排序方式: 共有74条查询结果,搜索用时 630 毫秒
21.
A method of synthesis of 2,6-diazido-3,5-dicyanopyridine, 2,4,6-triazido-3,5-dicyanopyridine, and 2,3,4,5-tetraazido-6-cyanopyridine
was developed. The heats of formation and explosive properties of compounds obtained were determined; kinetics and the composition
of the gaseous thermolysis products were studied. The replacement of endocyclic nitrogen atoms by C-CN fragments in the aromatic
ring of polyazides strongly reduces the explosive risk of these compounds with retention of the energetic properties of the
molecules. 相似文献
22.
S. V. Chapyshev 《Chemistry of Heterocyclic Compounds》2001,37(7):861-866
2,4,6-Triazido-3,5-dichloropyridine was obtained in the reaction of pentachloropyridine with sodium azide. At room temperature, this azide reacts regioslectively with norbornene at the -azide group to give the corresponding 4-(3-azatricyclo[3.2.1.0]octanyl)-2,6-diazidopyridine in 88% yield. The cycloaddition of the dimethyl ester of acetylenedicarboxylic acid to this triazide proceeds at the azide groups at C(2) and C(6) in the pyridine ring to give 4-azido-2,6-di(4',5'-dimethoxycarbonyl)-1H-1,2,3-triazolopyridine. The analogous reaction of 2,4,6-triazido-3,5-dicyanopyridine with the dimethyl ester of acetylenedicarboxylic acid stops at the formation of 2,4-diazido-6-(4',5'-dimethoxycarbonyl)-1H-1,2,3-triazolopyridine. In contrast to reactions with electron-rich dipolarophiles, the cycloaddition of electron-deficient dipolarophiles to 2,4,6-triazidopyridines proceeds with thermodynamic control primarily a! t the azide groups bearing the highest orbital density in the HOMO. 相似文献
23.
24.
Photolysis of 4-azidotetrachloropyridine isolated in inert matrices at low temperatures leads to formation of triplet tetrachloro-4-pyridylnitrene as the sole product of the photochemical reaction. In the EPR spectrum, this nitrene gives an intense signal and is characterized by zero-field splitting parameters. The UV spectrum of nitrene in solid argon contains a series of high-intensity and medium-intensity absorption bands. The IR spectrum in solid argon agrees well with nonempirical and semiempirical calculations. On exposure to light, nitrene easily reacts with molecular carbon(II) oxide, forming the corresponding isocyanate. Irradiation with light does not result in formation of bicyclic azirine, but initiates the reverse reaction of fixation by nitrene of the molecular nitrogen contained in the solid argon, leading to the starting azide. 相似文献
25.
Sergei V. Chapyshev 《Journal of fluorine chemistry》2011,132(11):991-994
3-Chlorotetrafluoropyridine and pentafluoropyridine readily react with an excess of sodium azide in dimethylsulfoxide at room temperature to give corresponding 2,4,6-triazido-3-chloro-5-fluoropyridine and 2,4,6-triazido-3,5-difluoropyridine in high yields. The reaction of asymmetric 3-chlorotetrafluoropyridine with two equimolar amounts of sodium azide under similar reaction conditions occurs regioselectively to give 2,4-diazido-5-chloro-3,6-difluoropyridine as a sole product. 19F, 13C and 15N NMR spectral characteristics of the triazides suggest that these compounds can be of interest as cross-linking reagents for polymer chemistry and as starting materials for organic synthesis. 相似文献
26.
S. I. Kuzina S. V. Tokarev D. V. Korchagin G. A. Kolpakov D. V. Khudyakov S. V. Chapyshev A. I. Mikhailov V. A. Nadtochenko S. M. Aldoshin 《Russian Chemical Bulletin》2013,62(2):255-264
High-spin intermediates with S = 2 generated by γ-radiolysis of triazidopyridines at 77 K were studied using the ESR method in the X range. Their thermal stability at 77–240 K with the transition to the one-electron states (S = 1/2) due to intermolecular reactions at 100–200 K was shown. The study of saturation processes elucidated an effect of a sharp nonlinear increase in the intensity of the ESR signals from quintet dinitrenes with an increase in the microwave field power higher than 10 mW. This effect can be applied as a method of identification of high-spin molecules obtained together with other paramagnetic products of low multiplicity and in the search for systems with molecular magnetism. A set of principles was developed for making compact undulators based on static molecular magnetic structures using dynamic effects upon the interaction of an electron beam with a laser pulse counter. 相似文献
27.
