Some papaverine derivatives

Heating papaverine with chloral hydrate and benzoyl chloride formed products of the replacement of the hydrogen at the 15-C atom of papaverine: 15-(-trichloro--hydroxyethyl)papaverine and 15-benzoylpapaverine. In reactions with monochloro- and trichloroacetic acids under mild conditions in the cold, salts at the nitrogen atom were formed: the monochloroacetate and the trichloroacetate. The products were characterized by the results of TLC (type KSK silica gel fixed with gypsum), elementary analyses, and IR and PMR spectroscopy.V. I. Nikitin Institute of Chemistry, Academy of Sciences of the Tadzhik SSR, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 500–502, July–August, 1984.     

An efficient immunoaffinity chromatographic method for extraction and purification of papaverine from samples of pericarpium papaveris and food products

A highly selective immunoaffinity column was obtained by coupling anti-papaverine polyclonal antibodies to CNBr-activated Sepharose 4B. It was found that the coupling efficiency and performance of the immunoaffinity column were greatly improved by prolonging the coupling reaction time from 3 h at 20 degrees C with shaking to incubation overnight at 4 degrees C after the 3 h shaking reaction. The pH and ionic strength were observed to be the most important factors that influence the binding of papaverine to the immunoaffinity column. Using 0.01 mol/L phosphate buffered saline (PBS, pH 8.3) and methanol-water (80:20, v/v) as the loading and eluting solutions, respectively, papaverine was first retained on the column and then quantitatively eluted out with a mean recovery of 86% at a loading concentration of 1 microg/mL. When applied to real samples of pericarpium papaveris and food products, the established immunoaffinity column showed high efficiency in removing the matrix interferences in the samples and satisfactory recovery results were obtained. The method was useful for extraction and purification of papaverine from related samples.     

Asymmetric hydrogenation catalyzed by a rhodium complex of (R)-(tert-butylmethylphosphino)(di-tert-butylphosphino)methane: scope of enantioselectivity and mechanistic study

The rhodium complex of (R)-(tert-butylmethylphosphino)(di-tert-butylphosphino)methane used in Rh-catalyzed asymmetric hydrogenation of representative substrates 3-14 demonstrated high catalytic activity coupled with wide scope and nearly perfect enantioselectivity. Mechanistic studies (NMR and DFT computations) were carried out in order to investigate the mechanism of the enantioselection in the asymmetric hydrogenation of (Z)-alpha-acetamidocinnamate (3). Although catalyst-substrate complexes 15a,b with the double bond coordinated near the non-"chiral" phosphorus atom were formed as kinetic products upon the addition of 3 to solvate complex 2 at -100 degrees C, they rapidly rearranged to more stable isomers 15c,d with the double bond coordinated near the "chiral" phosphorus atom. The thermodynamic and kinetic parameters of the interconversion between 15c and 15d were determined by NMR; mainly, the interconversion occurred intramolecularly via nonchelating catalyst-substrate complexes 16. The equilibrium between 15d and 16d was directly observed from NMR line shape changes at temperatures ranging from -100 to -40 degrees C, whereas no such equilibrium was observed for 15c. This result was accounted for computationally by determining the corresponding transition states for the methanol insertion into 15c,d. Three sets of experiments of the low-temperature hydrogenation of different catalyst-substrate complexes gave the same order and sense of enantioselectivity (97% ee (R)) even in the case when 15c, having Re-coordinated double bond, was hydrogenated under the conditions precluding its isomerization to 15d. It was concluded that the hydrogenation of 15c,d does not occur directly, but is preceded by the dissociation of the double bond to result in the more reactive species 16. This indicates that enantioselection must occur at a later step of the catalytic cycle. DFT computations of association and migratory insertion steps suggest that enantioselection takes place during the association step when chelating dihydride 19d.MeOH is formed from nonchelating dihydride 18d.     

Product studies and laser flash photolysis on alkyl radicals containing two different beta-leaving groups are consonant with the formation of an olefin cation radical.

