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1.
The prototropic rearrangement of 3-phenyl-1-propenes to the corresponding 1-phenyl-1-propenes was investigated in basic media utilizing 0.1M sodium ethoxide in absolute ethanol at 81°C. It was found that the effect of substituents on the rate of such isomerizations follows the order: p-NO2 > o-Cl > m-Cl ≥ m-F > p-Br > o-CH3 > m-CH3 > m-CH(CH3)2 > p-CH(CH3)2p-C(CH3)3 > o-OCH3. This is consistent with first-order kinetics and “BS” mechanism. Quantitative treatment in terms of Hammett's equation showed a straight line, with a slope (p value) of +2.25. An increase in the strength of the base was also found to cause an increase in the rate of isomerization.  相似文献   

2.
Loss of CO from the molecular ions ([CH3OC6H4COF]+˙) of o-, m- and p-anisoyl fluorides has been investigated by mass-analysed ion kinetic energy (MIKE) spectrometry. This reaction involves fluorine atom migration from the carbonyl group to the benzene ring. In the cases of o- and p-anisoyl fluorides, the fluorine atom migrates via a three-membered transition state to form the molecular ions ([CH3OC6H4F]+˙) of o- and p-fluoroanisoles, respectively. On the other hand, in the case of m-anisoyl fluoride, the fluorine atom migrates from the carbonyl group to the benzene ring via a three- or four-membered transition state.  相似文献   

3.
Benzyl o-, m-, and p-substituted phenyl methyl sulfonium salts ( 2b – 2g ) were synthesized and their activities as cationic initiators were evaluated in the bulk polymerization of phenyl glycidyl ether (PGE). Especially, their activities were estimated with respect to the effect of substituents on the aryl groups. In the polymerizations of PGE with a series of benzyl p-substituted phenyl methyl sulfonium salts, the order of their activities was found to be 2c (CH3OCOO) > 2b (CH3COO) > 2d (CH3O) ~ 2a (HO). In particular, 2c was the most active initiator of all, capable of initiating the polymerization of PGE even at room temperature. In the polymerizations with 2a, 2e (m-Cl), 2f (o-CH3), and 2g (m-CH3), the activity of 2e was the highest of all while those of 2a, 2f , and 2g were almost the same. These results strongly suggested that the electron-withdrawing group placed on the aryl group undoubtedly enhanced the activity of the sulfonium salts as the cationic initiators.  相似文献   

4.
The crystal structure of [(p‐CH3C6H4)3GeCH(o‐CH3C6H4)CH2CO2]2Sn(C4H9)2 consists of a monomer with the atoms of tin and germanium both occupying tetrahedral geometries. However, the tin atom is distorted towards a skew trapezoidal bipyramid geometry as a result of weakly chelating carboxylate ligands. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

5.
The coordination polymers [Ag4(O2CCF3)4(phen)3] ? phen ? arene ( 1? phen ? arene) (phen=phenazine; arene=toluene, p‐xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o‐xylene and m‐xylene as the solvent yield the solvent‐free coordination polymer [Ag4(O2CCF3)4(phen)2] ( 2 ). Toluene, p‐xylene and benzene have been successfully used in mixed‐arene syntheses to template the formation of coordination polymers 1? phen ? arene, which incorporate o‐ or m‐xylene. The selectivity of 1? phen ? arene for the arene guests was determined, through pairwise competition experiments, to be p‐xylene>toluene≈benzene>o‐xylene>m‐xylene. The largest selectivity coefficient was determined as 14.2 for p‐xylene:m‐xylene and the smallest was 1.0 for toluene:benzene.  相似文献   

6.
The fungicidal activity of a series of aryltin com‐<?tw=99%>pounds, Ar3SnOAc (Ar = m‐Tol (m−CH3C6H4),<?tw>­3,5‐Xyl [3,5‐(CH3)2C6H3], o‐Tol (o−CH3C6H4) or Mes [2,4,6‐(CH3)3C6H2]) and (Ar3Sn)2O [Ar = m‐Tol, m‐Anis (m‐CH3OC6H4), or o‐Tol] as well as (Mes)3SnOH, for which IR and NMR (119Sn) data are reported, has been assessed­by radial growth assays on Aspergillus niger, Botrytis cinera, Mucor hiemalis, Fusarium solani and Penicillium chrysogenum, and the results­are compared with those for the corresponding triphenyl‐ and tris (p‐tolyl)‐tin compounds. In general, sterically hindered systems (Ar =­Mes) which are unlikely to achieve a trigonal‐bipyramidal five‐coordinate geometry at tin­with oxygen atoms in the axial positions, are ineffective as fungicides. However the o‐tolyltin compounds, particularly the acetate, show some fungicidal activity. A larger size (m‐Anis) or number (3,5‐Xyl) of meta groups decreases fungicidal activity (to zero against P. chryso‐­genum) in comparison with (m‐Tol)3SnX. Indeed, where test substances are inactive as fungicides, they promote the growth rate of P.chrysogenum by up to 60%. The steric effects implied by these data suggest that dimensions of active sites in the F0 unit of the ATPase enzyme may differ significantly for each fungus studied. A model for the active site is proposed, based on the need of the Ar3Sn+ unit first to be able to reach the active site and then to occupy it with the required five‐coordinate geometry so as to inhibit the activity of the ATPase enzyme. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

