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1.
The gas-phase reaction of ozone with eight 1,2-disubstituted alkenes has been investigated at ambient temperature (T = 286–296 K) and p = 1 atm. of air. The reaction rate constants, in units of 10−18 cm3 molecule−1s−1, are 144 ± 17 for cis-3-hexene, 157 ± 25 for trans-3-hexene, 89.8 ± 9.7 for cis-4-octene, 131 ± 15 for trans-4-octene, 114 ± 13 for cis-5-decene, ≥ 130 for trans-5-decene, 38.3 ± 5.0 for trans-2.5-dimethyl-3-hexene, and 40.3 ± 6.7 for trans-2.2-dimethyl-3-hexene. Substituent effects on alkene reactivity are examined. Cis-1,2-disubstituted alkenes are less reactive than the corresponding trans isomers. The 1,2-disubstituted alkenes that bear bulky substituents (substitution at the 3-carbon) are ca. 3 times less reactive than the corresponding n-alkyl substituted compounds. The atmospheric persistence of 1,2-disubstituted alkenes is briefly discussed. © 1996 John Wiley & Sons, Inc. 相似文献
2.
The mean-square radius of gyration of poly(1,1-disubstituted ethylene)s is calculated according to a method already developed for poly(methyl methacrylate), poly(α-methylstyrene) and polyitaconate. During the derivation both the effect of side groups and the masses of skeletal atoms were taken into account. A hypothetical polymer chain was introduced, in which the mass of the substituents on every Cα was considered to be concentrated in their center of mass, and the virtual side bond vector runs from Cα to this center. The mean-square radius of gyration of poly(1,1-disubstituted ethylene)s consists of two parts, one of which is the mean-square radius of gyration of the hypothetical molecule described before and the other is related to the geometrical characteristics of the side groups. Numerical calculations indicated that the dependence of the mean-square radius of gyration of poly(1,1-disubstituted ethylene)s on the molecular weight is analogous to that of vinyl polymers, 〈S2〉 = aMb, where a and b are constants characteristic of the polymer. 相似文献
3.
Zdzisław Brzozowski 《合成通讯》2013,43(11):1639-1645
Several N,N-disubstituted aromatic amines (3a–g) was obtained in very good yield by the reaction of adequate doubly activated aromatic or heteroaromatic halides (1a–e) with N,N-disubstituted formamides (2a–c). Analogously, starting from 4-chloro-3-pyridinesulfonamide, the appropriate 4-dialkylamino-1H +-pyridinium-3-(N-formyl)sulfonamidates (5a,b) were obtained in 52–60% yield. Mechanisms of the reactions are discussed. 相似文献
4.
Tomohiro Hirano Misato Sugiura Ryuya Endo Miyuki Oshimura Koichi Ute 《Journal of polymer science. Part A, Polymer chemistry》2020,58(20):2857-2863
The stereochemical analysis of polymers derived from N,N-disubstituted acrylamides is usually difficult. The diad tacticity can be determined from the 1H nuclear magnetic resonance (NMR) signals of the main-chain methylene groups. However, the splitting because of the configurational sequences is poor, even in 13C NMR, which does not allow determination of the tacticity at the triad level. In contrast, the stereochemical analysis of polymers derived from N-monosubstituted acrylamides is easily conducted and the triad tacticity can be determined from the 13C signals of the main-chain methine groups. Thus, stereochemical analysis of N,N-disubstituted polymers should be able to be conducted if the polymers are transformed into N-monosubstituted polymers with retention of the configurational sequence. Poly(N-tert-butyl-N-n-propylacrylamide) was radically prepared, and de-tert-butylation was conducted by treatment with scandium triflate in a mixed solvent of CH3CN and 1,4-dioxane at 50, 80, and 110°C. 1H NMR analysis of the resulting polymers indicated quantitative conversion after 72 hr, regardless of the temperature. 13C NMR analysis of the transformed polymers confirmed that the configurational sequences were retained during the reaction. Thus, the triad stereochemical analysis of N,N-disubstituted polymers was successfully conducted by de-tert-butylation as a polymer reaction, followed by 13C NMR analysis of the transformed polymers. 相似文献
5.
Krishna C. Joshi Vijai N. Pathak Urmila Garg 《Journal of heterocyclic chemistry》1979,16(6):1141-1145
Nine new fluorine containing 5-amino-1,3-disubstituted pyrazoles have been synthesized and characterized by spectral studies. Condensation reactions of these 5-amino-1,3-disubstituted pyrazoles with fluorinated 1,3-diketones in the presence of glacial acetic acid have been studied and the structures of the resulting 1H-pyrazolo[3,4-b]pyridines have been confirmed by ir, pmr and 19F nmr spectral studies. 相似文献
6.
