DMF Boiling Point, Density & Key Physical Properties
A Complete Reference Guide to Dimethylformamide Physical & Chemical Properties
📋 Table of Contents
- Quick-Reference Property Summary
- Boiling Point - Data, Pressure Dependence & Process Implications
- Density & Specific Gravity
- Melting Point & Flash Point
- Vapor Pressure vs. Temperature
- Viscosity & Surface Tension
- Polarity, Dielectric Constant & Refractive Index
- Thermal Properties: Specific Heat, Latent Heat & Decomposition
- DMF vs. Common Solvents - Side-by-Side Comparison
- Frequently Asked Questions
- Request a Quote from Sinolook Chemical
1 📊 Quick-Reference Property Summary
The table below consolidates the most frequently referenced physical and chemical properties of N,N-Dimethylformamide (DMF, CAS 68-12-2). Values are given at 25 °C / 1 atm unless otherwise specified.
| Property | Value | Unit | Condition |
|---|---|---|---|
| Boiling Point | 153 | °C | 1 atm |
| Melting Point | −61 | °C | 1 atm |
| Flash Point | 58 | °C (closed cup) | Pensky-Martens |
| Density | 0.944 | g/mL | 25 °C |
| Molecular Weight | 73.09 | g/mol | - |
| Vapor Pressure | 3.7 | mmHg | 25 °C |
| Viscosity | 0.92 | cP (mPa·s) | 25 °C |
| Surface Tension | 35.2 | mN/m | 25 °C |
| Dielectric Constant (ε) | 37.1 | - | 25 °C |
| Refractive Index (nD) | 1.4305 | - | 20 °C |
| Specific Heat (Cp) | 1.50 | J/(g·K) | 25 °C |
| Latent Heat of Vaporization | 46.9 | kJ/mol | at bp |
| Dipole Moment | 3.82 | D (Debye) | liquid |
| Water Miscibility | Fully miscible | - | all proportions |
| Auto-ignition Temperature | 445 | °C | 1 atm |
2 🌡️ Boiling Point - Data, Pressure Dependence & Process Implications
DMF boils at 153 °C (307 °F) at standard atmospheric pressure (760 mmHg). This relatively high boiling point is a direct consequence of the strong dipole–dipole interactions between DMF molecules, driven by the highly polar amide C=O group (dipole moment ≈ 3.82 D).
Boiling Point Under Reduced Pressure
In industrial solvent recovery and pharmaceutical purification, DMF is typically removed by vacuum distillation to reduce thermal stress on products and minimize decomposition risk. The table below gives approximate boiling points at common reduced pressures.
| Pressure (mmHg) | Boiling Point (°C) | Typical Application |
|---|---|---|
| 760 (1 atm) | 153 | Atmospheric distillation, standard process |
| 100 | ~111 | Mild vacuum stripping from temperature-sensitive polymers |
| 20 | ~76 | Pharmaceutical API drying, rotary evaporator |
| 5 | ~52 | High-vacuum removal from heat-labile compounds |
| 1 | ~27 | Near-ambient vacuum stripping |
✅ Process Advantages of High Boiling Point
- Enables reactions at 100–140 °C without reflux pressure
- Slower evaporation reduces worker exposure during open handling
- Allows prolonged reaction times without solvent loss
- Compatible with high-temperature oven-curing of coatings
💡 Process Challenges to Consider
- Complete removal requires vacuum distillation or long drying cycles
- Forms azeotrope with water (bp ~152 °C at ~25 wt% H₂O) - simple atmospheric distillation cannot fully dry wet DMF
- Higher energy cost for solvent recovery vs. low-bp solvents
3 ⚖️ Density & Specific Gravity
DMF has a density of 0.944 g/mL at 25 °C, making it slightly lighter than water (1.000 g/mL). It is denser than many common organic solvents such as toluene (0.867 g/mL) or ethyl acetate (0.902 g/mL), but lighter than chlorinated solvents like DCM (1.325 g/mL).
Density vs. Temperature
DMF density decreases linearly with rising temperature. Accurate density values are important for tank volume calculations, pump selection, and concentration determinations.
| Temperature (°C) | Density (g/mL) | Specific Gravity (vs H₂O at 4 °C) |
|---|---|---|
| 0 | 0.9730 | 0.973 |
| 20 | 0.9487 | 0.949 |
| 25 | 0.9440 | 0.944 |
| 40 | 0.9286 | 0.929 |
| 60 | 0.9090 | 0.909 |
💡 Engineering Note: When calculating the mass of DMF in a storage tank, always apply the temperature-corrected density. A 1000-litre IBC at 20 °C contains approximately 948.7 kg of DMF, not the 944 kg one would calculate from the 25 °C reference density.
