共查询到20条相似文献,搜索用时 31 毫秒
1.
V. Yu. Korotaev Yu. A. Skorik A. Yu. Barkov M. I. Kodess A. Ya. Zapevalov 《Russian Chemical Bulletin》2005,54(11):2545-2549
3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride
followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated
in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu2+, Ni2+, Zn2+) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu2+ ions increase with an increase in the number of N-carboxyethyl groups.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2465–2469, November, 2005. 相似文献
2.
Thermosensitive hydrogels were prepared by free-radical polymerization in aqueous solution from N-isopropylacrylamide (NIPA) and acrylamide (AAm) monomers. N,N-Methylenebis(acrylamide) (MBAAm) was used as a crosslinker. A kinetic study of the absorption determined the transport mechanism. The diffusion coefficients of these hydrogels were calculated for the Fickian mechanism. It was shown that the swelling behavior of the P(NIPA-co-AAm) hydrogels can be controlled by changing the amount of MBAAm. The swelling equilibrium of the P(NIPA-co-AAm) hydrogels was also investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). In SDS and DTAB solutions, the equilibrium swelling ratio of the hydrogels increased, this is ascribed to the conversion of non-ionic P(NIPA-co-AAm) hydrogel into polyelectrolyte hydrogels due to binding of surfactant molecules through the hydrophobic interaction. Additionally, the amount of free SDS and DTAB ions was measured at different temperatures by a conductometric method, it was found that the electric conductivity of the P(NIPA-co-AAm)—surfactant systems depended strongly on both the type and concentration of surfactant solutions. 相似文献
3.
Xiu-Kui Qu Lan-Ying Zhu Ling Li Xi-Lian Wei Feng Liu De-Zhi Sun 《Journal of solution chemistry》2007,36(5):643-650
As a continuation of our previous investigation, interactions between cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and alkyl trimethylammonium bromides in aqueous solutions have been studied with titration calorimetry and 1H NMR at 298.15 K. The results are discussed in terms of the amphiphilic interaction of CD with surfactants and the iceberg
structure formed by water molecules existing around the hydrophobic tail of surfactant molecules. The stoichiometry of the β-CD–surfactant system is 1:1 whereas that of the γ-CD–surfactant system is 1:2. The corresponding formation enthalpy (negative) of the complexes of the two systems decreases
with an increase in the number of carbon atoms (n) in hydrophobic chain of surfactant molecule, C
n
H2n+1, whereas the entropy increases with the enlargement of n. 相似文献
4.
Mohamed El-Sayed Hardy Müller Gerd Rheinwald Heinrich Lang Stefan Spange 《Monatshefte für Chemie / Chemical Monthly》2003,134(3):361-370
Summary. N-(2′-Hydroxy-4′-N,N-dimethylaminobenzylidene)-4-nitroaniline [HDBN] has been used as a model for investigating intra- and intermolecular D–A (donor–acceptor) interactions in various environments
by means of UV/Vis spectroscopy. UV/Vis spectra of HDBN have been measured in various solvents, ethanolic solutions of different pH, adsorbed on silica, and in the solid state. A bathochromic shift of νmax is observed with increasing the dipolarity/polarizability and HBD (hydrogen bond donor) capacity of the solvent, which is
described by means of a multiple LSE (linear solvation energy) relationship in terms of the empirical Kamlet-Taft solvent polarity parameters. The adsorption of HDBN on Aerosil? 300-silica particles in non-HBA (hydrogen bond acceptor) solvents is explained in the same sense. Mobile protons and sol–gel
entrapping cause a hypsochromic shift due to protonation of the lone electron pair of the 4′-N,N-dimethylamino group. Hydroxide ions attack the 2′-hydroxy group which causes a bathochromic shift. A strong intramolecular
hydrogen bond between the 2′-hydroxyl hydrogen and the imine nitrogen atom is present in the solid-state structure causing
an unprecedented bathochromic shift.
Corresponding author. E-mail: stefan.spange@chemie.tu-chemnitz.de
Received July 8, 2002; accepted (revised) September 30, 2002 相似文献
5.