Dr. Anthony Choi Dr. Ashraf El-Tunsi Yuhang Wang Prof. Anthony J. H. M. Meijer Jia Li Dr. Xiabing Li Dr. Ilaria Proietti Silvestri Prof. Iain Coldham 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(45):11670-11675
Kinetic resolution of 2-arylindolines (2,3-dihydroindoles) was achieved by treatment of their N-tert-butoxycarbonyl (Boc) derivatives with n-butyllithium and sparteine in toluene at −78 °C followed by electrophilic quench. The unreacted starting materials together with the 2,2-disubstituted products could be isolated with high enantiomer ratios. Variable temperature NMR spectroscopy showed that the rate of Boc rotation was fast (ΔG≠≈57 kJ/mol at 195 K). This was corroborated by DFT studies and by in situ ReactIR spectroscopy. The enantioenriched N-Boc-2-arylindolines were converted to 2,2-disubstituted products without significant loss in enantiopurity. Hence, either enantiomer of the 2,2-disubstituted products could be obtained with high selectivity from the same enantiomer of the chiral ligand sparteine (one from the kinetic resolution and the other from subsequent lithiation-trapping of the recovered starting material). Secondary amine products were prepared by removing the Boc group with acid to provide a way to access highly enantioenriched 2-aryl and 2,2-disubstituted indolines. 相似文献
7.
Cycloaddition of dichloroketone to N,N-disubstituted (E)-4-aminomethylene-3,4-dihydro-1-benzoxepin-5(2H)-ones gave N,N-disubstituted 4-amino-3,3-dichloro-3,4,5,6-tetrahydro-2H-pyrano[3,2-d]-1-benzoxepin-2-ones II, which are derivatives of the new heterocyclic system 2H-pyrano[3,2-d]-1-benzoxepin. Dehydrochlorination with triethylamine of II afforded N,N-disubstituted 4-amino-3-chloro-5,6-dihydro-2H-pyrano-[3,2-d]-1-benzoxepin-2-ones III in good to moderate yields. In the triethylamine treatment of IIh (NR2 = diphenylamino), 3-chloro-5,6-dihydro-2H-pyrano[3,2-d]-1-benzoxepin-2-one was isolated in low yield near to IIIh, whereas IIc (NR2 = diisopropylamino) gave in low yield 4-diisopropylamino-5,6-dihydro-2H-pyrano(3,2-d)-1-benzoxepin-2-one. 相似文献
8.
Summary The acid promoted decomposition of 2-(10-diazo-10H-anthracen-9-ylidene)-malonodinitrile in the presence of water, methanol, ethanol, acetic and propionic acid, ethyl thioglycolate,p-thiocresole, and acetyl acetone yielding 9,10-disubstituted 9,10-dihydroanthracenes was investigated. Treatment of the reaction products with tri-ethyl amine followed by hydrochloric acid caused their tautomerization to the corresponding 9,10-disubstituted anthracenes. A mechanism for this reaction is proposed. The first example of an intermolecular C-C-bond formation during the protic acid promoted decomposition of a diazo compound in the presence of CH-acids was found. An improved procedure for the preparation of the starting diazo compound, which may serve as a convenient precursor of 9,10-disubstituted anthracenes, is described.Cordially dedicated to Prof. Dr.K. Winsauer on the occasion of his 70th birthday 相似文献
9.
New Heteroarenes: Synthesis and Spectroscopic Properties of Indolizino[6,5,4,3-aij]quinoline (‘Ullazine’) and of some Derivatives The synthesis, 1H-NMR, 13C-NMR and electronic absorption spectra of indolizino[6,5,4,3-aij]quinoline (6a) , a new π-excess heteroarene, and of three 3,9-disubstituted derivatives are described. 相似文献
10.
The13C-chemical shifts ofN, N-disubstituted andN-monosubstituted 4-aminomethylene-2-pyrazolin-5-ones are reported and discussed. On the basis of coupling constants3
J(13C–H) it is demonstrated that the intramolecular hydrogen bond ofN-monosubstituted compounds1 b, c is not cleaved in a dipolar aprotic solvent, such asDMSO. 相似文献
11.
