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

  • Henry, Thomas Anderson, 1873-1958
Date:
[1930.]
Catalogue details

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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    less platelets from alcohol, m. p. 166—167° (corr.), which on admix¬ ture depress the melting point of 5-bromo-2-hydroxy-4-methoxy- benzaldehydephenylhydrazone to 140—150°. The latter is described as pale yellow leaflets, m. p. 177—178°; our specimen was colour¬ less and melted at 183° (corr.). The new bromo-compound on further bromination yielded a product which crystallised from alcohol in colourless needles, m. p. 96—97°, and did not depress the melting point of 3 : 5-dibromo-2-hydroxy-4-methoxybenz- aldehyde prepared by Rao, Srikantia, and Iyengar’s method (Found: C,30-9; H,2-l. Calc, for C8H603Br2 : 0,310; H, 1-95%). 2-Hydroxy-5-methoxybenzaldehyde.—In the earlier attempts to mercurate this aldehyde, the reaction in boiling 50% alcohol was found to be complete in 50 minutes but difficulty was experienced in isolating the mercury compound owing to demercuration taking place wrhen the reaction mixture was worked up. The following procedure was found satisfactory, although the yield varied slightly in different experiments. A mixture of 2-hydroxy-5-methoxy- benzaldehyde (6 g.) and mercuric acetate (48 g.) in 50% alcohol (200 c.c.) containing acetic acid (3 c.c.) wras boiled under reflux for an hour. The hot solution was filtered from mercurous acetate (5-25 g.) into 600 c.c. of 3% aqueous sodium hydroxide. The mercuric oxide was filtered off (21-0 g.), and the clear orange- coloured filtrate acidified with hydrochloric acid. The yellow pre¬ cipitate was collected, washed well with water, and dried in a desiccator (9-4 g.). From the filtrate 2-hydroxy-5-methoxybenz- aldehyde (T3 g.) was recovered by steam distillation. The yellow precipitate consisting of 3-chloromercuri-2-hydroxy-5-metJioxybenz- aldehyde is slightly soluble in alcohol, acetone, and chloroform, rather more so in benzene. From the last solvent it crystallises in three forms : (a) rosettes of rather wide, flat, yellow needles, (b) yellow spherical crystals, and (c) fine, hair-like, yellow needles. The conditions under which these forms arise have not been definitelv %/ elucidated, but they appear to separate as follows : (a) when solutions at a temperature below' about 50° are left to cool, (b) from solutions above that temperature, and (c) w'hen solutions saturated at room temperature are allowed to evaporate spontaneously. The compound melts at 242—243° (corr.; decomp.) (Found: C, 24-7; H, 1-9; Hg, 51-8. C8H703ClHg requires C, 24-8; H, 1-8; Hg, 51-8%). The substance formed on replacement of the chloromercuri- group by bromine crystallised from light petroleum (b. p. 40—60°) in bundles of stout yellow7 needles, m. p. 110—111° (corr.), which did not depress the melting point of 3-bromo-2-hydroxy-5-meth- oxybenzaldehyde prepared by Rubenstein’s method (loc. cit.) and