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1.
The infrared and Raman spectra of 1,2-dichloro-, 1-chloro-2-bromo- and 1,2-dibromopropane were recorded as liquids, in polar and non-polar solvents and in the crystalline state at low temperatures. The infrared spectrum of a high pressure crystal of 1,2-dibromopropane was recorded at ambient temperature. Dipole measurements were carried out in CCl4 and C6H6solutions.Each of the 1,2-dihalopropanes existed as a mixture of three conformers in the liquid state, the one with the halogens in the anti position was in large abundance. Spectral and dipole measurements revealed a comparatively larger concentration of the two polar gauche conformers in polar solvents. All the compounds crystallized in the anti form. The C-halogen stretching vibrations have been interpreted in detail. Vibrational analyses of the anti conformers have been carried out and a tentative assignment of the majority of the gauche bands has been proposed.  相似文献   

2.
13C cross-polarisation magic angle spinning NMR data have been reported for four derivatives of 4-aryl-octahydro-pyrido[1,2-c]pyrimidine-1,3-dione and the X-ray diffraction data for two (with 2′-Me and 2′-OMe). The crystal structures show the presence of centrosymmetric cyclic dimers with intermolecular C1O?H-N or C3O?H-N hydrogen bonds, the configuration at the chiral centres (C4 and C4a) was determined as RR (SS). The twisting of aromatic ring at C4 with respect to the pyrido[1,2-c]pyrimidine skeleton is about 68-109°.  相似文献   

3.
Functionalized 1,2-dithioles have been synthesized by a ring opening-closing process of 5-substituted- and 5-unsubstituted-2-alkylidene-4-oxothiazolidines with Lawesson's reagent. The 13C NMR data confirmed the meso-ionic structure of these aromatic-type 1,2-dithioles.  相似文献   

4.
A new, one-pot and three-component synthesis of 4H-pyrido[1,2-a]pyrimidines, 4H-pyrimido[1,2-a]pyrimidines, and 4H-pyrazino[1,2-a]pyrimidines is described. The reactive 1:1 zwitterionic intermediate, formed by the addition of isocyanides to dialkyl acetylenedicarboxylates, was trapped by N-(2-heteroaryl)amides to yield a ketenimine intermediate, which was cyclized and then rearranged under the reaction conditions to afford the title compounds under mild reaction conditions in good yields. Single-crystal X-ray analysis conclusively confirms the structure of the obtained bridgehead bicyclic 6-6 heterocyclic compounds.  相似文献   

5.
The crystal and molecular structure of 1,2-diphenyl-1,2-diphospholane-1, 2-disulphide has been determined from three dimensional X-ray diffraction data
by Patterson and Fourier techniques. The structure has been refined by full matrix least squares methods to a final R value of 0.055 based on 1733 observed reflexions. The unit cell is orthorhombic, space group P212121, with dimensions a = 13.867 Å, b = 12.379 Å and c = 9.312 Å (all ± 0.003 Å), and contains 4 molecules. The PP bond length of 2.253 ± 0.002 Å is similar to that in several diphosphine disulphides and phosphorus sulphides, and indicates the absence of any π bonding in the PP bond.  相似文献   

6.
Electrochemical behavior of [1,2-b]selenophenes and 4H-selenochromenes in organic media and their interaction with hydrogen sulfide have been studied. In aprotic solvents (CH2Cl2 and CH3CN), the organoselenium compounds are oxidized at anode to give cation-radicals. In the presence of hydrogen sulfide, at its oxidation potential (1.60 V) [1,2-b]selenophenes and 4H-selenochromenes undergo recyclization into corresponding thiophenes and thiochromenes. The recyclization yielding sulfur analogs have been studied in the presence of organic electromediators, including the transition metal complex with redox-active ligands, as well.  相似文献   

7.
The molecular structure and conformational behavior of 3-cyclopropyl-1,2-dimethyldiaziridine have been for the first time experimentally studied by gas-phase electron diffraction and quantum chemical calculations. The two most stable conformers at 298 K possess anti and gauche mutual ring orientation (with prevalence of the anti conformer) whereas only one anti conformer is observed in solution. The determined structural parameters of gaseous 3-cyclopropyl-1,2-dimethyldiaziridine have been compared with those for 3,3-bidiaziridine structural analogues in the crystal phase. The simple and convenient procedure for the synthesis of 3-cyclopropyl-1,2-dimethyldiaziridine comprising cyclopropane and diaziridine rings in one molecule was developed. The standard enthalpy of formation of 3-cyclopropyl-1,2-dimethyldiaziridine in the gas phase was calculated using Gaussian-4 theory, yielding value of 281.9?±?5.0 kJ/mol.  相似文献   