4 🧊🔥 Melting Point & Flash Point
🧊 Melting Point: −61 °C
DMF remains liquid at all commercially relevant temperatures, including cold-climate storage environments. Its melting point of −61 °C (−78 °F) means it will not freeze even in Arctic logistics conditions.
✅ No winterization required for storage or transport. Compatible with standard unheated warehousing in all climates.
🔥 Flash Point: 58 °C (closed cup)
DMF is classified as a flammable liquid, Category 3 under GHS (flash point 23–60 °C range). UN number: 2265. Packing Group: III.
⚠️ Keep away from open flames, sparks and hot surfaces. Use explosion-proof electrical equipment in storage areas.
Flammability Range
| Parameter | Value | Implication |
|---|---|---|
| Flash Point (closed cup) | 58 °C | Vapors ignite above 58 °C if ignition source present |
| Auto-ignition Temperature | 445 °C | Self-ignition risk on very hot surfaces (e.g. pipe lagging) |
| Lower Explosive Limit (LEL) | 2.2 % v/v in air | LEL sensor alarm threshold; confined-space risk |
| Upper Explosive Limit (UEL) | 15.2 % v/v in air | Broad flammable range - monitor closely |
5 💨 Vapor Pressure vs. Temperature
DMF has a low vapor pressure of 3.7 mmHg at 25 °C - much lower than acetone (231 mmHg), ethyl acetate (97 mmHg) or even toluene (29 mmHg). This low volatility is a double-edged property: it limits airborne exposure during normal handling, but also means residual DMF is difficult to remove without heat or vacuum.
| Temperature (°C) | Vapor Pressure (mmHg) | Vapor Pressure (kPa) |
|---|---|---|
| 0 | 0.6 | 0.08 |
| 20 | 2.7 | 0.36 |
| 25 ★ | 3.7 | 0.49 |
| 40 | 8.3 | 1.11 |
| 60 | 20.7 | 2.76 |
| 80 | 46.0 | 6.13 |
⚠️ Occupational Hygiene Note: Even though DMF vapor pressure is low at room temperature, prolonged exposure in poorly ventilated areas can lead to cumulative inhalation and skin absorption. Because DMF is readily absorbed dermally, air monitoring alone is insufficient - glove integrity and skin protection must be enforced simultaneously.
6 🌊 Viscosity & Surface Tension
Dynamic Viscosity vs. Temperature
| Temp (°C) | Viscosity (cP) |
|---|---|
| 0 | 1.38 |
| 20 | 0.92 |
| 25 ★ | 0.86 |
| 40 | 0.65 |
| 60 | 0.48 |
Why Viscosity Matters for Coatings
With a viscosity of only 0.86–0.92 cP at ambient temperature, DMF is among the lower-viscosity high-boiling solvents available. For coatings and ink formulation, this means:
- ✅ Excellent pigment and resin wetting
- ✅ Good flow and leveling on substrate
- ✅ Enables high-solids formulations without excessive viscosity increase
- ✅ Compatible with standard coating application equipment (roll, knife, spray)
🔬 Surface Tension: 35.2 mN/m at 25 °C. Lower than water (72 mN/m) but higher than most hydrocarbons. Good substrate wetting for metal and polymer surfaces without the need for co-solvents or surfactants.
7 🔬 Polarity, Dielectric Constant & Refractive Index
Polarity is the most commercially important property of DMF as a solvent. Its dielectric constant (ε) of 37.1 places it firmly among high-polarity aprotic solvents, well above common solvents like THF (7.6) or toluene (2.4), and close to acetonitrile (36.6).
| Polarity Parameter | DMF Value | What It Means Practically |
|---|---|---|
| Dielectric Constant (ε) | 37.1 | Excellent ability to dissolve ionic compounds and highly polar polymers |
| Dipole Moment | 3.82 D | Strong permanent dipole; dominant intermolecular interaction is dipole-dipole |
| Polarity Index (P') | 6.4 | Snyder polarity scale; useful for HPLC mobile phase selection |
| UV Cutoff | 268 nm | Not suitable as UV-transparent HPLC solvent below 268 nm; use HPLC/GC grade for analytical work |
| Refractive Index (nD²⁰) | 1.4305 | Standard QC identity/purity check by refractometry |
✅ QC Tip: Refractive index measurement is a fast, reliable purity check for incoming DMF batches. Pure DMF has nD²⁰ = 1.4305. Deviation of more than ±0.0005 may indicate water contamination or off-spec material and should trigger further GC or Karl Fischer analysis.
