The main methods used in industry for the preparation of Pure Eugenol are isolation and chemical synthesis from natural essential oils. However, the isomers produced by chemical synthesis have very close boiling points and are extremely difficult to separate. In actual production, the separation method is the main method. The natural essential oil isolation method is based on the perennial subshrub clove basil as raw material, and the mixture of essential oil and water is obtained by steam distillation. Add 20% sodium hydroxide to the oil-water mixture, and then perform steam distillation to remove non-acidic substances.
At 50 ° C, the obtained Pure Eugenol sodium solution was added to 30% sulfuric acid and stirred to neutralize to Ph=2~3 (aqueous layer). After standing, the crude clove oil of the lower layer is separated, and the finished product of eugenol is obtained by distillation under reduced pressure. Or use essential oils containing a large amount of eugenol such as clove oil, add 30% sodium hydroxide solution, add inorganic acid or introduce carbon dioxide gas to make it precipitate. Or add it with sodium acetate, so that it can be freed and then steam distilled to obtain pure product.
A method for preparing eugenol from clove oil, characterized in that:
(1), will be pulverized to 5-10 object clove raw materials, add the extraction solvent of 10 times of amounts in extractor, temperature is controlled at 75-90 ℃, stirring and extracting 3 hours, totals 3 times;
(2), merge extract, after the solvent is recovered by concentrating under reduced pressure and vacuum, obtain dark brown clove oil;
(3), in clove oil, add the alkaline aqueous solution of 5 times of content 3-15%, after constant temperature 65-85 ℃ of stirring 3 hours, leave standstill layering, remove alkaline aqueous phase oil layer and collect for subsequent use;
(4), the alkaline water layer adds the activated clay of 5% of total volume, and after stirring 30 minutes, the activated clay is filtered and separated, and the acid solvent is gradually added in the filtrate, and the pH value is adjusted 6-7, and the eugenol is separated and separated out in the solution, and the lower layer is Eugenol oil layer;
(5), the eugenol oil layer collected is also washed with deionized water, and the eugenol after washing is distilled, and the slightly yellowish distillate collected is a pure eugenol oil product;
(6), Pure Eugenol oil product is dehydrated and dried to obtain a slightly yellowish eugenol product in chromaticity.