1-Bromo-2-methoxy-1-phenylpropan-2-yl (3) and 2-methoxy-1-phenyl-1-diphenylphosphatopropan-2-yl (4) were generated under continual photolysis from the respective PTOC precursors in a mixture of acetonitrile and methanol. The radicals undergo heterolytic fragmentation of the substituent in the beta-position to generate the olefin cation radical (5). Z-2-Methoxy-1-phenylpropene (15) is the major product formed in the presence of 1,4-cyclohexadiene, and is believed to result from hydrogen atom transfer to the oxygen of the olefin cation radical, followed by deprotonation. Laser flash photolysis experiments indicate that reaction between 5 and 1,4-cyclohexadiene occurs with a rate constant of approximately 6 x 10(5) M(-1) s(-1). 2,2-Dimethoxy-1-phenylpropane (18) is observed as a minor product. Laser flash photolysis experiments place an upper limit on methanol trapping of 5 at k <1 x 10(3) M(-1) s(-1) and do not provide any evidence for the formation of reactive intermediates other than 5. The use of two PTOC precursors containing different leaving groups to generate a common olefin cation radical enables one to utilize product analysis to probe for the intermediacy of other reactive intermediates. The ratio of 15:18 is dependent upon hydrogen atom donor concentration, but is independent of the PTOC precursor. These observations are consistent with the proposal that both products result from trapping of 5 that is formed via heterolysis of 3 and 4.     

Matrix isolation and theoretical study of the photochemical reaction of CrCl2O2 with chloroethenes

The matrix-isolation technique has been combined with infrared spectroscopy to identify and characterize the products formed by irradiation of cage-paired CrCl(2)O(2) and a series of chloroethenes, C(2)H(x)()Cl(y)() (x + y = 4). For each system, oxygen-atom transfer occurred upon irradiation, yielding the corresponding acetyl chloride derivative and the Cl(2)CrO species. The products were formed in the same matrix cage and strongly interacted to form a distinct molecular complex after formation. Three different modes of interaction were explored computationally: eta(1) to the oxygen atom, eta(2) to the C=O bond, and eta(1) to the chlorine atom. In addition, a five-membered metallocycle and the chloroepoxide species were considered. No evidence was obtained for the chloroacetaldehyde derivative, indicating the occurrence of oxygen-atom attack at the more substituted carbon of the chloroethene. Evidence tentatively supporting the formation of the metallocycle was obtained as well. Theoretical calculations indicated that the acetyl chloride derivative was approximately 10 kcal/mol more stable than the corresponding chloroacetaldehyde species for each system at the B3LYP/6-311++g(d,2p) level of theory. The binding energy of each of the complexes was also found to be near 10 kcal/mol at this level of theory.     

Gas-phase electrophilic attack of a double bond exhibits stereoselectivity

Protonated acetaldehyde (ion 1) reacts with allyltrimethylsilane (allyl-TMS) in the gas phase to yield cis-piperylene (cis-1,3-pentadiene) as the major product. The cis isomer predominates over trans by a factor >/=15:1, a degree of stereoselectivity that is unprecedented in a reaction where the double bond geometry has not been specified in the reactant. The neutral products were assessed by creating tritiated 1 via decay of a tritium nucleus in gaseous ethanol molecules labeled with >1 tritium atom. The radioactive C5H8 products must result from addition of the electrophilic ion to the allyl group followed by an elimination. Deprotonation of C5H9+ cannot account for the product stereochemistry. One possible explanation is that addition of the electrophile to the double bond is followed by elimination of Me3SiOH2+ on a time scale faster than that by which the initially formed adduct ion can change its conformation.     

Spectrophotometric method for estimation of alkaloids precipitable with Dragendorff's reagent in plant materials

A rapid, easy, and simple spectrophotometric method was developed for the estimation of total alkaloids precipitated by Dragendorff's reagent (DR) in plant materials. It is based on the formation of yellow bismuth complex in nitric acid medium with thiourea. The yellow-colored complex formed obeys Lambert-Beer's law in the concentration range of 0.06-50 microg/mL with lambdamax at 435 nm. Using this method, the alkaloidal percentage of certain alkaloids (ajamalicine, papaverine, cinchonine, piperine, berberine) and some plant materials containing alkaloids (Berberis aristata, Solanum nigrum, and Piper longum) were determined. The method was compared with other methods. It can be used for routine analysis of commercial samples by industries dealing with herbal drugs for standardization of plant materials containing alkaloids and for alkaloid-containing pharmaceutical products.     

聚酰胺热氧化降解机理

通过详细分析测定反应产物 ,研究了聚酰胺 (PA6)的热氧化降解机理 .用化学方法测定了PA6热氧化过程中几种主要基团含量的变化 ,对PA6热氧化的气相挥发产物进行收集和分析鉴定 ,还对经过氧化的PA6样品进行水解并用GC MS法对水解产物进行了分析鉴定 .在这些实验结果的基础上 ,提出了较完整的聚酰胺热氧化降解机理 .该机理包含了自由基在与酰胺基的羰基相连的亚甲基上的夺氢反应及一系列自由基加成环化和诱导断链的反应 ,能很好地解释反应产物的分析结果 .     

