Karstedt's catalyst explained
Karstedt's catalyst is an organoplatinum compound derived from divinyl-containing disiloxane. This coordination complex is widely used in hydrosilylation catalysis. It is a colorless solid that is generally assumed to be a mixture of related Pt(0) alkene complexes.[1] [2] The catalyst is named after Bruce D. Karstedt, who developed it in the early 1970s while working for General Electric.[3]
Applications
Carbon-silicon bonds are often generated via hydrosilylation of alkenes. This reaction has very important applications to industry. While it is favorable thermodynamically, hydrosilylation does not proceed in the absence of a catalyst, such as Karstedt's catalyst. The catalyst is produced by treatment of chloroplatinic acid by the divinyltetramethyldisiloxane.[4] [5]
The catalyst can also be used in a reductive amination reaction between a carboxylic acid and an amine with phenylsilane as the reducing agent.[6]
Structure and bonding
The oxidation state of the platinum is 0. Using X-ray crystallography, the structure of Pt2[(Me<sub>2</sub>SiCH=CH<sub>2</sub>)<sub>2</sub>O]3 has been confirmed. Each Pt(0) center is surrounded by three alkene ligands provided by three 1,1,3,3-tetramethyl-1,3-divinyldisiloxane ligands. The Pt center and six coordinated carbon atoms are approximately coplanar, as found for simpler complexes such as Pt(C2H4)3.[7]
References
- Lewis. Larry N.. Stein. Judith. Gao. Yan. Colborn. Robert E.. Hutchins. Gudrun. Platinum catalysts used in the silicones industry. Platinum Metals Review. 1997. 41. 2. 66–74. 10.1595/003214097X4126675 . 53707148 .
- Stein. Judith. Lewis. L. N.. Gao. Y.. Scott. R. A.. In Situ Determination of the Active Catalyst in Hydrosilylation Reactions Using Highly Reactive Pt(0) Catalyst Precursors. Journal of the American Chemical Society. 1999 . 121. 15. 3693–3703. 10.1021/ja9825377.
- US . 3775452 . Patent . Platinum complexes of unsaturated siloxanes and platinum containing organopolysiloxanes . 1973-11-27 . 1971-04-28 . 1971-04-28 . Bruce D. Karstedt . General Electric.
- 10.15227/orgsyn.075.0078. Synthesis of Chiral (E)-Crotylsilanes: [3R- and 3S-]-(4E)-Methyl 3-(Dimethylphenylsilyl)-4-Hexenoate. Organic Syntheses. 75. 78. 1998. Richard T. Beresis, Jason S. Solomon, Michael G. Yang, Nareshkumar F. Jain, James S. Panek.
- 10.15227/orgsyn.073.0094. Regio- and Stereoselective Intramolecular Hydrosilylation of a-hydroxy Enol Ethers: 2,3-syn-2-Methoxymethoxy-1,3-Nonanediol. Organic Syntheses. 73. 94. 1996. Kohei Tamao . Yoshiki Nakagawa . Yoshihiko Ito .
- Sorribes. Iván. Junge. Kathrin. Beller. Matthias. Direct Catalytic N-Alkylation of Amines with Carboxylic Acids. Journal of the American Chemical Society. 136. 40. 29 September 2014. 14314–14319. 10.1021/ja5093612. 25230096.
- Hitchcock. Peter B.. Lappert. Michael F.. Warhurst. Nicholas J. W.. Synthesis and Structure of arac-Tris(divinyldisiloxane) diplatinum(0) Complex and its Reaction with Maleic Anhydride. Angewandte Chemie International Edition in English. 1991 . 30. 4. 438–440. 10.1002/anie.199104381.