The natural abundance 13C NMR spectra of 2,2′-dimethyl-, 2,2′-dimethoxy- and 2,2′-dihydroxybiphenyls, and a series of 2,2′-dimethoxy-5,5′-disubstituted biphenyls were recorded. Unambiguous signal assignments of the carbons ortho and para to an aryl ring in biphenyls were made by selective deuteration and/or the graphical method for 1H single frequency off-resonance decoupled spectra. Contrary to the reported assignments, it was shown that the signal for C-6 in 2,2′-dimethylbiphenyl clearly appears at lower field than that for C-4. The signals for the ortho carbons (C-6) of 2,2′-dimethoxy-5,5′-disubstituted biphenyls generally appeared at lower fields than those for the para carbons (C-4). The validity of applying deuterium isotope shifts to the assignments of 13C chemical shifts of di- and tetra-substituted biphenyls is also discussed. 相似文献
12.
《Journal of Coordination Chemistry》2012,65(3):247-252
Abstract Mercury(II) complexes of imidazolidine-2-thione and its derivatives have been synthesized and their 1H, 13C and 199Hg NMR spectra measured. HgCl2 forms L2HgCl2 type complexes (where L = imidazolidine-2-thione and its derivatives). The NH group of the ligand is shifted downfield by about +1.37 ppm in the 1H NMR after complexation. The C-2 carbon in the 13C NMR is shifted by—6.50 ppm for mono N-substituted ligands, but by—5.30 ppm for N,N''-disubstituted ligands. The 199Hg NMR resonance is shifted by about—60 ppm for N-substituted ligands, but—140 ppm shifts were observed for N',N'-disubstituted ligands. 相似文献
13.
The gas-phase reaction of ozone with eight alkenes including six 1,1-disubstituted alkenes has been investigated at ambient T (285–298 K) and p = 1 atm. of air. The reaction rate constants are, in units of 10−18 cm3 molecule−1 s−1, 9.50 ± 1.23 for 3-methyl-1-butane, 13.1. ± 1.8 for 2-methyl-1-pentene, 11.3 ± 3.2 for 2-methyl-1,3-butadiene (isoprene), 7.75 ± 1.08 for 2,3,3-trimethyl-1-butene, 3.02 ± 0.52 for 3-methyl-2-isopropyl-1-butene, 3.98 ± 0.43 for 3,4-diethyl-2-hexene, 1.39 ± 17 for 2,4,4-trimethyl-2-pentene, and >370 for (cis + trans)-3,4-dimethyl-3-hexene. For isoprene, results from this study and earlier literature data are consistent with: k (cm3 molecule−1 s−1) = 5.59 (+ 3.51, &minus 2.16) × 10−15 e(−3606±279/RT), n = 28, and R = 0.930. The reactivity of the other alkenes, six of which have not been studied before, is discussed in terms of alkyl substituent inductive and steric effects. For alkenes (except 1,1-disubstituted alkenes) that bear H, CH3, and C2H5 substituents, reactivity towards ozone is related to the alkene ionization potential: In k<(10−18 cm3 molecule−1 s−1) = (32.89 ± 1.84) − (3.09 ± 0.20) IP (eV), n = 12, and R = 0.979. This relationship overpredicts the reactivity of C≥3 1-alkenes, of 1,1-disubstituted alkenes, and of alkenes with bulky substituents, for which reactivity towards ozone is lower due to substituent steric effects. The atmospheric persistence of the alkenes studied is briefly discussed. © 1996 John Wiley & Sons, Inc. 相似文献
14.
The proton NMR spectra of four cis/trans pairs of 1,2-disubstituted olefins have been analysed. The observed trends of the olefinic, vicinal and allylic proton-proton coupling constants are discussed in terms of rehybridization at the sp2 carbon atoms. It is found that in these substances the trans-allylic couplings are generally more negative than the cis-allylic couplings contrary to Barfield's1 theoretical prediction but in agreement with some earlier experimental data. Steric hindrance between cisoid substituents is cited as the probable origin of this end related trends. 相似文献
15.
A series of 3,4-disubstituted ( 4a , b ) or 3,4-fused ( 4c - e ) 1,1-di-fluorocyclopropabenzenes, including the very strained 1,1-difluoro-3,4-dihydro-1 H-cyclobuta[a]cyclopropa[d]benzene ( 4e ) have been synthesized and characterized. Dissolution of these difluoro derivatives in fluorosulfonic acid affords the fluoro cations 3a – e . 1H-, 19F-, and 13C-NMR data of the cations are reported and discussed with respect to those of the precursors. 相似文献
16.
