34883-43-7Relevant academic research and scientific papers
Pd-Catalysed Suzuki-Miyaura cross-coupling of aryl chlorides at low catalyst loadings in water for the synthesis of industrially important fungicides
Goetz, Roland,Hashmi, A. Stephen K.,Orecchia, Patrizio,Petkova, Desislava Slavcheva,Rominger, Frank,Schaub, Thomas
supporting information, p. 8169 - 8180 (2021/11/01)
The Suzuki-Miyaura coupling reaction of electron-poor aryl chlorides in the synthesis of crop protection-relevant active ingredients in water is disclosed. Optimisation of the reaction conditions allowed running the reaction with 50 ppm of Pd-catalyst loading without an additional organic solvent in the cross-coupling reaction step in short reaction times. The system was optimised for the initial cross-coupling step of the large scale produced fungicides Boscalid, Fluxapyroxad and Bixafen up to 97% yield. It is also shown that the Suzuki-Miyaura reaction can be easily scaled up to 50 g using a simple product separation and purification using environmentally benign solvents in the work-up. To show the usability of this method, it was additionally applied in the three-step synthesis of the desired active ingredients.
Unusual Acetonitrile Adduct Formed via Photolysis of 4′-Chloro-2-Hydroxybiphenyl in Aqueous Solution
Zhang, Xiting,Guo, Yan,Dallin, Erin,Ma, Jiani,Dai, Mingdong,Phillips, David Lee
supporting information, p. 11635 - 11640 (2020/10/23)
In this work, 2,4′-dichlorobiphenyl (1) yielded 4′-chloro-2-hydroxybiphenyl (2) after photolysis in neutral acetonitrile aqueous (ACN-H2O) solutions. Ultrafast spectroscopic measurements and density functional theory (DFT) computations were performed for 2 in ACN and ACN-H2O (v/v, 1:1). These results were compared with previously published results for 2-hydroxybiphenyl (3). The counterparts 2 and 3 went through a singlet excited state intramolecular proton transfer (ESIPT) in ACN but behaved differently in ACN-H2O with a dehydrochlorination process occurring for 2 and an ESIPT taking place for 3. Computational results indicate that the phenol O-H bond elongates after photoexcitation to induce a concerted asynchronous process with the C-Cl bond increasing first followed by HCl elimination. A biradical intermediate (IM1) is then formed with some spin located at the phenyl 4′-C radical that appears to favor a hydrogen atom transfer (HAT) process and some spin located on phenoxyl that appears to prefer a subsequent a CH2CN radical rebound. The hydrogen bond promotes HCl elimination, while this is disfavored for ESIPT, making 4′-Cl extrusion the predominant process in ACN-H2O solutions. The mechanistic investigations have fundamental and significant implications for the understanding of polychlorinated biphenyl photolysis in an aqueous environment and hence the photodegradation of these kinds of pollutants in the natural environment.
Visible-Light-Promoted, Catalyst-Free Gomberg-Bachmann Reaction: Synthesis of Biaryls
Lee, Juyoung,Hong, Boseok,Lee, Anna
, p. 9297 - 9306 (2019/08/12)
Biaryls were synthesized via a novel visible-light-promoted Gomberg-Bachmann reaction that does not require a photosensitizer or any metal reagents. The formation of an electron donor-acceptor complex between aryl diazonium salts and pyridine allows, under visible-light irradiation, the synthesis of biaryls in moderate-to-high yields.
Regularities of Pd/C-catalyzed reduction of trichlorobiphenyls with 2-propanol in basic medium
Kostenko,Eliseenkov,Petrov
, p. 1656 - 1662 (2017/09/25)
Reduction of a series of trichlorobiphenyls with 2-propanol in basic medium catalyzed by Pd/C has been studied. Regioselectivity of the reduction has been determined. In the studied cases, the chlorine atom in para or meta positions of the more substituted ring has been more reactive. Using isotope labeling, it has been demonstrated that the reaction occurs via the stage of 2-propanol dehydration on palladium catalyst, followed by catalytic hydrogenation of the polychlorinated biphenyls.
