Reaktion #4981

Reaktionsgleichung

2,4-dihydroxy-3-methylbenzaldehyde

Phosphoric acid

→

solid

Ausbeute 72.0%

2,4-dimethylresorcinol

Ausbeute 72.0%

Lösungsmittel

isopropanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturcooled in a 5 L 3-neck flask
2. 2
   Sonstigefitted with a magnetic stirrer
3. 3
   Sonstigethe solution was sparged with nitrogen
4. 4
   Sonstige(c. 1.5 hour)
5. 5
   Sonstigewas again sparged with nitrogen
6. 6
   Filtrationfiltered through Celite®
7. 7
   Waschenthe resulting solution washed with water (4×100 mL)
8. 8
   ExtraktionThe water washes were back-extracted with ethyl acetate
9. 9
   Trocknenthe combined organic layers dried over sodium sulfate

Vorschrift

A solution of 2,4-dihydroxy-3-methylbenzaldehyde (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 d10% 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 torr) 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).

Quelle