D. V. Shishkin A. R. Shaimuratova A. N. Lobov N. Z. Baibulatova L. V. Spirikhin M. S. Yunusov N. S. Makara N. Zh. Baschenko V. A. Dokichev 《Chemistry of Natural Compounds》2007,43(2):190-196
Derivatives of N-(2-hydroxyethyl)cytisine, N-(2-hydroxypropyl)-, N-(2-hydroxy-2-(1-adamantyl)ethyl)-, and N-(2-hydroxy-2-phenylethyl)cytisine, were synthesized by reduction of N-(2-oxopropyl)-, N-(2-oxo-2-(1-adamantyl)ethyl)-and N-(2-oxo-2-phenylethyl)cytisine with metal hydrides. The antiarrhythmic and analgesic activities of the prepared compounds
were investigated.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 157–162, March–April, 2007. 相似文献
6.
A. R. Burilov A. S. Gazizov N. I. Kharitonova M. A. Pudovik W. D. Habicher I. Baier A. I. Konovalov 《Russian Chemical Bulletin》2007,56(2):330-335
Condensation of one molecule of α-methylaminoacetaldehyde dimethyl acetal with two molecules of resorcinol or methylresorcinol
in hydrohalogen acid solutions led to substituted N-(2,2-diarylethyl)-N-methylamine hydrohalides. Reactions of the corresponding amines with acetic anhydride, mono-and diisocyanates, and formaldehyde
were studied. Conditions for formation of calixarene from resorcinol and α-methylaminoacetaldehyde dimethyl acetal were invented.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 319–324, February, 2007. 相似文献
7.
D. V. Shishkin E. R. Mukhamed’yarova N. Z. Baibulatova V. A. Dokichev Yu. V. Tomilov 《Chemistry of Natural Compounds》2007,43(3):293-297
Diastereomers of N-(2-(1-adamantyl)-2-hydroxyethyl)cytisine were synthesized by reduction of N-(2-(1-adamantyl)-2-oxoethyl)cytisine with NaBH4. Their structures were established using x-ray structure analysis.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–247, May–June, 2007. 相似文献
8.
M. Madesclaire V. P. Zaitsev J. V. Zaitseva S. Kh. Sharipova 《Chemistry of Heterocyclic Compounds》2007,43(10):1325-1332
A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds
was studied.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007. 相似文献
9.
Reactions of N-pyrrolylpotassium with fluorinated electrophiles yielded N-substituted pyrroles containing polyfluoroalkyl, polyfluoroalkenyl, polyfluoroalkylsulfonyl, and polyfluoroaryl substituents.
N-Polyfluoro-substituted pyrroles did not isomerize at ≥100 °C; they were found to be reactive in [4+2] cycloaddition reactions
with perfluorobut-2-yne.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1890–1895, August, 2005. 相似文献
10.
I. M. Aladzheva O. V. Bykhovskaya P. V. Petrovskii K. A. Lyssenko M. Yu. Antipin T. A. Mastryukova 《Russian Chemical Bulletin》2005,54(11):2635-2641
A facile method was developed for the synthesis of N-(3-phosphonopropyl)-substituted α-amino acids and their phosphine oxide analogs based on hydrolysis of 2-oxo-1,2-azaphospholanes
and 1,2-azaphospholanium salts prepared from readily available reagents. A chelate CuII
N-[(3-diphenylphosphoryl)propyl]glycinate was isolated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2551–2556, November, 2005. 相似文献
11.
Data on the effect of the acid-base properties of the medium on the yield and composition of the products of N-dimethoxyphenylation of azoles (pyrazole, triazole, their substituted derivatives, and tetrazole) upon galvanostatic electrolysis
of azole—1,4-dimethoxybenzene mixtures in nucleophilic (MeOH) and neutral (MeCN) media were considered and the trends of this
process were discussed. The generation of arenium cations (1,4-dimethoxy-1-azolylbenzenium in MeCN and 1,1,4-trimethoxybenzenium
in MeOH) as the key intermediates of electrosynthesis of N-(dimethoxyphenyl)azoles, was proved experimentally. A new approach to the synthesis of N-(dimethoxyphenyl)azoles through electrosynthesis of 1,1,4,4-tetramethoxycyclohexa-2,5-diene by electrooxidation of 1,4-dimethoxybenzene
in MeOH as the first step and the reaction of this quinone diketal with azoles as the second step was suggested. The efficiency
of this route to N-(dimethoxyphenyl)azoles is comparable with the efficiency of the purely electrochemical one-step process.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2101–2109, November, 2007. 相似文献
12.
