Search

In this work, thermodynamic and kinetic factors that affect formation and phase transformation process of different solid forms of levofloxacin hydrochloride were investigated in detail. Dynamic vapor sorption experiments (DVS) and varying temperature-powder X-ray diffraction (VT-PXRD) experiments were carried out to study moisture-dependent stability, thermal stability as well as the transformation process between Form I and Form II. Critical water activities of levofloxacin hydrochloride were determined in temperature range of 5.0–45.0 °C. Raman spectroscopy was applied to in situ monitor the temperature-induced phase transformation and the hydration process of levofloxacin hydrochloride, and one possible mechanism consisting of multiple chemical equilibria was proposed to analyze the effect of thermodynamic and kinetic factors on the formation and transformation of different solid forms. Results show that the anhydrate, Form II would transform to the monohydrate, Form I more easily with the increasing water content. And the transition point moves toward higher water contents as the temperature increases. The results suggested that, except for thermodynamic factors, kinetic factors also play an essential role in controlling the solid forms of polymorphic compounds.

In order to investigate the nucleation behavior of arbidol hydrochloride monohydrate (AHM) in the aqueous THF (Tetrahydrofuran) solutions, metastable zone width (MSZW) was experimentally determined via the polythermal method, and then modified Sangwal’s theory was employed to explain the nucleation process. Via the MSZW investigation, the existence of hydrochloric acid might contribute to the nuleation of the AHM from the crystallization mother liquor, which accords with our previous experiment result that it is vital to manufacture AHM in a solvent system with hydrochloric acid. Based on the classic nucleation theory, modified Sangwal’s theory was also employed to estimate the solid-liquid interfacial tension, critical nucleus size and the nucleation Gibbs energy, severally. Moreover, it is also proved that the solid-liquid interfacial tension not only reliance on temperature, but also on nucleation driving force. The surface roughness factor fr was estimated to imply the occurrence of continuous growth at the crystal interface of AHM in aqueous THF solutions. Finally, the comparisons of the calculated and experimental induction time indicate that Kubota theory has a high applicability for AHM in the aqueous THF system.

This contribution focuses on the coordination behaviour of 2-[2-(diphenylphosphino)phenyl]-1,3-diisopropylguanidine (1), which is a representative of the unique P,N-ligands combining phosphine moieties with strongly basic guanidinium substituents. This new compound was conveniently prepared by the reaction of 2-(diphenylphosphino)aniline with 1,3-diisopropylcarbodiimide in the presence of diethylzinc (10 mol.%). When mixed with [MCl2L2] (M = Pd, Pt; L = weakly bonding ligand), ligand 1 gives rise to P,N-chelate complexes [MCl2(1-κ2P,N)]. However, in the case of kinetically inert Pt(II), the products of partial substitution and chloride ionisation, [PtCl(1-κ2P,N)(L)]Cl, where L = Me2SO or η2-cycloocta-1,5-diene, can be intercepted. Ionisation also occurs in the reaction with [PdCl(η3-C3H5)]2, leading to [Pd(η3-C3H5)(1-κ2P,N)]Cl, while [Pd(MeCN)4][BF4]2 produces the bis-chelate complex, cis-[Pd(1-κ2P,N)2][BF4]2. In contrast, the corresponding hydrochloride (1H)Cl behaves as simple phosphine, reacting with PdCl2 surrogates to give the zwitterionic species [PdCl3(1H-κP)] and the bis-phosphine complex trans-[PdCl2(1H-κP)2]Cl2, depending on the metal-to-ligand ratio.

