Sanger s reagent, 2,4-dinitrofluorobenzene

Acid fluondes such as oxalyl fluoride, tnchloroacetyl fluonde, propionyl fluonde, as well as Sanger s reagent, 2,4-dinitrofluorobenzene, easily cleave N,N-acetals (aminals) to give high yields of fluoromethyldialkylamines [82] (equation 20) (Table 5)... 

Sanger s reagent, 2,4-dinitrofluorobenzene, can also be employed for the colormetric detection of amino acids. The reagent reacts with both primary and secondary amines and derivatives are detected at 420 nm. The molar absorptivity of the reagent is 10", allowing quantification of amino acids at the micromolar level. The reagent also reacts with thiols and alcohols, but these products are relatively unstable. 

Dinitrofluorobenzene (Sanger s reagent) [70-34-8] M 186.1, m 25-27 , b 133 /2mm, 140-141 /5mm, d 1.483. Crystd from ether or EtOH. Vacuum distd through a Todd Column (see p. 174). If it is to be purified by distn in vacuo, the distn unit must be allowed to cool before air is allowed into the apparatus otherwise the residue carbonises spontaneously and an EXPLOSION may occur. The material is a skin irritant and may cause serious dermatitis. 

Nucleophilic aromatic substitution is much less common than electrophilic substitution but nevertheless does have certain uses. One such use is the reaction of proteins with 2,4-dinitrofluorobenzene, known as Sanger s reagent, to attach a "label" to the terminal NH2 group of the amino acid at one end of the protein chain. 

The reaction of 2,4-dinitrofluorobenzene (DNFB) (Sanger s reagent [10]) with amino acids is another useful technique which is often employed for the analysis of N-terminal amino acids by TLC and column chromatography after derivatization. The reaction involved in product formation is shown in Fig.4.6. The separated derivatives are determined by measuring the quenching of fluorescence on TLC plates or by UV analysis after column chromatography. The generalized absorption curves of dinitrophenyl (DNP)-amino acids in acidic and alkaline solutions are shown in Fig. 4.7. 

A method for determining the N-terminal amino acid of a peptide. The peptide is treated with 2,4-dinitrofluorobenzene (Sanger s reagent), then completely hydrolyzed. The derivatized amino acid is easily identified, but the rest of the peptide is destroyed in the hydrolysis, (p. 1180)... 

Hitherto we have concentrated on electrophilic aromatic substitution. However, certain n-deficient aromatic rings are deactivated towards electrophilic attack but are susceptible to nucleophilic addition and a subsequent elimination. A particular example is 2,4-dinitrochloroben-zene. The electron-withdrawing nitro groups facilitate a Michael-type addition of a nucleophile to give a so-called Meisenheimer intermediate (Scheme 4.8). Collapse of the Meisenheimer intermediate and reversion to the aromatic system may lead to expulsion of the halide ion, as exemplified by the preparation of 2,4-dinitrophenylhydrazine. 2,4-Dinitrofluorobenzene is known as Sanger s reagent and is used for the detection of the N-terminal amino acids in peptides. 

Determination of N-terminal amino acid residues by use of 2,4-dinitrofluorobenzene (Sanger s reagent). 

Solution 5-dimethylaminonaphthalenesulfonyl chloride (dansyl chloride) reacts with an amino acid in the same manner as does 2,4 dinitrofluorobenzene (Sanger s reagent) it bonds with the unprotected a-amino group. 

Sandoz Sulfate WE. See Sodium laureth sulfate Sandoz Sulfonate 3B2. See Sodium decyl diphenyl ether sulfonate Sandoz Sulfonate AAS 35S, Sandoz Sulfonate AAS 40FS, Sandoz Sulfonate AAS 45S. See Sodium dodecylbenzenesulfonate Sandoz Sulfonate AAS 50MS. See Ammonium dodecylbenzene sulfonate Sandoz Sulfonate AAS 60S. See TEA-dodecylbenzenesulfonate Sandoz Sulfonate AAS 70S. See Sodium dodecylbenzenesulfonate Sandoz Sulfonate AAS 75S. See Calcium dodecylbenzene sulfonate Sandoz Sulfonate AAS 90. See Sodium dodecylbenzenesulfonate Sandoz Sulfonate AAS 98S. See Dodecylbenzenesulfonic acid Sandoz Sulfonate AAS-Special 3. See Isopropylamine dodecylbenzenesulfonate Sandranol 3/070540. See 2-Ethyl-4-(2,2,3-tri methyl-3-cycl openten-1 -yl )-2-buten-1 -ol Sanduvor 3041 Disp.. See2-Hydroxybenzophenone Sanduvor PR-31 Powd.. See Bis (1,2,2,6,6-pentamethyl-4-pi peridi nyl) 2-(4-methoxybenzylidene) malonate Sanduvor VSU Disp., Sanduvor VSU Powd.. See 2-Ethyl, 2 -ethoxy-oxalanilide Sanger s reagent. See 2,4-Dinitrofluorobenzene Sanibrom 40 Sanibrom 45, Sanibrom S. See Sodium bromide... 

An alkylator which has found use in analytical work (sequencing of proteins the determination of the sequence in which the amino acid monomers are arranged in the protein polymer) is 2,4-dinitrofluorobenzene Sanger s reagent). 

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