The Alcoholic Fragrance

The safety constraint has been defined in the brief and can be checked by computer analysis or by the safety officer at any time. 

A search is made for ingredients that have the desired odour characteristics. For the Business Scents Ltd brief, market research indicates that exotic, tropical, fruity and watery floral muguet notes 

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The first problem to be encountered is almost certainly one of cost. The client will not be willing to pay the same amount of money for the perfume oil used in the range as for that used in the alcoholic fragrance. 

If the product is to be a white soap, will any of the ingredients in the perfume formula cause discoloration, either immediately or in time How will the total perfume perform in the soap bar Will it cover the fatty smell of the base If not, which ingredients perform best in the dry bar and in use To overcome some of these problems, certain ingredients in the alcoholic fragrance need to be substituted. For example, to prevent discoloration on storage, vanillin may be substituted by ethyl vanillin which, because it is more intense, can be dosed at about one-third the vanillin level. Small quantities of Ultravanil are also incorporated to boost the vanilla effect without causing discoloration. 

Uses ndReactions. Some of the principal uses for P-pinene are for manufacturing terpene resins and for thermal isomerization (pyrolysis) to myrcene. The resins are made by Lewis acid (usuaUy AlCl ) polymerization of P-pinene, either as a homopolymer or as a copolymer with other terpenes such as limonene. P-Pinene polymerizes much easier than a-pinene and the resins are usehil in pressure-sensitive adhesives, hot-melt adhesives and coatings, and elastomeric sealants. One of the first syntheses of a new fragrance chemical from turpentine sources used formaldehyde with P-pinene in a Prins reaction to produce the alcohol, Nopol (26) (59). 

Acetylation of the alcohol mixture yields cedryl acetate [61789-42-2] (94) and a range of quaUties are available from manufacturers. Gedryl methyl ether [19870-74-7] is readily made and is useful in formulating woody-amber fragrances (188). 

CgHioO, Mr 122.17, mp 20°C, Z pioi.skPa 203°C, df 1.0135, ng 1.5275, has been identified as a volatile component of food (e.g., in tea aroma and mushrooms). The alcohol is a colorless liquid with a dry, roselike odor, slightly reminiscent of hawthorn. It can be prepared by catalytic hydrogenation of acetophenone. 1-Phenylethyl alcohol is used in small quantities in perfumery and in larger amounts for the production of its esters, which are more important as fragrance materials. 

Uses. Cinnamic alcohol is valuable in perfumery for its odor and fixative properties. It is a component of many flower compositions (lilac, hyacinth, and lily of the valley) and is a starting material for cinnamyl esters, several of which are valuable fragrance materials. In aromas, the alcohol is used for cinnamon notes and for rounding off fruit aromas. It is used as an intermediate in many syntheses (e.g., for pharmaceuticals such as the antibiotic Chloromycetin). 

In comparison with the araliphatic alcohols discussed in Section 2.5.2, very few phenol alcohols are used as fragrance and flavor materials. Neither the alcohols corresponding to vanillin, ethylvanillin, and heliotropin nor their esters have special organoleptic properties. Anise alcohol and its acetate are the only products that are used to some extent in perfume and aroma compositions. 

A cationic Ir complex possessing phosphanodihydrooxazole 26 is usable for asymmetric hydrogenation of allylic alcohols. (E)-2-Methyl-3-phenyl-2-propen-l-ol can be converted in CH2C12 containing 1 mol % of the Ir complex to the saturated product in 95% yield and 96% ee (Scheme 1.26) [141]. The process is used in the enantioselective synthesis of the artificial fragrance filial. 

Another example employed Mitsunobu reaction for the inversion reaction (Figure 10(b)).A single enantiomer of a (stereo)chemically labile allylic-homoallylic alcohol was obtained in 96% yield and 91% ee from the racemate through a lipase-catalyzed kinetic resolution coupled with in situ inversion under carefully controlled (Mitsunobu) conditions. Using this reaction, the algal fragrance component, (S)-dictyoprolene, was synthesized. 