Significant stabilization of palladium by gold in the bimetallic nanocatalyst leading to an enhanced activity in the hydrodechlorination of aryl chlorides
Karanjit, Sangita,Jinasan, Atchaleeya,Samsook, Ekasith,Dhital, Raghu N.,Motomiya, Kenichi,Sato, Yoshinori,Tohji, Kazuyuki,Sakurai, Hidehiro
supporting information, p. 12724 - 12727 (2015/08/06)
The stabilization effect of Au towards Pd changed the reactivity of Pd in Au/Pd bimetallic nanoclusters, altering the reaction mechanism from homogeneous to heterogeneous in dechlorination reaction of aryl chlorides. This phenomenon was illustrated by the observed enhancement of the rate of reaction by in situ generated Au-rich bimetallic Au/Pd nanoclusters.
Three-component coupling based on flash chemistry. Carbolithiation of benzyne with functionalized aryllithiums followed by reactions with electrophiles
Nagaki, Aiichiro,Ichinari, Daisuke,Yoshida, Jun-Ichi
supporting information, p. 12245 - 12248 (2014/11/08)
A flow microreactor method for three-component coupling of benzyne was developed based on flash chemistry. o-Bromophenyllithium generated from 1-bromo-2-iodobenzene and a functionalized aryllithium generated from the corresponding aryl halide were mixed at -70 °C. In the subsequent reactor o-bromophenyllithium is decomposed to generate benzyne without affecting the functionalized aryllithium at -30 °C, and carbolithiation of benzyne with the aryllithium took place spontaneously. The resulting functionalized biaryllithium was reacted with an electrophile in the subsequent reactor to give the corresponding three-component coupling product. The precise optimization of reaction conditions using the temperature-residence time mapping is responsible for the success of the present transformation. The present method has been successfully applied to the synthesis of boscalid.
Highly chemoselective Mono-Suzuki arylation reactions on all three dichlorobenzene isomers and applications development
Ullah, Ehsan,McNulty, James,Robertson, Al
supporting information; experimental part, p. 2127 - 2131 (2012/06/01)
A Pd catalyst system is described that allows very high chemoselective monoarylation on all three isomers of dichlorobenzene. Direct application of these commodity chemicals to high-value ligands, anilines, azides, and carbazoles was achieved through this process discovery.
Physical, spectral and chromatographic properties of all 209 individual PCB congeners
Bolgar,et al.
, p. 2687 - 2705 (2007/10/03)
Through the use of two capillary GC columns: 40% octadecyl/ 15% phenyl methyl siloxane and 50% phenyl methyl siloxane, it was possible to separate 201 PCB congeners with only four unresolved pairs. The data compiled in this study for all 209 congeners will aid in the identification of selected individual components of these environmental pollutants. The use of this data also presents the opportunity for the improved quantification of the commercial PCB formulations. -from Authors
Polar Effects in Reactions of Carbon-Centered Radicals with Diazonium Salts: Free-Radical Diazocoupling
Minisci, Francesco,Coppa, Fausta,Fontana, Francesca,Pianese, Giuseppe,Zhao, Lihua
, p. 3929 - 3933 (2007/10/02)
Carbon-centered radicals react with diazonium salts by addition, leading under reductive conditions to azo derivatives (free-radical diazocoupling), or by electron-transfer in chain processes.The reaction is highly sensitive to polar effects and it has been investigated by three different processes: (i) alkyl radicals, generated from alkyl iodides, H2O2, Fe(II) salt, and DMSO, have been utilized to develop a new general synthesis of alkylarylazo compounds; (ii) the reaction of aryl radicals with diazonium salts in the presence of Ti(III) or Fe(II) salts has been investigated, also in relation to the fact that the reaction products (azoarenes and biaryls) are often detected as side products in classical organic reactions of diazonium salts, catalyzed by Cu(I) salts, such as the Sandmeyer, Meerwein, and Pschorr reactions; (iii) adducts from addition of aryl radicals to vinyl acetate or vinyl ether react with diazonium salts either by diazocoupling reaction or by electron-transfer; a general synthesis of arylazo compounds has been developed.