Objective: The study was aimed to improve the dissolution and bioavailability of developed stable amorphous solid dispersions (SDs) of pioglitazone hydrochloride (PGH), a poorly water-soluble drug. Significance: Poor aqueous solubility of PGH was overcome by the design of SDs. Level A correlation demonstrated between in vitro release and bioavailability of PGH, suggest its biowaiver potential. Methods: The effects of semicrystalline copolymers (poloxamer 407 and gelucire 50/13) and methods of preparations on dissolution behavior, in vivo performance, and stability of PGH SDs were investigated. All the SDs were characterized by FTIR, TGA, DSC, XRD, and SEM. Results: FTIR and TGA showed the compatibility with the polymers. The significant change in melting pattern of the PGH observed in the DSC thermograms supported by XRD patterns & SEM indicated a change from a crystalline to an amorphous state. Gelucire 50/13 was observed to have greater ability to form SDs than poloxamer 407 in solvent evaporation method (SM). Prevention of recrystallization during storage suggested stability of the formulation. Gelucire 50/13 based SD, prepared by SM remarkably increased the dissolution within 15 min (87.27 ± 2.25%) and was supported by dissolution parameters (Q15, IDR, RDR, % DE, f1, f2). These SDs showed pH-dependent solubility. In vivo test showed significantly (p < .05) higher AUC0–t and Cmax, which were about 3.17 and 4.34 times that of the pure drug respectively. Conclusion: Gelucire 50/13 was found to be a suitable carrier for SM for preparation of SDs of PGH as evident from increased dissolution and bioavailability.

An efficient, robust, and cost-effective synthetic process of fasudil hydrochloride 1 was developed. Starting from readily available ethylenediamine and 5-isoquinoline sulfonyl chloride, the target...

Determination of the solution conformation of both small organic molecules and peptides in water remains a substantial hurdle in using NMR solution conformations to guide drug design due to the lack of easy to use alignment media. Herein we report the design of a flexible compressible chemically cross-linked poly-4-acrylomorpholine gel that can be used for the alignment of both small molecules and cyclic peptides in water. To test the new gel, residual dipolar couplings (RDCs) and J-coupling constants were used in the configurational analysis of strychnine hydrochloride, a molecule that has been studied extensively in organic solvents as well as a small cyclic peptide that is known to form an α-helix in water. The conformational ensembles for each molecule with the best fit to the data are reported. Identification of minor conformers in water that cannot easily be determined by conventional NOE measurements will facilitate the use of RDC experiments in structure-based drug design.

Thiamin hydrochloride promoted highly efficient and ecofriendly approach has been described for the chemoselective N-tert-butyloxycarbonylation of amines under solvent-free conditions at ambient temperature. The demonstrated approach has been applicable for the N-Boc protection of variety of aliphatic, aryl, heteroaryl amines. The chemoselective protection of amino group occurs in chiral amines and amino alcohol without racemization in high yield. Thiamin hydrochloride is stable, economical, easy to handle and environmentally friendly.

Commercially viable manufacturing process for Flecainide Acetate (I) conforming to regulatory specification and cost effective process is reported. Specifically, an improved process for the preparation of Flecainide Acetate allows isolation of anhydrous hydrochloride salt of Compound III, which facilitates the reduction of the pyridine ring with the only catalytic amount of platinum on carbon within 2 hours Therefore, simplifies the synthesis and isolation of Flecainide acetate on a commercial scale to a considerable extent.

Elution of strong and weak anion exchangers with sodium chloride gradients is commonly employed for analysis of sample mixtures containing different isomers of plasmid DNA. Gradient elution of a weak anion exchanger (diethylaminoethyl) in the presence of guanidine hydrochloride (Gdn) roughly doubles resolution between open-circular (oc) and supercoiled (sc) isomers. It also improves resolution among sc, linear, and multimeric/aggregated forms. Sharper elution peaks with less tailing increase sensitivity about 30%. However, elution with an exclusively Gdn gradient to 900 mM causes more than 10% loss of plasmid. Elution with a sodium chloride gradient while maintaining Gdn at a level concentration of 300 mM achieves close to 100% recovery of sc plasmid while maintaining the separation improvements achieved by exclusively Gdn elution. Corresponding improvements in separation performance are not observed on a strong (quaternary amine) anion exchanger. Other chaotropic salts do not produce a favorable result on either exchanger, nor does the inclusion of surfactants or EDTA. Selectivity of the diethylaminoethyl-Gdn method is orthogonal to electrophoresis, but with better quantification than agarose electrophoresis, better quantitative accuracy than CE, and resolution approaching CE.

Aiming at selective adsorption and separation of Y(III) from the Y(III)-Sr(II) group in acid solution, a silica-based TODGA impregnated adsorbent [(TODGA+1-dodecanol)/SiO2-P-F600] has been prepared. Batch adsorption experiments were conducted under the effect of contact time, acid concentration, solution temperature, and adsorption capacity etc. Chromatography recovery of more than 90% Y(III) was successfully achieved under elution with 0.01 M DTPA solution in nitric acid adsorption system, and 0.1 M HCl solution in hydrochloride adsorption system, respectively.

