2,2,5-Trimethyl-4-phenyl-3-azahexane-3-nitroxide
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Product Description
2,2,5-Trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO), also known as N-(tert-butyl)-N-(2-methyl-1-phenylpropyl)-N-oxyl, is a stable nitroxide radical widely used in polymer chemistry. Its unique structure, featuring a bulky geminal dimethyl group and a phenyl group, stabilizes the radical, preventing dimerization or decomposition, which is crucial for its role in controlled polymerization processes. TIPNO is commonly employed as an initiator or mediator in nitroxide-mediated radical polymerization (NMP), a technique that allows for the synthesis of polymers with well-defined structures. This nitroxide radical is paramagnetic and EPR-active, making it useful as a spin label and radical probe. The steric bulk provided by the 2,2,5-trimethyl substitution pattern enhances its stability, similar to TEMPO, while the 4-phenyl substituent influences its solubility, redox potential, and steric environment. TIPNO is commercially available for research and polymer synthesis applications, and it exhibits unique solubility and reactivity in supercritical carbon dioxide (scCO₂) media, further expanding its utility in polymerization reactions.
Common Name
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Common Name: TIPNO
Synthesis Methods
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TIPNO is synthesized through a series of chemical reactions involving the introduction of methyl and phenyl groups onto a nitrogen-containing hexane backbone, followed by the addition of a nitroxide group. Specific synthesis methods can be found in various polymer chemistry papers and reviews.
Uses
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Polymer Chemistry: Extensively used as a nitroxide mediator in nitroxide-mediated polymerization (NMP) to synthesize polymers with controlled molecular weights and narrow distributions.
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Research: Used in various polymer chemistry studies to compare its performance with other nitroxides like TEMPO and SG1.
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Industrial Applications: Employed in the production of well-defined polymers with specific architectures, such as linear, graft, and star polymers.
Physical Properties
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Density: ≈ 0.953 g·mL⁻¹ at 25 °C
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Flash Point: ≈ 96 °C
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Storage/Handling: Stored cold (−20 °C) and kept sealed
Structural Formula
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Parent Chain: 3-azahexane (6-carbon chain with a nitrogen at position 3)
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Substituents:
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2,2-Dimethyl (two methyl groups at carbon #2)
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5-Methyl (one methyl group at carbon #5)
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4-Phenyl (phenyl group at carbon #4)
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Functional Group: 3-Nitroxide (nitrogen with an unpaired electron and an oxygen atom)
Hazards Identification
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Primary Hazards: Oxidizer, Acute Toxic
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GHS Classification:
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Signal Word: Warning
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Hazard Statements:
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H272: May intensify fire; oxidizer
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H301: Toxic if swallowed
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Precautionary Statements:
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P210: Keep away from heat/sparks/open flames/hot surfaces. - No smoking
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P220: Keep/Store only in original container
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P264: Wash hands thoroughly after handling
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P270: Do not eat, drink or smoke when using this product
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P280: Wear protective gloves/protective clothing/eye protection/face protection
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P301+P316: IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician
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P321: Specific treatment (see label)
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P330: Rinse mouth
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P370+P378: In case of fire: Use CO₂, dry chemical, or foam for extinction
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P405: Store locked up
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P501: Dispose of contents/container to an approved waste disposal plant
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Handling and Storage
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Precautions for Safe Handling:
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Handle empty containers with care because residual vapors are flammable.
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Do not handle until all safety precautions have been read and understood.
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Ensure good ventilation of the work station.
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Do not breathe fumes, mist, spray, vapors.
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Wear personal protective equipment.
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Avoid contact with skin and eyes.
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Keep away from ignition sources (including static discharges).
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Proper grounding procedures to avoid static electricity should be followed.
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Use only non-sparking tools.
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Conditions for Safe Storage:
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Keep container closed when not in use.
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Keep away from ignition sources.
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Air sensitive.
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Keep contents under inert gas.
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Store in dry, cool, well-ventilated area.
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Kinetic and Reactivity Notes
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TIPNO-type nitroxides exhibit different redox/homolysis/recombination equilibria compared to TEMPO.
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Often enables polymerization of acrylates where TEMPO fails.
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Reaction kinetics (kd, kc) for alkoxyamines derived from TIPNO are reported in various polymer chemistry papers, though exact values depend on the specific alkoxyamine structure and experimental conditions.
EPR and Electrochemical Data
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EPR Spectroscopy: TIPNO is EPR-active, and many studies use EPR to monitor reactions involving TIPNO, such as polymerization and alkoxyamine homolysis.
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Redox Potentials: TIPNO has characteristic redox behavior relevant to its stability and role in NMP. Specific formal potentials (E°) can be found in electrochemical studies or supplementary sections of polymerization papers.