Olfactory Chemistry-Damascones

Part of the purpose of this series is to illustrate how the most simple of changes can have dramatic effects on not only the odor profile but even the stability of the molecules themselves. The class of molecules known as Damascones portray both of these qualities.

ionone damascone

As you can see the Damascones are closely related with the only structural difference being the reversal in position of the C=O and double bond. As I wrote in the installment on Ionones those molecules all carry a variation on iris and woods. The Damascones are one of the key natural products which make up rose oil. The name itself comes from the Damask rose from which it was isolated and the structure determined. These molecules impart a dark rose or fruity quality when used.

beta ionone damascone

The other difference is the stability of the molecules. Ionones are a work horse molecule in perfumery and are used far and wide. The Damascones were used and, because of their nature, a little goes a long way but they are much more prone to degradation. In a paper presented at the 2000 meeting of The International Federation of Essential Oils and Aroma Trades (IFEAT) Dr. Robert Bedoukian showed this difference. Beta-ionone and beta-Demascone were left open to the air in a clear glass flask for 24 days taking samples at day 6, day 17, and day 24. Dr. Bedoukian was looking for a common oxidation product which forms called a peroxide and measured the levels of peroxide. Beta ionone showed values of 20, 60 and 85 mmol/I of peroxide on days 6,17, and 24. Beta-Damascone showed levels of 45, 130, and 150 mmol/l over the same time points. You can see that the rate of decomposition is more than twice as fast for the damascone than the ionone.

Even with all of that Damascones are the key ingredient in three of the most important fragrances ever made. One of its earliest uses was in Guerlain Nahema in 1979 it gave texture and depth to the central rose in Nahema that makes it to my mind the best rose perfume ever. Damascones also played a part in Christian Dior Poison in 1985 and in the perfume considered the “best ever”, 1981’s Shiseido Nombre Noir. None of these have survived reformulation unscathed as IFRA called out the Damascones as sensitizers and the possibility of being reactive. The levels of Damascone able to be used was reduced to less than 0.02%. Which especially for Poison and Nombre Noir, which used the damascones in overdose, forced a significant effort to reformulate in the case of Poison and Nombre Noir was simply discontinued.

Mark Behnke

Title Image: Shattered Rose by 8manderz8