For chemical scientists and R&D professionals, a deep understanding of molecular structure and reaction mechanisms is fundamental to innovation. Tri-(4-hydroxy-TEMPO) phosphite (CAS 2122-49-8), widely known in the industry as Inhibitor 705, is a fascinating molecule that serves as a highly efficient polymerization inhibitor. As a specialized manufacturer and supplier of fine chemicals, we aim to demystify the chemistry of this compound and highlight its critical functions for our scientific clientele.

Molecular Architecture and Functionality

The efficacy of Tri-(4-hydroxy-TEMPO) phosphite stems directly from its unique chemical architecture. At its core, the molecule features a phosphite (P(OR)3) backbone. Attached to this central phosphorus atom are three identical groups derived from 4-hydroxy-TEMPO. The TEMPO (2,2,6,6-tetramethylpiperidinyloxy) radical is a stable nitroxyl radical, renowned in organic chemistry for its ability to participate in single-electron transfer reactions and act as a potent radical scavenger. In Inhibitor 705, these TEMPO radicals are tethered via oxygen linkages to the phosphorus atom, forming ester bonds.

Mechanism of Radical Scavenging

The primary mechanism by which Tri-(4-hydroxy-TEMPO) phosphite inhibits polymerization is through the donation of a hydrogen atom or an electron to reactive free radicals. When a propagating polymer chain radical (P•) or an initiating radical (R•) is present, the TEMPO radical within the inhibitor can react with it:

TEMPO-O-P-(OR)2 + P• → TEMPO-P-(OR)2 + P-H (Hydrogen abstraction)

Alternatively, the phosphite ester itself can act as a reductant. The key is that the TEMPO radical, or a species derived from it, effectively terminates the growing polymer chain or neutralizes initiators, thus preventing further propagation of the polymerization chain reaction. This process is highly efficient and can be sustained as long as active TEMPO radicals are available.

Chemical Properties and Synthesis Considerations

Supplied typically as a carmine crystalline powder, Tri-(4-hydroxy-TEMPO) phosphite exhibits good thermal stability and low volatility, making it suitable for demanding polymerization processes. Its synthesis involves the reaction of phosphorus trichloride with 4-hydroxy-TEMPO, followed by careful purification to achieve the desired purity levels (often >=97.0%). Understanding these chemical properties is vital for scientists when designing formulations or troubleshooting process issues.

Why Partner with Us for Your Chemical Needs?

As a leading China-based manufacturer and supplier, we are committed to providing scientists with high-quality chemical intermediates like Tri-(4-hydroxy-TEMPO) phosphite. We offer detailed technical specifications, competitive pricing, and reliable supply. We invite researchers and laboratory managers to contact us for samples and quotes, enabling you to leverage the advanced chemistry of Inhibitor 705 in your groundbreaking work.