Synthetic eugenol

While it is true that materials of identical chemical structure have the same odor qualities and are indistinguishable in their effect upon the skin irrespective of their origin, it is also true that very often synthetic and natural perfume materials that have the same name are not really identical in the chemical sense. Rhodinol from geranium oil consists of a different mixture of optical isomers than synthetic rhodinol. Eugenol from clove leaf oil is accompanied by different impurities than synthetic eugenol. Hence the natural and synthetic materials do differ in their odor quality, and they may differ in their effects upon the skin. 

SYNS 4-ALLYLGUAtACOL 4-ALLYL-l-HYDROXY-2-METHOXYBENZENE 4-ALLYL-2-METHOXYPHENOL CARYOPHYLLIC ACID EUGENIC ACID Fa 100 FEMA No. 2467 1-HYDROXY-2-METHOXY-4-ALLYLBENZENE 4-HYDROXY-3-METHOXYALLYLBENZENE 1-HYDROXY-2-METHOXY-4-PROP-2-ENYLBENZENE 2-METHOXY-4-ALLYLPHENOL 2-METHOXY-4-PROP-2-ENYLPHENOL 2-METHOXY-4-(2-PROPENYL)PHENOL 2-METOKSY-4-ALULOFENOL (POUSH) NCI-C50453 SYNTHETIC EUGENOL... 

Synonyms cas 97-53-0 4-ALLYLGUAIACOL 4-ALLYL-1-HYDR0XY-2-METH0XYBENZENE 4-ALLYL-2-METH0XYPHEN0L CARYOPHYLLIC ACID EUGENIC ACID SYNTHETIC EUGENOL... 

Dallmeier K, Carlini EA 1981 Anesthetic, hypothermic, myorelaxant and anticonvulsant effects of synthetic eugenol derivatives and natural analogues. Pharmacology 22 113-127... 

Eugenol is a natural product available from a variety of essential oils (cinnamon-tree or pimentos leaves). Its isomerization (Eq. 49) into isoeugenol, the starting material for synthetic vanillin, is rather difficult and proceeds in modest yields under relatively harsh conditions. It can, however, be very efficiently prepared by use of 2.2 molar equivalents of base and catalytic (5 %) amounts of Aliquat in the absence of solvent. 

Individual compounds can be isolated from essential oils containing one or only a few major components by distillation or crystallization. Examples are eugenol from clove oil, menthol from commint oil, citronellal from Eucalyptus citriodora oil and citral from Litsea cubeba oil. These compounds are used as such or serve as starting materials for the synthesis of derivatives, which are also used as flavor and fragrance substances. However, the importance of some of these oils has decreased substantially because of the development of selective synthetic processes for their components. 

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). 

Methyl eugenol 013,4-dimethoxy-l-allylbenzene [95-15-2] was fust characterized in 1915 as a powerful attractant for the male oriental fruit fly, Dams dorsalis, and attracts at least 60 other closely related Dams spp. Raspberry ketone [5471-51-2] or l-(4-/>-hydroxyphenyl)-2-butanone [5471-51-2] (174) is an equally powerful attractant for the melon fly, Dams mmrbitae, and the Queensland fmit fly, D. tryoni, and at least 180 other closely related Dams spp. The acetyl ester (cue-lure) (175) is more volatile and is a synthetic parakairomone especially effective for monitoring infestations by these species. Methyl eugenol and cue-lure [3572-06-3] have been used successfully in "male annihilation" of the oriental fmit fly and the melon fly by applying them to fiber board blocks or pieces of twine together with malathion or naled insecticides and distributing them over infested areas at doses of 15 g of attractant and 1 g of the insecticide per ha. 

In 1986 the largest ever smell survey was carried out involving 1.5 million people from all over the world. They were given scratch and sniff cards and a questionnaire to answer. The scents tested were androstenone, isoamyl acetate (banana), glaxolide (a synthetic musk), eugenol (cloves), rose, and a mercaptan (the one added to natural gas to make it detectable). Of those who took part, 50% were able to detect all six smells and only 1% could detect none of them. Women were found to be better than men. The smell that was sensed the least was androstenone, and if this really is a human pheromone then it does not operate by having an irresistible odour. 

In studies of the substantivity of nine aroma chemicals in a fabric softener application, head-space gas chromatography showed that benzyl salicylate, aldehyde C12 MNA, lilial, musk ketone, and the synthetic musk Fixolide were lost to a far lesser extent upon drying than were alpha ionone, eugenol, or linalool (Muller, Neuner-Jehle, and Etzweiler, 1992) (Figure 13.2). This result corresponds to the relative vapor pressures of these materials, except for aldehyde C12 MNA which is a special case. 

Isolated aroma chemicals are aroma-active substances isolated from natural sources mainly by means of crystallization, distillation, and adduct formation/decomposition. Although synthetic materials are in many cases convenient to use, isolated aroma chemicals continue to be advantageous, especially when chirality is the issue. Even if chirality is not a problem, in some cases (eg., 1,8-cineole (1), eugenol (2), and limonene (3)), isolated natural chemicals serve better than their synthetic counterpart (Table 3). 3 Isolated aroma chemicals can be useful as such for the industry, and they are also utilized as starting materials for further synthetic manipulations.34,35... 

Vanillin has been known as a flavouring substance since about 1816, and by 1858 the pure chemical had been obtained from ethanolic extracts of vanilla beans. It was not until 1872 that Carles established its correct formulation and in 1874, Tiemann and Haarmann reported it as 3-methoxy-4-hydroxy-benzaldehyde (Fig. 3.60). Finally, Reimer synthesized vanillin from guaiacol and thus proved its chemical structure. For many years, the most important source of vanillin was eugenol, from which it was obtained by oxidation. Today, the major portion of commercial vanillin is obtained by processing waste sulfite liquors, the rest through fully synthetic processes starting from guaiacol [21 ]. 

Methyl-eugenol and cue-lure are highly active commercialized synthetic kairomone lures to the oriental fruit fly, Bactrocera dorsalis, and the melon fly, Bactrocera cucurbitae, respectively (e.g., Vargas et al., 2000) ... 

A number of alkenyiphenols of natural origin are of great importance in the perfume and flavour industries, such as eugenol (1), the principal component of oil of cloves, its semi-synthetic isomerisation product iso-eugenol (2), the phenolic ether, anethole (3) from fennel and oil of aniseed (umbelliferacae), and also of semisynthetic origin from chavicol (4). Their chemistry is not included in the present account which is devoted to less well-known substances. 

I. a. both species-specific pheromones and natural or synthetic foreign substances, provided that they possess insect-attracting properties, are used. o-MeAyl-eugenol, anisylacetone, geraniol/ eugenol have proved to be useful in various mixtures as I. a. for certain species. 4-(p-Hydroxyphenyl)-2-butanone (CI oH 12O2, Mr 164.20) and its acetate are commercially available as I. a. for the Mediterranean fruit fly Cera-titis capitata see also pheromones, allomones, syn-omones, kairomones, semiochemicals. 

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