Alexander Konkin Frank Wendler Frank Meister Hans-Klaus Roth Albert Aganov Oliver Ambacher 《Cellulose (London, England)》2007,14(5):457-468
Degradation processes of N-methylmorpholine-N-oxide monohydrate (NMMO), cellulose and cellulose/NMMO solutions were studied by high performance liquid chromatography (HPLC)
and electron spin resonance (ESR) spectroscopy. Kinetics of radical accumulation processes under UV (λ = 248 nm) excimer laser
flash photolysis was investigated by ESR at 77 K. Beside radical products of cellulose generated and stabilized at low temperature,
radicals in NMMO and cellulose/NMMO solutions were studied for the first time in those systems and attributed to nitroxide
type radicals ∼CH2–NO•–CH2∼ and/or ∼CH2–NO•–CH3∼ at the first and methyl •CH3 and formyl •CHO radicals at the second step of the photo-induced reaction. Kinetic study of radicals revealed that formation and recombination
rates of radical reaction depend on cellulose concentration in cellulose/NMMO solutions and additional ingredients, e.g.,
Fe(II) and propyl gallate. HPLC measurements showed that the concentrations of ring degradation products, e.g., aminoethanol
and acetaldehyde, are determined by the composition of the cellulose/NMMO solution. Results based on HPLC are mainly maintained
by ESR that supports the assumption concerning a radical initiated ring-opening of NMMO. 相似文献
13.
Linda M. Guiney Alissa D. Agnello Julia C. Thomas Koko Takatori Nolan T. Flynn 《Colloid and polymer science》2009,287(5):601-608
We report the synthesis of N-isopropylacrylamide-based hydrogels containing either an anionic (acrylic acid) or cationic ([2-(acryloyloxy)ethyl]trimethylammonium
chloride) co-monomer. These hydrogels were cross-linked with a cleaveable (N,N′-cystaminebisacrylamide) and/or inert (N,N′-methylenebisacrylamide) molecule in four combinations. Gold nanostructures were then synthesized within these hydrogel matrices
by in situ reduction of a metal ion precursor. The resulting eight nanocomposites and their non-gold-containing (native) analogs
were characterized with several analytical methods. UV–visible and infrared spectroscopy revealed differences among the samples
based largely on the concentration and identity of cross-linking agent. Equilibrium swelling masses and phase transition behavior
point to differences among samples on charge of the hydrogel backbone, cross-linker type, and presence or absence of gold
nanostructures. A molecular level explanation for these observations is described. 相似文献
14.
N-Bromo and N-chlorosuccinimides add to 1-phenyltricyclo[4.1.0.02,7]heptane in CH2Cl2 with cleavage of the C(1)-C(7) bond to give isomeric 1 : 1 Markownikoff-type endo, anti-adducts of the norpinane structure in a ∼3 :7 ratio corresponding to N and O alkylation of succinimide.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No.2, pp. 457–460, February, 2005 相似文献
15.
A. D. Dubonosov V. P. Rybalkin Ya. Yu. Vorob’eva V. A. Bren’ V. I. Minkin S. M. Aldoshin V. V. Tkachev A. V. Tsukanov 《Russian Chemical Bulletin》2004,53(10):2248-2252
It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004. 相似文献
16.
V. V. Barbakadze E. P. Kemertelidze I. Targamadze K. Mulkidzhanyan J. Kemink A. J. J. van den Berg K. J. Beukelman A. I. Usov 《Chemistry of Natural Compounds》2005,41(4):374-377
Two high-molecular-weight (>1000 kDa) water-soluble preparations were isolated from stems of Symphytum asperum and S. caucasicum. Their basic component was established as poly[hydroxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene], analogous to that of high-molecular-weight
(>1000 kDa) preparations from roots of these same plants, using IR and NMR spectral data.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 303–305, July–August, 2005.
