Growth and characterization of 2-hydroxy-4-methoxybenzophenone single crystal using modified vertical Bridgman technique

The 2-hydroxy-4-methoxybenzophenone single crystal has been grown by the modified vertical Bridgman technique using the double wall ampoule. The grown crystal was confirmed by single and powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses. High resolution X-ray diffraction (HRXRD) analysis indicates the crystalline perfection of the grown crystal. The cutoff wavelength of the grown crystal was analyzed by optical studies. The dielectric measurements were carried out and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The thermal property of the grown crystal was studied by thermo gravimetric (TG) and differential thermal analyses (DTA).     

Growth and characterization of organic material 2-methylamino-5-chlorobenzophenone single crystal by modified vertical Bridgman technique

The organic material 2-methylamino-5-chlorobenzophenone single crystal has been grown by modified vertical Bridgman technique using the single wall ampoule with nano translation. The grown crystal was confirmed by single crystal and powder X-ray diffraction analyses. Fourier transform infrared analysis was used to identify the functional groups present in the grown crystal. High resolution X-ray diffraction studies show the crystalline perfection of the grown crystal. The optical property of the grown crystal was analyzed by UV-vis-NIR and photoluminescence spectral studies. The thermal behavior of the grown crystal was analyzed by thermogravimetric and differential thermal analyses. The dielectric measurements of the grown crystal were carried out with different frequencies and temperatures and the results indicate an increase in dielectric and conductivity parameters with the increase of temperature at all frequencies. The microhardness measurements were performed to analyze the mechanical property of the grown crystal.     

Characterization of the singlet and triplet excited states of 3-chloro-4-methylumbelliferone

An extensive photophysical characterization of 3-chloro-4-methylumbelliferone (3Cl4MU) in the ground-state, S(0), first excited singlet state, S(1), and lowest triplet state, T(1), was undertaken in water, neutral ethanol, acidified ethanol, and basified ethanol. Quantitative measurements of quantum yields (fluorescence, phosphorescence, intersystem crossing, internal conversion, and singlet oxygen formation) together with lifetimes were obtained at room and low temperature in water, dioxane/water mixtures, and alcohols. The different transient species were assigned and a general kinetic scheme is presented, summarizing the excited-state multiequilibria of 3Cl4MU. In water, the equilibrium is restricted to neutral (N*) and anionic (A*) species, both in the ground (pK(a) = 7.2) and first excited singlet states (pK(a)* = 0.5). In dioxane/water mixtures (pH ca. 6), substantial changes of the kinetics of the S(1) state were observed with the appearance of an additional tautomeric T* species. In low water content mixtures (mixture 9:1 v:v), only the neutral (N*) and tautomeric (T*) forms of 3Cl4MU are observed, whereas at higher water content mixtures (water mole fraction superior to 0.45), all three species N*, T*, and A* coexist in the excited state. In the triplet state, in the nonprotic and nonpolar solvent dioxane, the observed transient signals were assigned as the triplet-triplet transition of the neutral form, N*(T(1)) → N*(T(n)). In water, two transient species were observed and are assigned as the triplets of the neutral N*(T(1)) and the anionic form, A*(T(1)) (also obtained in basified ethanol). The phosphorescence spectra and decays of 3Cl4MU, in neutral, acidified, and basified solutions, demonstrate that only these two species N*(T(1)) and A*(T(1)) exist in the lowest lying triplet state, T(1). The radiative channel was found dominant for the deactivation of the anionic species, whereas with the neutral the S(1) ? S(0) internal conversion competes with fluorescence. For both N* and A* the intersystem crossing yield represents a minor deactivation channel for S(1).     

Synthesis of enkephalins by the method of polymeric activated esters based on 4-hydroxy-3-nitrobenzophenone

Leucine- and methionine-enkephalins have been synthesized by the successive growth of the peptide chain from the C-end by the method of polymeric activated esters based on 4-hydroxy-3-nitrobenzophenone with yields of 90 and 70%, respectively, calculated on the initial C-terminal amino acid. Polystyrene with 2% of divinylbenzene was used as the polymeric matrix. Using the synthesis of methionine-enkephalin as an example, the possibility has been shown of using polymeric activated esters for the synthesis of peptides with a free carboxy group. Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 547–553, July–August, 1989.     

Synthesis of enkephalins by the method of polymeric activated esters based on 4-hydroxy-3-nitrobenzophenone

Leucine- and methionine-enkephalins have been synthesized by the successive growth of the peptide chain from the C-end by the method of polymeric activated esters based on 4-hydroxy-3-nitrobenzophenone with yields of 90 and 70%, respectively, calculated on the initial C-terminal amino acid. Polystyrene with 2% of divinylbenzene was used as the polymeric matrix. Using the synthesis of methionine-enkephalin as an example, the possibility has been shown of using polymeric activated esters for the synthesis of peptides with a free carboxy group.Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 547–553, July–August, 1989.     

