Iso eugenole

The best yield, however, is obtained by first converting the eugenol into iso-eugenol, OH. OCH3. . CH CH. CH3, bv treating it with... 

For the manufacture of vanillin, eugenol is first isomerised to iso-eugenol, in which a rearrangement in the side chain has taken place. 

Figure 2. Scores of 17 volatile phenols on two PLS factors. 1 = eug ol, 2 = iso-eugenol, 3 = 4-meUiyl-guiacol, 4 = 4-ethyl-guiacol, 5 = 4-hydroxy-benzaldehyde, 6 = 2,4-dihydroxy-benzaldehyde, 7 =...

Vanillin1 can be formed by electrolytic oxidation of the sodium salt of iso-eugenol. According to the process of F. von Heyden Nchfg. a 15 per cent, alkaline solution of the sodium salt forms the anolyte, and the cathode compartment is filled with caustic soda solution (10-20 per cent.). The temperature is maintained at 60s C., and the lead peroxide anode evidently acts as a catalyst, since with platinum the discharged oxygen is evolved without effecting the oxidation —... 

Hydrogen peroxide with Milas reagent is also suitable for the cleavage of olefins. The system has been used to prepare aromatic aldehydes such as anisaldehyde from anethole, pipernal from isosafrole and vanilin from iso-eugenol.170,171 Hydrogen peroxide and chromium(III) can be used to cleave methyl methacrylate to methyl pyruvate.172... 

Wang, J. and Pichersky, E. (1998) Characterization of S-adenosyl-L-methionine (iso) eugenol O-methyltransferase involved in floral scent production in Clarkia breweri. Arch. Biochem. Biophys., 349,153-60. 

Eiigenole and Safrole.—The chief constituent of a more common essential oil is eugenole which occurs in oil of cloves. It is the monomethyl ether of di-hydroxy 7-phenyl propene in which the methoxy group is meta and the hydroxyl group is para to the propene chain. It is thus a propene derivative of the mono-methyl ether of pyro-catechinol. The alpha isomer is known as iso-eugenole. 

The conversion of eugenole into iso-eugenole and of safrole into iso-safrole is accomplished by boiling with alcoholic potassium hydroxide. The oxidation products of these ethers are other important essential oil constituents. Eugenole yields the corresponing aldehyde which is known as vanillin, the chief constituent of vanilla beans from which vanilla extract is made. Safrole by oxidation yields a compound known as piperonal also as heliotropine. It has the odor of heliotrope flowers and is used as artificial heliotrope essence. These latter compounds and also constituents of other essential oils will be considered in detail later in their proper chemical relationship (p. 66i, etc.). 

It will be recalled that the difference between eugenole and safrole on the one hand and the corresponding iso compounds, iso-eugenole and iso-safrole, on the other is, that in the latter and also in coniferyl alcohol, anol and anethole, the benzene ring is in the alpha or i position in the unsaturated propene or propenol chain. When such an unsaturated side chain compound is oxidized the chain breaks at the double bond and yields the aldehyde of the benzene compound. 

Heliotropin, Piperonal.— Heliotropin receives its other name of piperonal from its relation to compounds occurring in pepper. In black pepper, Piperus nigra there is present an alkaloid known as piperine (p. 888). From this alkaloid an acid, piperic acid, is obtained. This acid is a methylene di-ether containing an alpha unsaturated side chain as in iso-eugenole, etc. On oxidation the side chain breaks at the double bond, as has been explained, and yields an aldehyde which is piperonal. 

Safrole (oxidation to the corresponding acids) appeared to be the chief constituent methyl eugenol was also present, and a small quantity of methyl iso-eugenol. Fraction 130-145° was optically active, and showed evidence of the presence of a sesquiterpene, whilst the highest fraction solidified on cooling, and proved to be asarone, melting point 62-63°. 

Double-bond isomerases Changing the double bond position Topnote flavour (e.g. (iso)eugenol)... 

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

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. 

WANG, J., DUDAREVA, N., BHAKTA, S., RAGUSO, R. A., PICHERSKY E., Floral scent production in Clarkia hreweri (Onagraceae) II. Localization and developmental modulation of the enzyme S-adenosyl-L-methionine (Iso)eugenol O-methyltransferase and phenylpropanoid emission. Plant Physiol., 1997,114,213-221. 

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