8.
Neutron inelastic scattering spectra of 1,2-dichloroethane crystal have been measured at three temperatures above and below 177°K where the crystal undergoes a broad phase transition. Two and three peaks have been observed in the high and low temperature phases, respectively. The frequency distribution g(v) has been calculated in the first Brillouin zone for the low temperature phase and is compared with the observed spectra. The results show that the phase transition at 177°K is associated with rotational motion of the molecule around the axis passing through two chlorine atoms.  相似文献   

9.
An efficient one-pot procedure has been developed for the synthesis of bis-1,5,3-dithiazepanes by reaction of ethane-1,2-dithiol with formaldehyde and ammonium salts. According to the X-ray diffraction data, the heterorings in 3,3′-[ethane-1,2-diylbis(sulfanediylmethanediyl)]bis(1,5,3-dithiazepane) in crystal adopt a chair conformation with axial orientation of the substituent on the nitrogen atom.  相似文献   

10.
Infrared spectra of 1,2-dicyanotetrafluoroethane have been recorded in the vapour, glassy solid, and crystalline solid states. Raman spectra have been recorded of the liquid and the crystalline solid. The trans form is shown to exist alone in the crystal, while trans and gauche forms co-exist in the vapour, liquid and in the amorphous solid with the trans conformer dominating.Complete vibrational assignments are proposed for the trans and for the gauche conformers. The latter in particular places heavy reliance upon the normal coordinate calculations.  相似文献   

11.
I.D. Biggs  J.M. Tedder 《Tetrahedron》1978,34(9):1377-1380
Twelve 4(N-arylamino)-1,2-naphthoquinones (1) have been prepared by the direct addition of substituted anilines to 1,2-naphthoquinone, and their spectra have been studied. In the solid and in ethanol solution the 1,2-naphthoquinone tautomer (1a) predominates, but in trifluoroacetic acid the 2-hydroxy-1,4-naphthoquinone-4-aryliminium (2a) is the major species.  相似文献   

12.
A series of benzyl, 2-picolyl, 3-picolyl armed tetrahomodioxacalix[4]arene tetraamideswith four p-phenyl groups on the upper rim were synthesized. They were found to be in the C-1,2-alternate conformation by 1H, 13C NMR, andX-ray crystal structure.The nitrogen atom of the 2-picolyl group played an important role in the metal ion complexation.  相似文献   

13.
The molecular and crystal structure of 2,3a-dimethyl-4-phenyl-3-ethoxycarbony-5-oxo-4a,5-dihydro-4H-indeno[1,2-b]pyridine has been determined, and its reduction and alkaline and acid hydrolysis reactions have been studied.Translated from Khimiya Geterotsiklicheskikh Soedineii, No. 10, pp. 1388–1392, October, 1984.  相似文献   

14.
In situ inclusion of the laser dyes coumarin 466, coumarin 7, pyridine 2 and DCM has been conducted successfully in AlPO4-5 crystals. The charged molecule pyridine 2 interacts with the framework and leads to bundle-like morphologies with increasing dye content. Uncharged molecules (DCM, coumarin 7, coumarin 466) are included, although corresponding molecular dimensions are exceeding pore size. These dyes probably induce local defects in the pore walls of AlPO4-5 which are healed during crystal growth leading to well-developed hexagonal prisms. Spectroscopic studies show interactions of the dyes with the solid-state matrix which are reflected by shifts of absorption and emission maxima of the dyes. For the first time, laser activity is demonstrated on a perfect hexagonal single AlPO4-5/DCM crystal.  相似文献   

15.
A novel organic assembly, formed between 3,5-dinitro-4-methylbenzoic acid and trans-1,2-bis(4-pyridyl)ethene under hydrothermal conditions in the presence of Pr(III) and a layered structure obtained by direct co-crystallization of the reactants at ambient conditions is reported. The structures of the complexes were established, unambiguously, by single crystal X-ray diffraction methods.  相似文献   

