Second derivative spectrophotometric determination of partition coefficients of phenothiazine derivatives between human erythrocyte ghost membranes and water

The absorption spectra of six phenothiazine derivatives, chlorpromazine, triflupromazine, promazine, promethazine, trifluoperazine and prochlorperazine, measured in the solutions containing various amounts of human erythrocyte ghosts (HEG) showed bathocromic shifts according to the amount of HEG. Due to the strong background signals caused by HEG, the baseline compensation was incomplete, even though the sample and the reference solutions contained the same amount of HEG, hence further spectral information could not be obtained. The second derivative spectra of these absorption spectra clearly showed the derivative isosbestic points, indicating that the residual background signal effects were entirely eliminated. The derivative intensity differences of the phenothiazines (ΔD values) before and after the addition of HEG were measured at a specific wavelength. Using the ΔD values, the partition coefficients (K_p) of these drugs were calculated and obtained with R.S.D. of below 10 %. The fractions of partitioned phenothiazines calculated from the K_p values agreed well with the experimental values. The results indicate that the derivative method can be applicable to the determination of partition coefficients of drugs to HEG without any separation procedures.     

Synthesis of N-trinitroethyl derivatives of linear and heterocyclic nitrogen-containing compounds

Earlier unknown N-trinitroethyl derivatives of acetylhydrazine, 4-amino-1,2,4-triazole, and 2,4,6-triamino-1,3,5-triazine, which are potential components for gas-generating formulations, were synthesized. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1306–1309, May, 2005.     

A new method for the synthesis of aziridine derivatives

The photoinduced reaction ofN-trialkylstannyl-N-triorganylsilyl-substituted allylamines with perfluorocarbonyl iodides results in the formation of 1-triorganylsilyl-2-(,a-dihydroperfluoroalkyl)aziridines.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 3, pp 759–760, March, 1996.     

Spectrophotometric determination of cysteine andN-acetylcysteine in pharmaceutical preparations

An accurate fast spectrophotometric method for the determination of cysteine andN-acetyl-cysteine is presented, based on the oxidation of these amino acids by ferric ions in the presence of ferrozine, whereby a violet-coloured complex is formed which absorbs at 562 nm. The method was satisfactory for the determination of cysteine andN-acetylcysteine in samples within the range 0.02–6.00 gml^–1. Effects of time, acidity, ferric ions, ferrozine, sodium perchlorate concentrations and the tolerance limit for other amino acids have been reported. The method was applied to the determination of cysteine in amino acids mixtures andN-acetylcysteine in pharmaceutical preparations.     

Geminal systems. 50. Synthesis and alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas,carbamates, and benzamides

Procedures were developed for the synthesis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and benzamides by the reactions of the corresponding N-alkoxy-N-chloro derivatives with sodium carboxylates in MeCN. N-Chloro-N-ethoxy-p-toluenesulfonamide was inert in this reaction. Alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and tert-alkylamines afforded the corresponding N,N-dialkoxy derivatives, whereas alcoholysis of N-acetoxy-N-ethoxybenzamide gave rise to alkyl benzoates.     

Synthesis of N-haloacyl and N-hetarylthioacyl derivatives of 2-amino-5-aryl-6H-1,3,4-thiadiazine

Conditions for N-acylation of 2-amino-5-aryl-6H-1,3,4-thiadiazines with trifluoroacetic anhydride and halogen-substituted carboxylic acid halides with retention of the initial heterocyclic system were found. 5-Aryl-2-haloacylamino-6H-1,3,4-thiadiazines were obtained in preparative yields. Their reactions with hetarenethiols afforded N-hetarylthioacyl derivatives. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1570–1575, August, 2007.     