Oxygenation of benzyldimethylamine by singlet oxygen. Products and mechanism

[reaction: see text] A product study of the reaction of benzyldimethylamine (1) with thermally and photochemically generated 1O2 in MeCN was carried out. Benzaldehyde and N-benzyl-N-methylformamide are the reaction products, oxygenation representing ca. 9% of the overall quenching of 1O2 by 1. The temperature effect and the intermolecular and intramolecular kinetic deuterium isotope effects were also determined. It is suggested that the products derive from an intracomplex hydrogen atom transfer in a reversibly formed charge-transfer complex.     

尿素在ZnO(1010)表面的吸附

运用VASP(Vienna ab-initio simulation package),采用基于密度泛函理论(DFT)的第一原理计算,研究了尿素在ZnO(101軈0)表面的吸附行为.计算结果表明:尿素分子在ZnO(101軈0)表面主要发生分子吸附,稳定的吸附产物通过尿素分子中的氮原子或氧原子与表面锌原子之间的键合作用而形成,吸附能分别为-1.48和-1.41eV;表面吸附的尿素分子也可以发生解离,生成表面吸附的异氰酸根、氨气和一个表面羟基,吸附能为-1.66eV.     

Spectrophotometric study of scandium(III) complexation with 2,2′,3,4-tetrahydroxy-3′-sulfo-5′-nitroazobenzene in the presence of papaverine, dibazole, and urotropine

Complexes of scandium(III) with 2,2′,3,4-tetrahydroxy-3′-sulfo-5′-nitroazobenzene were studied in the absence and presence of a third component, papaverine, dibazole, or urotropine. Optimal conditions for their formation were found, and their spectrophotometric parameters were determined. It was found that binary compounds ScR and mixed-ligand compounds formed at pH 2 exhibited absorption maxima at 477, 482, 479, and 478 nm. The stability constants of the complexes were calculated. The determination of scandium(III) with 2,2′,3,4-tetrahydroxy-3′-sulfo-5′-nitroazobenzene in the presence of papaverine, dibazole, and urotropine was found to be selective in comparison to the other known reagents. A procedure was developed for the photometric determination of scandium in hard rocks.     

Synthesis of the first 1,2,3,4-azatriphospholene complex

Synthesis of the first 1,2,3,4-azatriphospholene complex was achieved by heating a solution of a P-phenyl-substituted 7-phosphanorbornadiene tungsten complex and triphenylphosphonio cyanomethylide, whereby CH-insertion products were formed in a competing reaction; these results also provide first evidence for the ability of electrophilic terminal phosphanediyl complexes to react at the ylide carbon atom and at the carbonitrile nitrogen atom of Wittig-ylides having a nitrile functional group; the structures of both complexes were established through X-ray single-crystal diffraction studies.     

The Route of Alkylation of 5-Substituted 1,3,4-Thiadiazoline-2-thiones

The reaction of 5-anilino(toluidino-, morpholino)-1,3,4-thiadiazoline-2-thiones at 80°C with allyl bromide and benzyl chloride in alcohol, acetonitrile or DMF in the presence of KOH and also with phenoxymethyloxirane in alcohol in the absence of base gives the corresponding novel allyl-, benzyl-, and 2-hydroxy-3-phenoxypropyl products substituted at the exocyclic S atom. Alkylation of the indicated thiones with benzyl chloride at 150-153°C in DMF in the presence of KOH occurs similarly. Under these conditions, allyl bromide forms alkylation products at the endocyclic N(3) atom as a result of an SN thio-Claisen rearrangement of the initially formed product which is allyl substituted at the exocyclic S atom.     

The photochemistry of 6‐phenanthridinecarbonitrile I. Product analysis

When 6‐phenanthridinecarbonitrile ( 3 ) is irradiated at 2537 Å in neutral 9:1 2‐propanol/water, three major products are formed. These are dimethyl‐(6‐phenanthridinyl)methanol ( 4 ), phenanthridine ( 5 ) and 6,6′‐biphenanthridine ( 6 ). When benzophenone is present in the reaction mixture, diphenyl‐(6‐phenanthridinyl)‐methanol is also formed. 6‐Phenanthridinyl radical which is common to the formation of all these products, is formed by a monophotonic process involving hydrogen atom abstraction from an alcohol molecule by an excited state of 3 . Unlike what is generally found with other nitrogen‐heterocycles, the photochemistry of 3 appears to involve only a π,π* singlet state. The fluorescence of 3 is quenched with the triplet quencher cis/trans‐piperylene as a function of the concentration of the diene without the accompaniment of an exci‐plex emission.     