An erratum to this article is available at . 相似文献
17.
Two diimide-dicarboxylic acids, 2,2-bis[N-(4-carboxyphenyl)phthalimidyl]hexafluoropropane (p-I) and 2,2,-bis[N-(3-carboxyphenyl)phthalimidyl]hexafluoropropane (m-I), were prepared by azeotropic condensation of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and p-aminobenzoic acid or m-aminobenzoic acid at a 1:2 molar ratio in N,N-dimethylacetamide/toluene. Two series of organosoluble and colorless poly(amide–imide)s were synthesized from diimide–diacid
p-I or m-I with ten kinds of aromatic diamines by direct polycondensation using triphenyl phosphite and pyridine as condensing agents.
The thin films cast from N,N-dimethylacetamide were measured by UV–vis spectroscopy and Macbeth color-eye colorimetery, the cutoff wavelengths of almost
all the films were below 400 nm (361–389 nm) and the values of the parameter b* were between 15.31 and 34.72; these polymers are much lighter in color than other analogous polymers. Almost all the polymer
were soluble in N-methyl-2-pyrrolodone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide, and some polymers could dissolve in less polar solvents, such as dioxane and tetrahydrofuran,
etc. The cast films exhibited yield strengths of 95–131 MPa, tensile strengths ranging from 92 to 130 MPa, elongations at
break from 9 to 27%, and initial moduli from 2.1 to 3.3 GPa. The poly(amide–imide)s had glass-transition temperatures between
259 and 328°C and 10%-weight-loss temperatures above 510 °C in nitrogen and air, indicating excellent thermal stability.
Received: 25 April 2001 Accepted: 27 June 2001 相似文献
18.
N-tert-Butoxycarbonyl-7-and N-tert-butoxycarbonyl-8-bromo-10-azabicyclo[4.3.1]deca-3,7-dienes are convenient substrates for further modification using replacement
of the Br atom by a cyano group or a Li atom. Treatment of lithium derivatives with dimethylformamide and N-methoxy-N-methylacetamide gave the corresponding α,β-unsaturated aldehydes (67–84%) and ketones (∼70%). Ketone 4b is a direct precursor of a homolog of the alkaloid ferruginine.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1794–1796, September, 2007. 相似文献
19.
Heating of 3-nitro-2-trifluoromethyl-and 3-nitro-2-trichloromethyl-2H-chromenes with indole, N-methylindole, and N-methylpyrrole under solvent-free conditions led with high stereoselectivity and in good yields to cis-trans-3-nitro-2-trifluoromethyl-or trans-cis-3-nitro-2-trichloromethylchromanes substituted by the indol-3-yl (pyrrol-2-yl) fragment in position 4.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1985–1990, October, 2007. 相似文献
20.
Jinghong Ma Yajing Xu Qingsong Zhang Liusheng Zha Borun Liang 《Colloid and polymer science》2007,285(4):479-484
A new kind of pH- and temperature-responsive semi-interpenetrating polymer network hydrogel based on linear carboxymethylchitosan
(CMCS) and poly (N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was prepared. The pH-and temperature-responsive behaviors, the
deswelling kinetics, and the mechanical properties of the hydrogel were investigated. The hydrogels exhibited a volume phase
transition temperature around 33 °C with no significant deviation from the conventional PNIPA hydrogels. The results of the
influence of pH value on the swelling behaviors showed that the minimum swelling ratios of the hydrogels appeared near the
isoelectric point (IEP) of CMCS, and when pH deviated from the IEP, the hydrogels behaved as polycations or polyanions. The
novel hydrogels had much higher response rate than the conventional CMCS/PNIPA hydrogels. Moreover, the semi-IPN hydrogels
crosslinked by clay could be elongated to more than 800% and the elongation could be recovered almost completely and instantaneously. 相似文献