- Synthesis, characterization, and antibacterial activity of diorganotin(IV) complexes of 4-methylphenol
-
Diorganotin(IV) complexes R2Sn(OC6H 4Me-4)2 (R = Ph, Me, and n-Bu) have been synthesized in good yields by the reaction of Ph2SnCl2, n-Bu 2SnCl2, and Me2SnCl2 with NaOC 6H4Me-4, while complex n-Bu2SnCl(OC 6H4Me-4) has been obtained from the reaction of n-Bu 2SnCl2 with 4-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, molecular weight determination, IR, 1H, 13C, and 119Sn NMR spectroscopy as well as by mass spectrometry. The reactions of the complexes with 2- and 3-cyanoanilines yielded 1:2 coordination compounds authenticated by physicochemical as well as by IR, 1H, and 13C NMR spectroscopic data. The bases behaved as monodentate ligands wherein 2-cyanoaniline is bonded through nitrile nitrogen atom, while 3-cyanoaniline is coordinated through amino nitrogen atom. The diorganotin(IV) complexes have also been screened for their antibacterial activity against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Shigella flexneri, Proteus mirabilis, and Pseudomonas aeruginosa. The minimum inhibitory concentration values of these complexes show enhanced activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright Taylor & Francis Group, LLC.
- Sharma, Neeraj,Kumar, Vijay
-
-
Read Online
- Iminophosphorano-Substituted Bispyridinylidenes: Redox Potentials and Substituent Constants from Tolman Electronic Parameters
-
Bispyridinylidenes (BPYs) have emerged as an important class of neutral organic electron donors, with redox potentials that vary widely with choice of substituent. Methods to predict the effect of substitution on the redox potential are therefore highly desirable. Here we show that the redox potential of BPYs featuring iminophosphorano substituents (R3P=N-), which represent the most reducing class of BPYs, can be predicted based on the well-known Tolman electronic parameter (TEP) for the respective phosphine fragment (R3P). Moreover, building on earlier work relating redox potentials to Hammett-type substituent constants, it is now possible to quantitatively predict σp+ values for iminophosphorano substituents from TEP values. These results provide a path for precisely tailoring redox potentials of iminophosphorano-substituted BPYs, but also give quantitative descriptors for how these highly versatile iminophosphorano substituents can impact the properties of any molecular scaffold.
- Decken, Andreas,Dyker, C. Adam,Hetherington, Sydney M.,Khor, Chun Keat,Mills, Scott L.,Richard, Nicholas A.
-
-
Read Online
- Synthesis, characterization and antibacterial activity, of triorganotin(IV) complexes of 4-methylphenol
-
The triorganotin(IV) complex of composition Ph3Sn(OArMe-4) has been synthesized in good yields by the reaction of Ph3SnCl with Me3SiOArMe-4/NaOArMe-4, while com-plexes of composition Me 3Sn(OArMe-4) and n-Bu3Sn(OArMe-4) (where -OArMe-4 = -OC6H4CH3-4) have been obtained from the reaction of Me3SnCl and n-Bu3SnCl with 4-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, mo-lecular weight determination and IR, 1H and 13C NMR and mass spectral studies. Ther-mal behaviour of the complexes has been studied by TG and DTA techniques. The organotin(IV) complexes have also been screened for their antibacterial properties and are found to exhibit appreciable activity. The reactions of the complexes with 2-, 3-, 4-cyanopyridines yielded 1:1 adducts as confirmed by physicochemical and IR spectral data.
- Sharma, Neeraj,Kumar,Thakur,Kumari,Chaudhry
-
experimental part
p. 2051 - 2065
(2010/09/04)
-
- METHODS FOR PRODUCING PERFLUOROALKANEDI(SULFONYL CHLORIDE)
-
Novel methods for preparing perfluoroalkanedi(sulfonyl chloride) are disclosed as are uses for these compounds. In one aspect, a method comprising reacting dibromoperfluoroalkane with Na2S2O4 followed by treating with chlorine, an organic compound, and then chlorine to form perfluoroalkanedi(sulfonyl chloride) is provided. Novel perfluoroalkanedi(sulfonyl bromide) compounds are also disclosed.
