Uemura
Is this the procedure you were using?
Patent US3855306
3,4,5-Trimethoxybenzaldehyde.
Bromination of vanillin with Br in 48% HBr gave 99.4% 5-bromovanillin (I). Hydrolysis of I in NaOH-H2O in the presence of powd. Cu gave 83.3% 5-hydroxyvanillin (II). Methylation of II with Me2SO4 in Me2CO in the presence of powd. Na2CO3.H2O gave 90% 3,4,5-trimethoxybenzaldehyde of purity 99.3%, useful as intermediate for pharmaceuticals.
Well the melting point of 5-OH-vanillin is 132.5-134.0C so i would bet your produce is fairly pure.
this is the patents extraction procedure
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The reaction product, 5-hydroxyvanillin, is suitably isolated from the reaction mixture by a procedure of hot liquid-liquid extraction. In this procedure, the hot reaction mixture, after acidification with a strong acid, preferably a mineral acid such as concentrated hydrochloric acid, is continuously extracted with a water immiscible organic solvent at an elevated temperature, preferably between about 60 DEG and about 100 DEG. Suitable solvents for the hot liquid-liquid extraction include hydrocarbons, e.g., benzene or toluene; esters, e.g., ethyl acetate; and so forth. An especially preferred solvent for the hot liquid-liquid extraction is toluene.
The reaction product extracted into the organic solvent in the above step is then purified by recrystallization. An especially preferred solvent for recrystallization is toluene. In a preferred procedure, toluene is used as the extracting solvent in the hot liquid-liquid extraction and also serves by cooling of the hot extract, as a recrystallization solvent.
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Here is a procedure for "next time"
3,4-Dihydroxy-5-methoxybenzaldehyde.
Zikan, Viktor; Roubinek, Frantisek; Eichler, Jaroslav.
Czech. (1984), 5 pp. CODEN: CZXXA9
CS 216633 B 19841001 Patent written in Czech.
Abstract
Alk. solvolysis of 3,4,5-Br(HO)(MeO)C6H2CHO (I) yielding the title compd. (II), is catalyzed with CuO which is optionally prepd. in situ. Thus, a soln. of 122.4 g NaOH in 750 mL water was treated dropwise at 50° with 4 g CuSO4 in 40 mL water, 100 g I was added at 70° and the mixt. was refluxed 27 h under H. The resulting brown-green soln. was made acidic, cleared with C and worked up as usual to give 91.38% II of 99.5% purity.
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