Oxygenated constituents

Terpenes are commonly employed for diluting lemon, orange, and bergamot oils. The addition lowers the specific gravity, increases the optical rotation, and lowers the proportion of oxygenated constituents. Terpinolene, a by-product in the manufacture of terpineol, has been detected in some oils, notably citronella and spike, lavender. It can be detected by its odour in the fractionated oils. 

The odour of pepper oil is described as fresh, dry-woody, warm-spicy and similar to that of the black peppercorn (Purseglove et al., 1981). The flavour is rather dry-wood and lacks the pungency of the spice since the alkaloids are not extracted by steam distillation. Very few studies are reported in the literature on correlation of oil composition to odour characteristics. Hasselstrom et al. (1957) attribute the characteristic odour of pepper oil to the small amounts of oxygenated constituents present. Lewis etal. (1969) consider that a number of monoterpenes present in the oil are necessary for strong... 

Oxygenated constituent A general term relating to constituents of essential oils that contain combined oxygen, e.g. monoterpene alcohols. 

PROP A volatile oil. Principal constituents include d-pinene, camphene, l-terpineol-4, and other oxygenated constituents. From steam distillation of the fruit of Juniperus communis h, (Fam. Cupressaceae) (FCTXAV 14,307,76). Colorless to faint green-yellow liquid aromatic bitter taste. Sol in fixed oils, mineral oil insol in glycerin, propylene glycol. 

Volatile or essential oils, as their name implies, are volatile in steam and are generally complex mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons. The odour and taste of volatile oils is mainly determined by these oxygenated constituents. In chemical structure, most essential oils are terpenoids in origin. Testing and evaluation of the antimicrobial activity of essential oils is difficult because of their volatility, their water insolubility and their complexity. However, in recent years a large number of studies have been conducted on the antimicrobial activity of essential oils from the Anthemideae tribe. These reports concerned mainly the genera Achillea and Artemisia. 

As previously mentioned, hydrogen (as a elemental component of water) is the only heteroatom we consider in this review. The adorption and subsequent chemical behaviour of moecules on surfaces is certainly one of the most active areas of both experimental and computational surface science studies. For such a small and seemingly simple adorbate, the many types of possible interactions of water on oxide surfaces lead to richly complex chemistry. Water may be physisorbed intact, chemisorbed molecularly or dissociatively. In the last case, surface hydroxyls are formed, with the oxygen constituent of the hydroxyl originating either from the dissociated water molecule or the surface oxygen atoms. The H atom in the hydroxyls may be considered to be acidic (added to or abstracted from oxide anions as tf) or basic (as part of OIT added to or removed from metal cations). For all adsorbed species, molecular or dissociated, water or hydroxyl, there is the capability of strong hydrogen bond formation between other H, OH or O surface species. 

Besides the benzophenanthridine bases having oxygen constituents at the C-3 and C-4 atoms, some bases having oxygen substituents in the positions C-2 and C-3 (alkaloids nitidine, oxynitidine, and avicine) could be isolated from the plant genera Toddalia and Zanthoxylum (Rutaceae). Sanguinarine and similar bases have recently been synthesized by Dyke et al. (134a-c). 

Volatile or essential oils, as their name implies, are volatile in steam and are generally complex mixtures of hydrocarbons and oxygenated compounds derived from these hydrocarbons. The odour and taste of volatile oils is mainly determined by these oxygenated constituents. In chemical structure, most essential oils are terpenoid in origin. 

Extraction fractions F-1 and F-8 yielded relatively low yields of PAH on pyrolysis, the former because of its thermally stable hydrocarbon content, and the latter because of its polar oxygenated constituent content. Such oxygenated compounds, having a relatively low carbon content yield low... 

The local environment of the metal and the oxygen constituents in the bulk and at the surface... 

The yields and compositions of the tars obtained from the thermal decomposition of the individual petrographic components (Table 13.3) exhibit the most marked differences in the lower-rank coals, in which the oxygen constituents appear to play a more significant role in the decomposition processes. 

The investigation on the solubility of essential oils in other media is also widely accepted, such as the evaluation of the presence of water by means of a simple procedure the addition of a volume of essential oil to an equal volume of carbon disul de or chloroform in case the oil is rich in oxygenated constituents, it may contain dissolved water, generating turbidity. A further solubility test, in which the oil is dissolved in an aqueous solution of potassium hydroxide, is applied to oils containing molecules with phenolic groups nally, the incomplete dissolution of oils rich in aldehydes in a dilute bisul te solution may denote the presence of impurities. 

A very simple and standardized fractionation in terms of speed and simplicity has been published by Kubeczka (1973) using dry-column chromatography. The procedure, which has been proved useful in numerous experiments for prefractionation of an essential oil, allows a preseparation into five fractions of increasing polarity. The preseparation of an essential oil into oxygenated constituents, monoterpene hydrocarbons, and sesquiterpene hydrocarbons, which is—depending on... 

Constituents of Tobacco.—Extensive studies of the volatile constituents of Greek tobacco Nicotiana tabacum L.) have been made by the Swedish Tobacco CompanyIn addition to methyl esters of the Cg—Cgo straight-chain fatty acids, which represent the largest group of oxygenated constituents found in Greek tobacco, several isomeric megastigmatrienones, (206)—(210), dehydration products of 3-oxo-a-ionol (205), have recently been reported. ... 

The known constituents of juniper oil are the terpenes, a-pinene, and camphene, the sesquiterpene cadinene, and a small amount of oxygenated constituents. The principal of these bodies is terpinenol. A second alcohol (or possibly a mixture of alcohols) has also been separated, having the following characters boiling-point, 218 to 226 specific... 

This oil contains a-pinene ( ), principally as the laevo-rotatory variety, and phellandrene. The oxygenated constituents include cineol, Z-linalol, geraniol, eugenol, and methyl-eugenol. The highest boiling fractions contain a sesquiterpene and a sesquiterpene alcohol. 

The value of the oil depends on its percentage of all the oxygenated constituents, which are soluble in weak alcohol. 

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