To improve the antimicrobial properties of chitosan films, cinnamon essential oil (CEO) nanoemulsion (1% and 3% v/v CEO) stabilized by ethyl-Nα-lauroyl-l-arginate hydrochloride (LAE) alone or co-stabilized by LAE and hydroxypropyl-β-cyclodextrin (HPCD) were incorporated into chitosan matrix. The micromorphology, physical and antimicrobial properties of the composite films were compared. The dense structure of the CEO nanoemulsion co-stabilized by LAE and HPCD reduced the water vapor permeability and water content. The incorporation of the CEO nanoemulsion co-stabilized by LAE and HPCD, reduced the adverse effects of CEO on the mechanical properties and microstructure of the film, and even slightly increased the tensile strength. In addition, the antimicrobial properties of chitosan films were enhanced due to the encapsulation and emulsification effect of HPCD and LAE on CEO. This work indicated that the prepared chitosan based edible films had the potential to be used in the field of food packaging to improve food safety.

Niosomes are increasingly explored for enhancing drug penetration and retention in ocular tissues for both posterior and anterior eye delivery. They have been employed in encapsulating both hydrophilic and hydrophobic drugs, but their use is still plagued with challenges of stability and poor entrapment efficiency particularly with hydrophilic drugs. As a result, focus is on understanding the parameters that affect their stability and their optimization for improved results. Pilocarpine hydrochloride (HCl), a hydrophilic drug is used in the management of intraocular pressure in glaucoma. We aimed at optimizing pilocarpine HCl niosomes and evaluating the effect of sonication on its stability-indicating properties such as particle size, polydispersity index (PDI), zeta potential and entrapment efficiency. Pilocarpine niosomes were prepared by ether injection method. Composition concentrations were varied and the effects of these variations on niosomal properties were evaluated. The effects of sonication on niosomes were determined by sonicating optimized drug-loaded formulations for 30 min and 60 min. Tween 60 was confirmed to be more suitable over Span 60 for encapsulating hydrophilic drugs, resulting in the highest entrapment efficiency (EE) and better polydispersity and particle size indices. Optimum sonication duration as a process variable was determined to be 30 min which increased EE from 24.5% to 42% and zeta potential from (−)14.39 ± 8.55 mV to (−)18.92 ± 7.53 mV. In addition to selecting the appropriate surfactants and varying product composition concentrations, optimizing sonication parameters can be used to fine-tune niosomal properties to those most desirable for extended eye retainment and maintenance of long term stability.

The copolymers of methacryloylguanidine hydrochloride with methacrylamide and diallyldimethylammonium chloride are synthesized by radical polymerization. The reactivity ratios of these monomers are determined, and the dependence of the biocidal activity of the copolymers on the structure of the macromolecule chain is studied. It is shown that manifestation of the biocidal activity is determined not only by the composition of the copolymer but also by the nature of the distribution of methacryloylguanidine hydrochloride units along the macromolecule chain.

2-Cyanopyrazolo[1,5-a]pyrimidine derivative 3 reacted with some aromatic aldehydes, arenediazonium salts, hydrazine hydrate, and guanidine hydrochloride to create a series of novel pyrazolo[1,5-a]pyrimidine derivatives. Spectroscopic data confirmed the structure of the newly synthesized compounds. Some target compounds were tested in vitro for anticancer efficacy against three cancer cell lines: HepG-2, MCF-7, and Hela. On the most efficient anticancer compounds 6b,c, 6f, and 6h,i, the CDK-2 enzyme was evaluated. Using the HepG-2 cancer cell line, compounds 6b and 6i demonstrated the most effective inhibitory activity against CDK-2, with IC50 values of 0.199 ± 0.005 μg/ml and IC50 = 0.206 ± 0.007 μg/ml, respectively, compared to Dinaciclib and Roscovitine, which had IC50 values of 0.021 ± 0.002 and 0.230 ± 0.007 μg/ml, respectively. In cell cycle assay, compounds 6b, 6f and 6i arrest cell cycle at G2/M, G1/S and G2/M phases, respectively. Compound 6f has a stronger apoptosis induction effect (27.82%) than compounds 6b (7.92%) and 6i (19.21%). Also, silico studies (Molecular docking and Lipinski’s rules) for compounds 6b, 6f and 6i were carried out.

