Dimethyl Sulfoxide-d₆ (DMSO-d₆): The Heavyweight Solvent for Challenging NMR Samples

When it comes to NMR spectroscopy, solvent choice is critical—not just for solubility, but for spectrum clarity and accuracy. Among deuterated solvents, DMSO-d₆ (Dimethyl sulfoxide-d₆) stands out for its unique solubility range, thermal stability, and ability to handle polar and high-melting compounds.

In this post, we’ll explore what DMSO-d₆ is, how it’s used in spectroscopy and research, and what precautions are necessary when working with it.

What Is DMSO-d₆?

DMSO-d₆ is the deuterated form of dimethyl sulfoxide (DMSO), where all six hydrogen atoms in the methyl groups are replaced with deuterium (²H or D). This significantly reduces its signal in proton NMR, making it ideal for analyzing organic compounds without solvent interference.

• Chemical Formula: (CD₃)₂SO

• Molecular Weight: 84.17 g/mol

• Appearance: Colorless, hygroscopic liquid

• Boiling Point: ~189°C

• Melting Point: ~18.5°C

• Density: ~1.19 g/cm³ at 20°C

• Deuterium Content: ≥ 99.9% D (typical for spectroscopy-grade DMSO-d₆)

Why Use DMSO-d₆ in NMR Spectroscopy?

DMSO-d₆ is especially useful in NMR when dealing with compounds that:

• Have low solubility in less polar solvents like CDCl₃

• Are highly polar, ionic, or hydrogen-bonded

• Need to be analyzed at elevated temperatures

Benefits in NMR:

• Minimal interference in proton spectra due to deuteration

• Excellent solvent for polar and ionic compounds (e.g., salts, peptides, sugars)

• Stable under a wide range of temperatures

• Often used in ¹H, ¹³C, and multinuclear NMR (e.g., ¹⁹F, ³¹P)

Residual Peaks in NMR

Even deuterated solvents contain trace amounts of non-deuterated material. For DMSO-d₆:

Spectrum Type	Residual Peak Position
¹H NMR	~2.50 ppm (singlet)
¹³C NMR	~39.5 ppm (septet due to ¹³C–²H coupling)

 

These peaks serve as convenient internal standards for chemical shift referencing.

Solubility and Compatibility

DMSO-d₆ is miscible with water, alcohols, acetonitrile, and many organic and inorganic salts. It's an ideal choice for:

• Biomolecules (e.g., peptides, nucleotides)

• Ionic compounds

• Hydrogen bonding studies

• Hydrolytically sensitive compounds, if moisture is carefully excluded

How Is DMSO-d₆ Made?

DMSO-d₆ is typically synthesized via:

1. Exchange of methyl protons with deuterium using D₂O in the presence of a base or catalyst.

2. Subsequent distillation and purification to reach the required deuterium enrichment for NMR use.

The high cost reflects this energy-intensive and careful preparation.

Handling and Storage

Though generally safe and non-volatile, DMSO-d₆ requires some precautions:

Storage Tips

• Store in airtight, amber bottles

• DMSO-d₆ is hygroscopic—it absorbs water from air, which can degrade NMR performance

• Desiccators or dry boxes are recommended for long-term storage

Handling Tips

• Always use dry pipettes or syringes to prevent contamination

• Avoid skin contact—DMSO can carry small molecules through the skin, including toxins or drugs

Safety Notes

• Low toxicity but unusual transdermal properties

• May cause skin irritation or interact with other substances if absorbed

• Use gloves and lab coat, especially if working with bioactive or hazardous samples

DMSO-d₆ vs. Other Deuterated Solvents

Property	DMSO-d₆	CDCl₃	Acetone-d₆	D₂O
Polarity	High	Low	Moderate	Very high
Boiling Point	189°C	61°C	56°C	100°C
Hydrogen Bonding	Excellent	Poor	Moderate	Excellent
Water Solubility	Miscible	Slight	Miscible	N/A (it's water)
Best for	Polar compounds	Non-polar organics	Keto compounds	Ionic/aqueous

 

Applications Beyond NMR

While DMSO-d₆ is mainly used for spectroscopy, its non-deuterated version (DMSO) is used in:

• Cryopreservation

• Drug delivery systems

• Polymer science

• Electrochemistry and battery research

Conclusion

DMSO-d₆ is the go-to deuterated solvent when standard NMR solvents like CDCl₃ or acetone-d₆ fall short—especially for polar, high-melting, or ionic compounds. Its high boiling point, broad solubility, and clean spectral properties make it a must-have for complex NMR work.

Just be mindful of its hygroscopic nature and transdermal effects, and it will serve as a reliable ally in both academic and industrial research.

Contact Us

Phone : +49 1512 4714765 ( Germany )
Phone : +1 (702) 381-3042 ( USA )
Email : [email protected]
Address : Cunostraße 56, 14193 Berlin. Germany
Address : 7373 Rowlett Park Dr, Tampa, FL 33610, United States.