1-Fluoro-2,4-dinitrobenzene

• 2,4-dinitro- 1 -fluorobenzene
• Dinitrofluorobenzene
• DNFB
• 4-fluoro- 1 ,3 -dinitrobenzene

Pale yellow crystals

Fixed

1.482 g · cm -3 ( 25 ° C)

25.8 ° C

296 ° C

Attention

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1-fluoro- 2 ,4-dinitrobenzene, or Sanger's reagent is a yellow crystalline solid, which is used for protein sequencing. The structure consists of a benzene ring with a fluorine (-F) and two nitro groups (- NO2) as a substituent. It belongs to a group of substances with the result from different arrangement of the substituents six constitutional isomers.

History and presentation

1-fluoro- 2 ,4 -dinitrobenzene was first represented by Holleman and Beekman in 1903. They received it by nitration of p- fluoronitrobenzene, which had previously shown for p-nitroaniline. In 1936, Gottlieb presented a synthesis, was treated at the 1-chloro- 2 ,4 -dinitrobenzene in nitrobenzene with potassium fluoride (KF ).

Significant improvements of this method presented Cook and Saunders before in 1947, which were based on a significant reduction in the amount of potassium fluoride and the steps. They also heated 1-chloro- 2 ,4-dinitrobenzene with anhydrous potassium fluoride in nitrobenzene at 190 to 195 ° C. The product was then purified by distillation. For the use of sodium fluoride (NaF ) in place of potassium fluoride, however, no reaction was practically observed.

Properties

1-fluoro- 2 ,4-dinitrobenzene is a yellow crystalline solid, melting at 25.8 ° C and boiling at 296 ° C. It crystallizes in the orthorhombic crystal system, space group P2i2i2i with the lattice parameters a = 621.0 pm, b = 945 pm and c = 1285 pm and four formula units per unit cell.

Use

In 1945, Frederick Sanger described the use of 1-fluoro- 2 ,4-dinitrobenzene to the determination of the N -terminal amino acids in the polypeptide, especially in insulin. B. C. Saunders asked him the chemical kindly made ​​available, both worked at the time at the University of Cambridge in England. Sanger's first results showed that insulin was a smaller molecule than previously thought ( molar mass 12.000 g · mol -1), and that they consist of four chains (two ends with glycine and two ends with phenylalanine). Sanger continued to work on insulin with dinitrofluorobenzene in combination with other techniques continue to ultimately achieve the full sequencing of insulin (consisting of only two chains with a molar mass of 6000 g · mol -1). Due to this work, the substance was given the additional name of Sanger's reagent.

Following the initial Sanger's the dinitrofluorobenzene method has been widely applied for the study of proteins, until it was replaced by other reagents for terminal analysis (eg, dansyl chloride and aminopeptidases and carboxypeptidases later ) as well as other general methods for the determination of the sequence ( for example, the Edman degradation ).