394-41-2Relevant articles and documents
Synthesis method of intermediate 3-fluoro-4-nitrophenol
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Paragraph 0022; 0029; 0036; 0038; 0043; 0050, (2018/05/16)
The invention discloses a synthesis method of intermediate 3-fluoro-4-nitrophenol. The method comprises steps as follows: (1) 2,4-dibromonitrobenzene and water are mixed, the mixture is heated to 50-60 DEG C, cobalt acetate is added under the protection of inert gas, the mixture is stirred and mixed uniformly, ammonia water is dropwise added, the mixture is subjected to a reflux reaction and continuously stirred for a reflux reaction for 1-2 h after ammonia water is dropwise added, centrifugation and separation are performed after the reaction is completed, an organic phase is collected, reduced pressure distillation is performed, a mixture of 3-bromo-4-nitrophenol and 5-nitrophenol-2-nitrophenol is prepared, and 3-bromo-4-nitrophenol is prepared through water steam distillation, ether extraction, recrystallization and isomeride separation; (2) 3-bromo-4-nitrophenol is added to DMSO, polyethylene glycol-400 is added, the mixture is stirred and mixed uniformly and then heated to 40-50 DEG C, potassium fluoride is added, the mixture is stirred for a reaction for 4-5 h, reduced pressure distillation is performed after the reaction ends, and 3-fluoro-4-nitrophenol is prepared through recrystallization. The synthesis method is simple to operate and mild in condition, fewer by-products are produced, the product purity is high and the product yield is higher.
Method for synthesizing 3-fluoro-4-aminophenol
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Paragraph 0045, (2017/02/09)
The invention provides a method for synthesizing 3-fluoro-4-aminophenol. The method comprises the following steps: (1) preparing a composite catalyst from nickel nitrate, palladium chloride and butyl titanate through a sol-gel method; (2) enabling metallic sodium and 2,4-difluoronitrobenzene and methanol to react so as to prepare 2-fluoro-4-methoxyl-nitrobenzene; (3) performing a demethylation reaction on 2-fluoro-4-methoxyl-nitrobenzene through aluminum chloride so as to prepare 3-fluoro-4-nitrophenol; (4) performing a catalytic hydrogenation reaction on the 3-fluoro-4-nitrophenol by using a composite catalyst, thereby obtaining 3-fluoro-4-aminophenol. The method is relatively high in yield, and the product is also relatively high in purity.
Probing synergy between two catalytic strategies in the glycoside hydrolase O-GlcNAcase using multiple linear free energy relationships
Greig, Ian R.,Macauley, Matthew S.,Williams, Ian H.,Vocadlo, David J.
supporting information; experimental part, p. 13415 - 13422 (2010/01/16)
Human O-GlcNAcase plays an important role in regulating the post-translational modification of serine and threonine residues with β-O-linked N-acetylglucosamine monosaccharide unit (O-GlcNAc). The mechanism of O-GlcNAcase involves nucleophilic participation of the 2-acetamido group of the substrate to displace a glycosidically linked leaving group. The tolerance of this enzyme for variation in substrate structure has enabled us to characterize O-GlcNAcase transition states using several series of substrates to generate multiple simultaneous free-energy relationships. Patterns revealing changes in mechanism, transition state, and rate-determining step upon concomitant variation of both nucleophilic strength and leaving group abilities are observed. The observed changes in mechanism reflect the roles played by the enzymic general acid and the catalytic nucleophile. Significantly, these results illustrate how the enzyme synergistically harnesses both modes of catalysis; a feature that eludes many small molecule models of catalysis. These studies also suggest the kinetic significance of an oxocarbenium ion intermediate in the O-GlcNAcase-catalyzed hydrolysis of glucosaminides, probing the limits of what may be learned using nonatomistic investigations of enzymic transition-state structure and offering general insights into how the superfamily of retaining glycoside hydrolases act as efficient catalysts.