Study of alkaloids of the Siberian and Altai flora. 10. Synthesis of N(20)-deethyllappaconitine derivatives

Efficient procedures were developed for N-deethylation of lappaconitine to give N(20)-deethyllappaconitine. Alkyl derivatives of N(20)-deethyllappaconitine, including labeled lappaconitine, and N(20)-acetoxy-N(20)-deethyllappaconitine were prepared for the first time. The assignments of the signals for the carbon atoms in the ¹³C NMR spectra of lappaconitine and related lappaconine were refined using ¹³C—¹³C 2D INADEQUATE and 2D ¹³C—¹H correlation experiments.     

Heterocyclic derivatives of long-chain diacetylenic acids

Acyl derivatives of 2-aminopyridine, 2-aminopyrimidine, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl were obtained from long-chain diacetylenic acyl chlorides and the corresponding heterocyclic compounds. Spreading isotherms of monolayers on a water surface show that lengthening of the hydrocarbon chain and replacement of the pyridyl groups in these compounds by the more hydrophilic pyrimidyl groups render the films more condensed. Long-chain acyl derivatives of nitroxyl radicals form monolayers possesing a low collapse pressure. ESR spectra of Langmuir-Blodgett films of these radicals before and after photopolymerization were recorded.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2009–2012, October, 1995.The authors are grateful to S. A. Dzyuba for his help in recording ESR spectra and for helpful discussion.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-04027).     

Synthesis,structures and properties ofN-(trihalogermylmethyl)-substituted amides,lactams and imides,the derivatives of the five-coordinate germanium

The formation of trichlorogermyl-substituted amides, lactams, and imides occurs when 2Et₂O·HGeCl₃ is condensed with compounds possessing the -NCH₂Cl fragment and equally well when HGeCl₃ interacts with compounds containing -NCH₂OH and-NCH₂OSiMe₃ groups. In some cases, the use of the latter is more advantageous from the preparative point of view. In compounds thus obtained, the germanium is five-coordinate due to the coordination . Deceased August 13, 1993. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1793–1799, October, 1993.     

Extraction and spectrophotometric determination of titanium(IV) withN 1-hydroxy-N 1,N 2-diphenylbenzamidine and thiocyanate

A precise, reliable, sensitive, and selective method for the determination of titanium(IV) is described. Titanium(IV) reacts withN ¹-hydroxy-N ¹,N ²-diphenylbenzamidine (HDPBA) and thiocyanate to form an orange-coloured mixed-ligand complex of stoichiometry 112 (Ti SCN^– HDPBA). The complex is quantitatively extractable into toluene from 0.05–0.15M hydrochloric acid. The spectrum of the complex exhibits an absorption maximum at 400 nm with a molar absorptivity of 20000M ^–1 cm^–1 and the coloured system obeys Beer's law in the concentration range 0.20–3.0 gml^–1 titanium. The effects of foreign ions and of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of titanium. The precision of the method has been evaluated and the relative standard deviation has been found to be 0.53%. The method has been successfully applied to the determination of titanium in synthetic matrices corresponding to titanium-containing ores, minerals, and alloys.     

Synthesis of 2-methyl-4,5,6,7,8,9,10,11,12,13-decahydrocyclododeca[b]pyrrole and its N-substituted derivatives from 2-acetonylcycIododecanone and 2-propargylcyclododecanone

A new and facile method is proposed for the synthesis of 2-acetonylcyclododecanone and 2-(chloromethyl)-3,5-dioxa-1-hexene under phase transfer catalysis conditions. 2-Methyldecahydrocyclododeca[b]pyrrole and its N-substituted derivatives are easily obtained when 2-acetonylcyclododecanone reacts with ammonia or primary amines. 2-Methyl-N-phenyldecahydrocyclododeca[e]pyrrole was prepared from easily accessible 2-propargylcyclo-dodecanone and aniline under mild conditions using HgCl₂ as the catalyst.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 416–417, February, 1993.     

