Phenols 3-fluoro-4-nitro

Difunctional compounds, including certain halogenated ethers, aldehydes, ketones, phenols, amines, and nitro compounds, have been prepared by the Sandmeyer reaction. However, fluorophenols and fluoro acids are best obtained from the corresponding ethers and esters, respectively, which have been fluorinated by the Schiemann reaction. ... 

Potentiometric titration methods have been used to measure equilibrium quotients at 25 for reactions of type l and 2, with X equal to ortho, meta and para nitro-, fluoro-, chloro-, bromo- and iodo-phenol. The medium was in all cases aqueous 0,10 M perchlorate (NaClO /HClO ). 

A series of twenty-nine substituted phenols (e.g., alkyl, phenyl, fluoro, cbloro, bromo, nitro, and multisubstituted) was studied using a diol column and a 50/50 chloroform/iso-octane mobile phase [611]. In general, retention increased as the polar nature of the solute increased (e.g., in order of increasing retention 2,4,6-tributylphenol < 4-amylphenol < 4-methylphenol < phenol < 4-chlorophenol < 4-nitrophenol). As might be expected, this system showed good isomer selectivity k for 3-nitrophenol=4.20, for 4-nitrophenol = 5.50). However this selectivity was not as pronounced as that found using an underivatized silica support. 

Ort/io-selectivity is generally observed in the reactions of 2,4-dichloro- and 2,4-difluoro-nitrobenzene with alkoxide and thiophenoxide ions [199]. Also in less activated systems, nucleophiles generated from phenols and thiophenols with potassium fluoride-alumina and 18-crown-6-polyether will react in DMSO with cyano- or nitro-substituted fluoro- or chloro-benzenes [200]. Interestingly, the reaction of difluorobenzenes with two diffoent alcohols can occur sequentially. Introduction of the first etho" function deactivates the ring, and use of more forcing conditions allows substitution of the second fluorine [201]. Consecutive displacements of fluorine and nitro groups have been observed in the reaction of ort/io-fluoronitrobenzene with chiral acyl bicyclic lactones in a highly enantioselective synthesis of spirooxindoles [202]. 

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