Floral aldehydic odors

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... 

The most classical artificial substances used in perfumery are as follows (Figure 5). Hydroxycitronellal (99) was found to exhibit the odor of lily of the valley, the essential oil of which is not possible to prepare in the first place. Other classics include ct-amylcinnamaldehyde (100) and musk ketone (101), which were discovered to be good substitutes for jasmine and musk, respectively. Furthermore, perfume No. 5 (Chanel, launched 1921) contained 2-methylundecanal, 1 with so unique an aroma character that it established No. 5 as the pioneer of a new fragrance class — floral aldehydic. 

Sorbic aldehyde Empirical CsHsO Formula HCOCHCHCHCHCH3 Properties Colorless to yish. liq. pungent fatty sweet green aldehydic floral citrusy odor citruslike taste sol. in alcohol insol. in water m.w. 96.13 sp.gr. 0.871-0.898 b.p. 69 C (20 mm Hg) acid no. 5 flash pt. 67 C ref. index 1.538-1.545 (20 C)... 

Hydrocinnamide 3-Phenylpropanal 3-Phenyl-1-propanal 3-Phenylpropionaldehyde p-Phenylpropionaldehyde Phenylpropionic aldehyde Phenylpropyl aldehyde 3-Phenyl propyl aldehyde Empirical C9H10O Formula C6H5CH2CH2CHO Properties Colorless to si. yel. liq., strong floral hyacinth odor misc. with alcohol, ether insol. in water m.w. 134.19 dens. 1.010-1.020 b.p. 221-224 C flash pt. 203 F ref. index 1.520-1.532 Toxicology LD50 (IV, mouse) 56 mg/kg poison by IV route human skin irritant eye irritant TSCA listed... 

Lyral (68) [31906-04-4] is another important fragrance ingredient produced from myr-cene. This hydroxy aldehyde has a sweet, hght, floral (muguet) odor with excellent tenacity and radiance. More than 2000 tonnes are produced annually and sold under a variety of tradenames, such as Kovanol, HydroxyEmpetal, and LandoM in addition to the original, Lyral [82, 83],... 

Aldehydic Floral Family. This is an important family of fragrances, the typical odor of which is the class odor of the aldehydes. The aldehydes are present in small quantities in nature and have an uimatural brilliance. Although they have sharp, slightly fmity odors alone, they blend beautifully and unexpectedly in florals. 

Terpenoid alcohols appeared early in the history of synthetic perfumery because several were readily available from inexpensive essential oils. Alpha-terpineol, citronellol and linalool shown in Figure 7 are important constituents of pine stump oil, citro-nella oil and rosewood oil, respectively. The fourth material listed, hydroxycitronellal, is a hydroxy aldehyde which perhaps has a questionable place in this discussion. It is included because it is one of the most important fragrance chemicals used today. "Hydroxy" is almost a perfume unto itself. Its soft flowery, linden blossom odor blends very well in many floral perfumes. 

The difference between citronellol and citronellal is typical of that between an alcohol and an aldehyde. Although they are clearly related in odor, the aldehyde is, as we would expect from quite a small molecular structure, very much more powerful and harsh. In hydroxycitronellal the addition of an—OH and—H across the double bond (in effect by adding a molecule of water, a process known as hydration) produces an alcohol group near to the other end of the molecule, away from the aldehydic group. The material still maintains some of its aldehydic character but now, in addition, has some of the softness and floral character associated with an alcohol. The presence of more than... 

Since the blossom oil of lily of the valley is not commercially available, the perfumers have to rely on synthetic substitutes, such as hydroxy-citronellal (1), Lilial (3) and Bourgeonal (6) to create their muguet fragrances. The oldest lily of the valley odorants, hydroxycitronellal and cyclamen aldehyde (2) (Winthrop Chem. Corp., 1929), were discovered by chance. Serendipity still continues to play an important role. Anselmi et al. (1992) synthesized and organoleptically screened a series of 38 tetrahydropyranyl ethers. This class of compounds was chosen because of their ease of synthesis and purification, and because of their stability in alkaline media, conditions under which aldehydes tend to undergo aldol condensations. Two compounds (24 and 25) were described as having a white, floral odour reminiscent of hydroxycitro-... 

C14H240, Mr 208.34, df 0.870-0.877, ng1 1.468-1.473, not found in nature, is a clear, colorless to pale yellowish liquid. It has an aldehydic-floral odor reminiscent... 

