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Greener Synthesis of Potential Drugs
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Renata Studzińska, Renata Kołodziejska, Daria Kupczyk
Ionic liquids as solvents have also been used in electrophilic and nucleophilic bromine substitution reactions in 2-iodomethyl-2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one. The bromination reaction of 2-iodomethyl-2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one using NBS (N-bromosuccinimide) and bromine, in two ionic liquids, [BMIM]PF6 and [BMIM]Br, was conducted. The reaction led to two products: 6-bromo-2-(iodomethyl)-2,3-dihydrothiazolo-[3,2-a]pyrimidin-5-one and 6-bromo-2-(bromomethyl)-2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one. Similar to organic solvents, in ionic liquid, the composition of the reaction mixture depended on the brominating agent used. Regardless of the solvent, in the bromination reaction with Br2 the main reaction product was dibromo compound which was a result of the course of the two substitution reactions: electrophilic and nucleophilic. In [BMIM]Br, the reaction occurred completely selectively. The use of the ionic liquid as a reaction medium increased the rate of reaction in comparison with organic solvents. Dibromo compound was predominantly formed also in [BMIM]Br using NBS as a brominating agent. In [BMIM]PF6 dibromo compound was detected as 41.7% of the reaction mixture. In this case, the monobromo compound which was obtained as a result of electrophilic aromatic substitution was the main product of the bromination reaction (57.3%) [84].
Carbon Nanotubes: Preparation and Surface Modification for Multifunctional Applications
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials I, 2020
Jingyao Sun, Jing Zhu, Merideth A. Cooper, Daming Wu, Zhaogang Yang
Janas et al. reported an innovative halogenation reaction for CNT modification (Janas, Boncel, and Koziol, 2014). Bias voltage was applied to the horizontally aligned CNT films to generate an electrothermal effect, which provided an entirely controlled temperature, up to 300 °C, for the chemical modification of the CNT film. They exposed the heated CNTs to gaseous halogens (Cl2, Br2, I2) and kept monitoring the electrical properties. The conductivity of CNT films kept changing with the variety of experimental temperatures (100–300 °C). The maximum levels of Cl, Br, and I that can be successfully introduced into the framework of CNTs within one-minute reactions were found to be 6.7 %, 6.0 %, and 1.5 %, respectively. The conductivity of the CNT films was permanently increased and mildly purified compared with the starting CNT films because of the removal of various carbon–oxygen functional groups. The bromination of MWCNTs through both new and convenient methods was studied by Leila Moradi and Iman Etesami (Moradi and Etesami, 2016). Performing electrophilic addition and radical reactions using Br2, N-Bromosuccinimide (NBS), and NH4NO3/NBS under UV and thermal conditions allowed bromine to be successfully attached onto the surfaces of MWCNTs.
Thermochemistry, Electrochemistry, and Solution Chemistry
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Bromine monoxide Bromine pentafluoride Bromine trifluoride Bromoacetic acid Bromoacetone Bromoacetylene Bromobenzene Bromoborane(1) 1-Bromobutane 2-Bromobutane, ()Bromochlorodifluoromethane 1-Bromo-2-chloroethane Bromochlorofluoromethane Bromochloromethane 1-Bromo-2-chloro-1,1,2-trifluoroethane 2-Bromo-2-chloro-1,1,1-trifluoroethane Bromodichlorofluoromethane Bromodichloromethane Bromodifluoromethane 1-Bromododecane Bromoethane Bromoethene Bromofluoromethane Bromogermane 1-Bromoheptane 1-Bromohexadecane 1-Bromohexane Bromomethane 2-Bromo-2-methylpropane 1-Bromooctane Bromopentafluoroethane 1-Bromopentane 1-Bromopropane 2-Bromopropane cis-1-Bromopropene 3-Bromopropene Bromosilane Bromosilyldyne Bromosilylene N-Bromosuccinimide 4-Bromotoluene Bromotrichloromethane Bromotrichlorosilane 2-Bromo-1,1,1-trifluoroethane Bromotrifluoromethane Bromotrinitromethane 1,2-Butadiene 1,3-Butadiene Butanal Butanamide Butane 1,2-Butanediol, ()1,3-Butanediol 1,4-Butanediol 2,3-Butanediol 1,4-Butanedithiol Butanenitrile 1-Butanethiol 2-Butanethiol Butanoic acid Butanoic anhydride 1-Butanol
Difluoromethoxyl bridged substituted 2-cyano-pyrrole based pure organic luminescent liquid crystals towards white light emitting single-molecule
Published in Liquid Crystals, 2023
Shunyin Luo, Guoliang Yang, Mei Zhang, Liping Lu, Xiaofeng Mo, Majeed Irfan, Zhuo Zeng
A synthetic route for difluoromethyleneoxy moieties (5CCB) has been reported [39]. On the basis of oxidative fluorodesulfuration reported by the P. Kirch group in 2001, we have developed a simple and practical approach to avoid the use of hazardous and highly toxic elemental bromine to achieve a green and environmentally friendly synthetic pathway. The N-bromosuccinimide (NBS) has some advantages, such as high selectivity, mild reaction conditions and easy-to-handle as a solid brominated reagent in organic synthesis. In this case, the NBS is proven to be as effective as the Br2 substitute and we obtained 5CCB in 35% yield. In this work, the intermediate (5CCB) with a difluoromethoxy bridge was synthesised via the oxidative fluoride desulphurisation approach, followed by alkynyl addition to give a difluoromethyleneoxy moiety (5CCC) with phenylacetylene as terminal in 35% yield. The four new difluoromethoxy bridged LLCs were obtained by sonogarshira coupling reaction in 50–60% yield.