7.
Optically active cyclopropanes (e.g. 1 ) can be prepared by the use of tartaric acid derivatives as chiral auxiliaries in the palladium-catalyzed cross-coupling of optically active cyclopropylboronic acids with electrophiles. The absolute configuration of the chiral carbon atom is retained, and the reaction proceeds with good yields and enantiomeric excesses. R=H, p-Ph, o-CO2CH3, p-CO2CH3, p-NO2, o-OCH3, m-OCH3.  相似文献   

8.
The rates of cleavage of some XC6H4CH2SnMe3 bonds by aqueous-methanolic perchloric acid have been measured spectrophotometrically, and the rate of cleavage of the MeSn bonds of PhCH2SnMe3 and Me4Sn by monitoring the methane evolution. The results indicate that for X = H, p-Me, o-Me, p-But, o-, m- and p-F and -Cl, and o-Br, the cleavage of the CH2SnMe3 bond involves attack of the acid at the benzylic atom, and is not much faster than that of the SnMe bonds, but that a mechanism involving ring-protonation is important for X = m-Me, and greatly predominant for X = m-OMe.  相似文献   

9.
Five novel ortho‐, meta‐, and para‐methyl‐substituted triphenylmethyl methacrylate monomers, such as o‐tolyldiphenylmethyl methacrylate (o‐MeTrMA), di‐o‐tolylphenylmethyl methacrylate (o‐Me2TrMA), tris‐o‐tolylmethyl methacrylate (o‐Me3TrMA), tris‐m‐tolylmethyl methacrylate (m‐Me3TrMA), and tris‐p‐tolylmethyl methacrylate (p‐Me3TrMA) have been synthesized. The methanolysis rates of these monomers were measured in CDCl3‐CD3OD (1:1, v/v) by 1H NMR spectroscopy at 30 °C. It was found that the order of the methanolysis rates would be TrMA<o‐MeTrMA<o‐Me2TrMA<o‐Me3TrMA<m‐Me3TrMA except p‐Me3TrMA, which exhibited very good stability to methanolysis. The asymmetric polymerization of these monomers was investigated by chiral anionic complexes as initiators. The results showed that the ability to form a helical chain was effected not only by the types of chiral complex initiators, but also by the position and number of methyl‐substituted groups at the benzene rings of TrMA. The order of the ability of polymerization was o‐MeTrMA >o‐Me2TrMA>o‐Me3TrMA and m‐Me3TrMA> p‐Me3TrMA>o‐Me3TrMA. These differences would be attributed to the different sizes and “propeller” steric structures of the bulky side groups. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 430–436, 2001  相似文献   

10.
The kinetics of the reactions between sodium nitrite and phenol or m-, o-, or p-cresol in potassium hydrogen phthalate buffers of pH 2.5–5.7 were determined by integration of the monitored absorbance of the C-nitroso reaction products. At pH > 3, the dominant reaction was C-nitrosation through a mechanism that appears to consist of a diffusion-controlled attack on the nitrosatable substrate by NO+/NO2H2+ ions followed by a slow proton transfer step; the latter step is supported by the observation of basic catalysis by the buffer which does not form alternative nitrosating agents as nitrosyl compounds. The catalytic coefficients of both anionic forms of the buffer have been determined. The observed order of substrate reactivities (o-cresol ≈ m-cresol > phenol ≫ p-cresol) is explained by the hyperconjugative effect of the methyl group in o- and m-cresol, and by its blocking the para position in p-cresol. Analysis of a plot of ΔH# against ΔS# shows that the reaction with p-cresol differs from those with o- and m-cresol as regards the formation and decomposition of the transition state. The genotoxicity of nitrosatable phenols is compared with their reactivity with NO+/NO2H2+. © 1997 John Wiley & Sons, Inc.  相似文献   

