2.4- Dinitrofluorobenzene, reaction with

The dinitrophenyl group has been used to protect the imidazole — NH group in histidines (45% yield)" by reaction with 2,4-dinitrofluorobenzene and potassium carbonate. Imidazole —NH groups, but not a-amino acid groups, are quantitatively regenerated by reaction with 2-mercaptoethanol (22°, pH 8, 1 h)." The 2,4-... 

Fluorobenzene-type compounds have been used as functional groups in homobifunctional crosslinking agents (Chapter 4, Section 4). Their reaction with amines involves nucleophilic displacement of the fluorine atom with the amine derivative, creating a substituted aryl amine bond (Reaction 9). Detection reagents incorporating reactive aryl chemistry include 2,4-dinitrofluorobenzene and trinitrobenzenesulfonate (Eisen et al., 1953). These compounds form... 

The enhanced nucleophilicity in the cationic micelle is similarly expressed in the reaction with 2,4-dinitrofluorobenzene and vitamin B12 (Chaimovich et al., 1975 Nome and Fendler, 1977). In general, the extent of the rate increase observed in the thiolate reaction is somewhat smaller than that in oxyanionic reactions. This may be an important clue for elucidating the activation mechanism of the thiolate reaction. 

In contrast, the 0-aryl derivative of Af-methyl-6-(hydroxyamino)-l,3-dimethylpyrimi-dine-2,4(1/7,3i7)-dione 44, prepared by reaction with 2,4-dinitrofluorobenzene (DNFB), yields the corresponding barbiturate 45 by a spontaneous [3,3]-sigmatropic rearrangement (equation 14). 

Amine 212 was also coupled with peptides [233], acetic anhydride [215, 234], dinitrobenzoyl chloride [235] or a ferrocene carboxylic add chloride [215, 236] in good yields. Reaction with dinitrochlorobenzene [237] or dinitrofluorobenzene... 

The Sanger method for N-terminus determination is a less common alternative to the Edman degradation. In the Sanger method, the peptide is treated with the Sanger reagent, 2,4-dinitrofluorobenzene, and then hydrolyzed by reaction with 6 M aqueous HC1. The N-terminal amino acid is recovered as its 2,4-dinitrophenyl derivative and identified. 

The effects of micelles on the rates of nucleophilic aromatic substitution reactions (equations 42a-42e) follow a similar pattern. The rate constant for reaction (42a) was unaffected by the presence of micellar sodium dodecyl sulfate, even though 2,4-dinitrofiuorobenzene partitions strongly in favor of the micelles and the free base of glycineamide is not appreciably solubilized. On the other hand, the rate constant for the reaction with glycylglycine (equation 42b) decreased by a factor of 3-6 in micellar sodium dodecyl sulfate solution and increased by a factor of ca. 15 in the presence of CTAB (Herries et al., 1964). Since the rate retardation in NaLS solutions was observed to parallel the partitioning of 2,4-dinitrofluorobenzene in favor of the micellar phase and the... 

The covalent structure of insulin was established by Frederick Sanger in 1953 after a 10-year effort. This was the first protein sequence determination. Sanger used partial hydrolysis of peptide chains whose amino groups had been labeled by reaction with 2,4-dinitrofluorobenzene to form shorter end-labeled fragments. These were analyzed for their amino acid composition and labeled and hydrolyzed again as necessary. Many peptides had to be analyzed to deduce the sequence of the 21-residue and 30-residue chains that are joined by disulfide linkages in insulin. ... 

On the other hand, Nudehnan and Palleros104a reported a quadratic dependence of the observed second-order rate constant on the concentration of 2-methoxyaniline in its reaction with 2,4-dinitrofluorobenzene (DNF) in benzene. This behavior is similar to that previously reported in the reaction with 4-methoxyaniline in benzene104b. These kinetic results are interpreted in terms of reaction by the dimer of the amine which forms a cyclic intermediate with the substrate (Scheme 11). 

In 1992, Harada et al. prepared a compound in which many cyclodextrins are threaded on a single PEG chain and are trapped by end-capping groups at both termini of the main chain (Scheme 16) [111]. The pseudopolyrotax-ane formed in water from PEG bisamine (mass 3350) and a large excess of a-cyclo dextrin in an aqueous solution was isolated and then subjected to end-capping reaction with 2,4-dinitrofluorobenzene in DMF to yield polyro-... 

If 1,5-difluoro-2,4-dinitrobenzene is used as the activated halogen compound, then in boiling DMF solution a double ring-closure to the tetraphenyl-17/,9//-benzo[l,2-c 5,4-e ]bi-s[l,3,4]thiadiazine (294) (14%) is noted. 2,4-Dinitrofluorobenzene also undergoes reaction with dithizone (PhN=NCSNHNHPh) in acetonitrile at 25 °C to yield 6-nitro-l-phenyl-3-phenylazo-l//-4,l,2-benzothiadiazine (293) as purple needles in 79% yield (see also Section 6.17.7.1.3). 

Primary allylic chlorides. Primary allylic alcohols can be converted into the allylic chlorides by reaction with 2,4-dinitrofluorobenzene and tiiethylamine at room temperature. The resulting ether is then treated with lithium chloride in HMPT (Sn 2 displacement). Yields in both steps are high. 

The determination of AT-terminal amino acids of polypeptides or proteins by means of reaction with 2,4-dinitrofluorobenzene is used as a chemical method for the estimation of molecular weight. This operation is rather complex because of the need for hydrolysis, separation of DNP-amino acids, and colorimetric comparison with a standard curve. Schiedt and Restle (1954) have estimated the degree of polymerization of oligopeptides using dinitrophenylation and infrared spectroscopic... 

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