Reacción #4981

Ecuación de reacción

2,4-dihydroxy-3-methylbenzaldehyde

Phosphoric acid

→

solid

Rendimiento 72.0%

2,4-dimethylresorcinol

Rendimiento 72.0%

Disolventes

isopropanol

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturacooled in a 5 L 3-neck flask
2. 2
   Otrofitted with a magnetic stirrer
3. 3
   Otrothe solution was sparged with nitrogen
4. 4
   Otro(c. 1.5 hour)
5. 5
   Otrowas again sparged with nitrogen
6. 6
   Filtraciónfiltered through Celite®
7. 7
   Lavadothe resulting solution washed with water (4×100 mL)
8. 8
   ExtracciónThe water washes were back-extracted with ethyl acetate
9. 9
   Secadothe combined organic layers dried over sodium sulfate

Procedimiento

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).

Fuente