- -
-
Page/Page column 10
(2009/05/29)
-
- Mechanistic study of Protein Phosphatase-1 (PP1), a catalytically promiscuous enzyme
-
The reaction catalyzed by the protein phosphatase-1 (PP1) has been examined by linear free energy relationships and kinetic isotope effects. With the substrate 4-nitrophenyl phosphate (4NPP), the reaction exhibits a bell-shaped pH-rate profile for kcat/KM indicative of catalysis by both acidic and basic residues, with kinetic pKa values of 6.0 and 7.2. The enzymatic hydrolysis of a series of aryl monoester substrates yields a Bronsted βlg of -0.32, considerably less negative than that of the uncatalyzed hydrolysis of monoester dianions (-1.23). Kinetic isotope effects in the leaving group with the substrate 4NPP are 18(V/K)bridge = 1.0170 and 15(V/K) = 1.0010, which, compared against other enzymatic KIEs with and without general acid catalysis, are consistent with a loose transition state with partial neutralization of the leaving group. PP1 also efficiently catalyzes the hydrolysis of 4-nitrophenyl methylphosphonate (4NPMP). The enzymatic hydrolysis of a series of aryl methylphosphonate substrates yields a Bronsted βlg of -0.30, smaller than the alkaline hydrolysis (-0.69) and similar to the βlg measured for monoester substrates, indicative of similar transition states. The KIEs and the βlg data point to a transition state for the alkaline hydrolysis of 4NPMP that is similar to that of diesters with the same leaving group. For the enzymatic reaction of 4NPMP, the KIEs are indicative of a transition state that is somewhat looser than the alkaline hydrolysis reaction and similar to the PP1-catalyzed monoester reaction. The data cumulatively point to enzymatic transition states for aryl phosphate monoester and aryl methylphosphonate hydrolysis reactions that are much more similar to one another than the nonenzymatic hydrolysis reactions of the two substrates.
- McWhirter, Claire,Lund, Elizabeth A.,Tanifum, Eric A.,Feng, Guoqiang,Sheikh, Qaiser I.,Hengge, Alvan C.,Williams, Nicholas H.
-
scheme or table
p. 13673 - 13682
(2009/02/06)
-
- Synthesis of polyphosphazenes with sulfonimide side groups
-
The invention relates to sulfonimide bearing phenolic compounds and the use of those compounds to produce polyphosphazenes functionalized by one or more of those compounds alone, or in combination with cosubstituents. The invention also relates to blends of sulfonimide functionalized phosphazene polymers with other polymers, membranes formed of the functionalized polymers, and the use of those membranes in devices such as fuel cells.
- -
-
Page 7; 12-13
(2010/02/09)
-
- Kinetics and mechanism of alkaline hydrolysis of aryl carbazates
-
Hydrlysis of aryl carbazates (H2NNHCO2Ar with Ar=phenyl, 3- or 4-chlorophenyl, 3- or 4-nitrophenyl, 4-methylphenyl and 4-methoxyphenyl) and/or their 2- or 3-methyl derivatives in aqueous buffers or sodium hydroxide solutions gives phenolate and sodium carbazate. the kinetics and acidity constants and thermodynamic parameters are given.By analysing the pH profiles, the activation entropy, and effects of the substituent on the aromatic ring it was found that aryl carbazates containing a methyl group in the 2 position are hydrolysed by a BAc2 mechanism and the others by an E2cB mechanism.The pH profiles of nitrophenyl carbazates show a maximum.The rate of decarboxylation of carbazic acid decreases with increasing pH value.
