Portrait Sergii Pazenok

The Chemist of Fluorine Attraction


He’s had a challenging career – and this is why he loves his work in the laboratory: Sergii Pazenok is one of the world’s elite fluorine chemists.

Research never ends. Even if everything seems tested, years later something new can be discovered.
Dr. Sergii Pazenok
Dr. Sergii Pazenok
Chief Scientist

After the nuclear disaster in Chernobyl in 1986, I simply did what needed to be done: I helped with the cleanup. The accident happened on the 26th of April just 100 kilometers from Kiev, where I grew up. We were only informed about this catastrophe two weeks later. In the Ukrainian National Academy of Science, we had developed a special mixture to absorb radioactive dust, which we used to reduce the spread of these radioactive materials. Only years later I did understand the full danger of what the citizens of Ukraine and Kiev were exposed to.


Fluorine – an Element With its Own Chemistry

I probably wouldn’t act as selflessly today, but I’ve never lost my attraction to the chemistry and especially fluorine chemistry. My specialty is the element of fluorine. Worldwide, there are only a few hundred experts in this field – but fluorine is a fascinating element - with a big ego. Chemists say it has the highest electronegativity, and this brings unique characteristics to the compounds with fluorine. At Bayer, I built a fluorine network with my colleagues that we use for developing new fluorine containing pesticides or drugs. It’s my job to create the new processes to manufacture active ingredients safely and cost-efficiently – it’s a kind of chemistry puzzle. I most enjoy my work when I am in the lab, trying to find or optimize new processes, or synthesize complex molecules.

Fluorine can influence molecules like no other element, and gives me many options to modulate the polarity and solubility of a product.
Sergii Pazenok
Chief Scientist

I am happy that four of the products I worked on are available on the market. Two more compounds are in development. All of those substances undergo testing for toxicity, biodegradation, metabolization in the plant and soils, and stability upon storage. To get this done, I cooperate with a wide range of colleagues. We check the product itself for toxicity and also what happens when the product degrades, to ensure that neither damages the environment.

A healthy and friendly work atmosphere is very important to me. I’m lucky to work with a great team and good colleagues. Our success comes through their mutual support and professional exchanges, and this environment makes any failures tolerable.




Germany, Badminton and Kant

Even though Oktoberfest doesn't excite me too much, I love Germany and German culture. I’ve been living here for almost three decades now and decided two years ago to apply for German citizenship. I also visit my homeland from time to time, to see my mother and brother. For holidays, I prefer to explore other countries like Greece, Italy or France. Lying on the beach the whole day isn’t my thing though, as it doesn’t relax me. I’m more an active person. For leisure, I regularly play on a badminton team, and I enjoy reading – particularly Erich Maria Remarque and John Grisham. Sometimes I like to explain chemistry to my granddaughter, which allows me to bring my work home in a nice way.


CV Sergii Pazenok

1957 Born in Kiev, Ukraine
1979 Graduate chemist, Taras Shevchenko National University of Kyiv
1985 Thesis at National Academy of Sciences of Ukraine: “3H-Indoles and Benzindoles cyanine dyes with fluoro containing substituents”
1983-1986 Research Scientist, National Academy of Sciences of Ukraine
1986-1993 Senior Research Scientist and Team leader, National Academy of Sciences of Ukraine
1994 Fluorine Chemist, Hoechst AG, Frankfurt am Main, Germany
1996-1997 Project manager “Novel Halex Catalysts for fluorination,” Hoechst AG, Frankfurt am Main, Germany
1997-1998 Corpus Christi Technical Center, Hoechst Celanese, Texas
1999 Team Leader Agrxxx, Frankfurt am Main, Germany
2000 Team Leader Chemical Process R & D, Aventis Crop Science
From 2003 Laboratory Manager and Senior Fellow Researcher, Bayer Crop Science, Monheim, Germany.
Since 2016 Appointed as a Chief Scientist


Selected Publications

A new approach toward the synthesis of 2,4-bis(fluoroalkyl)-substituted quinoline derivatives using fluoroalkyl amino reagent chemistry.
Organic Chemistry Frontiers (2016), 3(11), 1392-1415.
Aribi, Fallia; Schmitt, Etienne; Panossian, Armen; Vors, Jean-Pierre; Pazenok, Sergiy; Leroux, Frederic R.


A Major Advance in the Synthesis of Fluoroalkyl Pyrazoles: Tuneable Regioselectivity and Broad Substitution Patterns.
Chemistry - A European Journal (2016), 22(32), 11239-11244.
Schmitt, Etienne; Panossian, Armen; Vors, Jean-Pierre; Funke, Christian; Lui, Norbert; Pazenok, Sergiy; Leroux, Frederic R.

Read on PubMed

A New Life for an Old Reagent: Fluoroalkyl Amino Reagents as Efficient Tools for the Synthesis of Diversely Fluorinated Pyrazoles
European Journal of Organic Chemistry (2013), 2013(20), 4249-4253.
Pazenok, Sergiy; Giornal, Florence; Landelle, Gregory; Lui, Norbert; Vors, Jean-Pierre; Leroux, Frederic R.



Selected Patents

Process for preparing 3-dihalomethylpyrazole-4-carboxylic acid derivatives
WO 2008022777 A2

Read on Google Patents

Method for producing 1-alkyl-/1-aryl-5-pyrazole-carboxylic acid derivatives
WO2011073101 A1

Read onGoogle Patents

Process for preparing tetrazole-substituted anthranilamide derivatives and novel crystal polymorph of these derivatives

Read on Google Patents



1996: Hoechst Research Award, Hoechst AG
2010: Bayer Crop Science Innovation Award for the development of the Fungicide Bixafen
2010: Bayer Crop Science Chairman Innovation Award for the development of the Insecticide Sivanto T
2016: Bayer Publication Award, Bayer AG