Sulfuric Acid → 3-Methoxy-2-MethylBenzoic Acid

HRID 260803Notes

Reaction equation

HRID 260803 reaction equation
N[C:2]1[C:3]([CH3:11])=[C:4]([CH:8]=[CH:9][CH:10]=1)[C:5]([OH:7])=[O:6].S(=O)(=O)(O)O.N([O-])=O.[Na+].[OH-].[Na+].S(OC)([O:26][CH3:27])(=O)=O>O.CO>[CH3:27][O:26][C:2]1[C:3]([CH3:11])=[C:4]([CH:8]=[CH:9][CH:10]=1)[C:5]([OH:7])=[O:6]

Participants

8

Reactant 5

HCID 1118Sulfuric AcidHCID 6497Dimethyl Sulfate2×HCID 14798Sodium Hydroxide2×HCID 27336993-Amino-2-methylbenzoic acidHCID 23668193Sodium Nitrite

Product 1

HCID 70214833-Methoxy-2-MethylBenzoic Acid

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 962WaterSolvent

Conditions

Temperature
55 °C

Procedure

3-Amino-2-methylbenzoic acid, 140.3 grams (g), 0.93 mole, reacted in four portions) in 5.7 mass equivalents of methanol, was treated with 1.5 mole equivalents of concentrated sulfuric acid. The mixture was heated to 55° C. and 1.05 mole equivalent of sodium nitrite dissolved in twice its mass of water was fed to the reaction over 30 to 45 minutes, maintaining the temperature between 55° and 65° C. Then 4.5 mole equivalents of 25% aqueous sodium hydroxide was added over one-half hour, followed by a half-hour feed of 2 mole equivalents of dimethyl sulfate at 50° to 60° C. After one-half hour the batch was assayed by gas chromatography (GC). Additional sodium hydroxide and dimethyl sulfate were added in portions until complete conversion was obtained, The methanol remaining was removed by vacuum, and the residue was partitioned between ethyl acetate and water made acidic with sulfuric acid. The ethyl acetate was removed under vacuum. The combined residues (152.8 g) dissolved in 350 g warm methanol were poured into a mixture of 278 g concentrated sulfuric acid and 1 liter (L) water. The resulting precipitate was collected by filtration, washed with water, and dried in vacuo, giving 135.8 g of material which was 96% pure as determined by GC.

Workup

  1. customwas fed to the reaction over 30 to 45 minutes
  2. temperaturemaintaining the temperature between 55° and 65° C
  3. waitfollowed by a half-hour
  4. customat 50° to 60° C
  5. waitAfter one-half hour the batch was assayed by gas chromatography (GC)
  6. customwas obtained
  7. customThe methanol remaining was removed by vacuum
  8. customthe residue was partitioned between ethyl acetate and water
  9. customThe ethyl acetate was removed under vacuum
  10. dissolutionThe combined residues (152.8 g) dissolved in 350 g
  11. temperaturewarm methanol
  12. additionwere poured into a mixture of 278 g concentrated sulfuric acid and 1 liter (L) water
  13. filtrationThe resulting precipitate was collected by filtration
  14. washwashed with water
  15. customdried in vacuo

Sources & evidence

ORD record
ord-5b811557972e4daeaff60246a366d139
Source dataset
uspto-grants-1996_06
Patent number
US05530028

Reaction notes

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