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Enantioselective halogenation via asymmetric phase-transfer catalysis
Lee Sunggi,Chung Won‐jin 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.7
The asymmetric phase-transfer catalysis (PTC) is a flourishing field of contemporary synthetic organic chemistry, and this prominent methodology has been tremendously successful in enantioselective halogenations. Both electrophilic and nucleophilic reaction manifolds were enabled through the exploitation of highly ordered ion pairing and/or hydrogen-bonding interactions around a carefully designed chiral phase-transfer catalyst with an insoluble halogenating reagent as well as a suitable substrate. Fluorination has been the most fruitful, and encouraging results have also been documented with heavier halogens. This review surveys examples of various enantioselective halogenations via the asymmetric PTC from its beginning to prosperity over the past decade.
sp<sup>3</sup> C-H Bond Halogenation through Microreversibility
윤영규,서성용 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
In order to develop a new halogenation of sp<sup>3</sup> C-H bond using microreversibility concept which is different from the known sp<sup>3</sup> halogenation, we set up a model reaction considering ease of synthesis, reaction tracking, and reaction conditions. After optimization study, we expanded the scope of halogenation using TfOH as a catalyst, NBS, and various acetate substrates in good yield up to 89% yield.
( Hee-chul Yang ),( Hee-chul Euna ),( Hyung-ju Kim ),( Keun-young Lee ),( Bun-kyung Seo ),( Kyu-tae Park ),( Hyeon-oh Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
Developing a thermochemical process to convert extremely low-level radioactive spent ion-exchange (IE) resins into recyclable carbon materials is an attractive goal from an economic perspective. This study investigated a noble thermochemical process, consisting of carbonization and halogenation, to convert spent IE resins into high-purity spherical carbon granules. Lowtemperature carbonization converts organic spent IE resins into spherical carbon granules with some inorganic constituents including radioactive metal species. Subsequent high-temperature halogenation treatment devolatilizes hazardous inorganic constituents in the form of halide vapors, producing high-purity carbon granules. Kinetic analysis of the carbonization process was conducted using TGAs coupled with FTIR gas analysis. Thermodynamic equilibrium model analysis was conducted to investigate the volatility characteristics of radioactive metals in the carbonized spent IE resins under the high-temperature halogenation conditions. A pilot-scale carbonization and halogenation treatment process, using mainly a graphite reactor, a plasma post-combustor, and a wet scrubber, was designed and implemented. Its performance was tested using simulated IE resins with radioactive metal surrogates such as cobalt and cesium.
Lee, Sang Uck Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.8
The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.
One‐Pot, Regioselective Consecutive Multihalogenation of 2,2′‐Bithiophene
Kim, Bo Ram,Kim, Eun Jung,Sung, Gi Hyeon,Kim, Jeum‐,Jong,Shin, Dong‐,Soo,Lee, Sang‐,Gyeong,Yoon, Yong‐,Jin WILEY‐VCH Verlag 2013 European journal of organic chemistry Vol.2013 No.14
<P><B>Abstract</B></P><P>The one‐pot regioselective consecutive multihalogenation of 2,2′‐bithiophene (<B>1</B>) was demonstrated. Compound <B>1</B> was consecutively halogenated with lithium halides such as lithium bromide, chloride, and/or iodide in the presence of lead tetraacetate in chloroform at room temperature or under reflux conditions to give 5‐bromo(or chloro)‐5′‐iodo(or chloro)‐, 3‐bromo(or chloro)‐5,5′‐dibromo(or dichloro, diiodo)‐, 3,3′‐dibromo‐(or dichloro)‐5,5′‐diiodo(or dibromo, dichloro)‐, and 3,3′,5‐tribromo(or trichloro)‐5′‐iodo(or bromo)‐2,2′‐bithiophenes. Notably, this process offers a regioselective method for consecutive multihalogenation in one pot, and the yields and selectivity are also higher than those obtained in the step‐by‐step and concurrent halogenation methods.</P>
이상욱 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.8
The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.
Ike, Ikechukwu A.,Karanfil, Tanju,Cho, Jinwoo,Hur, Jin Elsevier 2019 Water research Vol.164 No.-
<P><B>Abstract</B></P> <P>Advanced oxidation processes (AOPs) have been increasingly used for the treatment of source waters and wastewaters. AOPs characteristically produce oxidation byproducts (OBPs) from the partial degradation of dissolved organic matter (DOM) and/or the transformation of inorganic ions (especially, halides) into highly toxic substances including bromate and halogenated organic OBPs (X-OBPs). However, despite the enormous health and environmental risks posed by X-OBPs, an integral understanding of the complex OBP formation mechanisms during AOPs is lacking, which limits the development of safe and effective AOP-based water treatment schemes. The present critical and comprehensive review was intended to fill in this important knowledge gap. The study shows, contrary to the hitherto prevailing opinion, that the direct incorporation of halide atoms (X<SUP>•</SUP>) into DOM makes an insignificant contribution to the formation of organic X-OBPs. The principal halogenating agent is hypohalous acid/hypohalite (HOX/XO<SUP>−</SUP>), whose control is, therefore, critical to the reduction of both organic and inorganic X-OBPs. Significant generation of X-OBPs has been observed during sulfate radical AOPs (SR-AOPs), which arises principally from the oxidizing effects of the unactivated oxidant and/or the applied catalytic activator rather than the sulfate radical as is commonly held. A high organic carbon/X<SUP>−</SUP> molar ratio (>5), an effective non-catalytic activator such as UV or Fe<SUP>2+</SUP>, a low oxidant concentration, and short treatment time are suggested to limit the accumulation of HOX/XO<SUP>−</SUP> and, thus, the generation of X-OBPs during SR-AOPs. At present, there are no established techniques to prevent the formation of X-OBPs during UV/chlor(am)ine AOPs because the maintenance of substantial amounts of active halogen is essential to these processes. The findings and conclusions reached in this review would advance the research and application of AOPs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Halide atoms react oxidatively than additively with dissolved organic matter (DOM). </LI> <LI> Hypohalous acid/hypohalite is the principal halogenating agent during AOPs. </LI> <LI> SO<SUB>4</SUB>.<SUP>•-</SUP> and HO<SUP>•</SUP> generate similar halogenated oxidation byproducts (X-OBPs) </LI> <LI> X-OBPs from SO<SUB>4</SUB>.<SUP>•-</SUP> AOPs are due to the catalytic activator and unactivated oxidant </LI> <LI> DOM may suppress halide atom formation of organic and inorganic X-OBPs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Yusubov, Mehman S.,Yusubova, Rosa Y.,Funk, Tatyana V.,Chi, Ki-Whan,Kirschning, Andreas,Zhdankin, Viktor V. Georg Thieme Verlag Stuttgart, New York 2010 Synthesis Vol.2010 No.21
<P>A convenient procedure for the preparation of α-iodoketones by oxidative iodination of ketones using iodine and M-iodosylbenzoic acid as a recyclablehypervalent iodine oxidant is reported. Various ketones and β-dicarbonylcompounds can be iodinated by this reagent system under mild conditionsaffording the respective α-iodo-substituted carbonyl compoundsin excellent yields. The final products of iodination are convenientlyseparated from byproducts by simple treatment with anionic exchangeresin Amberlite IRA 900 HCO <SUB>3</SUB><SUP>-</SUP> andare isolated with good purity after evaporation of the solvent.The reduced form of the hypervalent iodine oxidant, M-iodobenzoic acid, can be recoveredin 91-95% yield from the Amberlite resin by treatmentwith aqueous hydrochloric acid followed by extraction with ethylacetate. </P>