Phosphoric Acid → 2,4-Dimethylresorcinol

HRID 1729128Notes

Reaction equation

HRID 1729128 reaction equation
[OH:1][C:2]1[C:9]([CH3:10])=[C:8]([OH:11])[CH:7]=[CH:6][C:3]=1[CH:4]=O.P(=O)(O)(O)O>[Pd].C(O)(C)C>[CH3:10][C:9]1[C:2]([OH:1])=[C:3]([CH3:4])[CH:6]=[CH:7][C:8]=1[OH:11]

Participants

5

Reactant 2

HCID 1004Phosphoric AcidHCID 803952,4-Dihydroxy-3-methylbenzaldehyde

Product 1

HCID 694522,4-DimethylresorcinolYield 72%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 3776IsopropanolSolvent

Procedure

A solution of 2.4-dihydroxy-3-methylbenzalde hyde (30.0 g, 197 mmol) with isopropanol (3 L) was ice-cooled in a 5 L 3-neck flask fitted with a magnetic stirrer. Phosphoric acid (4 mL) and 10% palladium on carbon were added and the solution was sparged with nitrogen, then hydrogen. When uptake was judged to be complete (c. 1.5 hour) the solution was again sparged with nitrogen and then filtered through Celite®. The solvent was stripped off, the residue taken up in ethyl acetate, and the resulting solution washed with water (4×100 mL). The water washes were back-extracted with ethyl acetate and the combined organic layers dried over sodium sulfate and stripped down. Sublimation (95°, 0.05 tort) afforded a colorless solid (19.6 g, 72%). M.p. 107°-8° C. (Lit. 108°-109° C. [W. Baker et al., J. Chem. Soc., 2834-5 (1949).]). NMR (DMSO-d6): δ 1.969 (s, 3H), 2.037 (s, 3H), 6.220 (d, J=8.1 hz, 1H), 6.637 (d, J=8.1 hz, 1H), 7.929 (s, 1H), and 8.785 (s, 1H).

Workup

  1. temperaturecooled in a 5 L 3-neck flask
  2. customfitted with a magnetic stirrer
  3. customthe solution was sparged with nitrogen
  4. custom(c. 1.5 hour)
  5. customwas again sparged with nitrogen
  6. filtrationfiltered through Celite®
  7. washthe resulting solution washed with water (4×100 mL)
  8. extractionThe water washes were back-extracted with ethyl acetate
  9. dry with materialthe combined organic layers dried over sodium sulfate

Sources & evidence

ORD record
ord-b93d7c09812f4a5aa9e35caf3ed6224c
Source dataset
uspto-grants-1994_07
Patent number
US05332666

Reaction notes

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