Perfumes, aldehydes

Advanced Example In research on violet perfumes, aldehyde (33) became a key Intermediate for a new series of compounds. Dlels-Alder disconnection gives acrolein and diene (34) which can he made by the Grignard method from available enone (36),... 

Finally, one still comes across fragrance discoloration on storage. The culprit here is invariably a Schiff s base (see Sec. II.B) formed between a perfume aldehyde and a trace of the -NH2 group coming from alkanolamide foam booster or even urea hydrotope. More subtle is the discoloration of water-white dishwash liquids, where care has to be given to formulating fragrances with minimal or no inherent color. 

Ring stmcture and location of the aldehyde group were estabUshed by the efforts of Baeyer, Markwald, and Harries (11—14). For some time, furfural was a laboratory curiosity and a compounding ingredient of perfumes. 

Aldehydes fiad the most widespread use as chemical iatermediates. The production of acetaldehyde, propionaldehyde, and butyraldehyde as precursors of the corresponding alcohols and acids are examples. The aldehydes of low molecular weight are also condensed in an aldol reaction to form derivatives which are important intermediates for the plasticizer industry (see Plasticizers). As mentioned earlier, 2-ethylhexanol, produced from butyraldehyde, is used in the manufacture of di(2-ethylhexyl) phthalate [117-87-7]. Aldehydes are also used as intermediates for the manufacture of solvents (alcohols and ethers), resins, and dyes. Isobutyraldehyde is used as an intermediate for production of primary solvents and mbber antioxidants (see Antioxidaisits). Fatty aldehydes Cg—used in nearly all perfume types and aromas (see Perfumes). Polymers and copolymers of aldehydes exist and are of commercial significance. 

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... 

Health and Safety. FEMA has examined cinnamaldehyde and estabhshed its GRAS status (No. 2286). The material has been used in some fragrance compositions, but RJEM (34) has noted its potential for sensiti2ation and limited the use in perfumes for skin contact at 1% in the formula. Eugenol and limonene have been used in conjunction with cinnamaldehyde as quenchers to neutrali2e the irritation reaction that some individuals have toward this aldehyde. 

Octyl Alcohol.—This is the primary normal alcohol of the formula CH3(CH2)gCH20H. It has an odour recalling that of opoponax, and is useful in the blending of perfumes of this type. It boils at 196° to 197°, and has a specific gravity 0"8278. It yields octyl aldehyde on oxidation, whose naphtho-cinchoninic acid compound melts at 234°. 

Duodecylic Aldehyde.—The twelve-carbon aldehyde, also known as lauric aldehyde, has the conssitution CH3(CH2)j3CHO. It was originally introduced for blending with violet perfumes, but it is not very... 

Phenylacetic aldehyde, CgHgO, is one of the most important of modern synthetic perfumes. It has not been found naturally in essential oUs. It possesses a powerful odour of hyacinths, and is extremely useful for the reproduction of all odours of this and the narcissus type. 

Anisic aldehyde, CgHgOj, is a methyl ether of para-oxy-benzaldehyde, which is found to a small extent in the oils of fennel and aniseed. It is manufactured on an extensive scale artificially, and is the basis of all the perfumes of the hawthorn or May blossom type. It is known commercially as aubepine . A certain amount of anisic aldehyde is obtained as a by-product in the manufacture of coumarin, but the greater- part of it is obtained by very careful oxidation of anethol, the characteristic constituent of aniseed oil, which has the constitution—... 

Anethol is the raw material from which most of the artificial hawthorn perfume is manufactured. This perfume consists of anisic aldehyde, known commercially under the name aubepine . 

Formaldehyde, as a gas or in water solution, has a distinctly unpleasant odor. Higher aromatic aldehydes such as those shown in Figure 22.10 (p. 594) are a lot more pleasant to deal with they are used in flavorings and even perfumes. 

The process mentioned above was successfully applied to a short and efficient synthesis of two perfume compounds, cyclamen aldehyde and foliaver (Scheme 10).32... 

IV-Aldehydes, platinum-group metal catalysts and, 19 621 Aldehydic floral perfumes, 18 357 Aldehydic odor, 3 227t Aldehydo sugars, 4 699 Alder, biomass production by, 17 298-299 Aldgamycins, 15 297t, 298 Aldicarb, 3 777, 778... 

Pd supported overlarge-pore tridimensional acidic zeolites such as HFAU are the more active and selective catalysts for the synthesis of bulkier ketones. Thus, in a 0.2% Pd-HFAU catalyst, yield and selectivity from cyclohexanone of 23 and 75% can be obtained in cyclohexylcyclohexanone synthesis. Furthermore, the S5mthesis of aldehydes can only be made selective by joining the hydrogenating metaUic sites (Pd) to basic sites (instead of acidic sites). Thus, 2-ethylhexanal, which is a component of perfumes and fragrances, can be synthesized with high yield and selectivity (64 and 91%, respectively) on a PdKX zeolite. Much lower yields and selectivities are obtained over nonzeolitic materials, such as Pd/MgO. 

Schiff base org chem RR C=NR" Any of a class of derivatives of the condensation of aldehydes or ketones with primary amines colorless crystals, weakly basic hydrolyzed by water and strong acids to form carbonyl compounds and amines used as chemical intermediates and perfume bases, in dyes and rubber accelerators, and in liquid crystals for electronics, shif, bas ... 

In general, esters have sweet odors. For this reason, many are useful in perfumes or as flavorings. The boiling points of esters are similar to those of aldehydes and ketones of compcirable molar masses, which means that the boiling points cire lower than comparable alcohols. 

P-hydroxy butyr-aldehyde Solvent Perfume, dyes, sedative (drugs) Skin irritant in concentrated form... 

Acetals derived from aliphatic aldehydes have odor characteristics that resemble those of the aldehydes but are less pronounced. These acetals contribute to the aroma of alcoholic beverages, but can rarely be used in flavoring compositions because they are not sufficiently stable. Since they are resistant to alkali, a number of them (e.g., heptanal dimethyl acetal and octanal dimethyl acetal) are occasionally incorporated into soap perfumes. 

Fatty aldehydes are generally produced by dehydrogenation of alcohols in the presence of suitable catalysts. The alcohols are often cheap and available in good purity. Aldehyde synthesis via the oxo process is less suitable since the resultant products are often not pure enough for flavor and perfume purposes. Specific syntheses for the branched-chain and unsaturated aldehydes that are important in perfumery and flavoring techniques are described under the individual compounds. 

CH3(CH2)9CH0, C11H22O, Mr 170.29, bp2Ave 1°C, df 0.8251, ng 1.4325, occurs in citrus oils. It is a colorless liquid with a flowery-waxy odor that has aspects of freshness. Undecanal is the prototype of the perfumery aldehydes and is widely used in perfume compositions for imparting an aldehydic note. ... 

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