Reaction of 2,4-dinitrophenylhydrazones of triphenyl(2-aroylethyl)phosphonium bromides with aqueous alkali and some transformations of the betaines formed

Triphenyl(2-p-toluoylethyl)- and triphenyl(2-p-bromobenzoylethyl)phosphonium bromide 2,4-dinitrophenylhydrazones were established to form a bipolar compounds with a negatively charged nitrogen atom and a positively charged phosphonium atom, under the action of aqueous alkali at 0°C. When refluxed in acetonitrile, the product formed from triphenyl(2-p-toluoylethyl)phosphonium bromide undergoes cleavage by a five-membered ring mechanism to give triphenylphosphine and tolyl vinyl ketone 2,4-dinitrophenylhydrazone. The reactions of the above betains with methyl iodide give rise to N-alkylation and cleavage products, but, in addition, iodide analogs of the starting phosphonium salt 2,4-dinitrophenylhydrazones which are probably formed via N→C negative charge transfer, C-methylation, and reaction of the resulting products with N-betaines.     

Chromato–Mass Spectrometric Identification of Unusual Products of 4-Isopropylphenol Oxidation in Aqueous Solutions

4-Isopropylphenol has been chosen as the simplest object to model the processes of oxidation of organic compounds with air oxygen in aqueous media, since it contains a hydrogen atom at the tertiary carbon atom in the α-position with benzene ring and a hydroxyl group enabling mass-spectrometric detection of the products in the negative ions mode. It has been stated that oxidation of 4-isopropylphenol with air oxygen in aqueous media becomes noticeable as the solution pH approaches the рK_а value of the substrate (10.25). The major product [4-isopropyl-2-(4-isopropylphenoxy)phenol] is formed via nucleophilic addition of the starting 4-isopropylphenol at the intermediate product of its oxidation, quinone methide. Intensity of electrochemical oxidation can be tubed by changing the electrode potential. The highest conversion of 4-isopropylphenol has been observed at potential 1.5–3.0 V, the formed compounds being the products of transformation of the same quinone methide intermediate. The obtained data have explained the formation and diversity of dimeric and oligomeric products of oxidation of natural flavonoids.     

高效毛细管电泳法测定罂粟壳中生物碱的含量

采用高效毛细管电泳法测定罂粟壳中可待因、吗啡和罂粟碱的含量,结果表明可待因的加样回收率为９６．６１％,吗啡为９５．９０％,罂粟碱为９５．３７％。方法简便、准确、重现性好,可作为生物碱的质量控制方法。     

Reactions of Nucleophilic Substitution in Bicyclic Nitroimidazodihydrooxazoles

This article describes numerous attempts of the S_N reaction of chlorine atom in chloromethyl group with nucleophilic compounds, such as the following: phenols, thiophenols, and amino compounds. The influences of ratios of nitroimidazodihydrooxazoles, nucleophiles and basic agent, and the polarity of solvent on the kind of formed products were established. Also, the comparison of reactivity with nucleophiles of close structural isomers of nitroimidazodihydrooxazoles has been made. The way of formation ring opening reaction products has been proposed.     

Effects of substituents in reactions of sulfenyl chlorides with derivatives of phosphonallenic acids

Conclusions In the reaction of sulfenyl chlorides with derivatives of allenylphosphonic acid, the structure of the products formed is determined by the effect of substituents at the P atom and the terminal C atom of the cumulene, and also by the nature of the organyl group attached to the S atom in sulfenyl chloride.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1851–1859, August, 1933.     

Polymerization Mechanism of α-Linear Olefin

The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl₃/AlEt₂Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetryrestrictions for reactants, products, the possible transition states, and intermediates wascalculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as flloes:(i) Coordination compounds were formed on the optimum configuration of TiCl₃/AlEt₂Cl.(ii) The transition states were formed. The energy di?erence between transition states and the coordination compounds was 40.687 kJ/mol. (iii) Double bond opened and Ti-C(4) bond fractured, and the polymerization was completed. The calculation results also showedthat the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization.