Eugenol, vanillin flavors

Exercise 26-12 Devise a reasonable sequence of synthetic steps for conversion of eugenol to the flavoring material vanillin, which is 3-methoxy-4-hydroxybenzene-carbaldehyde (Section 26-5). 

The flavoring vanillin occurs naturally as glucovanillin (a glucoside) in the vanilla bean (Section 20-5). It is made commercially in several ways. One is from eugenol, itself a constituent of several essential oils ... 

Phenolic compounds are commonplace natural products. Vanillin gives the vanilla bean its flavor, eugenol is present in the oil of cloves, and thymol in thyme. 

Ethyl valerate Ethyl vanillin Eucalyptol flavoring agent, synthetic food Eugenol Eugenyl acetate Eugenyl benzoate Eugenyl formate Farnesol... 

Phenols are found in several of the essential oils of plants, which produce the odor or flavor of the plant. Eugenol is found in cloves, vanillin in vanilla bean, isoeugenol in nutmeg, and thymol in thyme... 

Eugenol is the main component of the essential oil of the clove tree Syzygium aro-maticum) and is one of the cheapest and most common flavor ingredients easily obtained from natural sources. Its low market price makes it an attractive feedstock for vanillin production, but up to now the yields are still unsatisfactory. 

Vanilla contains vanillin (1.3-3.0%) as the major flavor component, with over 150 other aroma chemicals also present, most of which are present in traces, including p-hydroxy-benzaldehyde, acetic acid, isobutyric acid, caproic acid, eugenol, furfural, p-hydroxy-benzyl methyl ether, vanillyl ethyl ether, anisyl ethyl ether, and acetaldehyde. The vanillin content differs in different varieties of vanilla, with Bourbon beans containing generally higher amounts than Mexican and Tahiti beans (martindale rosengarten stake). 

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