1-Fluoro-2,4-Dinitrobenzen

Studies of micellar catalysis of himolecular reactions of uncharged substrates have not been frequent" ". Dougherty and Berg performed a detailed analysis of the kinetics of the reaction of 1-fluoro-2,4-dinitrobenzene with aniline in the presence of anionic and nonionic surfactants. Micelles induce increases in the apparent rate constant of this reaction. In contrast, the second-order rate constant for reaction in the micellar pseudophase was observed to be roughly equal to, or even lower than the rate constant in water. 

The compound 1 fluoro 2 4 dinitrobenzene is exceed ingly reactive toward nucleophilic aromatic substi tution and was used in an imaginative way by Frederick Sanger (Section 27 11) in his determination of the struc ture of insulin... 

Fluoro-2,4-dinitrobenzene is commonly referred to as Sanger s reagent... 

Burchfield, H.P. Comparative stabilities of d3rrene, 1 -fluoro-2,4-dinitrobenzene, dichlone, and captan in a silt loam soil, Contrlb. S. Boyce Thompson Inst, 20 205-215, 1959. 

The electrochemical behavior of l-fluoro-2,4-dinitrobenzene, l-chloro-2,4-dinitrobenzene, and l-bromo-2,4-dinitrobenzene in DMF was described (Gallardo et al. 2000) as follows. The 1-fluoro-2,4-dinitrobenzene anion-radical dimerizes before cleavage, whereas l-chloro-2,4-dinitrobenzene... 

Exercise 14-16 The reaction of 1 -fluoro-2,4-dinitrobenzene with dimethylamine is catalyzed by weak bases. How may this observation be explained (Consider possible intermediates, rate-determining steps, etc.)... 

Traditionally, most chemical methods for the direct determination of available lysine depended on the reaction of the e-amine with a chromophoric derivatizing reagent and then spec-trophotometric measurement. The most commonly employed chromophore is 1-fluoro-2,4-dinitrobenzene (FDNB), which was originally employed by Carpenter (102). Since then, numerous articles (103-106) have reported the direct (or indirect by difference) HPLC measurement of the FDNB-derivatized lysine. However, these methods can suffer from the problem that the reaction product of the FDNB-derivatized lysine (dinitrophenyllysine) is not entirely stable during acid hydrolysis (especially in the presence of carbohydrates) and correction factors are recommended (107). 

The presence of electron-withdrawing groups (notably the nitro group) sited in the ortho or para positions of an aryl halide facilitates the halogen replacement. Here the mechanism proceeds by an addition-elimination sequence and it is discussed and illustrated in the formation of 2,4-dinitroaniline and 2,4-dinitrophenylhydrazine (Section 6.8.2, p. 959), and in the use of 1-fluoro-2,4-dinitrobenzene in the derivatisation of an amino group in an amino acid (Section 9.6.23, p. 1279). 

Fluorobis(trifluoromethyl)phosphine, 0642 Fluorobis(trifluoromethyl)phosphine oxide, 0641 Huorocarbonyl azide, see Azidocarbonyl fluoride, 0338 Huorocarbonylperoxonitrate, 0337b Huorodiiodomethane, 0372 1 -Fluoro-2,4-dinitrobenzene, 2101 l-Fluoro-l,l-dinitrobutane, 1557 4-Fluoro-4,4-dinitrobutene, 1454 l-Fluoro-l,l-dinitroethane, 0745 2( )-Fluoro-1,1 -dinitroethane, 0746... 

Miscellaneous pesticides/insecticides Vegetables Ethyl acetate extraction, Qg Sep-Pak clean-up, solvent partitioning Derivatisation with 1-fluoro 2,4 dinitrobenzene, GC with ECD [128]... 

Figure 6-1 Reaction of amino acids with 1-fluoro-2,4-dinitrobenzene (FDNB). DNP = dinitrophenyl HF = hydrofluoric acid...

FLUORO-2,4-DINITROBENZENE see DUW 400 1,2,4-FLUORODINITROBENZENE see DLAX 400 FLUOROETHANE see FIBOOO FLUOROETHANOIC ACID see FICOOO... 

The reaction is carried out by mixing the peptide and 1-fluoro-2,4-dinitrobenzene in the presence of a weak base such as sodium carbonate. In the fu t step the base abstracts a proton from the terminal H3N group to give a free amino function. The nucleophilic amino group attacks l-fluoro-2,4-dinitrobenzene, displacing fluoride. 

An Important example of this behaviour is provided by the reaction of 1-fluoro-2,4-dinitrobenzene (3 with the terminal amino group of proteins. Subsequent acidic hydrolysis yields the yellow 2,4-dlnitrophenyl derivative of the terminal amino acid of the protein, which can then be identified. With the help of this technique of end-group analysis, Sanger was able to determine the primary structure 01 insulin. 

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