Ester fragrance

Acetophenone can react with formaldehyde to yield light-resistant resins which are used as additives in nitrocellulose paints. It is also used as a photoinitiator, and in the pharmaceuticals, perfumery, and pesticide industries (344). It can be hydrogenated to 1-phenylethanol which is used for the production of aromatic ester fragrances (345). Technical-grade acetophenone is available at 2.29/kg perfume-grade acetophenone was 6.50/kg in October 1994. 

Many of the fragrances and tastes from plants are due to esters. The smells we perceive are generally due to a combination of esters, but often one ester fragrance will dominant. By mimicking these natural esters, the food industry has synthesized hundreds of different flavoring agents. Three of these are shown in Figure 15.14. Many pheromones are esters. Pheromones are chemical compounds used by animals for communication. Many medications are also esters. Aspirin is an ester of salicylic acid (see Chapter 13). 

Vacuum stills for naturally occurring products, such as fatty acids, vegetable oils, and ester fragrances, typically handle a feed that consists... 

Chloroacetate esters are usually made by removing water from a mixture of chloroacetic acid and the corresponding alcohol. Reaction of alcohol with chloroacetyl chloride is an anhydrous process which Hberates HCl. Chloroacetic acid will react with olefins in the presence of a catalyst to yield chloroacetate esters. Dichloroacetic and trichloroacetic acid esters are also known. These esters are usehil in synthesis. They are more reactive than the parent acids. Ethyl chloroacetate can be converted to sodium fluoroacetate by reaction with potassium fluoride (see Fluorine compounds, organic). Both methyl and ethyl chloroacetate are used as agricultural and pharmaceutical intermediates, specialty solvents, flavors, and fragrances. Methyl chloroacetate and P ionone undergo a Dar2ens reaction to form an intermediate in the synthesis of Vitamin A. Reaction of methyl chloroacetate with ammonia produces chloroacetamide [79-07-2] C2H ClNO (53). 

Formic acid is used as an intermediate in the production of a number of dmgs, dyes, flavors, and perfume components. It is used, for example, in the synthesis of aspartame and in the manufacture of formate esters for flavor and fragrance appHcations. 

In certain brilliantine compositions, vegetable and animal oils are used as substitutes for mineral oil. In these systems, because of their potential for rancidity, antioxidants must be included. Other alternatives to mineral oils that have found utiHty in brilliantines are the polyethylene glycols which come in a variety of solubiHties and spreading properties. Use of these materials offers the advantage of chemical stabiHty to rancidity. Other additives found in brilliantines to improve their aesthetics include colorants, fragrance, medicated additives, lanolin, and fatty acid esters. 

Aroma chemicals are isolates, or chemically treated oils or components of oils. Some components are removed physically, others chemically. In most cases, they are further purified by distillation. For example, Bois de Rose (rosewood) oil may be distilled to isolate linalool, which may be then further treated chemically to yield derivatives such as linalyl acetate, an important fragrance ingredient and a primary component in its own right of lavender and lavandin oils. Vetiver oil Haiti, although containing only 70% alcohols, is treated with acetic anhydride, then carefully distilled to include valuable odor components in the distillate, even though they may not be esters. 

Another significant use of 3-methylphenol is in the production of herbicides and insecticides. 2-/ f2 -Butyl-5-methylphenol is converted to the dinitro acetate derivative, 2-/ f2 -butyl-5-methyl-4,6-dinitrophenyl acetate [2487-01 -6] which is used as both a pre- and postemergent herbicide to control broad leaf weeds (42). Carbamate derivatives of 3-methylphenol based compounds are used as insecticides. The condensation of 3-methylphenol with formaldehyde yields a curable phenoHc resin. Since 3-methylphenol is trifunctional with respect to its reaction with formaldehyde, it is possible to form a thermosetting resin by the reaction of a prepolymer with paraformaldehyde or other suitable formaldehyde sources. 3-Methylphenol is also used in the production of fragrances and flavors. It is reduced with hydrogen under nickel catalysis and the corresponding esters are used as synthetic musk (see Table 3). 

Growth appHcations for amyl alcohols appear to be shifting toward higher boiling esters as plasticizers, perfumes, fragrances, and production of fine chemicals. 

The main commercial apphcations for sahcylate esters are as uv sunscreen agents and as flavor and fragrance agents. Several have apphcation as topical analgesics. A number of sahcylate esters of commercial interest and their physical properties are hsted in Table 8. 

Isoamyl saUcylate is perhaps the most important ester of saUcyhc acid for perfumery purposes. Generally, it is manufactured by the transesterification of methyl saUcylate. It has a characteristic flowery aroma and is useful in soap fragrances. The May 1996 price was 5.30/kg (18). Other saUcylates of commercial interest as flavor and fragrance agents include isopropyl, isobutyl, phenethyl [87-22-9] and 2-ethyIhexyl saUcylates. 

Uses ndReactions. Camphene is used for preparing a number of fragrance compounds. Condensation with acids such as acetic, propionic, isobutyric, and isovaleric produce usehil isobomyl esters. Isobomyl acetate (41) has the greatest usage as a piae fragrance (81). The isobomyl esters of acryhc and methacrylic acids are also usehil ia preparing acryUc polymers. 

Uses ndReactions. The main use for citroneUol is for use in soaps, detergents, and other household products. It is also important as an intermediate in the synthesis of other important fragrance compounds, such as citroneUyl acetate and other esters, citroneUal, hydroxycitroneUal, and menthol. 

