p-alkoxyphenol writeup

[Vitus_Verdegast]

Unfortunately, in the 2 articles mentioned (J.Am.Chem.Soc.(1993) 115, 4397 and J.Org.Chem.(1996) 61, 3350) there's nothing to be found about methylating with MeI in DMSO   . I've got the refs from Synlett 2001(11)p 1811.

I did found this ref, which I will try and catch tomorrow:

"Methylation of 5-nitro-ortho-vanillin with Ag₂O and CH₃I in CHCl₃"
J. Chem. Soc. (1923) 123, 1575-93

[Antoncho]

Can't wait to hear more.....

[Vitus_Verdegast]

5-nitro-2,3-dimethoxybenzaldehyde

The above described nitro-o-vanillin is not conveniently methylated by means of methyl sulfate, but the methylation is easily carried out by application of Purdie's method.

Nitro-o-vanillin (7.4 grams), dissolved in a mixture of methyl iodide (5 cc.) and chloroform (30 cc.), is boiled with finely powdered silver oxide (7 grams) for three hours. The inorganic matter is filtered off, and most of the solvent removed, when the methylated product (mp. 115°) separates out in almost quantitative yield. Recrystallisation does not alter the melting point. 5-nitro-2,3-dimethoxybenzaldehyde consists of colourless needles which are very soluble in hot and somewhat soluble in cold MeOH, very slightly soluble in boiling water, and insoluble in cold NaOH solution.

5-nitro-2-methoxy-3-ethoxybenzaldehyde
The above nitroethoxysalicylaldehyde is methylated by boiling with silver oxide and methyl iodide in chloroform, the reaction being complete in one hour. The yield is almost quantitative and the methylation product separates in very light, colourless needles melting at 118.5°


It appears that Purdie's methylation method is used frequently in carbohydrate chemistry. A method that substitutes DMF for CHCl₃ is used in Carbohydrate Research 1977, 58(2), 527-536. Also a modified method using MeI and Al₂O₃ in DMF claimes 15-20% higher yields (for carbohydrates): Science and Culture (1974) 40( p 368-69