Quantitative determination of phenol derivatives fromOleum thymi

Summary The thymol and carvacrol content inOleum Thymi was determined by densitometry. Phenols were separated on a thin—layer of silica gel using two-step gradient elution. The dependence of measurement time on the amount of phenols was investigated. For comparison, the total phenolic content of the essential oil was also determined by colorimetry, the results indicating that the optimal measurment time at which the following measurements should be performed, is 5 min after the end of heating.     

Cavity size effect on ICT-dual emission of p-(N,N-dimethylamino)-2-styrylquinoline: complexation with cyclodextrin derivatives

The effect of cyclodextrin inclusion complex formation on the intramolecular charge transfer (ICT) of the included 4-N,N-dimethylamino-2-strylquinoline (2-StQ-NMe₂) has been studied in detail. 2-StQ-NMe₂ in presence of α-, β-, γ- and HP-α- and Hp-β-CDs predominantly exhibits ICT fluorescence predominantly than the emission from locally excited state, whereas in presence of HP-γ-CD the later is observed. In presence of α-CD, 2:1 complexation of the 2-StQ-NMe₂ is observed in addition to 1:1 complexation. The observed results are explained by the CD cavity size and an active role for the secondary hydroxyl groups present in the wider rim of the CD cavity and also which finds support from absorption, emission, lifetime and molecular modeling studies. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

A convenient synthesis of 3,3,3-trifluoroalanine derivatives

A one-pot synthesis of N-substituted 3,3,3-trifluoroalanine esters from alkyl trifluoropyruvates and carboxamides or substituted ureas was developed.     

Photochemical properties and structures ofN-amino andN-azomethine derivatives of 2,4,6-triphenylpyridinium perchlorates

The molecular structures of the initial compounds and the products of photocyclization involving amino and azomethine groups in perchlorates ofN-amino (1) andN-azomethine (2) derivatives of 2,4,6-triphenylpyridinium cations were studied. Cations1 and2 have an essentially non-coplanar arrangement of the -Ph rings, and the product of photocyclization of2, cation3, is characterized by a flattened structure. It was found that the orientation of the lone electron pair of the N atom with respect to one of the planes of the -Ph rings in molecule1 is more favorable for monocyclization involving the amino group. The structure of molecule2 allows two routes of the photoreaction,viz., O N proton transfer and monocyclization with an -Ph ring. However, the structural features of molecule2 are more favorable for photocyclization.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 296–301, February, 1995.     

Synthesis of anthrathiopyrantriones by heterocyclization of alkynoyl derivatives of chloroanthraquinones

A procedure was developed for the synthesis of 2-substituted, including 2-alkenyl-substituted, 4H-anthra[1,2-b]thiopyran-4,7,12-triones and 4H-anthra[2,3-b]thiopyran-4,6,11-triones by cyclocondensation of vic-alkynoylchloroanthraquinones with Na₂S.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2205–2209, October, 2004.     

Inverse photochromic systems based on ketoenamine derivatives

The results of studies into inverse photochromic systems (systems with negative photochromism) based on ketoenamines and ketoenehydrazines of benzo [b]annelated heterocycles and their acylated derivatives carried out at the Institute of Physical and Organic Chemistry at the Rostov State University in the last two decades are summarized.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 506–517, March, 2005.     

Spectrophotometric determination of clozapine in pharmaceuticals

New Spectrophotometric methods for the assay of clozapine (CZP) in pure and dosage forms are described. Method A is based on the oxidative coupling reaction of CZP with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ceric ammonium sulphate to form a coloured species (_max 570 nm). Method B is also based on the oxidative coupling reaction of CZP withP-,N,N-dimethylpheny-lenediamine dihydrochloride (DMPD) in the presence of sodium hypochlorite to form a coloured species (_max 690 nm). Method C is based on the formation of coloured charge-transfer complex between CZP and chloranilic acid (_max 540 nm). Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 2–25, 10–120 and 15–300 g/ml for methods A, B and C, respectively. The validity of the proposed methods was tested by analysing pharmaceutical dosage forms containing CZP and the relative standard deviation values were within 1.0%.