Thomas Seidensticker

Towards resource efficient chemistry: tandem reactions with renewables

In an economically expanding world new sustainable concepts have to be developed in order to overcome growing problems of resource availability. Merging different “Green principles” is a promising concept in this respect, e.g. the combination of tandem reactions and renewables. This review summarizes the trends in this field and demonstrates advantages and future demands. Four reactions, namely metathesis, hydroformylation, defunctionalisation and isomerisation, have been identified for transforming renewables in tandem reactions. Every reaction yields a reactive intermediate or secures a tailored selectivity in order to use the natural molecular structure of renewables.

Palladium-Catalyzed Aminocarbonylation of Aliphatic Alkenes with N,N-Dimethylformamide as an In Situ Source of CO

The palladium‐catalyzed aminocarbonylation of aliphatic alkenes is presented for the first time without the need for external CO pressure. N,N‐dimethylformamide (DMF) is used as an in situ source of both the required carbon monoxide and the amine substrate. The applied palladium catalytic system is well‐known for a number of carbonylation reactions, including those with CO surrogates and tandem isomerizing carbonylations. The reaction pathway was investigated and proved to proceed by an acid‐catalyzed DMF decomposition to CO and dimethyl amine with subsequent aminocarbonylation of the alkene. Pressure‐versus‐time curves gave more insight into the correlation between acid concentration and aminocarbonylation activity. Aliphatic alkenes (terminal and internal) are transformed, also in commercial glassware, into the corresponding linear N,N‐dimethylamides with excellent selectivities. Hence, amide synthesis by aminocarbonylation moves closer to application in standard organic laboratories.

Direct Synthesis of an α,ω-Diester from 2,7-Octadienol as Bulk Feedstock in Three Tandem Catalytic Steps

A new tandem catalytic process was designed and developed as a tool for the direct conversion of the widely available feedstock 2,7-octadienol into an α,ω-diester. This innovative auto-tandem catalysis is atom efficient and consists of three consecutive palladium-catalysed reactions: ether formation, ether carbonylation and alkoxycarbonylation. By using the design of experiments (DoE) approach, significant parameters were determined and the yield of the desired α,ω-diester was optimised. Model substrates allowed deeper insight into the progress of the reaction to be gained and, as a result, the reaction sequence was uncovered. Furthermore, by simply applying other ligands, a different reaction path was followed, allowing other, new tandem catalytic sequences to be explored and enabling new compounds to be obtained.

Tandem Reductive Hydroformylation of Castor Oil Derived Substrates and Catalyst Recycling by Selective Product Crystallisation

An orthogonal tandem catalytic system consisting of rhodium and ruthenium complexes yielded linear C12 α,ω‐bifunctional compounds from commercial, castor oil derived renewable substrates. With aldehyde yields up to 88 % and selectivities to the linear species of up to 95 %, this approach is direct and atom economic and provides easy access to potential polymer precursors for polycondensates. Additionally, a straightforward method for selective product crystallization was developed, which enabled recycling of the tandem catalytic system for two runs with excellent activity and simultaneously provided a high‐purity product.

Ruthenium-catalyzed hydroformylation: from laboratory to continuous miniplant scale

Hydroformylation of alkenes for the production of aldehydes is one of the most important homogeneously catalyzed reactions on an industrial scale. Mostly, these processes are based on expensive rhodium as the catalyst metal. In this contribution, we present for the first time the successful application of ruthenium as a cheaper alternative metal in a continuously operated miniplant. In the reaction of 1-octene, ex situ extraction of the oxo-products is conducted using the nonpolar solvent iso-octane, while the catalyst is retained in a polar DMF phase. After optimizing the reaction conditions on a batch scale, the recycling of the ruthenium catalyst was realized over a period of 90 h in a fully automated miniplant setup.

From Oleo Chemicals to Polymer : Bis-hydroaminomethylation as a Tool for the Preparation of a Synthetic Polymer from Renewables

Resource‐efficient bis‐hydroaminomethylation of the castor oil derived renewables methyl 10‐undecenoate and 10‐undecene‐1‐ol with piperazine furnished linear, bifunctional molecules. A structured and sustainable path towards a novel polyester from these monomers was developed. Key to success was the selective crystallization of the linear product directly from the crude reaction mixture in >98 % purity. Additionally, with this methodology, the homogeneous Rh catalyst was retained in the supernatant and was successfully recycled. Finally, polycondensation yielded a novel piperazine‐linked polyester.

Weimar 2016: Catalysis Strikes Back

What a start to the year—the German Catalysis Society (GeCatS) gathered for their annual meeting, which is traditionally held in the historical city of Weimar. The city is situated in the heart of Germany and is well known for its cultural and historical impact on the nation’s development throughout the centuries. This year’s 49th meeting took place from Wednesday March 16th to Friday March 18th and was attended by 535 participants (slightly fewer participants than previous years owing to a busy international conference timetable). Nonetheless, the scientific program was comprehensive and, as expected, set to a high scientific level, involving 5 plenary lectures, 31 presentations, and 269 posters on display. Special interest was recognized within these contributions in the fields of electrochemistry, selective oxidation/reduction, catalyst preparation, and selective (de-)hydrogenation. Moreover, YounGeCatS organized two poster workshops this year, in which attention was paid to ten selected poster contributions, mostly given by young scientists. The two poster workshops were dedicated to the topics of reaction engineering and molecular catalysis–biocatalysis, respectively. In addition to the scientific program, 27 companies were present to exhibit their latest products and innovations related to catalysis research and catalyst characterization throughout the conference. With 21 exhibitors in attendance the previous year, this significant growth clearly demonstrates how fruitful the interaction is for industry and academia meeting in Weimar.

Homogeneously Catalyzed 1,3‐Diene Functionalization – A Success Story from Laboratory to Miniplant Scale

For many years, the efficient use of resources has been a major and permanent challenge for the chemical industry. The implementation of alternative resources such as renewables and carbon dioxide has been a subject of considerable discussion, but also the more efficient use of long known bulk chemicals is of great interest. Among them, 1,3‐dienes such as 1,3‐butadiene from the C4 cut of the naphtha cracker as well as isoprene, piperylene and cyclopentadiene from the corresponding C5 section are important substrates. These dienes are presently employed in various markets, with the greatest importance being in the production of polymers and copolymers. However, homogeneous transition metal catalysis has proven to be a versatile tool to functionalize these important 1,3‐dienes to low molecular weight fine chemicals by introducing, for example, nitrogen, oxygen or silicon. Hence, an upgraded use of the corresponding products as agrochemicals, pharmaceuticals, fragrances or special detergents is close at hand. The main approaches in the topic of homogeneous functionalization reactions of the industrially relevant 1,3‐dienes will be summarized and discussed within the present article. Besides that, novel applications including renewable 1,3‐dienes, for example β‐myrcene and β‐farnesene, as well as the application of CO2 in telomerization, will be critically discussed.

Tandem Reactions with Renewables

Tandem catalytic reactions and related processes offer major benefits in comparison with the stepwise synthesis of intermediates and valuable chemicals. Hence, various investigations have been conducted during the last years aiming for the development of selective tandem catalytic systems in numerous chemical disciplines [1, 2, 3, 4, 5, 6, 7, 8]. Generally, in tandem systems, two or more individual chemical transformations are merged together, which minimises on the one hand time and effort.