5-ulose (12) was prepared in three steps. The addition reaction of dimethyl phosphonate to 12, followed by deoxygenation of 5-OH group, provided the 5-deoxy-5-dimethoxyphosphinyl-α-D-mannofuranoside derivative 15a and the β-L-gulofuranoside isomer 15b. Reduction of 15a and 15b with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by the action of HCl and then H2O2, afforded the D-mannopyranose (17) and L-gulopyranose analog 21, each having a phosphinyl group in the hemiacetal ring. These were converted to the corresponding 1,2,3,4,6-penta-O-acetyl-5-methoxyphosphinyl derivatives 19 and 23, respectively, structures and conformations (4C1 or 1C4, resp.) of which were established by 1H-NMR spectroscopy.

The common ion effect in sulfenylhalogenation of alkenes in formic acid

The reactions of 2,4-dinitrobenzenesulfenyl chloride with cyclohexene and allylbenzene in formic acid were studied. In this solvent, the reaction yields solvo-adducts and the products of addition of the reagent to the double bond. The reaction follows kinetics of the second order, first order with respect to each reagent. The hydrogen chloride evolved in the reaction has no effect on the overall rate of the process but sharply decreases the rate of accumulation of solvo-adducts due to the common ion effect. In the reaction with allylbenzene, the yield of the solvo-adduct can vary under the action of HCl from 88% at low degrees of reagent conversion to 30% when the reaction is complete.

Thermal Decomposition of Silver Amidotriphosphate Ag4P3O9NH2

Abstract Silver amidotriphosphate Ag4P3O9NH2, was heated at a rate of 5 K min−1 in a stream of dry air, humid air, or dry HCl. When heated to 245 °C in a stream of dry air, Ag4P3O9NH2 was decomposed mainly to oligophosphates with some phosphorus-nitrogen bonds. Condensation of Ag4P3O9NH2 by the action of HCl took place even at room temperature.

New method for synthesis of the aza analogs of tetrabenzoporphin

The reaction of 1-hydroxy-1-methyl-1H-3-(1-oxo-6-tert-butylisoindolin-3-ylidenemethyl)-5-tert-butylisoindole, which is the product from the condensation of potassium 4-tert-butylphthalimide and malonic acid, with phthalonitrile or 3-iminophthalimide leads to the formation of a mixture of the tert-butyl-substituted mono-, di-, and triaza analogs of zinc tetrabenzoporphin. The mixture was separated by chromatography on aluminum oxide. The zinc complex of di(4-tert-butylbenzo)di-benzodiazaporphin is demetallated by the action of HCl in acetic acid. The characteristics of the synthesized compounds are given.