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1.
The torsional frequencies have been rigorously evalulated in the compounds 1,2,4,5-tetrachloro-3,6-dinitrobenzene and 1,3,5-trichloro-2,4-dinitrobenzene
over an extended temperature range (77K–392K) using the experimental results of NQR and crystal structure data. The values
have been compared with those obtained by using the X-ray thermal parameters. 相似文献
2.
3.
I. A. Buryakov 《Technical Physics》2002,47(11):1453-1457
A technique for finding the electric field dependence of the coefficient of ion mobility in gases is suggested. For ions of 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, 1,3,5-trinitrobenzene, 1,3-dinitrobenzene, and dimethylmethylphosphonate, these dependences are taken in air by applying a variable periodic polarity-asymmetric specially shaped electric field. The accuracy of the technique suggested is estimated and compared with that of the conventional drift tube method. 相似文献
4.
Albert R. Matlin Karen Feit Brinton Belinda Tsao Nivaggioli 《Journal of Physical Organic Chemistry》2007,20(2):83-87
The effect of 4‐oxa substitution on the regiochemistry and rate of 5‐hexenyl radical cyclizations was investigated, as a potential model for [2 + 2] photocycloadditions of 2‐acyl‐4‐oxa‐1,5‐hexadienes. Increasing the electron density in the alkene decreases the rate of cyclization in the 4‐oxa‐hexenyl radicals, relative to the all carbon analogs, but has little effect on the regioselectivity of the cyclization. The radical model does not reproduce the high degree of 1,6 closure, observed in the [2 + 2] photocycloadditions for 4‐oxa‐1,5‐hexadiene 1a . However, the radical model does reinforce the interpretation that ground state conformational effects, engendered by substitution remote from the reacting centers have important rate consequences for cyclization reactions. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
5.
Claisen–Schmidt condensation of various substituted acetophenones with cinnamaldehyde catalyzed by KF–Al2O3 results chalconoid-like compounds, (2E,4E)-1,5-diarylpenta-2,4-dien-1-ones, in 67–92% yields in 5–60 min under ultrasound irradiation. 相似文献
6.
B.D. Nageswara Rao 《Molecular physics》2013,111(4):307-310
The 1H and 19F resonance spectra of 1-fluoro-2,4-dinitrobenzene in pure liquid and in 5 mole per cent solutions in benzene and acetone were obtained and analysed by an iterative computer calculation. The results for the pure liquid are in good agreement with perturbation calculations performed on this spectrum earlier. It is shown that the deviation between the values of coupling constants obtained earlier in benzene solution, acetone solution and pure liquid are not due to the method of analysis. 相似文献
7.
Thermodynamic,kinetic, and mechanistic examination of 1,5‐ dihydro‐3,4‐dihydroxy‐2‐pyrrolone derivatives as a new type of antioxidants to mimic vitamin C 下载免费PDF全文
Lin Yuan Yuan‐Yuan Mu Guang‐Bin Shen Xiao‐Qing Zhu 《Journal of Physical Organic Chemistry》2017,30(8)
In this work, 1,5‐dihydro‐3,4‐dihydroxy‐2‐pyrrolone derivatives (XH2) and their anions (XH?) were designed and synthesized as the synthetic vitamin C analogs. The thermodynamic driving forces of the 8 possible elementary steps for XH2 to release 2 hydrogen atoms to become X in acetonitrile were determined using experimental methods. The mechanisms and the possible reaction intermediates of XH2 and XH? reacted by DPPH ? in acetonitrile were examined or predicted using the determined thermodynamic analysis combining the kinetics. 相似文献
8.
An efficient, fast and facile pyrazolo[1,5-a]pyrimidine synthetic protocol has been established by the condensation of aminopyrazoles with 1,3-dicarbonyl components in
AcOH/H2SO4 system. The pyrazolo[1,5-a]pyrimidine sulfides were selectively oxidized to the sulfones via a temperature-controlled stepwise oxidative fashion. The
correlation between the substitution patterns of these pyrazolo[1,5-a]pyrimidines and their fluorescent spectroscopic properties were further examined, which provided the fundamentals for their
potential applications in the development of new fluorescent probes. Red-shifts were easily achieved by the incorporation
of unsaturated groups at the 5- and 7-positions, which suggested an approach for synthesizing long wavelength pyrazolo[1,5-a]pyrimidine dyes. The fluorescent spectroscopic properties were found to be sensitive to the hydroxy-containing and carbonyl-containing
media such as alcohol and acetone, which helps to confirm the promising perspectives of further investigations in this area. 相似文献
9.
Xu J 《Molecular diversity》2005,9(1-3):45-49
A 1H-azeto[2,1-d][1,5]benzothiazepin-1-one, -lactam derivatives of dihydrobenzothiazepines library derived from reactions of 2,4-disubstituted 2,3-dihydro-1,5-benzothiazepines and acyl chlorides, including phthalimidoacetyl chloride, chloroacetyl chloride, dichloroacetyl chloride and phenoxyacetyl chloride, was built up through parallel solution-phase synthesis. Stereochemistry of 1H-azeto[2,1-d][1,5]benzothiazepin-1-ones in the reaction process is discussed. 相似文献
10.
