452-72-2Relevant articles and documents
Preparation method of 2-bromo-4-fluoro-6-methylphenol
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Paragraph 0027-0029; 0032-0035, (2020/11/09)
The invention discloses a preparation method of 2-bromo-4-fluoro-6-methylphenol, and belongs to the technical field of fine chemical engineering. The preparation method of 2-bromo-4-fluoro-6-methylphenol comprises the following steps of: (1) diazotization hydrolysis reaction: carrying out diazotization hydrolysis reaction on 2-methyl-4-fluoroaniline to obtain 2-methyl-4-fluorophenol; and (2) bromination reaction: carrying out bromination reaction on the 2-methyl-4-fluorophenol prepared in the step (1) to prepare the 2-bromo-4-fluoro-6-methylphenol. According to the method, nitrosyl sulfuric acid is adopted as an acylation reagent, waste acid obtained after diazotization hydrolysis is completed does not contain salt, acidic wastewater is easy to treat, and industrial production is facilitated; bromine used in the bromination reaction is greatly reduced, and the technological process is more environmentally friendly.
Catalytic activation of unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols
Zhu, Jun,Wang, Jianchun,Dong, Guangbin
, p. 45 - 51 (2018/11/23)
Transition metal catalysis has emerged as an important means for C–C activation that allows mild and selective transformations. However, the current scope of C–C bonds that can be activated is primarily restricted to either highly strained systems or more polarized C–C bonds. In contrast, the catalytic activation of non-polar and unstrained C–C moieties remains an unmet challenge. Here we report a general approach for the catalytic activation of the unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols. The key is to utilize the phenol moiety as a handle to install phosphinites as a recyclable directing group. Using hydrogen gas as the reductant, monophenols are obtained with a low catalyst loading and high functional group tolerance. This approach is also applied to the synthesis of 2,3,4-trisubstituted phenols. A further mechanistic study suggests that the C–C activation step is mediated by a rhodium(i) monohydride species. Finally, a preliminary study on breaking the inert biphenolic moieties in lignin models is illustrated.
A novel improvement in ArLPdF catalytic fluorination of aromatic compounds
Samant, Bhupesh S.,Bhagwat, Sunil S.
experimental part, p. 191 - 194 (2012/01/05)
In this study, we used reverse micellar medium for overcoming the disadvantages of ArLMF catalytic fluorination of aromatic compounds. It not only enhanced the fluorination rate, but also widened the scope of reaction for bromoaromatics with electron donating and withdrawing functionalities at ortho position. Various bromoaromatic compounds were fluorinated using the biarylphosphine ligand i.e. cyclohexyl BrettPhos ligand, along with [cinnamylPdCl]2, and CsF as the fluoride source in reverse micellar media. The anisotropic palisade layer of reverse micelles provided the active site for reaction. The most crucial factor in the critical reductive elimination step could be the spatial orientation of ArLPdF complex in the palisade layer; forming ArF as the final product in high yield with excellent selectivity.