The aim of this study was to synthesize several small molecules of the type 5-nitroimidazole-sulfanyl and evaluate biological properties against the main Leishmania species that cause cutaneous leishmaniasis in Venezuela. Final compounds 4-7 were generated through simple nucleophilic substitution of 1-(2-chloroethyl)-2-methyl-5-nitroimidazole 3 with 2-mercaptoethanol, 1-methyl-2-mercaptoethanol, and 2-thyolacetic acid derivative. Compound 8 was synthesized via a coupling reaction between 7 and (S)-Methyl 2-amino-4-methylpentanoate hydrochloride. The inhibitory concentrations of (3, 4, 7, 8) against Leishmania (L.) mexicana and (V.) braziliensis in promastigotes and experimentally infected macrophages were determined by in vitro activity assays. Compounds 7 and 8 shown high activity against both species of Leishmania and were selected for the in vivo evaluation. Animals were infected with promastigotes of the two species and divided into four groups of ten (10) animals and a control group. Intralesional injection way was used for the treatment. The parasitological diagnostic after treatment was obtained by PCR using species specific oligonucleotides. The two Leishmania species were susceptible to compounds 7 and 8 in vivo assays. The results indicated that both compounds reduce significantly (96%) the size of the lesion and cure 63% of the mice infected with L (L) mexicana or L (V) braziliensis as was determined by PCR. The results are indicating that both compounds may represent an alternative treatment for these two Leishmania species.

Objective: To investigate and analyze the anesthetic effect of compound artevacaine hydrochloride in patients undergoing oral implantation. Methods: In this study, 60 patients receiving oral implant surgery in our hospital were selected as the research subjects, and the operation time was from July 2019 to March 2021. Patients were randomly selected and divided into groups for the study. 30 patients receiving lidocaine hydrochloride anesthesia were used as the control group, and 30 patients receiving compound artevacaine hydrochloride anesthesia were used as the research group. The anesthetic effect and safety of the two groups were compared and analyzed. Results: The anesthetic effect of the study group was significantly better than that of the control group (P < 0.05). The blood pressure and heart rate in the study group were significantly lower than those in the control group (P < 0.05). There was no significant difference in blood pressure and heart rate between the two groups before anesthesia (P > 0.05). There was no significant difference in the incidence of ADR between the two groups (P > 0.05). Conclusions: For patients undergoing oral implant surgery, choosing compound artevacaine hydrochloride as anesthetic drug has obvious anesthetic effect and can stabilize patients' life indexes. The anesthetic effect is obvious, and there is no obvious adverse reaction, and the clinical value is obvious.

Objective The aim of the present study was to evaluate the bioequivalence and safety of two types of daclatasvir hydrochloride tablets administered to healthy Chinese subjects under fasting and postprandial conditions. Materials and methods A total of 72 healthy Chinese subjects were randomly divided into two groups: the fasting group (n = 36) and the postprandial group (n = 36). A dose of 60 mg of both the test and reference preparations of the daclatasvir hydrochloride tablets was taken orally under fasting and postprandial conditions. Results The main plasma pharmacokinetic parameters of the test and reference preparations in the fasting group were as follows: T1/2 was 9.82 ± 1.00 and 9.67 ± 0.99 hours, respectively; tmax was 1.00 hour in both; Cmax was 1,528.25 ± 428.80 and 1,504.25 ± 414.50 ng/mL-1, respectively; AUC0-t was 14,553.04 ± 4,013.26 and 14,391.97 ± 4,078.18 h/ng/mL-1, respectively; the AUC0-∞ was 14,660.80 ± 4,018.37 and 14,494.85 ± 4,095.57 ng/mL-1, respectively. Meanwhile, the main plasma pharmacokinetic parameters of the test and reference preparations in the postprandial group were as follows: T1/2 was 10.18 ± 1.38 and 10.18 ± 1.69 hours, respectively; tmax was 2.00 and 1.75 hours, respectively; Cmax was 974.92 ± 248.50 and 981.44 ± 237.11 ng/mL-1, respectively; AUC0-t was 9,597.00 ± 3,094.28 and 9,982.83 ± 3,512.07 h/ng/mL-1, respectively; AUC0-∞ was 9,712.92 ± 3,130.43 and 10,113.97 ± 3,593.47 ng/mL-1, respectively. Conclusion Both types of daclatasvir hydrochloride tablets demonstrated good safety levels in healthy Chinese subjects under both fasting and postprandial conditions. Moreover, the two preparations were bioequivalent.