Ci2Hi80, Mr 178.27, is not reported as being found in nature. It is a viscous liquid or crystalline mass, mp 22 °C, po.oi3 kPa 74-76 °C, df 0.960, ng° 1.515-1.518, with a fresh floral odor, reminiscent of lily of the valley and linden blossoms. It is prepared by reaction of 3-methylbenzyl chloride with 2-methylpropanal in the presence of tetrabutylammonium iodide and reduction of the resulting aldehyde with NaBH4 [143]. 

C11H12O3, Mr 192.22, is not found in nature. It is a colorless to slightly yellow liquid, 1.159-1.167, p° 1.531-1.536, with green, floral odor with top notes of ozone and new mown hay. It can be prepared by condensation of heliotropin (see previous page) with propanal and partial hydrogenation of the intermediately formed unsaturated aldehyde. 

Synonyms Cumene aldehyde a-Formylethylbenzene Hyacinthal Hydratropaldehyde Hydratropic aldehyde a-Methyl phenylacetaldehyde o-Methyl tolualdehyde a-Methyl-a-toluic aldehyde 2-Phenylpropionaldehyde a-Phenylpropionaldehyde Empiiicai C9H10O Formula C6H5CH(CH3)CHO Properties Colorless to pale yel. liq., floral hyacinth-like odor m.w. 134.18 dens. 1.002 (20/4 C) b.p. 205-206 C flash pt. 169 F ref. index 1.518... 

A volatile oil from the fresh leaves of Eucalyptus globulus labill and other species of Eucalyptus and Myrtaceae. Constitutes 70-80% cineole (aucalytol), pinene, phellandrene, terpineol, citronelal, geranyl acetate, eudesmol, eudesmyl acetate, piperitone, and volatile aldehydes. The oil is a colorless to pale yellow, mobile liquid that has a strong and very fresh, rosy citronella like odor and a sweet, balsamic floral dryout note... 

Since the hydroformylation of 1-octene under the formation of -nonanal (pelargonaldehyde) is a model reaction in academia for testing new reaction conditions in hydroformylation, several efficient methods have been developed. The reaction works well with a Rh(BIPHEPHOS) catalyst (compare Table 6.1, entry 3). Alternatively, internal octenes can be used under the conditions of isomerizing hydroformylation [53]. The aldehyde is naturally occurring in citrus and rose oils. It has a fatty-rose-like odor and confers floral perfumes a typical rose nuance. 

In a few cases, even the raw oils directly isolated from the plant have been submitted to the transformation with syngas [67]. Product aldehydes possess an antimicrobial activity and have a pleasant smell. Therefore they can be used well with malodorous substances. In most cases, Rh or Co catalysts were submitted to hydroformylation. Also Pt/Sn catalysts should be taken into consideration, since undesired Wagner-Meerwein isomerization is suppressed. All aldehydes and acetals, as well as their mixtures, show woody, floral, and green, or balsam-like odors and can be employed as components of perfume accords. 

Dimethylocta-l,6-diene was used as a substrate for the highly -selective hydroformylation with a homogeneous Rh(Xantphos) catalyst (Scheme 6.21) [95]. The odor of the aldehyde yielded was described as fresh, orange peel, and herbaceous with coriander leaf accents. Subsequent reduction with NaBH yielded the unsaturated alcohol, which was characterized from the olfactory point of view as rustic with a note of floral, bergamot, and cinnamon. 

The odor impression of the product mixture was estimated to be slightly green, aldehydic, sweet, floral, spicy, cherry, and almond. 

X-Terpineol can be considered as a hydrate of limonene. Indeed, it is available by Markovnikov addition of trifluoroacetic acid to the latter, followed by hydrolysis [141]. The alcohol has a pleasant odor similar to lilac and is a constituent of cajuput, pine, and petitgrain oil. For technical applications, it is produced from a-pinene by acid-catalyzed isomerization/hydration [142]. Hydroformylation of a-terpineol has been conducted with an unmodified Rh catalyst at 69bar (Scheme 6.45) [132]. Under the conditions applied, besides the expected cyclic carbaldehydes also a linear aldehyde with a tertiary alcoholic group were obtained. The reaction product was distilled, and the main fraction collected showed a woody and nutty aroma with minty and floral topnotes. 

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