Preface to the Second Edition

Ese olor. Reconocía ese olor de algún lugar. Y se ponía nervioso. No era olor de comida, ni el olor de los pisos cuando se enceran. No era nada que formase parte de la rutina. Lo había sentido en el pasillo alguna vez, pero era difícil saber de dónde provenía. Quizá del techo o del suelo. [.] No era el olor a rancio del Papapa, ni los perfumes dulzones de la mamá ni el desodorante del papá ni el olor a sudor y barro de Sergio. Era mejor. Desesperantemente mejor. ¿De dónde vendría? Sintió un impulso desconocido y se preocupó. Sabía que era malo. [.] Cosas del olor.

That smell. He recognized that smell from somewhere. And it made him nervous. It wasn't the smell of food, nor was it the smell of floors being waxed. No ordinary smell at all. He had smelled it in the hallway once, but it was hard to tell where it was coming from. Maybe from the ceiling or the floor. [.] It wasn't Grandpa's rancid smell, nor was it Mom's sweet perfume, nor Dad's deodorant, nor Sergio's smell of sweat and mud. It was better. Desperately better. Where would it come from? He felt an unfamiliar urge and became worried. He knew it was bad. [.] The way smells are.

Santiago Roncagliolo, 'Pudor' [1].

If you are (still) reading this Preface, you most likely care for smells, scents, and odors. Even more so, you are probably deeply fascinated, impressed, and excited by these, and you want to understand why the things smell the way they do. Perhaps you even want to create and design new fragrant impressions, may that be on a molecular level or by compounding perfumes from natural and/or synthetic perfumery materials. Maybe you even read the first edition of 'Scent and Chemistry' and crave for an updated and extended version - one with (even) more focus on perfumery? If that is the case, then we do hope that this new and revised second edition is for you!

The original German edition of 'Riechstoffe und Geruchssinn: Die molekulare Welt der Düfte' by Günther Ohloff [2] was published 30?years ago, and the little booklet ('das Büchlein' as Ohloff called it) has since become the bible for fragrance chemists and perfumistas alike, growing from 233 in the original German, and 238 in its English translation 'Scent and Fragrances', to 418 pages in the first English edition. What was intended as an account on the current state of our knowledge about the sense of smell and its active principles, the odorant stimuli, has consequently turned into a solid little textbook on Fragrance Chemistry.

Fragrance Chemistry is no more and no less than the foundation of olfaction, a fascinating science that comprises structure-odor correlations as well as the Organic Synthesis of these structurally diverse active olfactory principles and the knowledge of their natural occurrence and the biochemistry, neurophysiology, and psychology of odorant perception. This book is written for everyone interested in the molecular basis of odor and the relationships between chemical structures and their olfactory properties. With the ease of access, the Internet has granted everyone to perfumery materials, e.g., [3-5], virtually, everybody can now study the olfactory properties of perfumery raw materials, enjoy their fragrant sensations, and even create accords and perfumes with these. Likewise, there is a vast number of Internet sites, e.g., [6-10], on which one can order perfume decants to build up a library of olfactory families, enjoy fragrant masterpieces, or study the composition of classic creations [11]. It was therefore only too logical that one of the major wishes expressed for the next edition of 'Scent and Chemistry' was the addition of an introduction to the basic techniques, creation, and composition methods in perfumery. To this purpose, we are thus extremely pleased to welcome Fanny Grau, a successful perfumer with a PhD degree in Organic Chemistry who has worked in all categories and segments and is now very active in the vibrant Latin American fine fragrance market for Symrise. Not only does she know a lot about compounding and composition techniques but also on structure-odor correlations, and since she was also self-taught before her official perfumery training with Marc vom Ende, who just took over as the head of the Symrise perfumery school and also works as research and commercial perfumer, she has an unconventional, hands-on, or in modern speech 'fresh-and-fruity' approach to teaching perfumery techniques.

