Speier's Catalyst (Chloroplatinic Acid Hexahydrate, H₂PtCl₆·6H₂O, CAS 18497-13-7): Historical Hydrosilylation Catalyst for Industrial RTV-2 and Silane Synthesis
SEMITECH supplies Speier's catalyst — chloroplatinic acid hexahydrate (CAS 18497-13-7) — as ready-to-dose 0.1%, 1% and 10% solutions in isopropanol. The historical and lower-cost alternative to Karstedt for industrial RTV-2 and laboratory hydrosilylation, accepted where chloride residue and slight cure colouration are tolerable. 100 g / 1 kg / 10 kg packing.
Contents
| 18497-13-7 | 0.1–10% | 100 g |
|---|---|---|
| CAS (hexahydrate) | IPA solution range | MOQ (samples) |
Chemistry & Specifications
H₂PtCl₆·6H₂O — orange-red crystalline solid; supplied as 0.1–10% IPA solutions; chloride-bearing.
Speier's catalyst (MW 517.9, Pt content 37.6%) was the first effective hydrosilylation catalyst (Speier, Dow Corning, 1957). SEMITECH stocks 0.1%, 1.0%, and 10% Pt solutions in IPA under nitrogen. Chloride content is the operational differentiator: it produces minor part discolouration and can induce corrosion on copper/silver — the reason Karstedt has displaced Speier in medical, food-contact, and optical applications.
Cure Mechanism: Pt(IV) Reduction → Active Pt(0) Hydrosilylation
Pt(IV) precatalyst reduced in situ by Si-H to active Pt(0) colloidal species; less selective than Karstedt.
Speier requires an induction period (1–5 min at 80°C) as Si-H reduces Pt(IV) to Pt(0) with Si-Cl and HCl byproducts. Once reduced, it proceeds through the same Chalk-Harrod cycle as Karstedt but with reduced selectivity.
- Loading 10–30 ppm Pt — industrial RTV-2 mould rubber for non-medical applications
- Loading 30–50 ppm Pt — silane synthesis and silicone polymer manufacture
- Loading 50–100 ppm Pt — laboratory hydrosilylation; difficult substrates with steric hindrance
Speier remains preferred for silane manufacture (chloride already present), industrial RTV-2 (appearance not critical), and R&D (lower cost per Pt mole).
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Applications & Formulation Guidance
Industrial RTV-2 (non-medical), silane and silicone polymer manufacture, lab hydrosilylation chemistry.
Industrial RTV-2 — concrete-form release moulds, low-cost prototype tooling at 20–40 ppm Pt; slight cure-yellowing acceptable. Silane synthesis — hydrosilylation of methyl-hydrogen silicone with α-olefins at 50–200 ppm Pt. Lab R&D — model substrate development and mechanism studies at 100–500 ppm Pt using 0.1% or 1% solutions.
Procurement, Storage and Quality Control
Tinted glass under N₂; CoA per shipment; 100 g samples to 10 kg drums; 12-month shelf life.
CoA per batch: Pt content (ICP-MS, ±0.05%), Cl:Pt ratio (6:1 ± 0.1), water content, appearance. MOQ 100 g samples, 1 kg production. Lead time 2–3 weeks for IPA solutions; crystalline solid 4-week make-to-order. Store sealed below 25°C in tinted glass. Speier is a strong oxidiser, corrosive — handle with full PPE under fume hood.
Speier's Catalyst (Chloroplatinic Acid IPA Solution) Specification Sheet
Three solution concentrations stocked; CoA per batch with ICP-MS Pt assay.
| Property | Speier 0.1% IPA | Speier 1% IPA | Speier 10% IPA |
|---|---|---|---|
| Pt content | 0.10 ± 0.005% | 1.00 ± 0.05% | 10.0 ± 0.1% |
| Source compound | H₂PtCl₆·6H₂O | H₂PtCl₆·6H₂O | H₂PtCl₆·6H₂O |
| CAS number | 18497-13-7 | 18497-13-7 | 18497-13-7 |
| Solvent | Isopropanol | Isopropanol | Isopropanol |
| Cl:Pt molar ratio | 6.0 ± 0.1 | 6.0 ± 0.1 | 6.0 ± 0.1 |
| Appearance | Yellow solution | Orange-yellow solution | Deep red solution |
| Density (20°C) | 0.79 g/cm³ | 0.80 g/cm³ | 0.85 g/cm³ |
| Water content | ≤0.5% | ≤0.5% | ≤0.5% |
| Typical use level | 50–500 ppm Pt | 50–500 ppm Pt | 20–200 ppm Pt |
| Packaging | 100 g / 1 kg amber glass | 100 g / 1 kg amber glass | 100 g / 1 kg / 10 kg amber glass |
| Storage | Tinted glass, N₂ blanket, <25°C | Tinted glass, N₂ blanket, <25°C | Tinted glass, N₂ blanket, <25°C |
| Shelf life | 12 months sealed | 12 months sealed | 12 months sealed |
FAQ
+When should I choose Speier over Karstedt?
Choose Speier when the substrate is already chloride-bearing, cost per Pt mole drives the decision and cure colour is acceptable, or you are doing R&D mechanism work. Choose Karstedt for medical, food-contact, optical, and electronic applications.
+What is the induction period and how do I shorten it?
Speier requires 1–5 min at 80°C for Pt(IV) → Pt(0) reduction. Shorten by raising temperature to 120°C, doubling Pt loading, or pre-mixing with vinyl-PDMS at 60°C.
+Can I substitute Speier with Karstedt without reformulating?
Mostly yes. Substitute on a Pt-mole basis (5–10 ppm Karstedt replaces 30–50 ppm Speier). Expect faster cure (add 100–200 ppm inhibitor to extend pot-life), colourless parts, and no chloride corrosion.