Aldehydic floral fragrances

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. 

Now compare the samples again, concentrating this time on other aspects of the fragrance such as the nature of the floral accord, the aldehydes, or the animal notes. To take a complete inventory of a complex perfume and its match may take considerable time and effort. It involves comparing the samples over and over again, at all stages of evaporation, from the first top note to the dry-out. 

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. 

Cyclopentanone readily undergoes aldol condensation with a variety of aldehydes to give the 2-alkylidenecyclopentanones (Scheme 4.66). These have jasmine-like odours, but are no longer used in perfumery since it was discovered that they have the potential to cause skin sensitization. The saturated products are safe and are used to give jasminic, fruity, floral odours in fragrances. The most widely used are the H-heptyl- (R = pentyl) and -hexyl- (R = butyl) derivatives. These are sold under tradenames such as Heptone and Jasmatone , respectively. 

The map indicates that the fragrances in the herbal, green and citrus areas are totally inappropriate for fragrance development for this brief they are perceived by the consumer as functional, cleaning, invigorating and refreshing. Neither is the sweet floral, aldehydic area appropriate as, although it is seen as feminine, it is also perceived as cosmetic... 

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-... 

Hydroformylation of Allyl Arenes, Propenyl Arenes, and Homologs Several prominent scents especially for the generation of muguet notes are based on 3-aryl-2-methylpropanals. Thus, 3-(4-isopropylphenyl)-2-methylpropanal, known as Cyclamen aldehyde has a powerful floral and green note (Figure 6.9). The fragrance is used in many floral, green, fresh, and marine accords preferentially... 

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],... 

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