This new edition of Scent and Chemistry therefore should even be more attractive to perfumistas and scent aficionados as the entry point into the Molecular World of Odors. Since olfactory art is currently emerging as a contemporary form of art [12-15], we would be most delighted to even reach olfactory artists, art critics, and art philosophers as well as aestheticians. Perfumes as such can already be works of art [16,17], but so can be odorant molecules and their syntheses.

Since the concept of the book has proven successful over all these years, the overall structure and content outline were not changed. It was not our aim to include all new compounds or developments, such as, for instance, precursor technologies, for such an endeavor reviews such as Ref. [18] are far better suited. But those new materials and findings that we expect to make a lasting impact on perfumery were of course added, all errors were eliminated, and all figures updated - to the very best of our knowledge. In this respect, we would like to thank all the readers that spotted typos and mistakes or suggested improvements. For current market data, we are indebted to Heinz-Jürgen Bertram, Symrise. For eliminating typos and for useful input, we are very grateful to Professor Albert Eschenmoser (Fig. 1), ETH Zurich; to Professor Konrad Tiefenbacher, University of Basel; and to Professor Ben List, Max-Planck-Institut für Kohlenforschung who was just awarded the Nobel prize in Chemistry "for the development of asymmetric organocatalysis." For additional proof-reading Philip Kraft is greatly indebted to his colleagues Johannes Panten and Alicia De Benito Cassado (both Symrise) and his student intern Anne Clisson (École Normale Supérieure de Paris, ENS Ulm). Certainly, also this edition will not be immaculate and error-free. So, let us know about any typos, mistakes, or incorrect formulas, you come across while reading as hopefully this will not be the last edition of our compact guide into the Molecular World of Odors.

Figure 1 Letter of Albert Eschenmoser to Philip Kraft, for Christmas 2011

Can you judge a book by its odor? For 'Scent and Chemistry' we hope you can, both by the inspiring fragrant chemistry inside and by the odoriferous impressions it conjures while reading, and in addition we hope that the book also feels good and smells good in your hands!

August 2021

Wilhelm Pickenhagen
Philip Kraft, and Fanny Grau
Geneva, Zürich, and São Paulo

References

1. 1 S. Roncagliolo, 'Pudor', Penguin Random House Grupo Editorial España, Barcelona, 2010, p. 35.
2. 2 G. Ohloff, 'Riechstoffe und Geruchssinn - Die molekulare Welt der Düfte', Springer-Verlag, Berlin and Heidelberg, 1990, 233 p.
3. 3 https://pellwall.com/product-category/ingredients-for-perfumery/
4. 4 https://shop.perfumersapprentice.com/
5. 5 https://perfumersupplyhouse.com/
6. 6 https://www.perfumersworld.com/aroma-ingredients.php
7. 7 https://www.theperfumedcourt.com/
8. 8 https://surrendertochance.com/perfume-decant-what-is-it/
9. 9 https://www.scentsplit.com/
10. 10 https://www.perfumesamplesanddecants.com/
11. 11 C. Burr, 'The Perfect Scent: A Year Inside the Perfume Industry in Paris and New York', Henry Holt and Company, LLC, 2008, 307 p.
12. 12 P. Kraft, Helv. Chim. Acta 2019, 102, e1800185.
13. 13 P. de Cupere (Ed.), 'Scent in Context | Olfactory Art', Stockmans Publishers, Duffel, Belgium, 2016, 472 p.
14. 14 C. Haley Epstein, 'Nose Dive - A Book for the Curious Seeking Potential Through Their Noses', Mindmarrow Publishers, Pacific Northwest, USA, 2019, 145 p.
15. 15 L. Shiner, 'Art Scents. Exploring the Aesthetics of Smell and the Olfactory Arts', Oxford University Press, Oxford, UK, 2020, 355 p.
16. 16 C. Burr, 'The Art of Scent 1889-2012, Museum of Arts and Design, 20 October 2012-24 February 2013', Museum of Arts and Design, New York, 2012, 28 p.
17. 17 Collectif, 'sentir, ressentir - Parfumeurs, odeurs et émotions', Mudac - musée de design et d'arts...