User:Scandiumgrp/sandbox
| Identifiers | |
|---|---|
| Properties | |
| Molar mass | 381.48 g/mol |
| Density | .855 g/ml at 25° C |
| Melting point | 12-13° C |
| Boiling point | 138° C |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Karstedt Catalyst
[edit]Overview
[edit]
This is a Platinum catalyst for hydrosilation that consists of platinum(0) and divinyltetramethyldisiloxane.[1] In the silicon industry hydrosilation is the main pathway used to make cross-links in the silicone polymers. This catalyst is important to this industry because it is an extremely active catalyst for hydrosilation. A karstedt catalyst is so active that it is usually used in such a low concentration that it never gets separated from the finished products.[2]
Synthesis
[edit]
The synthesis of the Karstedt catalyst is vital for hydrosilation reactions.[3] What makes the Karstedt catalyst unique is the vinyl-siloxane group (A). The reaction involves the vinyl-siloxane as a starting reagent reacting with a platinum halide (B) resulting in a catalyst that contains no halides. Previous platinum catalyst synthesized contains halides such as, chloroplatinic acid. Using this type of reagent could be used as the catalyst in a hydrosilation reaction, however the platinum cannot be recovered, and requires a larger amount of catalyst compared to Karstedt catalyst to achieve a reasonable reaction rate, as a result platinum halides are not economically favorable.
The key to reaction is to have a platinum halide and vinyl containing organosilicone
Vinyl containing organosilicone (A) some vinyl-reagents that could be used are: tetra-vinyl silane and divinylallylmethylsilane. There must also be groups off the silicone that contain radicals such as: methyl, ethyl, hexyl, and tolyl, along with many others.
Platinum Halides (B) This is the second reagent needed to synthesize the Kardstedt catalyst. Some platinum halides that could be used are: H2PtCl6, K2PtBr4, and PtCl2, or it could have hydrocarbon groups as well.
The resulting product must be kept in driest conditions possible, and will be relatively stable between -50 ˚C to 50 ˚C.[4]
Applications
[edit]
The Karstedt Catalyst is useful in its ability to produce monomers. These monomers are efficient in cross link polymerization. This synthesis is often utilized to produce organoplatinum. The most common example of organoplatinum is the Zeise’s salt. It was the first organometallic compound to be described and is still considered a prime example of transition- metal olefin chemistry.[5]
The most common application of the Karstedt is its use in hydrosilylation. Hydrosilylation is an addition of H-Si over an unsaturated bond. The mechanism for hydrosilylation is still disputed and multiple mechanisms are used. A generally accepted mechanism is shown at the right This is an important reaction to the production of the protective backing surface of adhesive labels along with coatings and sealants. Along with its use as a catalyst, Karstedt solution is used as a reagent in the production of dyes, preservatives, gels, foams, certain aerosols, skin care products, and dental products.[6]
References
[edit]- ^ Anca Gabriela Bejenariu, Julie Oblom Poulsen, Anne Ladegaard Skov, Lars Henriksen (2009). "A Comparative Study on the Influence of the Platinum Catalyst in Poly(dimethylsiloxane)". Annual Transactions of the Nordic Rheology Society.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Johnson Matthey Catalyst (2009). "Platinum Catalysts for Hydrosilation".
{{cite web}}: Missing or empty|url=(help); Unknown parameter|site url=ignored (help) - ^ Larry N. Lewis, Judith Stein, Yan Gao, Robert E. Colborn, Gudrun Hutchins (1997). "Platinum Catalysts Used in the Silicones Industry: Their Synthesis and Activity in Hydrosilylation". Platinum Metals Review. 41 (2): 66–75.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ [1], "Platinum- Vinylsiloxanes"
- ^ Francesco Faglioni, Mario Blanco, William A. Goddard III (2002). "Heterogeneous Inhibition of Homogeneous Reactions". Inorganic Chemistry. 106 (7): 1714–1721.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Johnson Matthey Catalyst (2009). "Platinum Catalysts for Hydrosilation".
{{cite web}}: Missing or empty|url=(help); Unknown parameter|site url=ignored (help)
Category:Platinum compounds Category:Organoplatinum compounds