Introduction
1,1,3,3-Tetramethylbutyl peroxypivalate (CAS 22288-41-1), also known as tert-octyl peroxypivalate or TOPP, is a peroxyester initiator featuring the highly branched 1,1,3,3-tetramethylbutyl (tert-octyl) group attached to the peroxypivalate functional group. This sterically hindered structure provides enhanced thermal stability compared to less branched analogs while maintaining effective initiation efficiency.
Key Facts
- CAS Number: 22288-41-1
- Molecular Formula: C13H26O3
- Molecular Weight: 230.35 g/mol
- Appearance: Colorless to pale yellow liquid
- 10-Hour Half-Life Temperature: ~55 deg C
- SADT: ~25 deg C
- Storage: Refrigerated, typically 0-10 deg C
Physical and Chemical Properties
| Property | Value |
|---|---|
| Appearance | Colorless to pale yellow liquid |
| Density | ~0.89 g/cm3 |
| Active Oxygen | ~6.9% (theoretical) |
| SADT | ~25 deg C |
Applications
PVC Polymerization
TOPP serves as a medium-temperature initiator for PVC suspension polymerization, operating effectively in the 50-65 deg C range. Its SADT of ~25 deg C is higher than many peroxyesters used in PVC, providing a wider safety margin for handling and potentially simplifying logistics in certain supply chain scenarios.
Acrylic Polymerization
The initiator is also applicable to acrylic and methacrylic polymer systems where its half-life characteristics align with process requirements, supporting the production of resins with well-controlled molecular weight.
Sustainability Considerations
TOPP’s lower active oxygen content relative to some alternative initiators means that a higher weight dosage is required. However, its higher SADT potentially reduces the energy consumption associated with deep refrigeration during storage and transport, representing a partial sustainability trade-off that may be favorable in certain logistics scenarios.
Safety
TOPP requires refrigerated storage (0-10 deg C) but does not require the deep-freeze conditions needed for peroxydicarbonates. Standard organic peroxide handling protocols apply.
Frequently Asked Questions
Q: What advantages does the tert-octyl group provide over tert-butyl peroxypivalate?
A: The bulky tert-octyl group increases steric hindrance around the peroxide bond, which can slightly increase thermal stability (higher T10h) without proportionally decreasing initiation efficiency. The larger alkyl group may also enhance solubility in nonpolar media and modify the decomposition products profile. Additionally, the tert-octyl radical generated upon decomposition has different reactivity and selectivity compared to tert-butoxy radicals, which can influence polymer end-group chemistry.
Key Takeaways
- 1,1,3,3-Tetramethylbutyl peroxypivalate (CAS 22288-41-1) is a medium-temperature peroxyester initiator.
- Its higher SADT (~25 deg C) compared to many PVC initiators simplifies cold chain requirements.
- The branched tert-octyl group provides steric stabilization and modified solubility characteristics.
- Shandong Do Sender Chemicals supplies this initiator for PVC and acrylic polymer applications.