The structures of o‐chlorobenzonitrile, C7H4ClN, (I), and o‐bromobenzonitrile, C7H4BrN, (II), have similar packing arrangements, even though Z′ = 4 in (I) and Z′ = 1 in (II). Both structures involve X⋯N interactions, as well as weak C—H⋯X and C—H⋯N hydrogen bonds. The four crystallographically independent molecules in (I) are related by pseudosymmetry. 相似文献
An efficient synthetic route to the concave‐shaped, potentially ionophoric syn‐ and anti‐isomers of 5,6,11,12,17,18‐hexahydro‐5,18:6,11:12,17‐triepoxytrinaphthylene ( 4 ) was elaborated. Starting from ‘oxabenzonorbornadiene’ ( 5 ), the stannylated precursor 9 was prepared in three steps, followed by cyclotrimerization catalyzed by copper(I) thiophene‐2‐carboxylate (CuTC) , which afforded 4 in a syn/anti ratio of 5 : 4. 相似文献
The title compound, C19H15N3, was prepared by condensation of 3‐nitrosocarbazole and aniline with subsequent methylation. The structure is built up of stacks of almost planar molecules. Density functional theory (DFT) calculations predict a completely planar conformation, different from that observed in the crystal lattice. HOMA (harmonic oscillator model of aromaticity) indices, calculated for three aromatic rings, demonstrate the small influence of the azo substituent on π electrons in the carbazole system. 相似文献
The molecule of the title compound (systematic name: 6‐chloroindolin‐2‐one), C8H6ClNO, is almost planar, with a dihedral angle of 1.13 (9)° between the planes of the constituent pyrrolidine and benzene rings. Centrosymmetric dimers are formed in the crystal structure by N—H...O hydrogen bonds, and these dimers are additionally linked by Cl...Cl and C—H...O interactions. Density functional theory (DFT) calculations at the B3LYP/6‐31 G(d,p) level of theory were used to optimize the molecular structure and the geometry was best reproduced by optimization of two interacting molecules. The bond orders in the molecule, estimated using the natural bond orbitals (NBO) formalism, are consistent with the observed bond lengths. In particular, the contribution of the lone pair of electrons on the N atom to the N—C bond in the N—C=O group is revealed. The measured IR spectrum of the compound shows a red shift of the N—H stretching frequency compared with the free molecule, due to the formation of the hydrogen bonds. 相似文献
A novel series of pyrazoline and thiazole derivatives incorporating 2‐pyrazolin‐5‐one moiety were synthesized starting from α,β‐unsaturated ketones under the effect of hydrazine derivatives and thiosemicarbazide. The obtained pyrazolines 4a , 4b were treated with different reagents to afford N‐substituted pyrazolines 5a , 5b , 6a , 6b , 7a , 7b , 8a , 8b . N‐Thiocarbamoyl pyrazolines 12a , 12b were cyclized using phenacyl bromide, 2,3‐dichloroquinoxaline, and monochloroacetic acid afforded the novel pyrazolinyl thiazoles 13a , 13b , 14a , 14b , 15a , 15b , 16a , 16b , 16c , 16d , 16e , 16f . The newly synthesized compounds were characterized by analytical and spectral data. 相似文献
The basic building unit in the structure of the title compound, C14H14FNO3, is pairs of molecules arranged in an antiparallel fashion, enabling weak C—H...O interactions. Each molecule is additionally involved in π–π interactions with neighbouring molecules. The pairs of molecules formed by the C—H...O hydrogen bonds and π–π interactions form ribbon‐like chains running along the c axis. Theoretical calculations based on these pairs showed that, although the main intermolecular interaction is electrostatic, it is almost completely compensated by an exchange–repulsion contribution to the total energy. As a consequence, the dominating force is a dispersion interaction. The F atoms form weak C—F...H—C interactions with the H atoms of the neighbouring ethyl groups, with H...F separations in the range 2.59–2.80 Å. 相似文献
Summary: Monomodal microwaves have overcome the safety uncertainties associated with the precedent domestic microwave ovens. After fast acceptance in inorganic and organic syntheses, polymer chemists have also recently discovered this new kind of microwave reactor. An almost exponential increase of the number of publications in this field reflects the steadily growing interest in the use of microwave irradiation for polymerizations. This review introduces the microwave systems and their applications in polymer syntheses, covering step‐growth and ring‐opening, as well as radical polymerization processes, in order to summarize the hitherto realized polymerizations. Special attention is paid to the differences between microwave‐assisted and conventional heating as well as the “microwave effects”.