OBJECTIVE To evaluate the efficacy and safety of photodynamic therapy (PDT) with the novel 10% aminolevulinic acid (ALA) hydrochloride gel (10% ALA gel) and BF-RhodoLED® light (635 nm; 37 J/cm2 ) in combination with intense pulsed light (IPL) to augment the medical and aesthetic improvement of photodamaged skin of the decollete. METHODS This was a single-site prospective, randomized, intraindividual split chest pilot study with 20 female subjects with moderate to severe photodamage of the decollete. Subjects were randomized to ALA-PDT + IPL to one split-side of the chest and ALA-PDT only to the contralateral side. Three blinded raters assessed aesthetic improvement using the global aesthetic improvement scale (GAIS). RESULTS Eighteen subjects completed the study. Superior GAIS results were achieved on the ALA-PDT + IPL treatment side than on the ALA-PDT only treatment side (p

Insecticides are extensively applied in crop production and sometimes at higher concentration than their recommended doses, which has become an environmental hazard. Sustainable agricultural practices highlight minimal application of insecticides at low concentration. Use of controlled release formulations (CRFs) of pesticides in which active compound is associated with inert materials has emerged as an appealing alternative. In this study, nanospheres of insecticide cartap hydrochloride were developed using chitosan (CS) in the presence of tripolyphosphate (TPP) as crosslinker with the help of ionic gelation method, for the delivery of cartap hydrochloride. The nanoformulations were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectra. The FESEM images revealed that the size of chitosan tripolyphosphate (CS-TPP) nanospheres (nps) was in range of 117.01–185.27 nm, whereas cartap hydrochloride entrapped chitosan tripolyphosphate (C-CS-TPP) nanospheres had a size of 163.50–276.74 nm. FTIR results confirmed loading of cartap hydrochloride into chitosan tripolyphosphate nanospheres. The nanospheres showed encapsulation efficiency of 86.1% and were stable for 30 days at ambient temperature. In vitro release kinetics of insecticide from nanospheres followed a non Fickian diffusion mechanism. These nanospheres can act as slow-release formulation for the delivery of insecticide to the target organisms over a period of time, which is effective as well as environmentally safe.

Due to the emergence of a new coronavirus infection COVID-19, scientists around the world are actively working on a vaccine against the SARS-CoV-2 coronavirus. At the same time, it is possible that existing medications can help in the fight against this disease. The local antiseptic drug benzidamine hydrochloride in the early stages of illness can prevent the virus from entering the lower respiratory tract and potentially reduce the severe illness associated with pneumonia and, as a result, reduce COVID19-related hospitalizations, which can significantly reduce the burden on the health care system.The aim: to evaluate the antiviral activity of benzidamine hydrochloride against SARS-CoV-2 in vitro.Material and methods. Antiviral properties of benzidamine hydrochloride were studied in vitro in non-toxic concentrations on monolayer of Vero-E6 cells infected with pandemic strain of SARS-CoV-2 coronavirus in treatment and prophylactic scheme of the compound and virus administration.Results. Benzidamine hydrochloride has antiviral activity (15,0 mcg/ml), the efficiency of its antiviral action is directly proportional to the concentration of the substance.Conclusions. Taking into account very limited range of antiviral drugs with direct action on SARS-CoV-2 virus, the studied preparation can be used in complex therapy at early stages of the disease, which can prevent virus penetration into lower respiratory tract and potentially reduce the number of complications.