Spectroscopic studies of a LiRbB4O7:Cu(II) crystal grown by the Czochralski technique

A copper-doped LiRbB4O7 crystal was grown by the Czochralski technique. Powder X-ray, EPR and optical absorption studies were carried out. The results and discussion of the copper doped LiRbB4O7 crystal indicate that the copper ions enter the host lattice by replacing Li ions. The Cu(II) ion spectrum is characteristic of a tetragonally elongated octahedral site. Lattice and spin-Hamiltonian parameters were evaluated. The bonding parameters indicate that the bonding between copper and the ligands is partly covalent.     

Growth and characterization of naphthalene single crystals grown by modified vertical Bridgman method

The large size 20 mm diameter naphthalene single crystals were grown by modified vertical Bridgman method. The optical quality of the grown crystal was analyzed by photoluminescence and ultraviolet visible absorption spectral measurements. Photoluminescence spectrum indicated violet emission at 410 nm. The UV–vis absorption spectrum shows the maximum at 219.32 nm. The microhardness measurements and differential thermal analysis performed to analyze the mechanical and thermal stability of the as grown crystals. The dielectric measurements were carried out at five frequencies, viz., 100 Hz, 1 kHz, 10 kHz, 100 kHz and 1 MHz and at various temperatures, ranging from 308 K to 348 K indicate an increase of the dielectric parameters with the increase of temperature at all the five frequencies. The conductivity of the material is understood to be more of electronic in nature. Also, the increase in the dielectric parameters with that of temperature is due to the temperature variation of electronic polarizability.     

Characterization of CuTe nanofilms grown by underpotential deposition based on an electrochemical codeposition technique

Journal of Solid State Electrochemistry - This study reports the synthesis of semiconductor CuTe nanofilms using underpotential deposition (UPD) technique based on the simultaneous,...     

Reactions of 4-chloro-7-dialkylamino- and 3-alkyl-4-chloro-7-dialkylaminocoumarins with primary and secondary alkylamines

Reaction of series of 4-chloro-7-dialkylaminocoumarins and 3-alkyl-4-chloro-7-dialkylaminocoumarins with primary and secondary amines, namely tert-butylamine, benzylamine, cyclohexylamine, monoethanolamine, diethylamine, piperidine, and morpholine, has yielded novel substituted 4,7-diaminocoumarins. The PMR spectra of these newly synthesized compounds are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 836–841, June, 1990.     

Reactions of 4-chloro-3-formyl-coumarin with primary amines

The reaction of 4-chloro-3-formylcoumarin with primary amines in the presence of triethylamine was studied. The reaction with aliphatic and aromatic amines leads to N-substituted 4-amino-3-formylcoumarins, whereas hetarylamines react primarily with the formyl group to form a mixture of the Z-and E-isomers of N-substituted 3-aminomethylenechroman-2,4-diones. Replacement of the triethylamine by anhydrous sodium acetate in the reaction of chlorocoumarin with 2-aminopyridines leads to the formation of the condensed benzopyranopyridopyrimidine system as a result of nucleophilic attack of the amino group by the chlorine atom at position 4. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 660–668, May, 2006.     

氯化镧单晶的坩埚下降法生长

报道了LaCl3单晶的非真空密闭条件下的坩埚下降法生长方法。依据差热/热重分析所揭示的LaCl3.7H2O脱水过程,采用干燥氯化氢保护下的焙烧脱水处理制备出无水LaCl3原料。将无水LaCl3密封于铂坩埚中,且添加少量活性碳粉,可避免熔体的氧化与挥发,从而实现在非真空条件下的LaCl3单晶生长。在单晶生长过程中,炉体控制温度为940~970℃,固液界面温度梯度为30~40℃.cm-1,坩埚下降速率控制于0.5~1.0 mm.h-1,在非真空密闭条件下成功生长出直径为25 mm的透明LaCl3单晶。综合运用差热/热重分析、X射线衍射、透射光谱、X射线激发发射光谱对所获单晶样品进行了测试表征,表明非真空密闭坩埚下降法适合于生长均匀透明LaCl3单晶。     

邻氯甲苯直接硝化法合成6-氯-3-氨基甲苯-4-磺酸

邻氯甲苯混酸硝化合成6-氯-3-氨基甲苯-4-磺酸(CLT酸)因其产率低及选择性差而未能实现工业生产,本文对该工艺进行了改进,采用酸性β沸石和乙酰硝酸酯作为催化剂和硝化剂,提高了硝化选择性和收率,分别为72％和97％;并改进了还原、异构体分离和磺化操作;CLT酸总收率提高到61％.     