By combining a three-component reaction of 2, 3-diaminomaleonitrile, ketones and isocyanides with a subsequent reaction of
1,6-dihydropyrazine-2,3-dicarbonitrile derivatives obtained from isocyanide-based three-component reaction with various alkyl
and aryl isocyanates or isothiocyanates can be assembled a new class of highly substituted imidazo[1,5-a]pyrazine derivatives. 相似文献
11.
Peter A. Wade James K. Murray Alma Pipic Robert J. Arbaugh Amutha Jeyarajasingam 《Journal of Physical Organic Chemistry》2009,22(4):337-342
Nitroaldol reaction of phenylsulfonylnitromethane with formaldehyde affords a mixture of 2,4‐dinitro‐2,4‐bis(phenylsulfonyl)butan‐1‐ol and 2,4‐dinitro‐2,4‐ bis(phenylsulfonyl)pentane‐1,5‐diol. Treatment of this mixture with base followed by reacidification affords 1,1'‐[(1,3‐dinitro‐1,3‐propanediyl)bis(sulfonyl)]bis(benzene) as a mixture of (R*, R*) and (R*, S*)‐diastereomers from which the (R*, S*)‐diastereomer can be obtained pure. The intermediate in the nitroaldol reaction is (1‐nitroethenyl)sulfonylbenzene and, if dienes are present, additional products are also obtained. If either (E)‐2‐methyl‐1,3‐pentadiene or 1‐(1‐methylethenyl)cyclohexene are present, typical Diels‐Alder adducts are obtained with the major isomers explainable by assuming a transition state in which the nitro group is endo. If furan is present, its formal conjugate addition product, 2‐[2‐nitro‐2‐(phenylsulfonyl)ethyl]furan, is formed. If cyclooctatetraene is present, it first dimerizes and then affords isomeric Diels‐Alder cycloadducts of the dimer. Semiempirical calculations comparing the LUMO energies of (1‐nitroethenyl)sulfonylbenzene to the corresponding trans‐1,2 isomer are presented to explain relative reactivity of 1,1‐ and 1,2‐disubstituted dienophiles. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
12.
Bamaprasad Bag 《Journal of luminescence》2007,126(1):27-36
A fluorescence signaling system (L1) has been synthesized in the format, ‘fluorophore-spacer-receptor’ with an ‘amino-alkyl-amino’ group as the receptor where an anthracene and a 2,4-dinitrobenzene moieties are attached at two ends. As evident from the photophysical behavior of this system, attachment of methyl groups to the donor N atoms not only increases the charge-transfer character of the signaling system, but imparts structural rigidity and perturbs the binding ability of the receptor core, that results in selective fluorescence enhancement in presence of Zn(II). Solid-state structure of L1 is determined by X-ray crystallography. 相似文献
13.
Ultrasonic intensification of ozone and electrochemical destruction of 1,3-dinitrobenzene and 2,4-dinitrotoluene 总被引:2,自引:0,他引:2
Abramov VO Abramov OV Gekhman AE Kuznetsov VM Price GJ 《Ultrasonics sonochemistry》2006,13(4):303-307
The removal of nitroaromatics from polluted water is difficult due to their high stability to conventional treatment methods. This paper presents a method for the destruction of 1,3-dinitrobenzene and 2,4-dinitrotoluene in aqueous solutions. The compounds are shown to be stable to reaction with ozone, even under ultrasonic activation. The use of ultrasound enhances the rate of electrochemical reduction but the overall rate of reaction is still slow. However, the simultaneous application of ultrasound and ozonation to the electrochemical reaction allows virtually complete destruction of the compounds in short times. The effect is attributed to the ultrasonic enhancement of the electrochemical process giving intermediates that are susceptible to ozone oxidation. While further analytical work is needed to deduce the exact contributions of the various possible degradation mechanisms, the work demonstrates the synergies that can be gained by using combined techniques for the destruction of these difficult compounds. 相似文献
14.
Traceless synthesis of 2-aminoimidazoquinoxalinones has been performed on soluble polymer support under open-vessel microwave
dielectric heating. The reaction progression is monitored directly by the conventional proton NMR which indicated no release
of the substrate from the support. Fmoc-deprotected amino acid polymer conjugates react with 1,5-difluoro-2,4-dinitro benzene
to yield polymer bound dinitro fluoro amines, which are further substituted by various primary amines to yield PEG-immobilized
dinitrodiamines. Simultaneous reduction of aromatic meta-dinitro group leads to the traceless release of 2-quinoxalinones, followed by N-hetero cyclization with various isothiocyanates
in the presence of mercury(II)chloride to furnish 2-aminoimidazoquinolinone rings with three points of diversity at rapid
pace. 相似文献
15.
2,4-Disubstituted benzo[b][1,5]thiazepines represent nonfluorescent intense yellow chromophores and are readily synthesized
from acid chlorides, terminal alkynes, and ortho-amino thiophenols by a consecutive one-pot three-component Sonogashira coupling–Michael addition–cyclocondensation sequence
under mild conditions in good yields. 相似文献
16.
