Of isoeugenol

The manufacture of vanillin shows the progress made in the chemistry and chemical engineering of the substance. Most commercial vanillin is synthesized from guaiacol the remainder is obtained by processing waste sulfite Hquors. Preparation by oxidation of isoeugenol is of historical interest only. 

There are several crystalline compounds useful for the identification of isoeugenol, amongst which are the following —... 

Benzoyl-isoeugenol, melting at 105°, is prepared by the addition to 10 parts of isoeugenol of a dilute solution of caustic soda, and then of 16 parts of benzoyl chloride. The temperature should be kept low, and crystals of benzoyl-eugenol will separate. 

If equimolecular proportions of isoeugenol and acetic anhydride are heated for four to five hours to 135°, and the mixture washed with dilute alkali, acetyl-isoeugenol results, which, when dissolved in benzene and precipitated by petroleum ether, crystallises in needles melting at 79° to 80°. 

Yamada, M., Y. Okada et al. (2007). Purification, characterization and gene cloning of isoeugenol-degrading enzyme from Pseudomonas putida IE27. Arch. Microbiol. 187(6) 511-517. 

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is widely used in foods, beverages, perfumes and the pharmaceuticals industries. Biotransformation of isoeugenol from essential oil to vanillin represents an economic route for the supply of vanillin, which has a limited supply due to the availability of vanilli pod plants. The conversion yield of isoeugenol to vanillin by the whole-cell biotransformation process of Bacillus fusiformis was low due to the product inhibition effect. Adding resin HD-8 to the whole-cell biotransformation eliminated the product inhibition effect, yielding 8 gL 1 of vanillin in the final reaction mixture [27]. The resin HD-8 also facilitated the separation of vanillin from the used substrate. The recovered isoeugenol can be used for the subsequent biotransformation reaction. 

Zhao, L.-Q., Sun, Z.-H., Zheng, P. and He, J.-Y. (2006) Biotransformation of isoeugenol to vanillin by Bacillus fusiformis CGMCC1347 with the addition of resin HD-8. Process Biochemistry (Barking, London, England), 41, 1673-1676. 

Isoeugenol can be hydrogenated catalytically to form dihydroeugenol. Vanillin was formerly prepared by oxidation of isoeugenol. Additional fragrance materials are prepared by esterification or etherification of the hydroxyl group. 

Production. Starting materials for the synthesis of isoeugenol are eugenol and guaiacol. 

C11H14O2, Mr 178.23, exists in cis (mp 35-36 °C) and in Irans mp 86°C) forms. The trans isomer has a sweet vanilla-like odor. Propenylguethol can be prepared from isosafrole by reaction with methyl magnesium chloride or by ethylation of isoeugenol followed by selective demethylation with alkali [169]. 

Li YH, Sim ZH, Zao LQ, Xu Y (2005) Bioconversion of isoeugenol into vanillin by crude enzyme extracted from soybean. Appl Biochem Biotechnol 125 1-10... 

Zhao LQ, Sun ZFl, Zheng P, Zhu LL (2005) Biotransformation of isoeugenol to vanillin by novel strain of Bacillus fusiformis. Biotechnol Lett 27 1505-1509... 

Freudenberg realized the importance of investigating this possibility. In 1937 he found that dehydrogenation of coniferyl alcohol with ferric chloride seemed to proceed in a way comparable with that of isoeugenol, and in 1943 he started his studies on the enzymatic dehydrogenation of coniferyl alcohol. It would not be possible here to give even a brief survey of the outstanding work which he has done since then. 

Eugenol has been used as a feedstock in the production of isoeugenol, which is needed in the manufacture of vanillin. Methylation of eugenol yields methyleugenol, which acts as a sex attractant for a certain type of fly (Dacus dorsalis) [7,8]. 

Scheme 5 MTO-catalyzed oxidative cleavage of isoeugenol and trans-iemlic acid to vanillin [89]...

Rao, S.R. and Ravishankar, G.A. (1999) Biotransformation of isoeugenol to vanilla flavour metabolites and capsaicin in suspended and immobilized cell cultures of Capsicum frutescens study of the influence of / -cyclodextrin and fungal elicitor. Process Biochemistry 35(3-4), 341-348. 

The earliest example of ozonation of a model compound with an alkene side chain is that of isoeugenol (Wood 1923). The anticipated product, vanillin, may be obtained in yields as high as 90% because of the retardation of further oxidation by the deactivating aldehyde group. Systematic studies on models of this type have been reported by Eriksson and Gierer (1985). The investigation by Kolsaker and Bailey (1967) is also relevant. 

Chardonnay wines in contact with Hungarian and Russian oak wood with low oak lactone contents scored well for oak wood sensory attributes. GC-sniffing analysis of these woods concluded that such other components as eugenol and the cis and trans isomers of isoeugenol, together with guaiacol and its derivatives, also contributed to the spicy , clove , cinnamon , and woody/oaky aromas. Oak lactones, on the other hand, elicited the odour descriptors sweet , vanilla , and oaky (Dfaz-Maroto et al. 2008). 

Oxidation of olefinic side chains with ozone to form aromatic aldehydes gives erratic results and therefore other oxidants are employed. For this purpose, the most widely used oxidant is nitrobenzene in dilute alkali the mixture is allowed to react at moderate temperatures for several hours. Thus, hydroxy benzaldehydes may be obtained from propenyl-phenols, which in turn are readily prepared by the Claisen rearrangement of Oalkyl ethers (method 100). Sodium dichromate in the presence of sulfanilic acid, which removes the aldehyde as it is formed, gives yields as high as 86% in the oxidation of isoeugenol and isosafrole. ... 

Carswell, T., S. Impoveraents in or relating to the Separation of Alkox Isoeugenol from Alkoxyisochavibetol and the Production of Isoeugenol from lb Separated Compounds 1930 GB 303,021... 

Two useful groups of related reactions may be discerned here, both of which are observed for prope-nyl-phenols. The first type is illustrated by the oxidation of isoeugenol (255) with aqueous iron(IIl) chloride,which yields the threo- and erythro-stereomers (55%) of the hydroxy ether (256), presum-... 

As has been shown by Quest International [31], lipoxygenases also accept a relatively broad spectrum of phenolic compounds as substrates. Of interest to the flavour industry are the lipoxygenase-catalyzed conversions of isoeugenol and coniferyl benzoate from Siam resin to vanillin (4-15% peld. Fig. 7.12). At present, the commercialization of these biotransformations is hampered by the... 

Use Perfumes, essential oils, medicine (analgesic), production of isoeugenol for the manufacture of vanillin, flavoring. 

FIGURE 12.9 Reaction of isoeugenol and dehydrodiisoeugenol with peracetic acid. (After Oki, T., Okubo, K., and Ishikawa, H., Mokuzai Gakkaishi, 18, 601-610, 1972.)... 

T Oki, K Oknbo, and H Ishikawa. The peracetic acid oxidation of isoeugenol and dehy-drodiisoeugenol. Mokuzai Gakkaishi 20 89-97, 1974. 

Production. The starting material for the synthesis of isoeugenol is eugenol. The sodium or potassium salt of eugenol is isomerized to isoeugenol by heating. Isomerization can also be carried out catalytically in the presence of ruthenium [164] or rhodium [165] compounds. 

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