Three new, precise, accurate and sensitive UV-Spectrophotometric methods namely Ratio Difference Spectroscopic Method (RDSM), First Derivative of Ratio Spectra Method (DR1) and Area Under Curve Method (AUC) were developed and validated for simultaneous assessment of alogliptin benzoate (ALO) and pioglitazone hydrochloride (PIO) in tablet dosage form. In RDSM, ratio spectra of both the drugs were recorded by dividing the mixtures using interfering drug as divisor. Then the difference between the amplitudes of obtained ratio spectra was measured at 288 and 291 nm for ALO and 236 and 245 nm for PIO. The second method DR1, where the first derivative of ratio spectra of both the drugs were recorded and the first derivative signal was measured at 290 nm for ALO and 276.8 nm for PIO. The scaling factor was fixed as 1 and wavelength interval (Δλ) as 2 for recording the first derivative of ratio spectra. In the third method (AUC), peak area of recorded zero order spectra was measured at 276 ± 10 nm for ALO and 267.8 ± 10 nm for PIO. All three proposed methods were validated according to “International Conference on Harmonization” (ICH) guidelines parameters. For all three methods, ALO and PIO obeyed Beer’s law in the range of 0.5-5 & 1.8-18 µg/ml, respectively. The % RSD of repeatability of measurement, intra-day and inter-day precision were found to be less than 2 for all three methods. Limit of detection (LOD) and Limit of quantification (LOQ) of the drugs were calculated which proved the sensitivity of the methods. The accuracy ranged between 98-101% for all three methods. No interference from pharmaceutical excipients present in the formulation was observed. These proposed methods were found to be simple, sensitive, accurate and precise and can be applied to the simultaneous estimation of ALO and PIO in combined tablet formulation and also appropriate for routine quality control analysis.

The comparative encapsulation of the Alzheimer’s drug memantine (3,5-dimethyladamantan-1-amine), used as its hydrochloride salt, within the cavity of two different sized para-sulfonatocalix[n]arenes (sCX[n]; n = 4 or 8) was analysed by 1H NMR spectroscopy. Addition of either macrocycle to memantine results in selective upfield shifts of all drug proton resonances of between 0.50 and 1.72 ppm for sCX[4] and between 0.80 and 1.53 ppm for sCX[8]. Memantine binding results in the observation of an extra sCX[4] resonance for the macrocycle’s methylene protons, which is not observed for the larger sCX[8], indicating a potential change in shape of the sCX[4] upon host–guest formation. Difference in changes to the chemical shift of the memantine doublet-of-doublets resonance for both macrocycles indicates a potential change in shape of memantine upon host–guest formation. From Job Plots, memantine binds to sCX[4] in a 1:1 ratio with a binding constant of 6.6 × 106 M−1, whereas binding to sCX[8] is in a 1:2 host–guest ratio. Overall, the results indicate that memantine forms subtly different host–guest complexes with different sized sCX[n] homologues, which could be used to tune the drug delivery potential of the macrocycle for different pharmaceutical applications.

The photophysical and photochemical properties of the protonated form of an unsymmetrical biphotochromic dyad D2 containing derivatives of 3-styrylbenzo[f]quinoline (SBQ) as photochromes have been studied. In hydrochloride of the dyad, D2.2HCl, interphotochromic energy transfer is observed, whose efficiency, estimated from the data of fluorescence spectroscopy, is 92%. Under the action of light, hydrochloride D2.2HCl undergoes the photoisomerization reaction of SBQ photochromes. In addition, upon prolonged irradiation of D2.2HCl, side reactions additional to photoisomerization are observed, the main of which, according to mass spectral studies, are breaking the bridging ether bond CH2–O between two SBQ photochromes, and the addition of an ethanol molecule to the ethylene group of one of the photochromes. These reactions lead to the destruction of the dyad and prevent it from functioning as a photonic switch and a molecular logic gate.

The kinetics and mechanism of the condensation and transaldimination of products of pyridoxal condensation with L-α-, D-α-, and β-alanines are studied via UV spectroscopy and polarimetry. It is found that pyridoxal hydrochloride interacts stereospecifically with L-α- and D-α-alanines, accompanied by the formation of intermediate products with a strictly defined structure that promote the elimination of hydrogen atoms (with L-α-alanine) or CO2 (with D-α-alanine) and the subsequent formation of a quinoid structure whose hydrolysis yields the final products. The reactions of transaldimination between pyridoxalidene-β-alanine, pyridoxalidene-L-α-, pyridoxalidene-D-α-alanines, and L-α- and D-α-alanines are studied. It is shown that transaldimination proceeds in two stages: the addition of L-α- and D-α-amino acids to Schiff bases with the formation of N-acetals of a strictly defined structure, and the cleavage of one of the amino acids with the formation of new Schiff bases. Schemes are proposed for the mechanisms of the studied reactions.