One of the most widely used aroma chemicals in perfumery is Iso E Super. Iso E Super was synthesized by International Flavor & Fragrances (IFF) chemists John B. Hall and James M. Sanders in 1973. In the book “Scent and Chemistry, The Molecular World of Odors” by Philip Kraft and Gunther Orloff they write that it had one of the most pronounced effect on fragrance development since Edmond Roudnitska introduced Hedione in Dior Eau Sauvage in 1966. What makes this such an influential molecule? One of the reasons that I will explore today is its size. If you look below at the structure of Iso E Super next to Limonene you can see they are closely structurally related but they have very different effects when used in perfume.
Limonene is one of the chemicals extracted from lemon rind. As is common citrus notes tend not to last very long on skin when used in a perfume and Limonene is no exception to that. Iso E Super has a very different effect. It is one of the great fixatives and base notes in all of perfumery. It is more well-known for its use in high percentages in some particularly seminal perfumes like Lancome Tresor, Hermes Terre D’Hermes, Perles de Lalique and of course Geza Schoen’s Molecule 01 which is 100% Iso E Super. In high percentages it does have a unique odor profile. Iso E Super has the influence cited my Kraft and Orloff for the effect it adds when used in small quantities.
Perfumer Andy Tauer has the best description of Iso E Super in small quantities in his blog entry of October 9, 2012. In that post he likens it to a layer in graphics program Photoshop. He says, “It adds lift, and it soften all notes, and it brings out contrasts and optimizes a fragrance in quite a spectacular way. In a sense it is present by its effect, and less by its scent. It is not by chance that you find Iso E Super in so many scents these days. Actually, the analogy to a photoshop layer is not so bad.” It is that lift and the ability to add to the longevity of the perfume which makes it so influential. That property is also related to its size.
One of the more unique features of Iso E Super is that some people can’t smell it easily, called anosmia. Just as people show anosmia for the large macrocyclic musks which are at similar molecular weight they do the same for Iso E Super.
When it comes to aromachemicals size does matter and Iso E Super is one of the larger molecules in regular use, and influence.
Title Picture: Bloom County by Berkley Breathed– "Size Matters"