11.
Collisional activation mass spectra confirm that tolyl ions can be produced from a variety of CH3C6H4Y compounds. High purity o-, m- and p-tolyl ions are prepared by chemical ionization of the corresponding fluorides (Y=F) as proposed by Harrison. In electron ionization of CH3C6H4Y formation of the more stable tropylium and benzyl ionic isomers usually accompanies that of the o-, m- and p-tolyl ions. Isomerization of low energy [CH3C6H4Y]+? to [Y–methylenecyclohexadiene]+? is proposed to account for most [benzyl]+ formation, while the tropylium ion appears to arise from the isomerization of tolyl ions formed with higher internal energies, [o-, m-, p-tolyl]+→ [benzyl]+→ [tropylium]+, consistent with Dewar's predictions from MINDO/3 calculations.  相似文献   

12.
Chemical shifts for tritons in chlorobenzene have been measured in the pure compound and in a dilute solution in cyclohexane using a 64 MHz NMR spectrometer. The order of shifts is o>m>p. Triton shifts in pure bromobenzene, fluorobenzene and toluene have also been measured and the influence of CCl4 solvent on the aromatic triton shifts in toluene explored. Complete resolution of the three aromatic triton positions is achieved in pure toluene, but the ortho and para shifts are not resolved in 25% solution in CCl4.  相似文献   

13.
The microstructure of the micelles formed in aqueous solution by gemini surfactants with aromatic spacers, [Br(CH3)2N+(C m H2 m +1)-(Ph)-(C m H2 m +1)N+(CH3)2Br, m=8 and Ph = o-, m- or p-phenylenedimethylene] has been examined by small-angle neutron scattering. Aggregation of the gemini surfactants with an o-phenylenedimethylene spacer brings about formation of premicelles and small micelles at concentrations below the second critical micelle concentration, while above this concentration marked micellar growth and variation in shape occurs. It is suggested that the minimum aggregate formed at this critical micelle concentration may be the trimer or tetramer and that this result supports the mechanism of “gemini → submicelle → assembly” for micellar growth. Received: 8 September 1998 Accepted in revised form: 27 November 1998  相似文献   

14.
5,10,15,20‐Tetrakis[4‐(triorganostannyloxy)phenyl]porphyrins, (R3SnO)4TPP [2, R = Cy (a), Ph (b), PhC(CH3)2CH2 (c)], have been synthesized by the condensation of 4‐(triorganostannyloxy)benzaldehyde, 4‐(R3SnO)C6H4CHO (1), with pyrrole in the presence of BF3 followed by oxidation by p‐chloranil and characterized by means of elemental analysis, IR, UV–visible and NMR (1H, 13C and 119Sn) spectra. The results of X‐ray single‐crystal diffraction show that 1a and 1b possess a trans‐C3SnO2 trigonal bipyramidal geometry with the axial positions occupied by the phenolate oxygen and formyl group oxygen of an adjacent molecule and form a one‐dimensional zigzag chain. In 2a, the macrocyclic core of the porphyrin is coplanar and each tin atom possesses a distorted tetrahedral geometry. These compounds (1 and 2) have potent in vitro cytotoxic activity against two human tumor cell lines – CoLo205 and MCF‐7 – and the activity decreases in the order Ph > Cy > PhC(CH3)2CH2 for the R group bound to tin. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

15.
Densities of sodium nitrobenzoate (o-, m-, p-) have been measured in dimethylformamide (DMF)–water mixtures at 298.15 K with an oscillating-tube densimeter. From these densities, apparent molar volumes of sodium nitrobenzoate in DMF–H2O-mixtures have been calculated and partial molar volumes at infinite dilution have been evaluated. Substituent and solvent effects on the transfer volumes of each isomer from water to DMF–H2O-mixed solvents have also been obtained. The results are explained in terms of solvent–solvent and solute–solvent interactions.  相似文献   

16.
N,N‐Diethyldithiocarbamate complexes of 2‐alkoxycarbonylethyltin trichloride, ROCOCH2CH2 SnCl3?x[S2CNEt2]x (R = CH3 ( a ); CH3CH2 ( b ); CH2?CHCH2 ( c ); CH3CH2CH2 ( d ); CH3CH2CH2CH2 ( e ); x = 1 ( 1 ), 2 ( 2 )) were synthesized and characterized by means of elemental analysis, IR, and NMR (1H, 13C and 119Sn) spectra. The crystal structure of 1b (i.e. R = CH3CH2, x = 1) was determined and shows that the tin atom adopts a distorted octahedral geometry with both a five‐membered chelate ring, formed via carbonyl coordination to tin, and a four‐membered chelate ring, formed by the bidentate dithiocarbamate. The spectral data and ab initio calculations indicate that intramolecular carbonyl‐oxygen to tin coordination in 1a–1e persists, but not in 2a–2e , owing to the preference of the dithiocarbamate ligands to chelate the tin centre. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

