- Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis
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Two unidentified chlorinated volatiles X and Y were detected in headspace extracts of the fungus Geniculosporium. Their mass spectra pointed to the structures of a chlorodimethoxybenzene for X and a dichlorodimethoxybenzene for Y. The mass spectra of some constitutional isomers for X and Y were included in our databases and proved to be very similar, thus preventing a full structural assignment. For unambiguous structure elucidation all possible constitutional isomers for X and Y were obtained by synthesis or from commercial suppliers. Comparison of mass spectra and GC retention times rigorously established the structures of the two chlorinated volatiles. Chlorinated volatiles are not very widespread, but brominated or even iodinated volatiles are even more rare. Surprisingly, headspace extracts from Streptomyces chartreusis contained methyl 2-iodobenzoate, a new natural product that adds to the small family of iodinated natural products.
- Wang, Tao,Rabe, Patrick,Citron, Christian A.,Dickschat, Jeroen S.
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supporting information
p. 2767 - 2777
(2014/01/06)
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- The kinetics of lignin reactions during chlorine dioxide bleaching. Part 1. Influence of pH and temperature on the reaction of 1-(3,4-dimethoxyphenyl)ethanol with chlorine dioxide in aqueous solution
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Rate constants as well as the products formed from the reaction between chlorine dioxide and the non-phenolic lignin model compound 1-(3,4-dimethoxyphenyl)ethanol have been determined in the pH interval 3-8. Spectroscopic data for the substrate and some products are given. The pH of the reaction mixture has a large influence on both the rate constant and the product distribution. Under technical chlorine dioxide bleaching conditions (pH 3, 40°C and an ionic strength of 0.3 mol kg-1 ) the rate constant has been found to be 0.12(2) M-1 s-1, which corresponds to a half-life of approximately 7 min in 0.01 M solution. The influence of temperature [Ea = 29(7)kJ mol-1] on the rate of reaction of this lignin model is small. At acidic pH (35) a large variety of both oxidized (quinones, lactones and ketones) and chlorinated products are formed. Above pH 8, one oxidation product, 3,4-dimethoxyacetophenone, predominates. No chlorinated products are found at a high pH. The mechanisms of formation of all these products are discussed. Acta Chemica Scandinavica 1996.
- Gunnarsson, N. Per-Ivar,Ljunggren, Sten C. Hj.
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p. 422 - 431
(2007/10/03)
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- 13C and 17O NMR Study of Methoxy Groups in Chlorinated Di- and Trimethoxybenzenes
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13C and 17O NMR data for the methoxy groups in isomeric 1,2-, 1,3- and 1,4-dimethoxybenzenes, 1,2,3-trimethoxybenzenes and most of their chlorinated derivatives and some related brominated compounds were measured for CDCl3 solutions.The 17O NMR chemical shifts show up to 60 ppm dispersion.Comparison between the compounds with and without adjacent chlorine atoms (2,6-di- and 2,4,6-trisubstitution) also showed a clear methoxy carbon chemical shift change.The number and position of the chlorine atoms in the aromatic ring give small but observable effects on the 17O NMR chemical shifts of the methoxy group if it is coplanar with the aromatic plane.Similarly, the degree and nature of the substitution have a minor effect (about 1 Hz) on the 1J(CH) direct coupling values.
- Knuutinen, J.,Kolehmainen, E.
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p. 315 - 317
(2007/10/02)
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- Facile Synthesis of Chloro-substituted Aromatic Ethers by Use of Benzyltrimethylammonium Tetrachloroiodate
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The reaction of aromatic ethers with a calculated amount of benzyltrimethylammonium tetrachloroiodate in acetic acid (or dichloromethane) under mild conditions gave, selectively, the objective chloro-substituted aromatic ethers in good yields.
- Kajigaeshi, Shoji,Shinmasu, Youichi,Fujisaki, Shizuo,Kakinami, Takaaki
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p. 415 - 418
(2007/10/02)
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- Mass Spectra of Chlorinated Veratroles (1,2-dimethoxybenzenes)
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The behaviour of all nine chlorinated veratroles (1,2-dimethoxybenzenes) under electron impact has been investigated.The most common fragmentation processes are interpreted using metastable ion analysis and deuterium labelled compounds.For all compounds studied, the most common fragmentation route seems to be the primary loss of a methyl radical followed by loss of carbon monoxide.The ion formed has a well-known quinonoid structure and fragments by several routes elucidated by metastable ion analysis.In general, the spectra of the positional isomers are shown to be practically similar and it is apparent the e.g. the 3- and 4-chloro isomers can be differentiated only from the abundance ratio of the +. and + ions.
- Knuutinen, J.,Korhonen, I. O. O.
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