Luisa Mosti Pietro Schenone Giulia Menozzi Fernando Sancassan Francarosa Baccichetti Franco Benetollo Gabriella Bombieri 《Journal of heterocyclic chemistry》1988,25(2):407-413
1,4-Cycloaddition of phenylchloroketene to N,N-disubstituted 5-aminomethylene-6,7-dihydrobenzo[b]- furan-4(5H)-ones gave the corresponding adducts, namely N,N-disubstituted 4-amino-3-chloro-3,4,5,6-tetra- hydro-3-phenyl-2H-furo[2,3-h]-l-benzopyran-2-ones II , which were dehydrochlorinated with DBN to N,N-disubstituted 4-amino-5,6-dihydro-3-phenyl-2H-furo[2,3-h]-1-benzopyran-2-ones III . Compounds III afforded the title compounds IV by dehydrogenation with DDQ. In the cycloaddition step, 3-phenylangelicin V , whose structure was confirmed by 1H-nmr shift reagents data and by X-ray crystal structure determination, was almost always formed, probably starting from II by dehydrochlorination, dehydrogenation and hydrogenolysis of the disubstituted amino group. Separation of V was achieved by alumina chromatography either in the cycloaddition step or, in most cases, in the dehydrochlorination step. 3-Phenylangelicin crystallizes in the trigonal system, space group R3, with cell parameters (hexagonal axes) a = b = 41.021(10), c = 3.888(2) Å. The angelicin moiety forms a dihedral angle of 42.1(1)° with the phenyl substituent. Disordered solvent molecules of ethyl acetate are clathrated in channels in the direction of the crystallographic axis c. 相似文献
17.
V. V. Kuznetsov E. A. Alekseeva V. V. Khudyakov Yu. A. Levshov 《Russian Journal of General Chemistry》2002,72(3):400-404
1H NMR spectroscopy and MM+ and AM1 calculations were used for configurational assessment of stereoisomers of 4-methyl-2,5-disubstituted 1,3,2-dioxaborinanes (differing in the configuration of the ring C4 atom). The molecules are conformationally inhomogeneous; this is due to the internal rotation of the substituent at the C5 atom, while in the cis isomers, in addition, by the equilibrium between the S-4e5a and S-4a5e
sofa conformations, shifted to the latter form. 相似文献
18.
Synthesis,Characterization, and Antimicrobial Potential of Some 1,4-Disubstituted 1,2,3-Bistriazoles
C. P. Kaushik Krishan Kumar Dharmendra Singh S. K. Singh Deepak Kumar Jindal Raj Luxmi 《合成通讯》2013,43(17):1977-1985
AbstractA convenient synthesis of some new 1,4-disubstituted 1,2,3-bistriazoles (3a–3f, 4a–4f, 6a–6b, 7a–7b) is reported via copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of various terminal alkynes with 1,4-bis(azidomethyl)benzene and 1,6-diazidohexane. The synthesized compounds were characterized by spectral techniques including infrared, 1H NMR, 13C NMR, and high-resolution mass spectrometry and tested in vitro for antimicrobial potential against Bacillus subtilis and Staphylococcus aureus (Gram-positive bacteria), Pseudomonas aeruginosa and Escherichia coli (Gram-negative bacteria), and Candida albicans and Aspergillus niger (fungi). Among the synthesized 1,4-disubstituted 1,2,3-bistriazoles, compounds 6a, 6b, and 7b displayed excellent antimicrobial potential against most of the tested strains. 相似文献
19.
A. V. Logvinov I. N. Polyakova E. L. Golod 《Russian Journal of General Chemistry》2010,80(11):2366-2373
Alkylation of 5-aminotetrazole with tert-butyl alcohol or adamantan-1-ol in sulfuric acid gave a mixture of isomeric N
1- and N
2-alkyl derivatives, as well as 1,3-dialkyl-5-aminotetrazolium salt. Adamantylation of 1-substituted 5-aminotetrazoles led
to the formation of mixtures of 1,3- and 1,4-disubstituted 5-aminotetrazolium salts which can be converted into the corresponding
free bases. 相似文献
20.
N. Arumugam P. Manisankar S. Sivasubramanian D. A. Wilson 《Magnetic resonance in chemistry : MRC》1984,22(9):592-596
Substituent effects on the 1H and 13C chemical shifts of 18 differently substituted (Z)-α,N-diaryl nitrones [N-(p-X-benzylidene)phenylamine N-oxides (Series I) and N-(benzylidene)-p-Y-phenylamine N-oxides (Series II)] have been obtained. A correlation has been found between the chemical shifts of the azomethine proton (H-α) and the Hammett σ parameters and the Swain and Lupton F and R parameters. Correlations of the chemical shifts of C-1 and C-4′ in Series I, and of C-α and C-1′ in Series II, with the same parameters have been investigated. In addition, the chemical shifts of the aromatic protons and carbons of the p-disubstituted (m-disubstituted in one case) benzene rings correlated with the appropriate substituent increments (Zi). These correlations confirm the dual behaviour of the nitrone group and the presence of through-resonance in these nitrones. 相似文献