Hydroxyterminated Disiloxane Equivalent For Sib1145.0 | CAS 18001-97-3
Chemical Synthesis Route for 1,3-Bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane
The production of 1,3-Bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane (CAS: 18001-97-3) primarily relies on a catalytic hydrosilylation synthesis route. This process involves the reaction of 1,1,3,3-tetramethyldisiloxane with allyl alcohol in the presence of a platinum-based catalyst, such as Karstedt's catalyst or chloroplatinic acid. The reaction mechanism proceeds via the addition of the Si-H bond across the carbon-carbon double bond of the allyl alcohol, resulting in the formation of the hydroxypropyl functional groups at both termini of the disiloxane backbone.
Temperature control is critical during the manufacturing process to prevent side reactions, such as the formation of cyclic siloxanes or etherification of the hydroxyl groups. Typical reaction temperatures range between 60°C and 90°C under an inert nitrogen atmosphere to mitigate oxidation risks. Following the completion of the hydrosilylation, the crude product undergoes neutralization to deactivate the catalyst, followed by filtration to remove platinum residues. Subsequent vacuum distillation is employed to isolate the target OH-functional siloxane from unreacted starting materials and higher molecular weight byproducts. At NINGBO INNO PHARMCHEM CO.,LTD., strict monitoring of distillation cuts ensures consistent batch-to-batch reproducibility regarding boiling point and purity profiles.
The stoichiometry of the reaction is typically adjusted with a slight excess of allyl alcohol to ensure complete consumption of the Si-H groups, minimizing residual hydride content which can interfere with downstream curing processes. The final product is a colorless liquid with a characteristic mild odor, stable under standard storage conditions provided moisture ingress is prevented. The molecular structure, defined by the formula C10H26O3Si2, provides a flexible siloxane backbone terminated by primary hydroxyl groups, making it highly reactive towards isocyanates, epoxies, and silanes.
Mitigating Impurities in Hydroxyterminated Disiloxane Equivalent For Sib1145.0
Achieving high industrial purity in Hydroxyterminated Disiloxane Equivalent For Sib1145.0 is essential for performance in sensitive applications such as optical coatings or medical device formulations. Common impurities include residual allyl alcohol, unreacted tetramethyldisiloxane, cyclic siloxanes (D4, D5), and linear oligomers. These contaminants can affect volatility, cure kinetics, and the mechanical properties of the final cured matrix. Analytical verification is conducted using Gas Chromatography-Mass Spectrometry (GC-MS) and High-Performance Liquid Chromatography (HPLC) to quantify trace components below 0.1%.
Residual hydride content is particularly critical; even trace amounts can lead to gas formation during high-temperature curing or interfere with platinum-cured silicone systems. Advanced stripping techniques are utilized during purification to reduce volatile organic compounds (VOCs). The table below outlines the typical physical and chemical specifications for standard versus high-purity grades available for R&D and bulk synthesis.
| Parameter | Standard Grade | High Purity Grade | Test Method |
|---|---|---|---|
| Appearance | Colorless Liquid | Colorless Liquid | Visual |
| Purity (GC Area %) | 92% - 95% | > 99.0% | GC-MS |
| Density (g/mL at 25°C) | 0.93 - 0.95 | 0.953 ± 0.005 | ASTM D4052 |
| Refractive Index (n20/D) | 1.447 - 1.450 | 1.4526 ± 0.0005 | ASTM D1218 |
| Boiling Point (°C/mmHg) | 75/20 - 150/2 | 148-150/2 | ASTM D1120 |
| Flash Point (°C) | 45 - 110 | 110 | ASTM D93 |
| Hydroxyl Value (mg KOH/g) | 380 - 400 | 400 ± 10 | Titration |
| Water Content (ppm) | < 500 | < 100 | Karl Fischer |
Water content is another critical parameter, as excess moisture can initiate premature condensation reactions in moisture-cure systems. High-purity grades are maintained below 100 ppm water content through molecular sieve treatment during packaging. For applications requiring strict regulatory compliance regarding extractables, additional filtration steps are implemented to ensure particulate matter is minimized. The refractive index serves as a quick quality control check for batch consistency, with deviations often indicating the presence of linear oligomers or incomplete reaction.
Formulation Compatibility and Stability
The Hydroxyterminated Disiloxane Equivalent For Sib1145.0 exhibits broad compatibility with various polymer systems due to its bifunctional hydroxyl termination. It acts effectively as an end capping agent for carbinol-terminated silicones, particularly in formulations used for contact lenses and other biomedical applications where clarity and biocompatibility are paramount. In polyurethane systems, the hydroxypropyl groups react readily with isocyanates to incorporate soft, flexible siloxane segments into the hard polymer backbone, enhancing elongation and tear strength without sacrificing tensile properties.
When utilized as a silicone modifier in epoxy resins, this disiloxane improves toughness and thermal shock resistance. The siloxane backbone provides low surface energy, which can be leveraged to create hydrophobic coatings with excellent water repellency. However, formulators must account for the potential migration of low molecular weight siloxanes to the surface, which can affect intercoat adhesion in multi-layer systems. Stability testing under accelerated aging conditions (e.g., 50°C at 75% RH) indicates minimal degradation of the hydroxyl functionality over 12 months when stored in sealed, amber glass or lined steel containers.
For those evaluating 1,3-Bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane silicone modifier for specific rheological adjustments, it is important to note its compatibility with common solvents such as toluene, xylene, and isopropanol. It is less soluble in polar solvents like water or methanol. In sealant and adhesive applications, the compound contributes to flexibility and strong adhesion properties, making it ideal for bonding in construction, automotive, and electronics industries. NINGBO INNO PHARMCHEM CO.,LTD. provides technical support to optimize loading levels, typically ranging from 1% to 5% by weight depending on the desired modification of surface properties versus bulk mechanical characteristics.
Thermal stability is maintained up to 200°C for short durations, though prolonged exposure above 150°C may lead to slow rearrangement of the siloxane backbone. In electrical insulation applications, the material provides excellent dielectric properties and resistance to environmental factors. For textile finishing, it imparts softness and crease resistance. In lubricant formulations, its thermal stability and low volatility make it suitable for high-temperature environments. Antifoaming applications also leverage its low surface tension to reduce foam formation in chemical manufacturing and wastewater treatment processes.
Procurement teams and R&D engineers should specify the required purity grade based on the sensitivity of the final application. High-purity grades are recommended for optical and medical uses, while standard grades suffice for industrial sealants and release agents. Consistent supply chain management ensures that batch-specific data is available to validate performance parameters prior to full-scale production runs.
To request a batch-specific COA, SDS, or secure a bulk pricing quote, please contact our technical sales team.