Mercuration of some polyhydroxybenzaldehydes and their monomethyl ethers / by T.A. Henry and T.M. Sharp.

  • Thomas Anderson Henry
Date:
[1930.]
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Licence: Public Domain Mark

Credit: Mercuration of some polyhydroxybenzaldehydes and their monomethyl ethers / by T.A. Henry and T.M. Sharp. Source: Wellcome Collection.

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    hydroxyl group in mercuration (compare Henry and Sharp, J., 1922, 121, 1055; 1924, 125, 1049; 1926, 2432) thus being con¬ firmed. For instance, isovanillin forms 2-acetoxymercurir3-hydroxy- 4-metkoxybenzaldehyde (VI), 2-hydroxy-4-methoxybenzaldehyde yields 3-acetoxymercuri-2-hydroxy-4:-methoxybenzaldehyde (VII), and 2-hydroxy-5-methoxybenzaldehyde gives rise to 3-chloromercuri- 2-kydroxy-5-methoxybenzaldehyde (VIII). CHO OH Hg*OAc OMe (VII.) (VIII.) CHO In the case of o-vanillin the acetoxymercuri-compound is no doubt first formed, but this on drying loses acetic acid with the formation of 2 : 5-anhydro-5-hydroxymercuri-2-hydroxy-3-'methoxy- benzaldehyde (IX). This formula accounts for all the properties of the substance, but a structure such as (X) is not excluded. The product is soluble only in acetic acid, which converts it into 5-acet- oxymercuri-2-hydroxy-3-methoxybenzaldehyde, and consequently the molecular weight, which would decide between these two formulae, could not be determined. (x) r o*Hg i ' ; Me0*C6H2(CH0)’Hg*0*C6H2(CH0)*0Me Although anhydride formation between a hydroxyl group and a hydroxymercuri-group in the ortho-position is quite common, a similar condensation between groups in the para-position (IX) does not seem to have been recorded previously. The constitution of the mercuri-compound from fsovanillin (VI) follows from its conversion into a bromofsovanillin, m. p. 211— 212°, which is shown to be the 2-bromo-derivative by the formation from it of methyl 2-bromoveratrate, of known constitution (Zincke and Francke, Annalen, 1896, 293. 185). The bromo-aldehyde is identical with a compound prepared by Pauly (Ber., 1915, 48, 2010) which he wrongly assumed to be 6-bromoisovanillin. In preparing Pauly’s bromoisovanillin, the authors obtained a second monobromo-derivative, m. p. 112—114°. This is shown to be 6-bromof50vanillin by (a) methylation to the known 6-bromo- 3 : 4-dimethoxybenzaldehyde (Pschorr, Annalen, 1912, 391, 23), and (b) oxidation to the corresponding acid and preparation of the methyl ester, m. p. 81—82° (corr.), for which Zincke and Francke
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