The positional delta(O-18) values of extracted and synthetic vanillin

The positional delta(O-18) values of vanillin (1) of different origins have been determined from the global values of 2-methoxy-4-methylphenol (4), ob tained from 1 upon Clemensen reduction, and of 3-methylanisole (5), obtaine d from 4 by removal of the phenolic O-atom. By these means, it is possible to differentiate samples of 1 of synthetic origin from those extracted from Vanilla plants or produced from lignin by chemical oxidation. The main dif ference between the samples derived from guaiacol and those possessing the aromatic moiety of natural origin is in the enrichment values of the O-atom s at C(3) and C(4), while the extractive materials from the pods are distin guished from the product from lignin on the basis of the carbonyl oxygen de lta(O-18) values, ranging from + 25.5 and + 26.2 in the natural material to + 19.7 parts per thousand in the lignan-based sample. The values for the p henolic O-atom vary from + 8.9 and + 12 parts per thousand of the synthetic materials to + 6.5, + 5.3, and + 6.3 parts per thousand, respectively, of the sample from lignin and the two samples from Vanilla pods, whereas the M eO O-atoms show the following values significance of the positional delta(O -18) values of polyoxygenated compounds for the definition of their origin.