- Vlasak, Petr,Mindl, Jaromir
-
p. 1401 - 1404
(2007/10/03)
-
- Free Radical Combination Reactions Involving Phenoxyl Radicals
-
The rates of phenoxyl radical reactions with the superoxide anion radical, O2.-, a peroxyl radical, HOC(CH3)2CH2OO., and an alkyl radical, HOC(CH3)2CH2., in aqueous solution have been measured for 15 different phenoxyl radicals by means of pulse radiolysis.In addition, the one-electron reduction potentials of 10 phenoxyl radicals have been determined.The fraction of electron transfer in the reaction of phenoxyl radicals with O2.- was determined by analysis of γ-irradiated samples.The experimental data can be accommodated by the Marcus theory for electron transfer, with the reorganization energy λ0 = 155 kJ/mol for the reaction between O2.- and phenoxyl radicals.
- Jonsson, M.,Lind, J.,Reitberger, T.,Eriksen, T. E.,Merenyi, G.
-
p. 8229 - 8233
(2007/10/02)
-
- Nucleophilic Attacks on Carbon-Carbon Double Bonds. 34. Intramolecular Element Effect in Competitive Expulsion of Two Halide Nucleofuges as a Tool for Investigating the Rapid Step of Nucleophilic Vinylic Substitution
-
The substitution of 9-(bromochloromethylene)fluorene (8) and β,β-bis(p-nitrophenyl)-α-bromo-α-chloroethylene (9) by p-toluenethiolate and p-cresolate ions gives the monobromo, the monochloro, and the disubstitution products.The / substitution product ratios were determined in CD3CN, DMSO-d6, and DMSO-d6-CD3OD under conditions where the disubstitution was negligible.The ratios were 2.0-3.2, were slightly higher for 8 than for 9, and showed no discernible solvent dependence.The ratios did not change in the presence of radical traps although an ESR spectrum was observed with 8 and p-MeC6H4S-.The "intermolecular element effects" kBr/kCl derived from competitive substitution of 8 or 9 with their dibromo or dichloro analogues were 1.2-1.76.The results were interpreted in terms of a multistep nucleophilic vinylic substitution proceeding via an intermediate carbanion, which may be formed either directly or by an initial single-electron transfer followed by combination of the anion radical and the radical.The ratios of the products were hence identified as the ratios of the rate constants for expulsion of Br- and Cl- (kel(Br)/kel(Cl)-the "intramolecular element effect") from the carbanion.The low ratios and their relative insensitivity to the solvent and to the delocalizing ability of negative charge of the β-substituents were ascribed to an early transition state for the expulsion of halide ions from the carbanion.Generalizations concerning the expulsion of poor and good nucleofuges from carbanions substituted by poor and good electron-withdrawing groups are discussed.
- Avramovitch, Bianca,Weyerstahl, Peter,Rappoport, Zvi
-
p. 6687 - 6697
(2007/10/02)
-
- EFFECT OF THE STRUCTURE OF THE LEAVING GROUP, MEDIUM, AND TEMPERATURE ON THE ALKALINE HYDROLYSIS OF PHENYL BENZOATES IN WATER-DIOXANE MIXTURES
-
A spectrophotometric study was carried out on the kinetics of the alkaline hydrolysis of a series of para-substituted phenyl benzoates PhCO2C6H4X-p in water, 30 and 70 vol. percent aqueous dioxane at 15 deg, 25 deg, and 55 deg C.The bimolecular rate constants depend on the medium composition, temperature, and structure of the leaving group.It is of value to apply linear free energy (LFE) principles in studying these factors, which permits description of the entire set of experimental data by a single multidimensional regression equation.The Arrhenius equation parameters were calculated and this reaction series was shown to be compensated, in contrast to the alkaline hydrolysis of phenyl acetates.The dependence of the ρ constants in the Hammett-Taft equation on the medium composition and temperature indicate that this value is not a linear function of the extent of formation and breakage of bonds in the transition state.
- Sukhoruchkov, Yu. I.,Polonov, V. M.,Finkel'shtein, B. L.,Istomin, B. I.
-
p. 1014 - 1019
(2007/10/02)
-