Rose-odor type

Every morning students should be given unmarked smelling strips of ten or more materials selected from those to which they have already been introduced. Those that a student fails to recognize should be discussed with the teacher and fellow students and notes made in the classification. At times the materials selected by the teacher should be as different in odor type as possible at other times they should be taken from the same olfactory group, such as the rose notes, woody materials, or chemically related materials such as the acetates. Once the basic materials have been learned and understood, it is easier to add new materials. In this way the intelligent student will even be able to name materials not previously encountered. For example, the student may identify phenylethyl phenylacetate from its characteristic rose note combined with the honey note typical of the phenylacetates. 

One important point on smell is that just as with taste molecules of different structures, often totally different molecules, have the same or different smell. An example of rose odor in reference (1.) sites the work of Wright (12) where rosetone, phenylethanol, geraniol and pelargol are compounds with very different structures but the same smell. He also attributes camphor smell to camphor, chloroethane and ethyl-tert-butyl ether (12). Other research of this type would be odorant molecules of similar structure with a different olfactory response. In 1929 Braun (13) studied a series of ketones where the carbonyl moved from carbon two through carbon six of an eleven carbon ketone. 

Use Perfumery (floral odors, mainly rose types). 

This is another low volume perfume chemical made from p-cresol where the -OH group has been replaced by a -OCeHs group. It has a very powerful odor of the hyacinth rose type. Also used as a germicide. World demand is not more than 50 tpa. However, it has been reliably learned that Sumitomo Chemical Co., Japan, has developed a catalyst to convert p-phenoxy toluene to / -phenoxy benzaldehyde for a new type of agrochemical. 

Phenylacetaldehyde has a very powerful and penetrating, pungent-green, floral and sweet odor of hyacinth-type (Arctander, 1967), which is lilac or rose for Motoda (1979), honey-like for Holscher et al. (1990). The flavor is described as green, floral, sweet, honey (Chemisis, 1996). A threshold of 4 ppb in water is given by Buttery et al. (1969b). 

The A. C,-C,2 occur in many essential oils, especially in citrus oils, coriander, caraway (C, and C9) and rose oil (C,-C o), as well as in traces in many aromas Their odors are described as orange-like (Cj), fatty-flowery, citrus-like (C,), fatty orange-like (C,o), flowery-fatty, rose-like (C,), and flowery-waxy, when highly diluted violet-like (0,2). Apart from citrus aromas Cg-C 2-A. are mainly used in perfumery for fragrances with an emphasis on aldehyde odors, e.g., of the Chanel No. 5 type. 

Essential oils of many plants and flowers are obtained by distilling the plant with water. The water-insoluble oil that separates usually has an odor characteristic of the particular plant (rose oil, geranium oil, and others). Compounds isolated from these oils contain multiples of five carbon atoms (that is, 5, 10, 15, and so on) and are called terpenes (some compounds of this type were described on page 222). They are synthesized in the plant from acetate by way of an important biochemical intermediate, isopentenyl pyrophosphate. The five-carbon unit with a four-carbon chain and a one-carbon branch at C-2 is called an isoprene unit (see A Word About... Biologically Important Alcohols and Phenols, in Chapter 7). 

G. is rarely used in - flavors but is one of the most frequently used - essential oils in perfumery, where its rosy-fiesh qualities make it useful in rose and other floral types. The minty-heihaceous aspects are main constituents of the tasy fougeie note and other herbaceous-floral types ( odor description). It blends well with lavender and citrus notes in men s colognes. 

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