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Short answer: the boiling point of N,N-dimethylformamide (DMF) at normal atmospheric pressure is 153 °C (the CRC Handbook value is 152.8 °C). Under reduced pressure it boils far lower: the Merck Index lists 76 °C at 39 mmHg and 25 °C at 3.7 mmHg. This page is a laboratory solvent datasheet that ties each number to its source and explains what it means at the bench. It is general reference information, not a safety data sheet or medical advice.
Definition and scope
DMF (CAS 68-12-2, formula HCON(CH3)2, molecular mass 73.1) is a colourless-to-yellow liquid with a characteristic odour, according to ILO-WHO International Chemical Safety Card 0457 (April 2014 edition, read 2026-11-07). It is miscible with water, which is why it is both a useful polar solvent and a difficult one to remove. The figures below come from that card and from the experimental-property records compiled in PubChem compound 6228 (read 2026-11-07).
DMF physical properties reference card
| Property | Value | Source and conditions |
|---|---|---|
| Boiling point | 153 °C | ICSC 0457; also PhysProp via PubChem |
| Boiling point | 152.8 °C | CRC Handbook, 94th edition, via PubChem |
| Melting (freezing) point | -61 °C (ICSC); -60.3 °C (CRC) | ICSC 0457; CRC via PubChem |
| Density | 0.9455 g/cm3 | 25 °C, PubChem; ICSC gives relative density 0.95 (water = 1) |
| Vapour pressure | 0.49 kPa; 3.87 mmHg | 25 °C; ICSC 0457 and Daubert and Danner (1985) via PubChem |
| Flash point | 58 °C closed cup; 67 °C open cup | ICSC 0457; Patty’s via PubChem |
| Auto-ignition temperature | 440 °C | ICSC 0457 |
| Viscosity | 0.802 cP at 25 °C; 0.85 mm2/s at 25 °C | Kirk-Othmer (2013) via PubChem; ICSC 0457 (kinematic) |
| Refractive index | 1.42083 (25 °C, D line); 1.4305 (20 °C, D line) | Merck Index; CRC via PubChem |
| Water solubility | Miscible | ICSC 0457 |
| Octanol/water partition (log Pow) | -0.87 | ICSC 0457 |
| pKa of the conjugate acid | -0.30 | Perrin (1972, IUPAC) via PubChem |
| Vapour density (air = 1) | 2.5 | ICSC 0457 |
Sources differ in the last digit for several properties (152.8 versus 153 °C; -60.3 versus -61 °C). The differences reflect rounding and different compilations, not different chemistry, so quote the source alongside the number in a methods section.
What the boiling point means at the bench
DMF boiling point under vacuum
The Merck Index pairs, reported in PubChem, are 76 °C at 39 mmHg and 25 °C at 3.7 mmHg. These are the only reduced-pressure values this page states; read a pressure-temperature chart or nomograph for other pressures rather than interpolating. Editorial interpretation: because the atmospheric boiling point is 153 °C, evaporating DMF on a rotary evaporator generally calls for a good vacuum source rather than a bath hot enough to boil it at ambient pressure.
Flash point and vapour pressure
The closed-cup flash point (58 °C) sits about 95 °C below the boiling point. ICSC 0457 states that above 58 °C explosive vapour/air mixtures may form and advises a closed system and ventilation above that temperature. A heated bath for DMF can therefore pass the flash point long before the liquid boils. The vapour is 2.5 times denser than air (ICSC), so it can collect at low levels.
Miscibility with water
Complete miscibility with water (ICSC) means DMF does not separate into its own layer in an aqueous extraction. The negative log Pow (-0.87) points the same way: DMF favours the aqueous phase over octanol.
DMF density, viscosity, refractive index and pKa
At 25 °C DMF is slightly less dense than water (0.9455 g/cm3) and has a viscosity of 0.802 cP, close to that of water (PubChem). Its refractive index is 1.42083 at 25 °C. The pKa of -0.30 is for the conjugate acid, meaning DMF itself is an extremely weak base.
DMF vs DMSO: boiling point of DMSO
The boiling point of dimethyl sulphoxide (DMSO) is 189 °C, per ICSC 0459 (November 2023 edition, read 2026-11-07).
| Property (ICSC) | DMF | DMSO |
|---|---|---|
| Boiling point | 153 °C | 189 °C |
| Melting point | -61 °C | 18.5 °C |
| Flash point (closed cup) | 58 °C | 87 °C |
| Auto-ignition temperature | 440 °C | 215 °C |
| Relative density (water = 1) | 0.95 | 1.1 |
| Water solubility | Miscible | Miscible |
DMSO melts at 18.5 °C, so it can be solid at cool room temperature, whereas DMF stays liquid well below freezing.
Hazards and reactivity
How does DMF smell?
ICSC 0457 describes DMF as a liquid with a characteristic odour. The card gives no further description, and odour is not a safe indicator of exposure.
How does DMF react?
ICSC 0457 lists these chemical dangers: it decomposes on heating, producing toxic fumes including nitrogen oxides; it reacts violently with strong oxidants, halogens, halogenated hydrocarbons and nitrates; and it attacks some plastics and rubber. The card’s GHS classification includes flammable liquid and vapour, harmful if inhaled, serious eye irritation, may damage fertility or the unborn child, and may cause damage to liver. It also notes that DMF may be absorbed through the skin. For exposure limits, see Permissible Exposure Limits vs TLVs and RELs; for a related amide solvent see Formamide: Uses, Hazards, CAS Number and Storage in the Lab.
Common misunderstandings
- “DMF boils at 153 °C, so it is safe below that.” The flash point is 58 °C, and ICSC advises a closed system and ventilation above it.
- “Freezing point and melting point are different numbers.” For a pure substance they describe the same transition; the -61 versus -60.3 °C difference is between sources.
- “A single boiling point applies at any altitude or vacuum.” 153 °C is the normal-pressure value; the Merck pairs above show how far it falls at reduced pressure.
FAQ
What is the boiling point of DMF?
153 °C at normal atmospheric pressure (ICSC 0457); 152.8 °C in the CRC Handbook, 94th edition.
What is the freezing point of DMF?
-61 °C per ICSC 0457, or -60.3 °C per the CRC Handbook.
What is the vapour pressure of DMF?
0.49 kPa at 25 °C (ICSC 0457); PubChem lists 3.87 mmHg at 25 °C from Daubert and Danner (1985).
Is DMF miscible with water?
Yes. ICSC 0457 lists its solubility in water as miscible.
What is the boiling point of DMSO?
189 °C (ICSC 0459).
How is DMF dried?
The sources read for this page give physical data and hazards, not drying procedures. Water content in solvents is commonly measured by Karl Fischer titration; see Karl Fischer Titrator: Electrodes, Methanol, Volumetric vs Coulometric. For solvent choice more broadly, see Green Chemistry in the Lab.
Sources
- ILO-WHO, International Chemical Safety Card 0457, N,N-Dimethylformamide (April 2014): inchem.org, read 2026-11-07.
- ILO-WHO, International Chemical Safety Card 0459, Dimethyl sulphoxide (November 2023): inchem.org, read 2026-11-07.
- National Library of Medicine, PubChem compound 6228, Experimental Properties (cites CRC Handbook 94th ed., Merck Index, Daubert and Danner 1985, Kirk-Othmer 2013, Perrin 1972, Patty’s): pubchem.ncbi.nlm.nih.gov, read 2026-11-07.
