P-Xylene → Benzene, 2-bromo-1,4-dimethyl-

HRID 990164Notes

Reaction equation

HRID 990164 reaction equation
[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([CH3:8])=[CH:6][CH:7]=1.[Br:9]Br>[Fe]>[Br:9][C:3]1[CH:4]=[C:5]([CH3:8])[CH:6]=[CH:7][C:2]=1[CH3:1]

Participants

4

Reactant 2

HCID 7809P-XyleneHCID 24408Bromine2×

Product 1

HCID 11121Benzene, 2-bromo-1,4-dimethyl-

Reagents, catalysts & solvents 1

HCID 23925IronCatalyst

Procedure

p-Xylene (934.4 g; 8.8 mol) and Fe powder (16 g) were placed in the reaction vessel and about 20 ml of bromine were slowly added dropwise. The commencement of the reaction (after about 10 minutes) could be recognized by gas evolution. After the reaction had begun, the remaining bromine (total: 1278.4 g; 8.0 mol) was added dropwise at RT, with water bath cooling (4 hours). The mixture was stirred further for 2 hours at RT. The slightly brownish reaction solution was filtered off and stirred first with water, and then with 480 ml of saturated aqueous Na2SO3 solution, subsequently shaken once with dilute aqueous NaOH and twice with H2O; the organic phase (clear and colorless) was dried over MgSO4, filtered and purified by being vacuum-distilled twice (diaphragm pump/oil bath, about 100-120° C./60 cm column).

Workup

  1. additionwere slowly added dropwise
  2. customThe commencement of the reaction (after about 10 minutes)
  3. temperaturecooling (4 hours)
  4. filtrationThe slightly brownish reaction solution was filtered off
  5. stirringstirred first with water
  6. stirringwith 480 ml of saturated aqueous Na2SO3 solution, subsequently shaken once with dilute aqueous NaOH and twice with H2O
  7. dry with materialthe organic phase (clear and colorless) was dried over MgSO4
  8. filtrationfiltered
  9. custompurified
  10. distillationby being vacuum-distilled twice (diaphragm pump/oil bath, about 100-120° C./60 cm column)

Sources & evidence

ORD record
ord-1930a15bfc3346d895cb26bdefe617c8
Source dataset
uspto-grants-2002_10
Patent number
US06458909B1

Reaction notes

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