Essential oils special properties

The following techniques are commonly applied to assess an essential oil physical properties [6,17] speci c gravity (SG), which is the most frequently reported physicochemical property and is a special case of relative density, [p] ° de ned as the ratio of the densities of a given oil and of water when both are at identical temperatures. The attained value is characteristic for each essential oil and commonly ranges between 0.696 and 1.118 at 15°C [4]. In cases in which the determinations were made at different temperatures, conversion factors can be used to normalize data. 

Special properties of essential oils synergy and quenching 127... 

SPECIAL PROPERTIES OF ESSENTIAL OILS SYNERGY AND QUENCHING... 

ABSTRACT Monoterpenoids are the components of essential oils, which are produced and accumulated, in large amounts by plants from certain families, including Labiatae, Pinaceae, Cupressaceae, Umbelliferae and Rutaceae. They are of special interest because of their industrial applications and on account of their chemical properties and biological activity. Monoterpenic composition can be useful in genetic and chemotaxonomic studies of coniferous species. 

The last chapter (i.e. chapter 2) of Part I deals with modem analytical methods used in crude oil chemistry. Modern and classical methods of petroleum and petroleum products characterization are explained. This chapter is an essential chapter for present and potential crude oil chemists since analytical chemistry constitutes an important part of crude oil chemistry. Besides, crude oil products have so many special properties that are important for the industry. The need to determine these properties gives rise to the very many analytical methods used in petroleum chemistry. 

Understanding, on the molecular scale, of processes relevant to microwave extraction has not yet reached the maturity of understanding of other topics in chemistry. Such a challenge is somewhat ambitious and requires a special approach. Microwave extraction interferes with polarization effects that cannot be readily separated from the physical and chemical properties of the extracted molecules. In this chapter we have discussed how the concept of microwave extraction has already become an important issue in the chemistry of natural products. Detailed analysis of past and present literature confirms explicitly the usefulness of this extraction technique. We have hope that this chapter will widen the scope of laboratory and commercial success for the potential applications of microwave technology in essential oil extraction. 

Most plants have trichomes on their aerial surfaces. The trichomes may be simple hairs or more specialized glandular trichomes, whose main function may be the production and accumulation of chemicals such as essential oils. The vast majority of these consists of monoterpenoids, sesquiterpenoids and diterpenoids with a high vapour pressure. They may be absorbed on the cuticular wax layer. The trichome secretions are closely related to plant-insect or plant-microbe interactions. Terpenoids can attract, rep>el or initiate defence reactions in insects. Apart from their ecological roles, plant terpenoids are widely used in the pharmaceutical and fragrance industries. The properties of essential oils are correlated with their qualitative and quantitative compositions. 

A final important class of composite materials is the composite hquids. Composite liquids are highly stmctured fluids based either on particles or droplets in suspension, surfactants, liquid ciystalhne phases, or other macromolecules. A number of composite liquids are essential to the needs of modem industiy and society because they exhibit properties important to special end uses. Examples include lubricants, hydraulic traction fluids, cutting fluids, and oil-drilling muds. Paints, coatings, and adhesives may also be composite liquids. Indeed, composite hquids are valuable in any case where a well-designed liquid state is absolutely essential for proper delivery and action. 

MoS is a black powder insoluble in most solvents. It crystallizes like graphite with hexagonal layer molecules MoSj infinitely extended in two dimensions (Figure 25.4). Within the layer the sulfur atoms are effectively close packed and the molybdenum atoms are situated in the octahedral holes. The layers are bound to each other by very weak van der Waals forces. Because of this the layers slip easily against each other and the sulfide has lubricant properties. It is an essential component in solid lubricants that can be used at much higher temperatures than conventional lubricants. They lubricate up to 350°C in air and 1200°C in vacuum or in an inert atmosphere. Molybdenum disulfide lubricants can also be suspended in special oils and used as lubricating aerosol sprays. 

Utilization of a processing plant, it would be necessary to be able to process multiple varieties such as cherry, plum, peach, apple, etc. It is essential that the cost of by-product remain reasonable once a successful recovery operation has been established. Most of the data reported here are for oil samples prepared under laboratory conditions. The extracting solvent used for the oil recovery was usually n-hexane, which is acceptable for edible purposes. Chlorinated solvents are unacceptable for the recovery of edible oils because they may contain chlorinated components such as tetrachloroethane which is not removable by heat treatment and which if present would make the oil too toxic to be consumed. Often oils that are recovered from by-products have properties that make them desirable in cosmetics and in medical preparations. Such specialized application may command a premium price. 

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