Chemistry in Perfumes: An Interview with Fragrance Chemist Philip Kraft

Philip Kraft is a fragrance chemist. I'm sure you've never heard of him before. You probably don't know his inventions by their chemical names. But you have definitely smelled some perfumes that were based on his scented molecules. Marc Jacobs Men was made by Ralf Schwieger with Super Muguet molecule (invented by Mr. Kraft). The adrenaline effect of Etat Libre d'Orange Sécrétions Magnifiques (perfumer Antoine Lie) was based on the potent marine odorant Azurone. Another example is the vibrant musk Serenolide, which Daniela Andrier so skillfully juxtaposed to galbanum in Maison Martin Margiela’s untitled.

1 Million Paco Rabanne with its dried-fruit effect at the start from Pomarose molecule. Top-note musk Sylkolide (for example, in great perfume Oh, Lola! Marc Jacobs by Calice Becker and Yann Vasnier). All of them—and now the list includes 27 patents—were invented by Prof. Philip Kraft.

So no wonder that he's one of the authors of a brilliant book Scent and Chemistry: The Molecular World of Odors. And his co-authors are legendary fragrance chemists Günther Ohloff and Wilhelm Pickenhagen. This book is real treasure for those who want to look inside perfumes more deeply and to know more about perfume constituents. I found the book through my friends on Facebook timeline, was charmed by the heaps of information and bought it next day. I do still read it from time to time—especially when trying to figure out what's the smell in a perfume. I had the fortune not only to buy the book, but also to know Mr. Kraft personally because he answers all the comments on the Scent and Chemistry FB page. So I asked Mr. Kraft to find some time in his very busy schedule and he kindly agreed to answer some questions for Fragrantica.

 

Philip Kraft: My fascination with perfumery indeed started via chemistry, and in a quite surprising way. At some point in my early teens, I was curious about hormones and hormone action, and bought a University Biochemistry book to find some answers. However, I had not yet had chemistry in school back then, and thus did not understand much of anything, which generated a strong desire to learn it. So on every birthday and Christmas occasion, I visited the same University bookstore in Hamburg, and bought, with the money I got as presents, some more chemistry textbooks in order to teach myself. As I was really an unusually young client in that University bookstore, this caught the attention of the sales girl of the Chemistry department, and she finally awarded me a test subscription to "Liebigs Annalen der Chemie," a pretty advanced Organic Chemistry journal that should have probably been given to chemistry student instead. But anyway, I felt honored and tried to read and understand it, and then there was this article of Professor Weyerstahl in it, who reported on rose oxide analogues, and how he modified and designed new odors and odorants. That was even more exciting and fascinating to me than hormones, as it was not just one action in response to a stimulus, but a whole new language of sorts, a way of communication really.

Philip Kraft: Both essential oils and synthetic perfumery materials contain odorant molecules, and very often even exactly the same. And the whole Chapter 7 of Scent and Chemistry really is dedicated to natural perfumery materials and the chemistry of their constituents. 

Philip Kraft: Synthetic odorants can be extremely expensive as is the case for the Ambrox/Ambrofix and macrocyclic musks that prevented the Tibetan musk deer from extinction by slaughtering for its musk pods. Natural essential oils, on the other hand, can be extremely cheap as is true for a lot of citrus oils, which are a by-product of the lemonade industry, and frequently used to perfume dishwashing liquids. But it is the creativity of the perfumer that creates the value of a perfume, not the price of the raw materials. People often forget that. Because certain functional products do not have the price margin to afford expensive perfumery raw materials, certain notes, however, became associated with cheap and non-prestigious functional products. Still these notes might play a completely different key role in an otherwise very expensive composition. Materials should be judged on the freedom of expression they give to a perfumer, not on their price of production. Of course a brief with a generous price target allows the perfumer a bigger palette to choose from and thus, greater creative freedom. 

