Functional fragrances

Flavors and fragrances are sensory stimuli. Of the two, flavors are more complex because they act on the olfactory bulb via their volatile components and on the taste buds which are stimulated by both volatile and non-volatile components. The overall response to a flavor is a synthesis of the effects of both types of components. The response to fragrances, on the other hand, results only from the action of volatile components. Because flavors and fragrances function via a common mechanism, many volatile materials are used for both purposes. This is nicely illustrated by the perfumers vocabulary for fragrance materials. A collection of some 160 words published by a famous perfumer, Ernest Shiftan (1) included 75 words usually associated with flavors such as almond, bacon, coconut, honey, lime, raspberry, spicy and vanilla. 

Liquid Fabric Softeners. The principal functions of fabric softeners are to minimize the problem of static electricity and to keep fabrics soft (see Antistatic agents). In these laundry additives, the fragrance must reinforce the sense of softness that is the desired result of their use. Most fabric softeners have a pH of about 3.5, which limits the materials that can be used in the fragrances. For example, acetals cannot be used because they break down and cause malodor problems in addition, there is the likelihood of discoloration from Schiff bases, oakmoss extracts, and some specialty chemicals. Testing of fragrance materials in product bases should take place under accelerated aging conditions (eg, 40°C in plastic bottles) to check for odor stabiUty and discoloration. 

Initial evaluations of chemicals produced for screening are performed by smelling them from paper blotters. However, more information is necessary given the time and expense required to commercialize a new chemical. No matter how pleasant or desirable a potential odorant appears to be, its performance must be studied and compared with available ingredients in experimental fragrances. A material may fail to Hve up to the promise of its initial odor evaluation for a number of reasons. It is not at all uncommon to have a chemical disappear in a formulation or skew the overall odor in an undesirable way. Some materials are found to be hard to work with in that their odors stick out and caimot be blended weU. Because perfumery is an individuaHstic art, it is important to have more than one perfumer work with a material of interest and to have it tried in several different fragrance types. Aroma chemicals must be stable in use if their desirable odor properties are to reach the consumer. Therefore, testing in functional product appHcations is an important part of the evaluation process. Other properties that can be important for new aroma chemicals are substantivity on skin and cloth, and the abiHty to mask certain malodors. 

Partial hydrogenation of acetylenic compounds bearing a functional group such as a double bond has also been studied in relation to the preparation of important vitamins and fragrances. For example, selective hydrogenation of the triple bond of acetylenic alcohols and the double bond of olefin alcohols (linalol, isophytol) was performed with Pd colloids, as well as with bimetallic nanoparticles Pd/Au, Pd/Pt or Pd/Zn stabilized by a block copolymer (polystyrene-poly-4-vinylpyridine) (Scheme 9.8). The best activity (TOF 49.2 s 1) and selectivity (>99.5%) were obtained in toluene with Pd/Pt bimetallic catalyst due to the influence of the modifying metal [87, 88]. 

The ability to efficiently synthesize enantiomerically enriched materials is of key importance to the pharmaceutical, flavor and fragrance, animal health, agrochemicals, and functional materials industries [1]. An enantiomeric catalytic approach potentially offers a cost-effective and environmentally responsible solution, and the assessment of chiral technologies applied to date shows enantioselective hydrogenation to be one of the most industrially applicable [2]. This is not least due to the ability to systematically modify chiral ligands, within an appropriate catalyst system, to obtain the desired reactivity and selectivity. With respect to this, phosphorus(III)-based ligands have proven to be the most effective. 

As already mentioned, the most important industrial application of homogeneous hydrogenation catalysts is for the enantioselective synthesis of chiral compounds. Today, not only pharmaceuticals and vitamins [3], agrochemicals [4], flavors and fragrances [5] but also functional materials [6, 7] are increasingly produced as enantiomerically pure compounds. The reason for this development is the often superior performance of the pure enantiomers and/or that regulations demand the evaluation of both enantiomers of a biologically active compound before its approval. This trend has made the economical enantioselective synthesis of chiral performance chemicals a very important topic. 

Detergent enzymes, 10 273—286 cleaning effects of, 10 275 functions of, 10 274—275 performance evaluation of, 10 276—278 Detergent fragrances, 18 362 Detergent industry... 

Functional food enhancers, 11 14 Functional food market, 17 674 Functional foods, 17 646 Functional fragrances, 18 361-364 Functional group analysis, for lignin, 15 10-12... 

If the new niche for the perfume is its use in cosmetics, toiletries or household product, then the niche-product interaction becomes very important. Perfumes are used specifically for their odor whereas in these new niches several new factors must be considered. For example, the perfume oil used in creams must not cause discoloration the fragrance used in a powdered detergent must be alkali resistant a fabric softener is expected to leave clothes with a pleasant odor and even a household cleanser must have a pleasant and functional odor, although active chlorine places difficulty on the stability of the perfume oil. Of course, decisions can affect or modify the product (perfume) or the niche (e.g. creams). 

For thousands of years, people have used some of these compounds as fiavors, dyes, fragrances, insecticides, hallucinogens, nutritional supplements, animal or human poisons, and therapeutic or pharmaceutical agents. While secondary compounds are an evolutionary adaptation in plants, they serve multiple functions for mankind. 

The perfumes consist of raw fragrances dissolved in aqueous ethanol. Functional products are in a different group, comprising detergents, shampoos, shower gels, and oven cleaners. Functional products have an elaborated chemically-reactive matrix that does not allow using traditional fragrances recourse is made to inexpensive, chemically inert, odoriferous materials. 

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