By the early part of the twentieth century, pure grades of volatile hydrocarbon solvents such as benzene and hexane became available through progress in petroleum-refining methods. They were found to be very useful for the extraction of fragrant plants and plant materials. If the plant material extracted is rich in waxes (as is generally the case with flowers, stems, and leaves), these are also taken up in the extract. After careful removal of the volatile solvent by distillation, a waxy concrete remains behind. This is then washed with alcohol to separate the fragrance materials, which are soluble in alcohol, from the insoluble waxes. An absolute is then produced by the removal of the alcohol by distillation, usually under reduced pressure. Certain plant materials that contain no water, such as resins or dried leaves and mosses, may be extracted directly with alcohol. The extracts obtained—often sticky, viscous, and resiny—are called resinoids. 

It is advisable when trying to match a perfume to obtain as fresh a sample as possible, since an older sample may have undergone chemical changes that make the analysis more difficult. Schiff bases may have formed in the presence of methyl anthranilate, and in alcoholic fragrances aldehydes will have been progressively converted to their diethyl acetals. Oxidation of some of the terpenes may have taken place, changing their relative proportions. 

The word "functional" in the title of this chapter may be thought of as redundant. One might argue that everything produced by humans, and certainly everything that is commercialized, has a function. Perfumers employ the expression "functional products" in a special way, that is, to denote all perfumed products other than alcoholic fragrances. The distinction is useful, and we will adopt it here. 

The perfumer must not only be aware of consumer expectations at each phase of product evaluation, he or she must also know, as intimately as possible, the conditions under which the product will be used. Populations for whom toilet soap is the only regularly used fragranced product have quite different expectations regarding its ability to perfume the skin than consumers accustomed to daily use of alcoholic fragrances and deodorants. In countries where fabric soft-... 

Examples of case 3 are the adaptation of an alcoholic fragrance for use in body lotions, skin creams, or room fragrances. In all three cases both top and base note should be deemphasized in favor of the heart note. In an extended use room fragrance, in particular, the range of volatility of the components should be reduced as much as possible in order to achieve constancy of odor character. 

As we will see later, the release of acids is characteristic of the breakdown of esters in the presence of water. This acidity, in alcoholic fragrances, can in turn result in the formation of acetals between the ethanol and any aldehydes that may be present in the perfume. Although this reaction is reversible in principle, where there is a large excess of alcohol in the product as opposed to aldehydes, as is usually the case, the aldehydes can be almost entirely lost, with a catastrophic effect on the odor. 

Pseudoesters, for example, 221, in which the alcohol portion is a fragrance (such as geraniol), have been developed for the slow release of scent. Alkaline hydrolysis of compound 221 requires time so that the rate at which scent is released is prolonged over that of simple evaporation <2001J(P2)438>. A similar approach involves the preparation of acyclic esters 222 and 223 from phthalide 224 and phthalic anhydride 225, respectively. In this case, the slow release of fragrance is the result of an intramolecular transesterification processes <2003USP20030148901>. 

Esterification is a reaction between an organic acid and an alcohol that forms as ester and water. The ester ethyl butanoate (C3H7COOC2FI5), which is responsible for the fragrance of pineapples, is formed when the alcohol ethanol (C2FI5OH) and butanoic acid (C3FI7COOFI) are heated in the presence of sulfuric acid. 

Spagyric Sulphur of plants) are obtained by steam distillation. Enfleurage is a technique particularly useful for elusive scents, such as jasmine and tuberose which break down at the temperatures of distillation. Petals are placed on a bed of scentless fat which absoibs the fragrance, repeating this daily for up to three months the fat becomes saturated with scent. It is then soaked in alcohol and warmed to extract the fragrance, then cooled, filtered and the alcohol evapourated to leave an ABSOLUTE. CONCRETES, waxy solids or thick liquids, are obtained using hydrocarbon solvents to extract the oils with other materials from plants processed with alcohol they too yield absolutes. 

While most perfumers employ raw citrus or petitgrain oils for usage in fragrance applications (solubility in alcoholic fragrances is sufficient and no thermal stress is required for fragrance applications), the usage of concentrated citrus oils is often called for in the food industry. Applications in beverages and foods require more sophisticated properties as far as solubility and stability are concerned. 

An interesting example of catalytic domino reaction is the synthesis of an ether fragrance reported by Corma and Renz [343] using either Sn-beta or Zr-beta, although the latter is preferable, giving at 100 °C (8h) complete conversion with virtually 100% overall selectivity, while the Sn-beta is equally selective but less active. Figure 2.69 reports the scheme of this reaction. In a first step, the alcohol is produced by a Meerwein-Ponndorf-Verley reduction at 100 °C. 

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