B.V. Pond C. Mullen I. Suarez J. Kessler K. Briggs S.E. Young M.J. Coggiola D.R. Crosley H. Oser 《Applied physics. B, Lasers and optics》2007,86(4):735-742
We report studies using laser photoionization and time-of-flight mass spectrometry to detect several explosive-related compounds
(ERCs). The ultimate goal of this work is the detection of buried land mines through their chemical signatures. Resonantly
enhanced multiphoton ionization using jet expansion cooling, with a nanosecond pulse laser, results in complete photofragmentation
of the parent ERC and appearance only of the NO+ ion, which forms all of the detected signal. This will also occur for compounds naturally occurring in the environment, such
as NO2 or peroxyacetylnitrate, rendering too many false alarms for this approach to be viable. Therefore, two other techniques were
evaluated. Single-photon ionization with nanosecond pulses in the vacuum ultraviolet is shown to produce only the parent ion,
and is probably the most suitable choice. For 2,4-dinitrobenzene we find a limit of detection of about 40 ppb, for a signal
to noise ratio of 3. This may be sufficient for land-mine detection, but improvement is likely with future work. Nonresonant
multiphoton ionization in the ultraviolet with a femtosecond laser produces fragmentation but retains some parent ERC ion
signal. The limit of detection is similar to that of single-photon ionization but it is harder to implement with lasers now
commercially available. Future directions are outlined.
PACS 07.07.Df; 33.80.Rv; 82.80.Ms; 82.80.Rt 相似文献
17.
Summary The phosphorus ylide obtained from the reaction between 2-aminobenzo[d]isothiazol-3-one and dimethyl acetylenedicarboxylate in the presence of triphenylphosphine undergoes a smooth intramolecular
Wittig-type reaction to produce, in a one-pot reaction, 3-H-benzo[d]pyrazolo[1,5-b]isothiazole-2,3a-dicarboxylic acid dimethyl ester, a novel functionalized heterocyclic compound. 相似文献
18.
Yana I. Sakhno Svetlana V. Shishkina Oleg V. Shishkin Vladimir I. Musatov Elena V. Vashchenko Sergey M. Desenko Valentin A. Chebanov 《Molecular diversity》2010,14(3):523-531
Heterocyclization reactions of pyruvic acids, aromatic aldehydes and 5-amino-N-aryl-1H-pyrazole-4-carboxamides yielding four different types of final compounds are described. The reactions involving arylidenpyruvic
acids lead with high degree of selectivity to either 4,7-dihydropyrazolo[1,5-a]pyrimidine-5-carboxylic acids or 5-[(2-oxo-2,5-dihydrofuran-3-yl)amino]-1H-pyrazoles, depending on the catalyst type or temperature regime. The interactions based on arylpyruvic acids can take place
under kinetic or thermodynamic control producing 7-hydroxy-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine-7-carboxylic acids or 3-hydroxy-1-(1H-pyrazol-5-yl)-1,5-dihydro-2H-pyrrol-2-ones, respectively. 相似文献
19.
基于THz光谱技术的1,3-二硝基苯挥发气体检测方法研究 总被引:1,自引:0,他引:1
针对工业生产过程中1,3-二硝基苯挥发气体突发性泄露等情况的发生,设计了一种基于太赫兹(THz)特征光谱吸收技术的检测方法,该方法可通过1,3-二硝基苯在THz波段的特征波长对痕量剧毒有害气体进行检测。系统设计了双气室结构,为THz波提供差分数据,一组为标准空气,另一组为待测样气。由1,3-二硝基苯在THz波段的四个主吸收带0.635,0.912,1.095和1.435THz可根据对应吸收带吸收系数的比例关系得到对应波长上的吸收幅值,最终反演气体浓度。经过对两种传统检测方法的实验分析和对THz吸收检测方法的仿真研究可知,色谱法检测速度无法实现实时检测,红外吸收法对环境湿度要求很高,需经干燥处理,而THz吸收法对环境湿度要求较低,且具备实时性,更适合于实际应用。 相似文献
20.
Three novel triazine based organic chromophores with D-π-A (Donor-π system- Acceptor) push-pull type have been synthesized from 2, 4-diamino-6-phenyl-1,3,5-triazine as a starting material. Structures of all the three compounds have been confirmed by UV-Visible absorption, FT-IR, NMR and Mass spectral techniques. Their photo physical and thermal properties have been investigated. Among the three compounds, 6-phenyl-2,4-((4-amino-1,5-dimethyl-2-phenyl pyrazol-3-ylidene)(4-nitro benzylidene))-diamino-1, 3, 5-triazine (NDP) showed positive solvatochromism compared to the other two compounds. The absorption in the UV region of these three compounds were found to be less dependent on solvent polarities, whereas the red shifted fluorescence was strongly dependent on solvent polarities. The TGA data indicates that all the three compounds are stable up to 160 °C. Measurement of non linear optical properties showed that there is an increased second harmonic generation (SHG) efficiency with respect to urea indicating the existence of high molecular nonlinearity in NDP. 相似文献