Extraction eugenol

A much more forgiving yet limited extraction method can be used to isolate phenol species such as eugenol and chavicol. You see farther back in this chapter where one can use dilute NaOH to remove eugenol from sassafras oil Well, why not use it to isolate the damn things for further research. It works like a charm ... 

Eugenol can also be extracted from the cement matrix by methanol (Molnar, 1967) this is further evidence of the weakness of the chelate, which is decomposed during the extraction. 

Little is known of the setting reaction and structure of EBA cement. The absence of an infrared band at 1750 cm" in the set cement indicates that no unreacted COOH is present (Brauer, 1972). So far, it is not certain whether zinc forms a six-membered chelate or merely a simple salt with EBA. Neither infrared spectroscopy nor solution studies are able to distinguish between these two forms. Eugenol is much less readily extracted and so more firmly bound in the complex than is EBA. The suspicion is that the EBA cement is fundamentally more prone to hydrolysis than the ZOE cement. 

Thus, if zinc 2-ethoxybenzoate is a weak chelate it will be preferentially extracted and the reaction will move to the left. Eventually the matrix will contain only eugenol, as, indeed, Brauer (1972) found. 

To add to the cost further, many of these compounds are rather sensitive to temperature and would decompose before vaporizing. For example, oil of cloves (from Eugenia caryophyllata) is rich in the phenol eugenol (V), which has a boiling point of 250 °C). We cannot extract the oils via a conventional distillation apparatus. 

To extract a relatively involatile oil such as eugenol (V) without charring requires a high pressure of steam, although the steam will not be hotter than 100 °C, so we generate a mixture of vapours at a temperature lower than that of the less volatile component. 

A chemical substance or simple mixture of substances obtained from natural sources by distillation or extraction such as citral from lemongrass oil or eugenol from clove bud. 

Production. Since sufficient eugenol can be isolated from cheap essential oils, synthesis is not industrially important. Eugenol is still preferentially isolated from clove leaf and cinnamon leaf oil (e.g., by extraction with sodium hydroxide solution). Nonphenolic materials are then removed by steam distillation. After the alkaline solution is acidified at low temperature, pure eugenol is obtained by distillation. 

CC>2-Extraction of cloves gives a yield of 18 to 25% with extraction conditions of 350 bar and 65°C. The extraction pressure should not be too high, otherwise waxes and bitter substances enter the extract. The content of volatile oil is more than 80%, of which the content of Eugenol is around 70%. 

B. o-Eugenol. The allyl ether (70 g.) is cautiously (Note 3) brought to boiling in a 500-ml. round-bottomed flask, refluxed for 1 hour, and cooled. The oil is dissolved in 100 ml. of ether (Note 4), and the solution is extracted with three 100-ml. portions of 10% sodium hydroxide. The combined alkaline extracts are then acidified with 100 ml. of concentrated hydrochloric acid diluted... 

For example, vanillin can be obtained via at least five different ways (i) by isolation from the orchid (Vanilla planifolia), which is a very expensive method (ii) by tissue culture followed by extraction (iii) by microbial transformation of eugenol, the main compound of clove (iv) from lignine by synthesis, and (v) from guaiacol, a natural aroma compound, with comparable molecular structure. Only the vanillin obtained via the first three methods is natural. The other routes afford a nature-identical vanillin. 

To obtain eugenol, clove oil is extracted further with alkali (10% NaOH). The alkaline extract is then separated by adding sulfuric acid, and further purification can be effected by distillation. The isolation procedure used to obtain eugenol from clove oil is as follows ... 

Reversed phase isocratic HPLC with ultraviolet detection at 280 nm was used to separate and identify eugenol in the ethanolic extract of whole tobacco and clove cigarettes [25]. The samples were analyzed at 30°C on a RP 18 column using methanol-water (80 20) as the mobile phase. This method was also applied to determine the eugenol content within the total particulate matter of mainstream tobacco condensate [26]. 

The curry leaf plant is highly valued for its characteristic aroma and medicinal value (Philip, 1981). A number of leaf essential oil constituents and carbazole alkaloids have been extracted from the plant (Mallavarapu et al., 1999). There are a large number of oxygenated mono- and sesquiterpenes present, e.g. c/s-ocimene (34.1%), a-pinene (19.1%), y-terpinene (6.7%) and P-caryophyllene (9.5%), which appear to be responsible for the intense odour associated with the stalk and flower parts of curry leaves (Onayade and Adebajo, 2000). In fresh bay leaves, 1, 8-cineole is the major component, together with a-terpinyl acetate, sabinene, a-pinene, P-pinene, P-elemene, a-terpineol, linalool and eugenol (Kilic et al., 2004). 

Clove yields three types of volatile oil - oil extracted from the leaves, the stem and the buds. These oils differ considerably in yield and quality. The yield and composition of the oil obtained are influenced by its origin, season, variety and quality of raw material, maturity at harvest, pre- and post-distillation treatments and method of distillation. The chief component of the oil is eugenol. 

Eugenol, the primary component of clove s volatile oils, functions as an antiinflammatory substance. In animal studies, the addition of clove extract to diets already high in anti-inflammatory components (like cod liver oil, with its high co-3 fatty acid content) brings a synergistic effect. In some studies, it further reduces inflammatory symptoms by another 15-30%. Clove also contains a variety of flavonoids, including kaempferol and rhamnetin, which also contribute to clove s anti-inflammatory and antioxidant properties. Another constituent of clove oil, /J-caryophyllene, also contributes to the anti-inflammatory activity (Ghelardini et al., 2001). 

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