Catalysts & Ligands

Catalysts and ligands from abcr

Catalysts & LigandsCatalysts & Ligands

Over 80 % of all chemical products are produced by means of catalytic processes. In the last ten years, the turnover for catalysts increased worldwide by approximately 20% - from approx. 16 billion US dollars in 2007 to over 20 billion US dollars in 2018 of which over 90% was generated by catalysts for heterogeneously catalysed processes. Market studies expect further growth of the worldwide total turnover to 22.4 billion US dollars by the year 2021.

The term “catalysis” is derived from the ancient Greek term “katálysis” and refers to the change in reaction kinetics. Catalysts can initiate, accelerate or purposefully guide the selectivity in a preferred direction.

In addition to metal-based homogenous and heterogenous catalysts, which have been known for a long time, organocatalysts and enzyme-based catalysts have established themselves in recent years in chemical synthesis. Chemically similar catalysts are available as kits for screening tests.

1.    Homogenous catalysts

abcr offers a multitude of homogenous palladium catalysts, which are used for C-C- and C-N coupling reactions. Many of these reactions discovered in the 1970s have meanwhile become a part of the established synthesis methods of organic chemistry. In 2010, Richard F. Heck, Ei-ichi Negishi and Akira Suzuki received the Nobel Prize for their comprehensive research in the field of catalysis.

Excellent catalysis researchers are also responsible for the Stille, Sonogashira or Kumada reaction. In the 1990s, Buchwald and Hartwig developed catalysts with sterically sophisticated phosphine-based ligands for amination. These catalysts were further developed over the last 20 years and are meanwhile available in multiple “generations”.

Replacing precious metals with cheaper and more environmentally friendly metals is regarded as a highly desirable goal in the field of catalysis. Environmental damage caused by the mining of precious metals can be minimised and process costs lowered. Several new cobalt and manganese catalysts with so-called “PN5P” triazine ligands can be used for hydrogenation and alkylation reactions and for the synthesis of heterocyclic compounds such as pyridines and pyrimidines.

abcr offers many of these products exclusively.

Hydrosilylation is regarded as the most important platinum application for homogenous catalysis. Karstedt’s catalyst “platinum divinyltetramethyldisiloxane in vinyl-terminated PDMS” as well as Speier’s catalyst hexachloroplatinic acid are available from us in various qualities.

Catalysts on ruthenium basis provide the best results for metathesis reactions. These catalysts tolerate various functional groups and therefore represent a useful tool for organic synthesis.

We additionally offer a multitude of metallocene catalysts. Metallocenes with various substituted cyclopentadienyl, indenyl and fluorine residues can be produced upon customer request. Their main application lies in the field of polymerisation and oligomerisation of olefins (= alkenes).

Chiral catalysts for enantioselective syntheses are also based on DACH ligands (= 1,2 diaminocyclohexane ligands) or bis(oxazoline) derivates.

2.    Organocatalysts

Chiral bis(oxazoline) ligands (“BOX”) have, for the most part, proven to be usable in asymmetric synthesis. Their excellent enantioselectivity is also demonstrated in Diels-Alder, Mannich, Negishi, Kumada and Heck reactions as well as for the hydrosilylation of ketones and the allylation of aldehydes. We offer these ligands in a high optical purity in the multi-kilogramme standard (bulk).

Chiral phosphoric acids with BINOL core structure provide access to new Building Blocks as organocatalysts in 1,3 dipolar cycloaddition reactions as well as in Mannich, Michael and Strecker reactions.

3.    Heterogenous catalysts

Precious metals and metal oxides on carrier materials are used in many industrial processes as heterogenous catalysts. Examples are provided in the following:

  • Adams’ catalyst/platinum(IV) oxide hydrate
  • Pearlman's catalyst/palladium hydroxide, Pd 20% on activated carbon, 50% water content

The heterogenous catalysts are, on the one hand, used for hydrogenation or reduction of alkenes, alkines and cyano groups. On the other hand, the conversion of biomass into chemically valuable intermediates represents a relatively new research area.

The carrier materials are mainly used as activated carbon, aluminium oxide, silica and poorly soluble salts such as barium sulphate.

4.    Biocatalysts

Enzyme-based catalysts offer a direct path to new chiral building blocks. Together with our partner Enzymicals, abcr offers a broad enzyme selection. Enzymicals’ portfolio comprises a consistently growing toolbox with innovative biocatalysts. All catalogue enzymes can be delivered individually ex-stock as screening kits. They are offered as recombinantly produced raw protein. All enzymes are also available in the bulk standard.

Our portfolio comprises esterases, recombinant pig liver esterases, lipases, imine reductases (IREDs), amine transaminases, Baeyer-Villiger monooxygenases (BVMOs), halohydrin dehalogenases (HHDHs) as well as phosphotransferases and aminoacylases.

Why are these enzymes of interest as biocatalysts for the synthesis of optically pure compounds? Interest is substantiated due to the fact that they do not require co-factors and are stable and even active in organic solvents.

Application of individual isoenzymes ensures reproducible enzyme activity and prevents undesired side reactions. The “recombinant expression platform” of Enzymicals ensures an animal-free production process.

The combination of a broad substrate spectrum and high selectivity makes, e.g., lipases ideal catalysts for regio and stereoselective organic transformations such as hydrolysis, esterification and aminolysis.

5.    Ligands

Chiral compounds with high purities and ee values are often used as ligands for catalytically active metal complexes. Thus, chiral diaminocyclohexanes (“DACH” compounds) act as ligands in metal-based pharma-active agents or the widely usable Jacobsen salen complexes.

In addition to chromanones, aminochromanes, aminoindanes and various phosphines, abcr also offers several chiral ferrocenylphosphines, which are mainly used in stereoselective cross-coupling and asymmetric hydrogenation.