Sulfuric Acid → 5-Fluoro-2-nitrophenol

HRID 965435Notes

Reaction equation

HRID 965435 reaction equation
F[C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[N+:9]([O-:11])=[O:10].[OH-].[K+].S(=O)(=O)(O)[OH:15].[F-].[Si](O)(O)(O)O.[OH-].[Ca+2].[OH-]>O>[F:8][C:6]1[CH:5]=[CH:4][C:3]([N+:9]([O-:11])=[O:10])=[C:2]([OH:15])[CH:7]=1

Participants

8

Reactant 6

HCID 1118Sulfuric AcidHCID 14797Potassium HydroxideHCID 14942Orthosilicic acidHCID 28179Fluoride IonHCID 679672,4-DifluoronitrobenzeneHCID 6093208Calcium Hydroxide

Product 1

HCID 99375-Fluoro-2-nitrophenolYield 78%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
60 °C

Procedure

In this example, the stirrer described in Example 1 was introduced via an axial face seal into an otherwise commercially available PTFE reactor, the axial face seal being made of α-silicon carbide. Instead of Asplit FN, Asplit CN and, as the shaft material, CFP (carbon fiber-reinforced plastic based on phenolic resin) were employed. 119.4 g (0.75 mol) of 2,4-difluoronitro-benzene were initially introduced into the PTFE reactor, 104.8 g (1.566 mol) of potassium hydroxide (85% strength) in 300 g of water were added dropwise at 55° C. in the course of 4 hours, and the temperature was then increased to 60° C. Specimens (stainless steel V4A) of material No. 1.4571 were positioned in the liquid and in the vapor space. After the end of the reaction, 96% strength sulfuric acid was added until pH 2.3 was reached and, as a fluoride-trapping agent, 40 g of highly disperse silicic acid (Aerosil®) and 38.0 g of calcium hydroxide were added, a pH of 4.2 being established. Introduction of steam was started, after which 5-fluoro-2-nitrophenol was distilled off with the steam. During the steam distillation, the pH was reduced to 1.5 in the course of 1.5 hours by means of 96% strength sulfuric acid, and was then kept at this value. The distillate was cooled to 10° C. and then filtered. 91.9 g (0.58 mol, 78%) of 5-fluoro-2-nitrophenol were obtained as a yellow solid. After the experiment had been repeated several times, the stirrer proved to be unchanged. Specimens of materials 1.4462 and 1.4539 showed uniform attack (integral rates of removal of material of between 1 and 6 mm/a) and partial pitting corrosion and stress corrosion cracking after an exposure time of only 50 hours.

Workup

  1. additionwas introduced via an axial face
  2. customthe axial face seal
  3. additionwere added dropwise at 55° C. in the course of 4 hours
  4. additionwas added until pH 2.3
  5. additionwere added
  6. distillationafter which 5-fluoro-2-nitrophenol was distilled off with the steam
  7. distillationDuring the steam distillation
  8. customwas reduced to 1.5 in the course of 1.5 hours by means of 96% strength sulfuric acid
  9. temperatureThe distillate was cooled to 10° C.
  10. filtrationfiltered

Sources & evidence

ORD record
ord-7f42b30032694f3a8f4566c2c040e7af
Source dataset
uspto-grants-1998_06
Patent number
US05773651

Reaction notes

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