The high resolution X-band electron para magnetic resonance (EPR) spectrum of quintet pyridyl-2,6-dinitrene was recorded after the photolysis of 4-amino-2,6-diazido-3,5-dichloropyridine in solid argon matrix at 15 K. This spectrum represents a new type of powder EPR spectra that are characteristic for quintet spin states with zero-field splitting parameters |E(q)/D(q)| approximately 1/4. All EPR lines of the quintet dinitrene were unambiguously assigned based on the eigenfield calculations of the Zeeman energy levels and angular dependencies of resonance magnetic fields. Owing to the high resolution of the experimental EPR spectrum, zero-field splitting parameters of the quintet dinitrene were determined with a high accuracy: D(q)=0.2100+/-0.0005 cm(-1) and E(q)=-0.0560+/-0.0002 cm(-1). These parameters provide correct information regarding the molecular angle Theta and distance r between two triplet sites in the molecule of quintet dinitrene. The measured molecular angle Theta=114.2 degrees+/-0.2 degrees is in excellent agreement with results of the density functional theory calculations. The analysis of the magnetic parameters shows that the spin population on the nitrene units in the quintet dinitrene is greater than that on the nitrene unit in the triplet nitrene. 相似文献
28.
Chemoselective Staudinger‐Phosphite Reaction on the Azido Groups of 2,4,6‐Triazido‐3,5‐dibromopyridine 下载免费PDF全文
Sergei V. Chapyshev Alexander V. Chernyak Igor K. Yakushchenko 《Journal of heterocyclic chemistry》2016,53(3):970-974
2,4,6‐Triazido‐3,5‐dibromopyridine reacts with an equimolar amount of triethyl phosphite in ether at room temperature chemoselectively on the γ‐azido group to form 2,6‐diazido‐3,5‐dibromo‐4‐triethoxyphosphoriminopyridine as a single product. The latter adds another molecule of triethyl phosphite to give a mixture of 6‐azido‐2,4‐bis(triethoxyphosphorimino)‐3,5‐dibromopyridine and its tetrazolo[1,5‐a]pyridine isomer, the acidic hydrolysis of which affords 6‐azido‐2,4‐bis(diethoxyphosphoramino)‐3,5‐dibromopyridine. The study shows that the Staudinger‐phosphite reactions with heterocyclic polyazides occur selectively on the most electron‐deficient azido groups, opening up new prospects for preparation of new polyfunctional heterocyclic compounds. 相似文献
29.
S. V. Chapyshev 《Russian Chemical Bulletin》2011,60(11):2301-2305
It was shown using IR spectroscopy and ESR spectroscopy that UV irradiation of 2-azido-4,6-dichloro-1,3,5-triazine isolated in solid argon resulted in triplet 4,6-dichloro-1,3,5-tri-azinyl-2-nitrene (D = 1.384 cm?1, E = 0.004 cm?1), whose further photochemical transformation included the consecutive formation of 3-didehydro-1,2,4,6-tetraazepine, 2-chloro-1-diazochloromethyl-2-isocyanocarboimide, and presumably triplet 2-chloro-1-chloromethyl-idene-2-isocyanocarboimide and isocyanodichloroacetonitrile. The photolysis of 2-azido-4,6-dimethoxy-1,3,5-triazine and 2-azido-4,6-di(dimethylamino)-1,3,5-triazine affords photo-chemically stable triplet 4,6-dimethoxy-1,3,5-triazinyl-2-nitrene (D = 1.436 cm?1, E = 0.0044 cm?1) and 4,6-bis(dimethylamino)-1,3,5-triazinyl-2-nitrene (D = 1.468 cm?1, E = 0.0042 cm?1) as the final products. 相似文献
30.
EY Misochko AV Akimov AA Masitov DV Korchagin IK Yakushchenko SV Chapyshev 《The Journal of chemical physics》2012,137(6):064308
High-spin organic molecules with dominant spin-orbit contribution to magnetic anisotropy are reported. Quintet 4-azido-3,5-dibromopyridyl-2,6-dinitrene (Q-1), quintet 2-azido-3,5-dibromopyridyl-4,6-dinitrene (Q-2), and septet 3,5-dibromopyridyl-2,4,6-trinitrene (S-1) were generated in solid argon matrices by ultraviolet irradiation of 2,4,6-triazido-3,5-dibromopyridine. The zero-field splitting (ZFS) parameters, derived from electron spin resonance spectra, show unprecedentedly large magnitudes of the parameters D: ∣D(Q1)∣ = 0.289, ∣D(Q2)∣ = 0.373, and ∣D(S1)∣ = 0.297 cm(-1). The experimental ZFS parameters were successfully reproduced by density functional theory calculations, confirming that magnetic anisotropy of high-spin organic molecules can considerably be enhanced by the "heavy atom effect." In bromine-containing high-spin nitrenes, the spin-orbit term is dominant and governs both the magnitude and the sign of magnetic anisotropy. The largest negative value of D among septet trinitrenes is predicted for 1,3,5-trinitrenobenzene bearing three heavy atoms (Br) in positions 2, 4, and 6 of the benzene ring. 相似文献