17.
The polymeric chains of [Sn(CH3)3(C28H25O3Ge)]n contain trimethyltin moieties bridging two neighboring 3‐(triphenylgermyl)‐3‐o‐methoxypropionate ligands via carboxyl groups. The germanium atom has a distorted tetrahedral geometry and the tin atom has a distorted trigonal‐bipyramidal geometry, the latter with three methyl groups in the equatorial plane and oxygen atoms defining the axial positions. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

18.
3-Aminopropanol reacts with aryl(or aralkyl or alkyl)isothiocyanates R? N?C?S to yield the corresponding thio-ureas R? NH? CS? NH? (CH2)3OH which, refluxed with hydrochloric acid, are cyclized by elimination of water. The cyclization products are identical with the hydrothiazines resulting by elimination of sulfate or phosphate from the sulfuric or phosphoric monoesters of these thio-ureas. The resulting hydrothiazines are either 2-(R-imino)-tetrahydro-m-thiazines (I) or 2-(R-amino)-dihydro-Δ2-m-thiazines (II). Their structure has been established by comparison of their spectra with those of model compounds in one of which the C?N double bond is certainly endocyclic (2-methyl-dihydro-Δ2-m-thiazine), the other presenting an exocyclic C?N double bond (3-methyl-2-phenylimino-tetrahydro-m-thiazine). When R is an aryl group, the C?N double bond is exocyclic (structure I with >C?N? Ar), and one may presume that this structure is stabilized by resonance. When R is an aralkyl or an alkyl group, the C?N double bond is endocyclic (structure II). The nmr spectra were taken with three types of solvent: CDCl3 or CCl4; (CD3)2SO; CF3COOH. In CF3COOH solution the benzylic protons of the hydrothiazine with R = pF? C6H4CH2? couple with NH (J=5,5cps) which confirms the endocyclic position of the C?N double bond in this case.  相似文献   

19.
Six new triorganotin complexes ( 1a – 1c and 2a – 2c ) of 5‐(salicylideneamino)salicylic acid, [5‐(3‐X‐2‐HOC6H3CH═N)‐2‐HOC6H3COO]SnR3 (X = H, 1 ; CH3O, 2 ; R = Ph, a ; Cy, b ; CH2C(CH3)2Ph, c ), have been synthesized by one‐pot reaction of 5‐aminosalicylic acid, salicylaldehyde and triorganotin hydroxide and characterized using elemental analysis and infrared and NMR (1H, 13C and 119Sn) spectra. The crystal structures of 1a , 1b , 2a ·CH3OH, 2b ·CH3OH and 2c ·CHCl3 have been determined using single‐crystal X‐ray diffraction. In non‐coordinated solvent CDCl3, the tin atoms in the complexes are all four‐coordinated. In the crystalline state, these compounds adopt a four‐ or five‐coordination mode. Complex 1a exhibits a 44‐membered macrocyclic tetrameric structure with trigonal bipyramidal geometry around the tin atoms in which the axial positions are occupied by the oxygen atom of carboxylate group of the ligand and the phenolic oxygen atom from the adjacent ligand. The coordination geometry of tin atom in 1b and 2c ·CHCl3 is a distorted tetrahedron shaped by three carbon atoms of alkyl groups and a carboxylate oxygen atom of the ligand. In 2a ·CH3OH and 2b ·CH3OH, the tin atom has a distorted trans‐C3SnO2 trigonal bipyramidal geometry formed by three alkyl groups, a monodentate carboxylate group and a coordinated methanol molecule. The molecules of 2a ·CH3OH and 2b ·CH3OH are linked via O─H···O hydrogen bonds into a one‐dimensional supramolecular chain and a centrosymmetric R44(22) macrocycle, respectively. Bioassay results against two human tumor cell types (A549 and HeLa) show the complexes are efficient cytostatic agents and may be explored as potential antitumor drugs.  相似文献   

20.
Some new bimetallic carboxylates of tin and germanium with general formula where R1 = m-CH3C6H4, p-CH3C6H4, C6H5, R2 = o-CH3C6H4, p-CH3C6H4, o-CH3OC6H4, C6H5, CH3, have been prepared by the condensation reaction of diethyltin oxide and triarygermyl(substituted)propanoic acid in 1:2 mole ratio, respectively, and characterized by multinuclear (1H, 13C, 119Sn) NMR, 119mSn Mössbauer and IR spectroscopy. The X-ray crystal structure of the ligand I4 [(C6H5)3GeCH(o-CH3OC6H4)CH2COOH] delineate four coordinated germanium atom with a peculiarity of having a molecule of solvent (CHCl3). The chiral center in the synthesized compounds was identified on the basis of 1H NMR data and measurements of angle of rotations.  相似文献   

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