2675-77-6Relevant academic research and scientific papers
Homogeneous catalysis and selectivity in electrochemistry
Michman, Michael,Appelbaum, Lina,Gun, Jenny,Modestov, Alexander D.,Lev, Ovadia
, p. 4729 - 4737 (2015/04/27)
The relationship between homogeneous catalysis and electrochemistry is examined in light of two examples based on our work concerning (a) catalyst activation, regarding selective electrochemical C-H oxidation with RuIII/RuIV mediation, and (b) catalyst suppression, regarding controlling selectivity in electrochemical aromatic chlorination. The first example (a) deals with the role of catalysis at the working electrode. The electrochemical (EC) oxidation of specific hydrocarbons such as tetralin and indane is performed using tris(acetonitrile)ruthenium trichloride (Ru(CH3CN)3Cl3) as a mediator. The role of this mediator in the oxidation of tetralin has been reported. This homogeneous C-H activation by electron transfer (ET) is accompanied by the redox transitions of the mediator in the course of the catalytic oxidation, and these are the main points of interest here. Additional studies with a rotating ring disk electrode (RRDE) provided a follow-up of creation and recovery of RuIII/RuII and RuIII/RuIV species in the process. Using electrochemistry linked with electrospray ionization mass spectrometry (EC/ESI-MS) gave additional information on the structure of the reduced and oxidized forms of Ru(CH3CN)3Cl3 and the effect of water in the solvent on their lifetimes. The second example (b) of electrochlorination has been reported elsewhere and is brought up as complementary remarks. Aromatic electrophilic chlorination of 1,4-dimethoxy-2-tertbutylbenzene is autocatalyzed and unselective. The EC procedure provides a simple means to inhibit the catalytic runaway reaction. This example shows how the counter electrode affects catalysis and selectivity. (Figure Presented)
Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis
Wang, Tao,Rabe, Patrick,Citron, Christian A.,Dickschat, Jeroen S.
supporting information, p. 2767 - 2777 (2014/01/06)
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.
Efficient, multigram-scale synthesis of three 2,5-dihalobenzoquiones
Lopez-Alvarado, Pilar,Avendano, Carmen,Menendez, J. Carlos
, p. 3233 - 3239 (2007/10/03)
2,5-Dibromo-, 2,5-dichloro- and 2,5-diiodobenzoquinone were conveniently prepared from 1,4-dimethoxybenzene in 87%, 97% and 84% overall yields. None of the two steps of the synthesis required purification.
Simple and practical halogenation of arenes, alkenes and alkynes with hydrohalic acid/H2O2 or TBHP)
Barhate, Nivrutti B.,Gajare, Anil S.,Wakharkar, Radhika D.,Bedekar, Ashutosh V.
, p. 11127 - 11142 (2007/10/03)
A simple protocol for the halogenation of arenes utilizing a combination of aqueous hydrogen peroxide (34 %) or tert-butylhydroperoxide (70 %) and hydrohalic acid is presented. A similar procure of oxyhalogenation involving the in situ generation of positive halogen reagents is applied for the preparation of vicinal trans-dibromoalkanes and dichloroalkanes from alkenes. The reaction of alkenes with a combination of hydrochloric acid and hydrobromic acid with hydrogen peroxide gave a mixture of 1-bromo 2-chloro alkanes and 1,2-dibromoalkanes: Oxidative bromination of alkynes is also reported under similar conditions.
Basal and chitinase broth compositions for enhancing anti-fungal activity of a chemical fungicide and methods for preparing and using same
-
, (2008/06/13)
An insecticidal composition and its method of preparation are presented. The composition comprises a basal broth, a chitinase broth and a chemical fungicide. The basal broth has proteins hydrolyzed by papain and pancreatin while the chitinase broth is pre
Simple and efficient chlorination and bromination of aromatic compounds with aqueous TBHP (or H2O2) and a hydrohalic acid
Barhate, Nivrutti B.,Gajare, Anil S.,Wakharkar, Radhika D.,Bedekar, Ashutosh V.
, p. 6349 - 6350 (2007/10/03)
A combination of aqueous tert-butylhydroperoxide (70%) or hydrogen peroxide (34%) and a hydrohalic acid was found effective in chlorination and bromination of aromatic compounds.
13C and 17O NMR Study of Methoxy Groups in Chlorinated Di- and Trimethoxybenzenes
Knuutinen, J.,Kolehmainen, E.
, p. 315 - 317 (2007/10/02)
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.
Facile Synthesis of Chloro-substituted Aromatic Ethers by Use of Benzyltrimethylammonium Tetrachloroiodate
Kajigaeshi, Shoji,Shinmasu, Youichi,Fujisaki, Shizuo,Kakinami, Takaaki
, p. 415 - 418 (2007/10/02)
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.
Highly Selective Aromatic Chlorinations. Part 2. The Chlorination of Substituted Phenols, Anisoles, Anilines, and Related Compounds with N-Chloroamines in Acidic Solution
Smith, John R. Lindsay,McKeer, Linda C.,Taylor, Jonathan M.
, p. 385 - 392 (2007/10/02)
Phenols, anisoles, anilines, and related compounds are chlorinated in trifluoroacetic acid at room temperature by N-chlorodialkylamines and N-chlorotrialkylammonium salts.With monsubstituted compounds and their 2- and 3-substituted derivatives the reaction occurs efficiently and selectively at the 4-position.The reactivity of these substrates and the selectivity of their chlorinations are determined by electronic rather than steric effects of the substituent.Blocking the reaction with a substituent at the 4-position generally leads to only poor or moderate yields of the 2-chlorinated product.Evidence for radical and cation radical intermediates has been obtained in the reactions of some of the 4-substituted reactants and the mechanism of chlorination is discussed in the light of these findings.The reactions of selected substrates have been scaled up to give laboratory syntheses.
