5-Hydroxyvanillin [3934-87-0-A] C8H8O4
In a 2-liter round-bottom flask, dissolve 61.2 g (1.53 mol) of sodium hydroxide in 750 ml of water. To the warm solution, add 50.0 g (0.217 mol) of 5-Bromovanillin and 0.5 g of copper powder (General Chemical Division, Allied Chemical Corporation). A white precipitate forms. The reaction mixture is stirred vigorously under a nitrogen atmosphere at reflux temperature. The color changes slowly from yellow to green to dark green, and after approximately 6 hours, the solid goes completely into solution. After heating the mixture at reflux temperature for 27 hours, the solution is acidified with 113 ml of concentrated hydrochloric acid (pH ≈ 2) and continuously extracted with toluene at 85 °C for 47 hours under constant stirring. The toluene container holds 450 ml of toluene, while the total volume of toluene in the system is approximately 1300 ml. The hot toluene extract is placed in a 1-liter beaker and cooled in an ice bath, causing the reaction product to crystallize. After cooling for approximately two hours, the product is filtered, washed with 100 ml of ice-cold toluene, and dried at 70 °C to constant weight. The yield is 30.4 g (83.3%); light brown flakes; melting point 132.5-134 °C.
Source: DE2248337 - Process for the production of 3,4,5-Trimethoxybenzaldehyde
Delivered by: Mephisto
Last updated: 17/12/2004
Other names: 3,4-Dihydroxy-5-methoxybenzaldehyde; 5-Methoxyprotocatechualdehyde; 4,5-Dihydroxy-3-methoxybenzaldehyde