Felix Müller

Photoinduced electron transfer (PET) in organic synthesis. [3 + 2]-type cycloaddition, cyclization and CC bond cleavage reactions

Abstract An area of growing interest, in organic photochemistry in particular, involves the use of light to induce an electron transfer from a donor (D) to an acceptor (A) molecule, designated photoinduced electron transfer (PET). Excitation of A or D leads to well-defined changes in their redox properties, i.e. A (D) becomes a stronger acceptor (donor). In general, the feasibility of producing radical ions can be predicted using the well-known Weller equation and moreover, polar solvents and salts effects support their formation. Following a brief introduction, we focus on the synthetic applications of PET, and discuss [3 + 2] cycloadditions, reductive and oxidative cyclizations and CC bond cleavage reactions. The PET ring cleavage of azirines results in the formation of 2-azaallenyl radical cations which may be trapped by dipolarophiles to give heterocyclic compounds. Using this method, we have developed a new route to heterophanes. Porphyrins can also be prepared by this procedure. Further studies aim ot reveal the scope and limitations of these new reactions. Radical cations and radical anions can attack π bonds within the same molecule. Depending on the reaction conditions chosen to generate the radical ions, five-or six-membered ring systems can be obtained. Under PET reductive conditions, radical anions arise which preferentially form five-membered ring molecules (Baldwin rule). However using PET oxidative conditions, radical cations are generated which preferentially form six-membered ring molecules due to their electrophilic character. In addition, we have developed a new reactive CC bond cleavage reaction with annular cyclopropanes and cyclobutanes and have applied this method to a new short synthesis of the hirsutene ring system.

Development and Analytic of Odor Absorber: 18. Vortragsveranstaltung der GDCh – Waschmittelchemie 29. – 30. April 2004 – Königswinter

Abstract The modern societies are not any more ready to accept malodors as an inevitable fact but they tend to control osmogens and spread good smells. Hereby the use of zinc ricinoleate has grown to a common system for odor control in recent years. Theoretical description of odor absorbing mechanism was done recently. For performance evaluation of these malodor absorbing systems a new analytical method, the solid phase micro-extraction (SPME), is now available. With this knowledge, the next task is to develop a malodor absorber system with required efficacy.

GDCh-Intensive Course Surfactants: Detergents, Cosmetics, Technical Applications

For many years the training programme of the German Chemical Society GDCh did not contain a training course on surfactants although both production and use of surfactants play a major role in Germany and interest was there from diverse sides. The sector group “Detergents” (Fachgruppe Waschmittelchemie) of GDCh was recently asked to provide such a course. After setting up a one-day course in Idstein under guidance of Professor Dr. Thomas Knepper and with contributions from experts from the Fachgruppe Waschmittelchemie in 2009 and 2010, the high interest in this event allowed the GDCh to establish a more intense two day course which covers the full spectrum of surfactant technologies including the Personal Care area. This was realised in September 2010 in Essen in the premises of Evonik Goldschmidt GmbH with a broad participation of leading scientists from surfactant research and specialists from the organising company. The participation in this course was again excellent. The participants from Germany and Switzerland came from diverse companies who produce or use surfactants. On day 1, after the welcoming words of Dr. Stefan Silber, Head of the Innovation Management and R & D of Evonik’s Business Unit Consumer Specialties and Dr. Felix M ller, Evonik Goldschmidt GmbH as the organizer of the training course, Professor Dr. Heinz Rehage from Technical University Dortmund started with the general introduction on surfactants and adressed phenomena like micells, CMC and did progress very quickly into the details of modern rheology and the options to study surfactant behaviour in detail making vesicles and liposomes visible and understandable. He went into video-enhanced contrast microscopy, NMR-spectroscopy and isothermal titration calometry as means to visualize surfactant properties. Prof. Dr. Cosima Stubenrauch from Stuttgart University continued with a detailed introduction into the secrets of emulsions and microemulsions, their applications and analytics. She addressed stability issues of emulsions as well as modern technologies like PIT emulsions and went thoroughly through the unique world of microemulsions and their special features. The stability of microemulsions was explained and their special phase diagrams. The third presentation was given by Dr. Peter Schmiedel from Henkel KGaA, who described in depth the current composition of the diverse laundry detergent products on the market, from European powder liquid systems to fabric softeners and special detergents for wool, black fabrics etc. He detailed the mechanisms of bleaching and dye transfer inhibition. He explained as well the actions and synergisms of various ingredients and gave an outlook for the further development of the laundry detergents in different parts of the world. Professor Dr. Thomas Knepper from Fresenius University in Idstein gave his insights into the special problems of surfactant analytics and explained the special environmental background of the fate of surfactants that will be usually intentionally released into wastewater and explained with examples from the Philippines what consequences the use of nonbiodegradable surfactants has for ground water pollution. He focussed as well especially on fluorinated surfactants and the approaches to avoid the bioaccumulation of these materials. Dr. Bernd Glassl from Industrieverband Kosmetik und Waschmittel (IKW, German industry group cosmetics and detergents) in Frankfurt gave finally on the first day an introduction into the special legal situation of surfactants in laundry and cosmetics, a field where European and German law contributes to a lot of details to observe when formulating products. He explained the different biodegradation test protocols and their respective use in different directives. The discussion of the contributions added value for the participants as fairly detailed questions and problems were well solved and addressed by the presenters. On the second day, it was Dr. Joachim Venzmer of Evonik Goldschmidt GmbH, Essen, who started with a presentation on silicone surfactants. He addressed properties and technical applications of this interesting surfactant class far beyond what is found in text books and explained state of art superspreading technology for agricultural applications as well as wetting and release coating, paint wetting and spreading of cosmetic oil explained some of the unique features of silicone surfactants. Dr. Sascha Herrwerth of Evonik Goldschmidt GmbH continued with a presentation on Rinse-Off cosmetic for hairand body cleansing, detailing formulas and explaining effects and properties which are under demand by consumers like foaming, mildness, conditioning and the demands which arise from new ingredients in Personal Care formulations. A special focus was on conditioning agents for shampoos as well as conditioning rinses to be used after washing the hair. The proper viscosity control was addressed as well and how to avoid the problems for rinse-off products at elevated temperatures (the sport-bag-effect). CONFERENCE AND MEETING REPORT