Eugenol KOH

Keywords eugenol KOH, phase transfer catalyst, microwave irradiation, isomerization, isoeugenol... 

GENERAL PROCEDURE The Alcoholic alkaline solution is prepared by prolonged stirring of 8.8g (or 4.4g) of KOH pellets in 30mL of alcohol. The alkaline solution is placed in a round-bottom flask provided with a reflux condenser (microwave or conventional systems). Then 4.0g of Safrole (or eugenol) is added and the solution heated."... 

Since isoeugenol is the important intermediate in the vanillin production from eugenol, the isomerization of eugenol attracted a considerable amount of attention. The first report on the isomerization reaction appeared in 1891, in which Tiemann reported 50% conversion in 24 hours using an ethanolic KOH solution at 80°C [13]. 

Peterson et al (1933) applied this method to study the kinetic of eugenol isomerization by chromatographic and spectroscopic techniques [14]. Lampman et al (1977) used the same alkaline solution method run in dimethyl sulfoxide, and obtained 80% conversion after 2 hours reaction at temperatures higher than 170°C [7]. Andrieux et al (1977) obtained 92% isoeugenol with 2 hours of reaction time using RhCU as a catalyst run at 20 oC [15]. Isoeugenol could also be obtained by adding KOH and hexa-decyl-tributylphosphonium bromide to clove oil at 150°C [16]. 

However, in the case of leaf oil, international standards do exist. In this case, a phenol content of 75-85% has been specified for oil of Sri Lankan origin (ISO, 1977). Cinnamaldehyde is another constituent of leaf essential oil, contributing to the total flavour, and the specification limits its content to 5%. In the USA, the FMA (Fragrance Materials Association) specifies the eugenol content (80-88%) in cinnamon leaf oil in terms of its solubility in KOH (FMA, 1992). 

The constant current electrolysis of methyl eugenol serves to illustrate some of the effects of ring substitution and electrolyte on the course of such reactions. When carried out in methanol containing 2% NaOH or KOH (with or without added NaC104), an approximately 1 1 mixture of or// o-quinone bisketal (LXVI) and para-quinol ether (LXVII) was obtained. In contrast, when the oxidation was carried out in methanol-NaC104 in the absence of base, only side-chain substitution product (LXVIII) was obtained [Eq. (33)] [77]. This work clarified an earlier mechanistic interpretation of the reaction [78]. 

Lamari et al. [15], in a recent work, studied the electrochemical detection of ascorbic acid (AA) by square wave voltammetry using a carbon paste electrode modified with a polymer of eugenol by voltammetric synthesis. Ascorbic acid, vitamin C, is an organic compound involved in several biological processes and has various applications [16-18]. To electropolymerizes eugenol by CV used a working electrode of stainless steel covered with carbon paste after anodic treatment, SCE reference electrode, platinum counter electrode, 0.1 mol L KOH as electrolyte and 4 rrrmol L eugenol. 

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