16.
The crystal structure of 3,5,7-triphenyl-4H-1,2-diazepine (monoclinic, a = 8.132, b = 13.180, c = 24.204 Å, β = 104.15°, space group P21/c. Z = 4) has been determined by X-ray analysis. The 1,2-diazepine ring adopts a boat conformation with a methylene group at the prow. The phenoxide group of the picrate moiety is bonded to one of the diazepine nitrogen atoms through an hydrogen bond.  相似文献   

17.
Irene Ortín 《Tetrahedron》2009,65(48):9944-6277
To avoid the epimerization of the C(11a)-stereocenter previously observed in 6,11a-cis-pyrazino[1,2-b]isoquinolin-1,4-diones, we present in this paper the C(3)-alkylation of 1-methoxy-pyrazino[1,2-b]isoquinolin-4-ones to obtain all-cis derivatives through a very reliable protocol. The success of the acid-promoted cyclization to get pentacyclic (R3=arylmethyl) or tetracyclic (R3=2-bromo-2-propenyl) compounds is dependent on the nature of the C(3)-unsaturated chain and of the N-substituent, but these limitations have been overcome by using trifluoromethanesulfonic as a superacid catalyst. The C-(3)-alkylation of pyrazino[1,2-b]isoquinolin-4-one is also studied.  相似文献   

18.
N,N-disalicylidene-(R,S)(S,R)-1,2-ethanediamine crystallizes in orthorhombic space group Pbca with a = 9.5634(6), b = 14.2917(9), c = 16.9181(8) Å and Z = 4. The crystal structure was solved by direct methods and refined by full-matrix least squares to final values R1 = 0.0 + 399 and wR2 = 0.1004 with 2755 reflections (I > 2σ(I)). The N,N-disalicylidene-(R,S)(S,R)-1,2-ethanediamine molecules exhibit intramolecular N-H...O and are connected by C-H...O and C-H...π interactions to form a 2D supramolecular network.  相似文献   

19.
A series of potential biologically active 2-[3-(4-phenyl-1-piperazinyl)propyl]-3-(4-substituted-benzoyl)-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides was synthesized in a straightforward manner by condensation of respective 3-substituted-4-hydroxy-1,2-benzothiazine 1,1-dioxides with 1-(1-chloropropyl)-4-phenylpiperazine. The structures of all of the newly formed compounds were identified by elemental analysis, FTIR and 1H NMR. The synthesized compounds were subjected to preliminary evaluation using differential scanning calorimetry (DSC) to determine the existence of multiple crystal forms. The DSC scans for all compounds show more than one endothermic effect, which might suggest dynamic proton transfer between two or three possible tautomeric forms: O-keto/O-enol, O-enol/O-keto and O-keto/O-keto/CH2 in crystals 2-[3-(4-phenyl-1-piperazinyl)propyl]-3-(4-substituted-benzoyl)-4-hydroxy-2H-1,2-benzothiazine 1,1-dioxides.  相似文献   

20.
The pressure-scanning differential thermal analyzer (DTA) measurements of the cubic (Cub)-smectic C (SmC) transition of thermotropic cubic mesogens of 1,2-bis-(4-n-octyloxybenzoyl)- and 1,2-bis-(4-n-dodecyloxybenzoyl)hydrazine, BABH(8) and BABH(12), were performed at isothermal condition using a high-pressure differential thermal analyzer. BABH(8) showed the same endothermic peak of the Cub-SmC transition in the pressurizing process as on heating at isobaric condition. On the other hand, BABH(12) showed only the cubic phase between the crystal and the isotropic liquid under pressures up to 16-17 MPa, but a high-pressure smectic C (SmC(hp)) phase was induced instead of the cubic phase under higher pressure. The Cub-SmC(hp) phase transition with a small exothermic peak occurred in the pressurizing process and the transition was observed reversibly. The Cub-SmC(hp) phase transition was in accordance with the morphological and structural observations mentioned before. The strange phenomenon of the inversion of sign of the Cub-SmC transition heat of BABH(n) homologues can be explained by the “Alkyl-chains as entropy reservoir” mechanism proposed by Saito et al.  相似文献   

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