Philip Kraft: Yes, as mentioned before, art in perfumery to me begins with the use of coumarin in Fougère Royal by Paul Parquet in 1894. The first chapter of Scent and Chemistry gives many more examples. When I smell an odor, I very often see in my mind certain geometrical features, design elements on a molecular level. To me the conceptualization of a new odorant is a design process as well. It is artistic as well, but it  is not a mystery at all. You have an idea for a smell, and you want to materialize it in the form an odorant. And to do so, as in every art, you need to master a certain degree of technical perfection to get there, in this case, in chemical synthesis. No mystery, no alchemy.

Philip Kraft: This really changes with fashion, and certain notes like patchouli can seem old-fashioned in a certain context, and very modern in another one. Fruitchoulies are certainly a major modern trend now, while the way patchouli is used in Aromatics Elixir is probably not considered very modern. Generally however, there is a tendency toward more transparency, although the sweet trendy gourmands are anything but transparent. The transparent notes of Lilial, Hedione, Iso E Super or Galaxolide certainly had a big influence on modern perfumery, and also the damascones with Poison. However so did maltol since Angel, in a non-transparent way.

Philip Kraft: You have to cover all areas really, and constantly try to challenge and revolutionize every important odor family, as every family has its place in perfumery creation. In the big domains of perfumery one needs to be active all the time, and these certainly include ambery materials, woody odorants, and musks, but of course also florals.

Philip Kraft: Ambergris is a complex odor sensation, which we described in Scent and Chemistry as an “exotic woody odor with incense-like, earthy, camphoraceous, tobacco and musk-like facets surrounded by smells of the ocean.” In the natural ambergris tincture, ambroxan or ambrox are mostly responsible for this odor sensation, but not solely. The different ambergris synthetics play on these different tonalities and facets of the natural ambergris impression. It is however not the idea to only reproduce this ambergris odor, but rather to accentuate certain olfactory attributes. In Fig. 2.8 of Scent and Chemistry, Wilhelm Pickenhagen, the co-inventor of Ambrocenide, and I even drew a whole ambergris spectrum. 

Such amber accords become characteristic trendy elements, recognizable as such; their function is not to imitate the smell of natural Tonquin musk or ambergris tincture. This would also leave no room for artistic creations. 

Philip Kraft: For rose absolutes or vetiver oils we even distinguish their geographical origin, and different companies have different suppliers, and then there are different harvests, so a 100% copy seems impossible, or at least extremely difficult. But if the differences should be just not be "customer-noticeable" that is much easier, and many famous brands change the compositions of their perfumes over the years without people noticing, or at least without them complaining. It is somewhat a question on how much effort one wants to invest. To imitate a rose or vetiver oil, you would just need the odor-active components, the odorless ones that may impact diffusion or substantivity could be replaced by other odorless ones of similar vapor pressure, and commercially unavailable ones can be replaced by other odorants of similar smell. Roman Kaiser has done an incredible job on headspace reconstitutions from single flowers, where even no essential oil can be produced because they might be endangered species. I did smell some of the original flowers, for instance on our trip to the Massoala peninsula in Madagascar, and I could not tell any difference with the natural flower smell. Headspace reconstitution has reached an amazing level of perfection. So a good rose absolute, yes, you should be able to do that rather well. A good vetiver oil, I have still some doubts. 

Philip Kraft: At first I try to evaluate technically only: Is the composition harmonious?  Which materials stick out? Is that on purpose because they were to be overdosed, or is it a compositional flaw? What is the main theme, what are the main accords? How are the central harmonies working together? Is there continuity from top to dry down, or are there any unexpected cliffs or holes in the unfolding of the scent? What was the concept behind the fragrance? How does the perfumer meet the storyline he is supposed to tell?  And how novel is the idea after all? Which related fragrances exist on the market? 

Philip Kraft: Find out at the next "Flavors and Fragrances" 2013 conference in Leipzig, September 11th–13th.