H₂PtCl₆·6H₂O — orange-red crystalline solid; supplied as 0.1–10% IPA solutions; chloride-bearing.

Speier’s catalyst is hexachloroplatinic(IV) acid hexahydrate — H₂PtCl₆·6H₂O, CAS 18497-13-7 (hexahydrate) or CAS 16941-12-1 (anhydrous). Molecular weight 517.9 g/mol (hexahydrate), platinum content 37.6% by weight. The compound is a strong oxoacid, supplied as orange-red to deep-red crystalline material that is hygroscopic and decomposes above 60°C. SEMITECH stocks Speier as ready-to-dose solutions at three concentrations — 0.1%, 1.0%, and 10% Pt by weight in isopropanol — packaged in tinted glass bottles under nitrogen. The crystalline solid form is available on request for laboratory synthesis where the user prefers to prepare custom solvent solutions.

Speier’s catalyst was the first effective hydrosilylation catalyst, reported by Speier and colleagues at Dow Corning in 1957 (US Patent 2,823,218). It remains in widespread industrial use as a lower-cost alternative to Karstedt where chloride residue is tolerated. Pt content 37.6% in the hexahydrate (0.1–10% in IPA solutions). Chloride content correspondingly high — 41.0% Cl in pure hexahydrate, scaled with concentration in solvent solutions. Chloride is the operational distinguishing feature: it produces minor part discolouration during cure (yellow to brown depending on Pt loading), induces minor corrosion in cured silicone in contact with copper or silver, and is the reason Karstedt has displaced Speier in modern medical, food-contact, and optical applications.

Pt(IV) precatalyst reduced in situ by Si-H to active Pt(0) colloidal species; less selective than Karstedt.

Speier’s catalyst is a Pt(IV) precatalyst that requires in-situ reduction to the catalytically active Pt(0) state before hydrosilylation can begin. The reducing agent is the Si-H functionality of the crosslinker itself: Si-H species reduce H₂PtCl₆ to colloidal Pt(0) clusters with formation of Si-Cl byproduct and HCl gas. The induction period — typically 1–5 minutes at 80°C — is the rate-limiting step in the early cure profile and is the source of much of the variability in Speier-cured silicone batch-to-batch consistency.

• Loading 10–30 ppm Pt — industrial RTV-2 condensation cure replacement; mould rubber for non-medical applications
• Loading 30–50 ppm Pt — silane synthesis and silicone polymer manufacture (e.g., methyl-H silicone fluid hydrosilylation with α-olefins to make alkyl silicones)
• Loading 50–100 ppm Pt — laboratory hydrosilylation chemistry; difficult substrates with steric hindrance

Once reduced to Pt(0), Speier-derived catalyst proceeds through the same Chalk-Harrod hydrosilylation cycle as Karstedt, but with reduced selectivity — colloidal Pt clusters are more prone to side reactions (β-hydride elimination, Si-H homologation, isomerisation of α-olefin substrates to internal olefins). The chloride ligand also inhibits some β-substituted vinyl substrates, requiring higher Pt loading to achieve equivalent cure rates. Speier remains preferred over Karstedt for: (1) silane manufacture where chloride byproduct is anyway present from chlorosilane chemistry; (2) industrial RTV-2 mould rubber where part appearance is not critical; (3) hydrosilylation R&D where cost-per-Pt-mole drives experimental design.

Industrial RTV-2 (non-medical), silane and silicone polymer manufacture, lab hydrosilylation chemistry.

Industrial RTV-2 mould rubber for non-medical applications — concrete-form release moulds, low-cost prototype tooling, candle and wax-art moulds — uses Speier 1% IPA solution at 20–40 ppm Pt loading. The slight cure-yellowing is acceptable when the mould rubber is itself not the visible final part. Cure cycle is 30 minutes to 2 hours at 80°C, or overnight at room temperature. Silane synthesis and silicone polymer manufacture — for example, hydrosilylation of methyl-hydrogen silicone fluid with α-olefins to make alkyl-modified silicones for cosmetic and lubricant applications, or addition of Si-H to vinyl-trichlorosilane to make functional silane intermediates — uses Speier at 50–200 ppm Pt loading because the substrates are inherently chloride-bearing and the reactor is designed to handle HCl byproduct. The 10% Pt IPA solution is the working stock for these applications.

Laboratory hydrosilylation R&D — model substrate development, mechanism studies, novel ligand screening — typically uses 0.1% or 1% Speier solutions at 100–500 ppm Pt loading because reaction-rate and conversion data (not finished-part appearance) drive experimental design. Speier is also commonly used in chloroplatinic acid-impregnated alumina catalyst preparations for fixed-bed continuous hydrosilylation reactors used in commodity silicone manufacturing.

Tinted glass under N₂; CoA per shipment; 100 g samples to 10 kg drums; 12-month shelf life.

SEMITECH issues a CoA on every batch with: platinum content (ICP-MS, target ±0.05% of nominal 0.1/1/10%), chloride assay (titration, target ratio Cl:Pt = 6:1 ± 0.1), water content (Karl Fischer for solid; standard for IPA solutions ≤0.5%), and visual appearance. Standard packing: 100 g (laboratory sample), 1 kg (small-volume production), 10 kg (industrial bulk) — all in tinted amber glass bottles under nitrogen. MOQ 100 g samples for qualification, 1 kg for production. Lead time 2–3 weeks ex-China for IPA solutions; the crystalline solid form has 4-week lead time as it is made-to-order. Air freight available for 100 g samples within 5 working days.

Storage: Speier IPA solutions store sealed below 25°C, away from sunlight, in original tinted glass; shelf life 12 months sealed. The crystalline hexahydrate form is hygroscopic and must be stored in a desiccator under nitrogen — it slowly loses crystal water on ambient exposure, shifting the effective Pt assay. Hazards: Speier is a strong oxidiser, corrosive to skin and eyes, and produces HCl fumes on contact with reducing agents or metals. Handle with full PPE — nitrile gloves, chemical-splash goggles, lab coat — under fume hood. Spill response: neutralise with sodium bicarbonate slurry and absorb on inert media before disposal. Pt as commodity: Pt content drives ~80% of catalyst cost; SEMITECH passes through monthly LBMA fixings on bulk orders. Conflict-mineral and ESG sourcing audit documentation available on request.

Speier is the historical hydrosilylation catalyst — Pt(IV) chloroplatinic acid that reduces in-situ to active Pt(0). Lower selectivity, chloride byproduct, lower cost per Pt mole than Karstedt. Use for industrial RTV-2 (non-medical), silane synthesis, lab hydrosilylation. For medical, food-contact, optical → Karstedt.

Three solution concentrations stocked; CoA per batch with ICP-MS Pt assay.