Results of search on number of publications on microwave‐assisted polymerizations, sorted by year. 相似文献
Prototype testing of perchlorate‐free hand‐held signal illuminants for the US Army’s M126 A1 red‐star and M195 green‐star parachute illuminants are described. Although previous perchlorate‐free variants for these items have been developed based on high‐nitrogen compounds that are not readily available, the new formulations consist of anhydrous 5‐aminotetrazole as the suitable perchlorate replacement. Compared to the perchlorate‐containing control, the disclosed illuminants exhibited excellent stabilities toward various ignition stimuli and had excellent pyrotechnic performance. The illuminants are important from both military and civil fireworks perspectives, as the perchlorate‐free nature of the illuminants adequately address environmental concerns associated with perchlorate‐containing red‐ and green‐light‐emitting illuminants. 相似文献
Isatin (1H‐indole‐2,3‐dione) derivatives represent synthetically useful substrates which can be used to prepare a broad range of heterocyclic compounds. In the title compounds, C18H17NO5, (I), and C15H10FNO2, (II), the isatin ring systems are planar and form a dihedral angle of 73.04 (7)° in (I) and 76.82 (11)° in (II) with the benzyl groups. The bicyclic scaffolds in both compounds are almost superimposable, with an r.m.s. deviation of 0.061 Å. The crystal structures of both derivatives are stabilized by C—H...O interactions. These contacts generate an R12(7) ring motif in (I) and a C(7) chain motif in (II). 相似文献
The title compounds of sulfur, C10H6N2O4S2, (I), and selenium, C10H6N2O4Se2, (II), are isomorphous. The crystallographically centrosymmetric molecules are planar. The bond distances and angles, except for those involving the S and Se atoms, are comparable. The molecules are disposed in layers parallel to the bc plane. The molecular axes differ by 75° for (I) and by 80° for (II) from one layer to the next. 相似文献
A one‐pot method is introduced for the successful synthesis of narrow‐distributed (Đ = 1.22) vinyl polymer with both ultrahigh molecular weight (UHMW) (Mw = 1.31 × 106 g mol−1) and micro‐/nanomorphology under mild conditions. The method involves the following four stages: homogeneous polymerization, polymerization‐induced self‐assembly (PISA), PISA and reorganization, and PISA and multiple reorganizations. The key points to the production of UHMW polystyrene are to minimize radical termination by segregating radicals in different nanoreactors and to ensure sufficient chain propagation by promoting further reorganizations of these reactors in situ. This method therefore endows polymeric materials with the outstanding properties of both UHMW and tunable micro‐/nanoparticles under mild conditions in one pot.
Chitosan ( 1 ) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, 1H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan ( 2 ), which was tritylated to provide 3a and methoxytritylated to 3b . Dephthaloylation of 3a with NH2NH2?H2O gave the 6‐O‐tritylated chitosan 4a . Similarly, 3b gave the 6‐O‐methoxytritylated 4b . CuSO4‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a , and uncatalyzed diazo transfer to 4b gave 82% of azide 5b . Further treatment of 5a with CuSO4 produced 2‐azido‐2‐deoxycellulose ( 7 ). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose ( 6 ), which was deformylated to 7 . The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8 – 15 in high yields. 相似文献