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All total 7 Articles be foundPolyoxometalate built-in conjugated microporous polymers for visible-light heterogeneous photocatalysis
Li, Yusen,Liu, Mingxuan,Chen, Long
supporting information, p. 13757 - 13762 (2017/07/12)
Herein, we report two novel Anderson-type polyoxometalate (POM) built-in conjugated microporous polymers (CMPs), Bn-Anderson-CMP and Th-Anderson-CMP prepared through Sonogashira-Hagihara cross-coupling of tetrabromo-bifunctionalized Anderson-type POMs and 1,3,5-triethynylbenzene. These two Anderson-CMPs exhibit outstanding heterogeneous photocatalytic activities towards degrading organic dyes in water. Control photocatalysis experiments with different radical scavengers demonstrate that hydrogen peroxide and singlet oxygen are the primary active catalytic species. Moreover, these two CMPs can be easily recycled at least five times without a noticeable decrease in photocatalytic performances.
Buttressing Effects Rerouting the Deprotonation and Functionalization of 1,3-Dichloro- and 1,3-Dibromobenzene
Heiss, Christophe,Marzi, Elena,Schlosser, Manfred
, p. 4625 - 4629 (2007/10/03)
A systematic comparison between 1,3-difluorobenzene, 1,3-dichlorobenzene, and 1,3-dibromobenzene did not reveal major differences in their behavior towards strong bases such as lithium diisopropylamide or lithium 2,2,6,6-tetramethyl-piperidide. Thus, all 2,6-dihalobenzoic acids 1 are directly accessible by consecutive treatment with a suitable base and dry ice. In contrast, (2,6-dichlorophenyl)- and (2,6-bromo-phenyl)triethylsilane (2a and 2b) were found to undergo deprotonation at the 5-position (affording acids 3 and, after deprotection, 4), whereas the 1,3-difluoro analog is known to react at the 4-position. The 2,4-dihalobenzoic acids 7 were selectively prepared from either the silanes 2 (by bromination at the 4-position, metalation and carboxylation of the neighboring position, followed by desilylation and debromination) or the 1,3-dihalo-2-iodobenzenes 8 (by base-promoted migration of iodine to the 4-position followed by iodine/magnesium permutation and subsequent carboxylation). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Substitution Reactions of Phenylated Aza-Heterocycles. Part 2. Bromination of Some 2,5-Diaryl-1,3,4-oxadiazoles
Blackhall, Alexander,Brydon, Donald L.,Javaid, Khalid,Sagar, Anthony J. G.,Smith, David M.
, p. 3485 - 3497 (2007/10/02)
Electrophilic bromination of the title compounds may be achieved using either bromine in oleum, or bromine and potassium bromate in a sulphuric-acetic acid mixture.Under the milder reaction conditions provided by the latter, 2-(p-nitrophenyl)-5-phenyl-1,3,4-oxadiazole (2), the model compound used in this study, is mono- and di-brominated in the phenyl ring.In the first bromination step, all three monobromo-isomers are produced in appreciable amount.The orientation of the second bromination is controlled entirely by the first bromine and not by the oxadiazole substituent: this is confirmed by a separate study of the bromination of the three monobromo-compounds (3a-3c).
