- Guaiacol intermediate and preparation method thereof
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The invention provides a guaiacol intermediate. A structure formula of the guaiacol intermediate is as shown in the description. The invention also provides a preparation method of the guaiacol intermediate. The preparation method comprises the following
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Paragraph 0031; 0032; 0033
(2016/10/10)
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- Phenylthio-derivatives of α-methylene-γ-lactones as pro-drugs of cytotoxic agents
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A series of substituted phenylthio-derivatives of grosheimin (1), a natural cytotoxic guaianolide, were investigated with the aim of providing insight into their mechanism of action as cytotoxic agents against KB cell lines. Hydrolysis data, kinetics, in the presence and in the absence of H2O2, and the valuation of lipophilicity were correlated with cytotoxicity values and with Hammett-σ-values of substituents (R) at the thiophenol ring. These compounds behave as 'pro-drugs' which release the cytotoxic agent grosheimin by sulphur-oxidation promoted by H2O2 and subsequent retro- elimination which depends on the nature and position of the R substituent.
- Fardella, Giuseppe,Barbetti, Paolo,Grandolini, Giuliano,Chiappini, Ione,Ambrogi, Valeria,Scarcia, Vito,Furlani Candiani, Ariella
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p. 515 - 523
(2007/10/03)
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- Acid-catalyzed transfer sulfonation of anisole using overcrowded polymethylbenzenesulfonic acids
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Transfer sulfonations of anisole using various polymethylbenzenesulfonic acids (PoMBR's) catalyzed by trifluoromethanesulfonic acid at 25 deg C are described.The observed reactivity order for transfer sulfonation increases in the order 2,4-DiMBS, 2,6-DiMB
- Koeberg-Telder, Ankie,Cerfontain, Hans
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- KINETICS AND MECHANISM OF HYDROLYSIS OF AROMATIC SULFONYL CHLORIDES IN AQUEOUS SULFURIC ACID SOLUTIONS
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The kinetics of the hydrolysis of 12 aromatic sulfonyl chlorides were studied by a spectrophotometric method in water and aqueous sulfuric acid solutions ( 1.0 - 60.5 wt.percent ) at 25 deg C and in 50percent sulfuric acid at several temperatures.It was shown that the reaction obeys the single-parameter equation log keff = log k0 + m'X, in which keff and k0 are the first-order rate constants in a solution with "excess acidity" X and in water respectively.The coefficient m' depends on the substituent in the ring and is equal to -0.85 to -0.38.The activity of the water does not enter into the equation for the calculation of keff.For the hydrolysis of nine substituted sulfonyl chlorides in 50percent sulfuric acid a satisfactory correlation is observed between log keff and the Σ?0.Palm induction constants ( ρ = -1.85 +/- 0.12 ).A reaction mechanism is proposed in which the rate-determining stage in the hydrolysis of the ArSO2Cl is the transformation of the complex H2O...SO2(Cl)Ar, in the form of which all the sulfonyl chloride dissolved in the water is present, into the reaction products.
- Gnedin, B. G.,Ivanov, S. N.,Shchukina, M. V.
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p. 731 - 737
(2007/10/02)
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- Aromatic Sulphonation. Part 91. The Sulphonation of Anisole, Phenol, Phenyl Methanesulphonate, Potassium Phenyl Sulphate, and a Series of Methyl-, Bromo-, and Chloro-substituted Anisoles and Phenols in Concentrated Aqueous Sulphuric Acid
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The (homogeneous) sulphonation of a number of aromatic ethers and alcohols, viz. anisole (1), 3-methyl- (2), 4-methyl- (3), 2-bromo- (4), 4-bromo- (5), 2-chloro- (6), and 4-chloro-anisole (7), phenol (8), 2-methyl- (9), 3-methyl- (10), 4-methyl- (11), 4-bromo- (12), 2-chloro- (13), and 4-chloro-phenol (14), phenyl methanesulphonate (15), and potassium phenyl sulphate (16) in concentrated aqueous sulphuric acid at 25.0 deg C has been studied, and rates and isomer distributions have been determined.The sulphonation is first-order in the aromatic substrate, and from the rate measurements it is concluded that the species undergoing sulphonation in the phenyl ring is an unprotonated substrate species.In the lower acid concentrations the sulphonating entity is H3SO4(1+).With increasing sulphuric acid concentration there is a gradual change-over in the sulphonating entity from H3SO4(1+) to H2S2O7.The acid concentrations of equal rate contribution by the two entities for anisole and phenol are 87 and 90 +/- 1percent, respectively.Sulphonation on the oxygen atom (i.e., sulphation) does not occur.The o/p-ratios for (1) and (8) do not vary over the studied sulphuric acid range of 75-90percent H2SO4.Partial rate factors for the 2- and 4-position of (1) and (8) are reported.The very low partial rate factors for the 4-substitution of (1) and (8) and the observed extreme suppression and compression of the reactivities of the substrates (1)-(14) are ascribed to hydrogen bonding of the substrates with the acidic solvent species present.It is tentatively suggested that the relatively high contents of sulphonation ortho to -OR with anisole (36percent) and phenol (48percent) are due to specific complexation of the substrates with the sulphonating electrophile.
- Cerfontain, Hans,Lambrechts, Hans J. A.,Schaasberg-Nienhuis, Zwaan R. H.,Coombes, Robert G.,Hadjigeorgiou, Panicos,Tucker, Geoffrey
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p. 659 - 668
(2007/10/02)
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