Perfume Ingredients Derived from Cyclopentanone

The chemistry of synthetic jasmine materials was given an enormous boost in the 1930s when Nylon 66 was launched as a product. Nylon 66 is a polyamide prepared using adipoyl chloride and hexamethylenetetramine as monomers. The 66 in the name refers to the fact that there are 6 carbons in each type of unit that lies between the amide links in the polymer chain. Thus, adipic acid is the key feedstock for Nylon 66 and the introduction of the latter meant that the former became a basic chemical commodity. Pyrolysis of the calcium or barium salt of adipic acid produces cyclopentanone, and so the availability of large quantities of the acid meant that the ketone could also be prepared at low cost. 

When the 2-alkylcyclopentanones are subjected to the Bayer-Villiger reaction, the resultant lactones are found to have sweet, buttery, peach and coconut odours. These are useful in floral fragrances, but their major use is as butter flavour in margarines. 

PERFUME INGREDIENTS DERIVED FROM DICY CLOPENT ADIENE 

Dicyclopentadiene is a feedstock for both the fragrance and polymer industries. It forms spontaneously from cyclopentadiene by a Diels-Alder reaction, and a retro-Diels-Alder reaction can be used to regenerate cyclopentadiene from it. A number of minor fragrance ingredients are produced by Diels-Alder reaction of the monomer with a variety of activated olefins in which the activating group X, is usually an aldehyde, ketone, ester or nitrile. However, the main fragrance uses stem from the dimer. 

The two double bonds of dicyclopentadiene are very different in reactivity and, consequently, selective reactions are easy to achieve. 

Dupical and Scentenal have fresh, floral, aldehydic odours, the others have varying proportions of floral and fruity notes. 

Ruzicka, M. Stoll and H. Schinz, Helv. Chim. Acta., 1926, 9, 249. 

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