Лако-красочные материалы — производство

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.

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 «-heptyl — (R = pentyl) and «-hexyl — (R = butyl) derivatives. These are sold under tradenames such as Heptone® and Jasmatone®, respectively.

The 2-alkylidenecyclopentanones are readily isomerized to give the corresponding 2-alkylcyclopent-2-enones by the action of acids or platinum group metals. Michael addition of dimethyl malonate to these, followed by partial hydrolysis and decarboxylation, gives jasmo — nic acid analogues. The most important of these is methyl dihydrojas — monate, methyl 2-(2-pentylcyclopentan-3-on-l-yl)acetate. This material differs from methyl jasmonate, the natural jasmine component, in that its side chain is saturated, whereas the natural material has a cis double bond between the second and third carbon atoms of the chain. Both compounds have similar jasmine odours. The odour is perceived as weak when a fresh sample of material is smelled. However, if the sample is left in a room, the whole room is filled with its delicate floral scent. In perfume compositions, methyl dihydrojasmonate has a blending, fixing and enhancing effect on the other components. These properties have made it one of the most important fragrance ingredients.

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.

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