Phosphoric Acid → 1,3-Benzenediol, 4-methyl-

HRID 743952Notes

Reaction equation

HRID 743952 reaction equation
[OH:1][C:2]1[CH:9]=[C:8]([OH:10])[CH:7]=[CH:6][C:3]=1[CH:4]=O.P(=O)(O)(O)O>CC(O)C.[Pd]>[CH3:4][C:3]1[CH:6]=[CH:7][C:8]([OH:10])=[CH:9][C:2]=1[OH:1]

Participants

5

Reactant 2

HCID 1004Phosphoric AcidHCID 72132,4-Dihydroxybenzaldehyde

Product 1

HCID 103331,3-Benzenediol, 4-methyl-Yield 98.1%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 3776IsopropanolSolvent

Procedure

2,4-Dihydroxybenzaldehyde (33.97 gm, 0.246 mol) (recrystallized from toluene) was dissolved in spectroscopic grade 2-propanol (3 L) in a round bottom flask fitted with a gas inlet and a bubbler outlet. 10% Palladium on carbon (1.35 gm) was added followed by phosphoric acid (3 mL) and the mixture was sparged with nitrogen. The nitrogen flow was switched to hydrogen and the mixture was rapidly stirred with ice cooling. After 3 hours hydrogen uptake was complete and the catalyst was removed by filtration. The filtrate was stripped down to 200 mL and 200 mL of ethyl acetate was added. The solution was washed with 4×200 mL of water and the combined water extracts back-extracted with ethyl acetate. These organic extracts were water washed and the combined organic layers dried over sodium sulfate and stripped down to afford the product as a colorless crystalline solid (29.95 gm, 98%). M.p.: 106° C. (Lit. 106°-107° C. [J. C. Bell, W. Bridge, and A. Robertson, J. Chem. Soc., 1542-45 (1937)]). NMR (DMSO-d6): δ1.961 (s, Me), 6.076 (dd, H-6, J[5,6]=8 hz, J[2,6]=2 hz), 6.231 (d, H-2), 6.760 (d, H-5) 8.867 (s, OH), and 9.008 (s, OH).

Workup

  1. customfitted with a gas inlet and a bubbler outlet
  2. customthe mixture was sparged with nitrogen
  3. customthe catalyst was removed by filtration
  4. additionwas added
  5. washThe solution was washed with 4×200 mL of water
  6. extractionthe combined water extracts back-extracted with ethyl acetate
  7. washwashed
  8. dry with materialthe combined organic layers dried over sodium sulfate

Sources & evidence

ORD record
ord-1417a0f640ef48bbbf09a5845270976e
Source dataset
uspto-grants-1996_09
Patent number
US05558991

Reaction notes

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