933-75-5Relevant academic research and scientific papers
Photocatalytic degradation of lindane by polyoxometalates: Intermediates and mechanistic aspects
Antonaraki,Triantis,Papaconstantinou,Hiskia
experimental part, p. 119 - 124 (2010/08/22)
The photocatalytic degradation of lindane (γ-1,2,3,4,5,6-hexachlorocyclohexane) has been studied in the presence of the polyoxometalate PW12O403- in aqueous solutions. Lindane is fully decomposed to CO2, Cl- and H2O, while a great variety of intermediates has been detected using GC-MS, including aromatic compounds (dichlorophenol, trichlorophenols, tetrachlorophenol, hexachlorobenzene, di- and trichloro-benzenodiol), non-aromatic cyclic compounds (penta-, tetrachlorocyclohexene, heptachlorocyclohexane), aliphatic compounds (tetrachloroethane) and condensation products (polychlorinated biphenyls). The number and nature of the intermediates implies that the mechanism of decomposition of lindane is based on both oxidative and reductive processes. Common intermediates have been reported during photolysis of lindane in the presence of titanium dioxide. A similar overall mechanism of polyoxometalates and TiO2 photocatalysis through the formation of common reactive species is suggested.
Electroreduction of Organic Compounds, 34 [1]. Cathodic Dehalogenation of Chloroarenes with Electron-Donating Substituents
Kranz, Olaf,Voss, Jürgen
, p. 1187 - 1200 (2007/10/03)
The electrochemical reduction of chlorinated arenes with electron-donating substituents, i.e. chlorotoluenes, -anisoles and -phenols, is studied. Preparative electrolyses are run in various solvent-supporting electrolytes under potentiostatic and galvanostatic conditions at lead or carbon cathodes. A partial and mostly regioselective hydrodechlorination of compounds with two or more chloro substituents is possible under suitable conditions. The replacement of one single chloro substituent, in particular in a para-position, is difficult. Highly toxic and persistent oligochloro derivatives are thus transformed into less problematic compounds with a low degree of chlorination. The chlorine content of real-life materials such as extracts of soil contaminated with chlorinated phenols and Nitrofen can also be significantly decreased by electroreduction.
Process for functionalising a phenolic compound carrying an electron-donating group
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, (2008/06/13)
The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
Identification of surrogate compounds for the emission of PCDD/F (I-TEQ value) and evaluation of their on-line realtime detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry
Blumenstock,Zimmermann,Schramm,Kettrup
, p. 507 - 518 (2007/10/03)
Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination 4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.
THERMAL DECOMPOSITION OF 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN
Samsonov, D. P.,Rakhmanova, T. V.,Peryunina, R. I.
, p. 149 - 154 (2007/10/02)
The pyrolysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin in an inert atmosphere in a closed system starts at temperatures above 350 deg C and can be described by a first-order equation.The presence of an oxidative or reductive atmosphere raises the rate of decomposition considerably.In an inert medium mainly dichlorination-chlorination processes occur.In the products of pyrolysis in air a considerable number of oxygen-containing compounds were identified.
Photochemistry of halogenated benzene derivatives. Part VI. Photoreactions of tetra- and pentachlorophenols in water-acetonitrile mixtures
Choudhry, Ghulam Ghaus,Wielen, Frans W. M. van der,Webster, G. R. Barrie,Hutzinger, Otto
, p. 469 - 475 (2007/10/02)
Laboratory photochemical studies of aqueous acetonitrile solution of some polychlorinated phenols (PCPs) such as 2,3,4,5-tetrachlorophenol (2,3,4,5-Cl4-Pn)(1), 2,3,4,6-Cl4-Pn(2), 2,3,5,6-Cl4-Pn(3), and pentachlorophenol (Cl5-Pn)(4) at λ>285 nm have been carried out for 6 and 24 h exposure times.All the investigated PCPs underwent reductive dechlorination.This process was dependent not only upon the position of OH group but also upon the relative positions of the Cl substituents on the benzene ring.The Cl4-Pn 2 (and 3) and Cl5-Pn (4) also yielded photoproducts of molecular formulae C8H4Cl3NO(M+.=235) and C8H3Cl4NO(M+.=269), respectively.Furthermore, phenol 3 is unique amongst the investigated PCPs; in addition to the above mentioned photoproducts, it yielded hexa-, hepta-, and octachlorodihydroxybiphenyl(s) as well as heptachlorohydroxydiphenyl ether.
THE REACTIONS OF UNACTIVATED ARYL HALIDES WITH SODIUM METHOXIDE IN HMPA; SYNTHESIS OF PHENOLS, ANISOLES, AND METHOXYPHENOLS
Testaferri, L.,Tiecco, M.,Tingoli, M.,Chianelli, D.,Montanucci, M.
, p. 193 - 198 (2007/10/02)
Sodium methoxide reacts with dichlorobenzenes in HMPA to give the chloroanisoles as a result of a SNAr process.Excess MeONa then effects the demethylation of the ethers to give the chlorophenols via an SN2 reaction.With tri- and tetrachlorobenzenes the initially formed chloroanisoles can be dealkylated to chlorophenols or can suffer further substitution to give the chlorodimethoxybenzenes; these react with excess MeONa to give the chloromethoxyphenols.The results obtained with the various isomers of the di-, tri-, and tetrachlorobenzenes are presented and discussed on the basis of the electronic effects of the substituents.
2-(Aminomethyl)phenols, a New Class of Saluretic Agents. 3. Effects of Functional Group Reorientation and Modification
Stokker, G. E.,Deana, A. A.,deSolms, S. J.,Schultz, E. M.,Smith, R. L.,et al.
, p. 1063 - 1067 (2007/10/02)
A series of modified 2-(aminomethyl)phenols was synthesized and tested orally in rats for saluretic and diuretic effects.Intravenous dog data are included as supplementary material to show that the diuretic responses, or lack thereof, may be obtained in a second species.Reorientation of the 2-(aminomethyl) group either meta or para to the hydroxyl substituent resulted in loss of diuretic effects.Similarly, replacement of either the phenolic hydroxyl or the aminomethyl group with other functional moieties substantially diminished saluretic effects.