In the soap, perfume, and flavor industries benzyl alcohol is primarily used in the form of its aUphatic esters. Benzyl benzoate [120-51-4] finds widespread use as a fragrance diluent. Benzyl alcohol is frequently employed in bar soap fragrances at 30—40 wt % of the fragrance. Benzyl alcohol is commercially available in five grades (Table 2). 

World Consumption. The estimated total world consumption of PEA and its esters for 1990 was 7000 t. Of this figure, one-fourth was used in North America and 43% in East and West Europe. Approximately 85% of the PEA is employed for fragrance use (102). 

Pyrolytic Decomposition. The pyrolytic decomposition at 350—460°C of castor oil or the methyl ester of ricinoleic acid spHts the ricinoleate molecule at the hydroxyl group forming heptaldehyde and undecylenic acids. Heptaldehyde, used in the manufacture of synthetic flavors and fragrances (see Elavors and spices Perfumes) may also be converted to heptanoic acid by various oxidation techniques and to heptyl alcohol by catalytic hydrogenation. When heptaldehyde reacts with benzaldehyde, amyl cinnamic aldehyde is produced (see Cinnamic acid, cinnamaldehyde, and cinnamyl... 

Economic Aspects. There are no pubhshed production figures for cinnamic acid. Most of the manufactured acid is consumed internally to generate a series of cinnamate esters for flavor and fragrance appHcations. With this in mind, it was possible to estimate a 1990 usage in the range of 175 metric tons. The cinnamic acid that does find its way into the marketplace has been sold for 12—14/kg in dmm quantities. 

Health and Safety. Cinnamyl alcohol has been evaluated by FEMA and given GRAS status (FEMA No. 2294). Two of its esters, cinnamyl cinnamate (FEMA No. 2298) and cinnamyl acetate (FEMA No. 2293), ate also used extensively in flavor and fragrance compositions. Cinnamyl alcohol has also been tested by RIFM (48) and found to be safe for use. There have been reported cases of irritation and several manufacturers market a desensitized alcohol for use in fragrance appHcations. 

Uses. Cinnamyl alcohol and its esters, especially cinnamyl acetate, are widely employed in perfumery because of their excellent sensory and fixative properties. They are frequently used in blossom compositions such as lilac, jasmine, lily of the valley, hyacinth, and gardenia to impart balsamic and oriental notes to the fragrance. In addition, they ate utilized as modifiers in berry, nut, and spice flavor systems. The value of cinnamyl alcohol has also been mentioned in a variety of appHcations which include the production of photosensitive polymers (49), the creation of inks for multicolor printing (50), the formulation of animal repellent compositions (51), and the development of effective insect attractants (52). 

Perfumes, Flavors, Cosmetics, and Soap. Many naturally occurring esters in essential oils and some synthetic esters are important fragrance and flavor compounds (61,62). They are used in perfumes, flavors, cosmetics, soaps, detergents, and air fresheners. Benzyl, butyl, ethyl, methyl, and phenyl esters of benzoic acid are used as flavors, perfumes, and food preservatives. Glyceryl 4-aminobenzoate [136-44-7] and 2-ethyUiexyl 4-dimethylaminobenzoate [21245-02-3] are used in cosmetic sunscreen preparations. Alkyl esters of 4-hydroxybenzoic acid, called parabens, have been used under various names for fungus infections of the skin, and as preservatives in lotions and creams (101). Soap and cosmetic fragrances use large amounts of amyl and benzyl saHcylate. Benzyl saHcylate [118-58-1] is also used in deodorant sprays. 2-Ethylhexyl saHcylate [118-60-5] and 2-ethylhexyl 4-methoxycinnamate [5466-77-3] are used in sunscreen formulations (102). 

Some oils consist almost entirely of esters for example, those of Oaultheria procumhens and Betula lenta contain about 99 per cent, of methyl salicylate. Bergamot and lavender owe the greater part of their perfume value to esters of linalol, of which the acetate predominates. Geranium oil owes its fragrance chiefly to geranyl esters, of which the tiglate is the chief. On the other hand, oils such as spike lavender, sandalwood, lemon-grass, and citronella contain but small quantities of esters, and owe their perfume value to entirely different types of compounds. 

Many esters have pleasant odors they are commonly found in natural and synthetic fragrances. 

Esters represent an important class of chemical compounds with applications as solvents, plasticizers, flavors and fragrances, pesticides, medicinals, surfactants, chemical intermediates, and monomers for resins. Recently, esters of amino acids have attracted attention regarding their use as biobased surfactants with excellent adsorption and aggregation properties, low toxicity, and broad biological activity. 

In this paper, we focus on synthesis and application of esters of bio-based organic acids. Organic acid esters are used or have potential for use in many industrial and consumer applications including solvents, paint strippers, surfactants, fragrances, and fuel stabilizers2. The chemicals used in these... 

The enantioselective hydrogenation of a,fj- or / ,y-unsaturated acid derivatives and ester substrates including itaconic acids, acrylic acid derivatives, buteno-lides, and dehydrojasmonates, is a practical and efficient methodology for accessing, amongst others, chiral acids, chiral a-hydroxy acids, chiral lactones and chiral amides. These are of particular importance across the pharmaceutical and the flavors and fragrances industries. 

Alcohols, flavors, fragrances, fatty acid methyl esters, amines, acids... 

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