Isothiazoles II: 5-chloro-4-isothiazolin-3-ones

Quantitative gas chromatographic analysis of the 3-hydroxyisothiazole product distributions formed in the chlorine induced cyclization of 3,3′ -dithiodipropionamide and 3-mercaptopropion-arnide has led to reaction conditions which yield respectively 3-hydroxyisothiazole, 5-chloro-3-hydroxyisothiazole, or 4,5-dichloro-3-hydroxyisothiazole as the predominant product. The 4-chloro analog was found in only small quantity. Similar glc analysis of the cyclization of N,N′-dimethyl-3,3′-dilhiodipropionamide showed 5-ehloro-2-methyl-4-isothiazolin-3-one to he the major 4-isothiazolin-3-one product under varied conditions. Also, a representative series of 5-chloro-2-subtiuted-4-isohiazolin-3-oncs were prepared under extrapolated reaction conditions.     

A concise synthesis of 2-chloro-3-amino-4-methylpyridine

An improved and commercially valuable process is developed for the scalable synthesis of 2-chloro-3-amino-4-methylpyridine (CAPIC), a key intermediate of Nevirapine. The synthesis was accomplished in four steps, featuring condensation starting from 4,4-dimethoxyl-2-butanone and cyanoacetamide with ammonium acetate and acetic acid as catalysts. The total yield of the process is 62.1%. The pure CAPIC sample was confirmed with FTIR, ¹H NMR, and ¹³C NMR spectra.     

An unexpected and efficient synthesis of 3-chloro-4-cyanopyridine

Reaction of 4-cyanopyridine N-oxide with phosphorus oxychloride/phosphorus pentachloride gave 3-chloro-4-cyanopyridine in good yield in sharp contrast to the expected chlorination in the 2-position. A mechanistic interpretation of the results is proposed involving a chloride attack at the 4-position as the main feature.     

Synthesis and Characterization of 2-Arylseleno-2-chloro-1,2,3-triorgano-1,3,2λ5-diazaphosphetidin-4-ones

The reactions of N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea 8 and N-methyl-N′-phenyl-N,N′-bis(trimethylsilyl)urea 9 with phenylselenenyl chloride 6 and p-chlorophenylselenenyl chloride 7 furnished the N-arylseleno-N,N′-diorgano-N′-(trimethylsilyl)ureas 10–13 . The reactions of 10–13 with MePCl₂ and PhPCl₂ resulted in the formation of a new class of compounds, the 2-arylseleno-2-chloro-1,2,3-triorgano-1,3,2λ⁵-diazaphosphetidin-4-ones 14–19 . The new selenophosphoranes 20 and 21 were obtained in the reaction of 15 and 17 with p-nitrophenol in the presence of triethylamine. The identity and structure of the new compounds were established by ¹H- and ¹³C-NMR spectroscopy, elemental analysis, ³¹P- and ⁷⁷Se-NMR spectroscopy in the case of the selenophosphoranes 14–21 , and mass spectrometry in the case of 11 and 13 . A possible mechanism of the reaction leading to the selenophosphoranes is discussed. Single-crystal X-ray structure analyses of the selenophosphoranes 19 and 20 were conducted. Both display distorted trigonal bipyramidal geometry at phosphorus, the major distortions being imposed by the four-membered rings.     

Thermal Stability of 4-chloro-2-nitro- and 4-chloro-3-nitrobenzoates of Rare Earth Elements: Influence of substituent positions

The physico-chemical properties and thermal stability in air of rare earth element 4-chloro-2-nitro- and 4-chloro-3-nitrobenzoates of the general formulae Ln(C₇H₃NO₄Cl)₃2H₂O were compared and the influence of the position of the Cl and NO₂ substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated salts with colours typical of Ln³⁺. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO₂ group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of rare earth elements were studied in the temperature range 293–1173 K, but those of 4-chloro-2-nitrobenzoates of those elements were studied only at 293–523 K because they decompose explosively above 523 K. The positions of the Cl and NO₂ substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO₂ substituents on the electron density in benzene ring.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis and three-dimensional structure of 4-hydroxy-4-methyl-3-chloro-6-alkyltetrahydropyrans

A method has been developed for the preparation of 4-hydroxy-4-methyl-3-chloro-6-alkyltetrahydropyrans based on the cycloalkylation of 4-hydroxy-2-methyl-3-chloro-1-butene with aldehydes. Dehydrochlorination of these compounds furnished the corresponding oxiranes of the tetrahydropyran series. The chlorine atoms in these newly synthesized chlorotetrahydropyranols have been found to favor equatorial positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1457–1460, November, 1986.