5,5-Dimethyl-1-pyrroline N-oxide

• CAS: 3317-61-1
• Catalog Number: ACM3317611
• Category: Main Products
• Molecular Weight: 113.16
• Molecular Formula: C6H11NO
• Synonyms: DMPO
• Boiling Point: 75 °C at 0.4 mmHg (lit.)
• Melting Point: 25-29 °C (lit.)
• Density: 1.015 g/mL at 25 °C (lit.)
• Appearance: Colorless to Very Dark Yellow Solid or Liquid

Case Study

5,5-Dimethyl-1-pyrroline N-Oxide as a Spin-Trap for Hydroxyl Radical Quantification in Fenton-Based AOPs

Fontmorin, J. M., et al. Water research 99 (2016): 24-32.

5,5-Dimethyl-1-pyrroline N-oxide (DMPO) is a nitrone spin-trap used to detect hydroxyl radicals (·OH) by electron paramagnetic resonance (EPR) via the stable adduct DMPO-OH. In advanced oxidation processes (AOPs) based on Fenton reaction, proper DMPO concentration is critical to avoid adduct degradation and spurious signals.
Experimental Protocol: Fenton reactions were conducted with H2O2 (1-100 mM) and Fe²⁺ (0.1-10 mM) at a fixed 10:1 ratio, pH 2.8. DMPO concentrations ranged from 5 to 500 mM. EPR spectra were recorded over 60 min. UV-Vis (520 nm) monitored diamagnetic products. Catalase and Na2SO3 were tested as H2O2 quenchers.
Performance Evaluation: At [DMPO]:[H2O2] > 16.8 and [DMPO]:[Fe²⁺] > 168, the DMPO-OH quartet (aN = aβH = 1.50 mT) remained stable for >60 min. Lower ratios caused rapid signal decay and formation of an additional triplet (aN = 1.51 mT), attributed to a paramagnetic dimer from tautomer oxidation. UV-Vis confirmed buildup of EPR-silent tautomers HDMPN/HDMPO. Na2SO3 reacted with DMPO-OH to form an interfering DMPO-SO3 adduct, while catalase quenched H2O2 without side reactions.
Conclusion: DMPO reliably quantifies ·OH in AOPs when used at sufficiently high excess (≥20× H2O2, ≥200× Fe²⁺). Catalase is recommended as a quencher.

5,5-Dimethyl-1-pyrroline N-Oxide as a Spin-Trap for Sulfur Oxide Radicals: A Combined EPR and DFT Study

Zamora, Pedro L., et al. The Journal of Physical Chemistry A 116.26 (2012): 7210-7218.

5,5-Dimethyl-1-pyrroline N-oxide (DMPO) is a nitrone spin-trap used to detect short-lived radicals by electron paramagnetic resonance (EPR). This study employed DMPO to trap sulfur trioxide (SO3·-) and sulfate (SO4·-) radicals generated photochemically, with density functional theory (DFT) calculations to identify adduct structures and formation pathways.
Experimental Protocol: SO3·- was generated by UV irradiation (254 nm) of 100 mM Na2SO3 with 2% H2O2 in PBS; SO4·- from 100 mM (NH4)2S2O8. DMPO concentration was 100 mM. EPR spectra were recorded at room temperature. DFT calculations (PCM/B3LYP/6-31+G**//B3LYP/6-31G*) predicted isotropic hyperfine coupling constants (hfcc), reaction free energies, and pKa values.
Performance Evaluation: DMPO trapped SO3·- to give an S-centered adduct (DMPO-SO3H, a^N = 14.5 G, a^βH= 16.1 G), consistent with DFT predictions (a^N = 12.2, a^βH = 14.1). SO4·- formed an O-centered adduct (DMPO-OSO3H, a^N = 13.7, a^βH = 10.5, 1.5 G). No adduct was detected for SO2·-. Both adducts decomposed to DMPO-OH over time. Isotopic labeling (H₂¹⁷O) confirmed hydrolysis at Cα of the O-centered adduct. Calculated free energies favored radical addition over the Forrester-Hepburn nucleophilic pathway.
Conclusion: DMPO reliably distinguishes S- vs. O-centered sulfur oxide radicals. DFT-predicted hfcc and thermodynamics support experimental assignments, validating DMPO for mechanistic studies in sulfur radical chemistry.

Custom Q&A

What is the molecular formula of 5,5-Dimethyl-1-pyrroline N-oxide?

The molecular formula is C6H11NO.

What is the molecular weight of 5,5-Dimethyl-1-pyrroline N-oxide?

The molecular weight is 113.16 g/mol.

What are the synonyms of 5,5-Dimethyl-1-pyrroline N-oxide?

The synonyms are 3317-61-1, DMPO, 5,5-Dimethyl-1-pyrroline-N-oxide, 5,5-Dimethyl-1-pyrroline-1-oxide.

What is the role of 5,5-Dimethyl-1-pyrroline N-oxide?

It has a role as a neuroprotective agent and a spin trapping reagent.

What is the IUPAC name of 5,5-Dimethyl-1-pyrroline N-oxide?

The IUPAC name is 2,2-dimethyl-1-oxido-3,4-dihydropyrrol-1-ium.

What is the InChI of 5,5-Dimethyl-1-pyrroline N-oxide?

The InChI is InChI=1S/C6H11NO/c1-6(2)4-3-5-7(6)8/h5H,3-4H2,1-2H3.

What is the InChIKey of 5,5-Dimethyl-1-pyrroline N-oxide?

The InChIKey is VCUVETGKTILCLC-UHFFFAOYSA-N.

What is the CAS number of 5,5-Dimethyl-1-pyrroline N-oxide?

The CAS number is 3317-61-1.

What is the physical description of 5,5-Dimethyl-1-pyrroline N-oxide?

It is described as a white solid or a light yellow, hygroscopic solidified mass or fragments with a melting point of 25-29°C.

What is the topological polar surface area of 5,5-Dimethyl-1-pyrroline N-oxide?

The topological polar surface area is 28.8Ų.

Synthetic Use

Upstream Synthesis Route 1

• 57620-49-2

• 3317-61-1

Reference: [1] Journal of Organic Chemistry, 1986, vol. 51, # 22, p. 4298 - 4300
[2] Journal of Chemical Research, Miniprint, 1995, # 8, p. 1853 - 1864
[3] Chemical and Pharmaceutical Bulletin, 1981, vol. 29, # 1, p. 25 - 28
[4] Synthetic Communications, 1986, vol. 16, p. 1377 - 1386

Upstream Synthesis Route 2

• 57620-56-1

• 3317-61-1

Reference: [1] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1995, # 4, p. 491 - 500

Upstream Synthesis Route 3

• 55482-04-7

• 3317-61-1

Reference: [1] Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999), 1995, # 2, p. 295 - 298

Downstream Synthesis Route 1

• 3317-61-1
• 78-67-1

• 130406-23-4

Reference: [1]Journal of the American Chemical Society,1990,vol. 112,p. 8279 - 8284

Downstream Synthesis Route 2

• 3317-61-1
• 1001-56-5

• 108817-85-2

Reference: [1]Journal of Organic Chemistry,1987,vol. 52,p. 3909 - 3917

Downstream Synthesis Route 3

• 3317-61-1
• 1712-36-3

• 108817-86-3

Reference: [1]Journal of Organic Chemistry,1987,vol. 52,p. 3909 - 3917

* For details of the synthesis route, please refer to the original source to ensure accuracy.