8 🌡️ Thermal Properties: Specific Heat, Latent Heat & Decomposition
Specific Heat (Cp)
1.50 J/g·K
at 25 °C
Latent Heat of Vaporization
46.9 kJ/mol
at boiling point
Decomposition Temp.
> 170 °C
produces DMA + CO
Decomposition & Stability
DMF is thermally stable under normal use conditions. However, above approximately 170 °C, and particularly in the presence of strong acids, strong bases, or Lewis acid catalysts, hydrolysis and decomposition can occur. The primary decomposition products are dimethylamine (DMA) and carbon monoxide (CO), both of which present toxicity and odor concerns.
- ⚠️ Avoid heating DMF with strong mineral acids (HCl, H₂SO₄) without adequate venting
- ⚠️ Contact with concentrated sodium hydroxide accelerates hydrolysis even at moderate temperatures
- ⚠️ Decomposition odor (fishy amine smell) is a warning sign of DMA formation - ventilate immediately
- ✅ Under normal anhydrous storage at ambient temperature, DMF is indefinitely stable
💡 Distillation Safety: Never distil DMF to complete dryness in the presence of strong base or Lewis acid residues. Concentrated decomposition products in the pot can generate toxic CO gas and cause pressure build-up. Always leave a residual heel and monitor pot temperature carefully.
9 ⚗️ DMF vs. Common Solvents - Side-by-Side Comparison
Use this table to evaluate DMF against other frequently used polar aprotic solvents and identify the best fit for your application.
| Solvent | BP (°C) | Density (g/mL) | Dielectric (ε) | Viscosity (cP) | Vapor Pressure (mmHg) | Protic? |
|---|---|---|---|---|---|---|
| DMF ★ | 153 | 0.944 | 37.1 | 0.92 | 3.7 | ❌ Aprotic |
| DMSO | 189 | 1.100 | 46.7 | 2.00 | 0.6 | ❌ Aprotic |
| DMAc (DMAC) | 165 | 0.937 | 37.8 | 0.93 | 1.3 | ❌ Aprotic |
| NMP | 202 | 1.028 | 32.2 | 1.67 | 0.3 | ❌ Aprotic |
| Acetonitrile (MeCN) | 82 | 0.786 | 36.6 | 0.37 | 89 | ❌ Aprotic |
| THF | 66 | 0.889 | 7.6 | 0.48 | 162 | ❌ Aprotic |
| Methanol | 65 | 0.791 | 33.0 | 0.54 | 127 | ✅ Protic |
💡 Key Insight: DMF offers the best combination of high dielectric constant, low viscosity, and moderate boiling point among polar aprotic solvents. DMSO has a higher dielectric constant but is far more viscous and harder to remove. NMP is less toxic than DMF but also harder to remove (bp 202 °C). DMAc is the closest substitute in terms of properties.
10 ❓ Frequently Asked Questions
Q1 · What is the boiling point of DMF?
DMF boils at 153 °C (307 °F) at atmospheric pressure (760 mmHg). Under vacuum it boils at lower temperatures: approximately 76 °C at 20 mmHg, useful for pharmaceutical residual solvent removal without thermal degradation.
Q2 · What is the density of DMF in g/mL?
The density of DMF is 0.944 g/mL at 25 °C, or approximately 0.949 g/mL at 20 °C. It is lighter than water (1.000 g/mL) and will float on water if spilled - relevant for spill containment design.
Q3 · What is the flash point of DMF?
The flash point of DMF is 58 °C (136 °F) by closed-cup method (Pensky-Martens). This classifies DMF as a GHS Category 3 Flammable Liquid. It must be stored and handled away from open flames, spark sources, and hot surfaces.
Q4 · Is DMF heavier or lighter than water?
DMF is lighter than water, with a specific gravity of approximately 0.944 at 25 °C (water = 1.000). However, DMF is fully miscible with water in all proportions, so it does not form a separate layer - instead it blends uniformly with water.
Q5 · What is the vapor pressure of DMF at room temperature?
At 25 °C, DMF has a vapor pressure of 3.7 mmHg (0.49 kPa). This is low compared to most common organic solvents, which means DMF evaporates slowly at room temperature. However, this low volatility does not eliminate inhalation risk in enclosed or poorly ventilated spaces.
Q6 · Does DMF have a freezing / melting point issue in cold climates?
No. DMF melts at −61 °C (−78 °F), so it remains liquid in all normal storage and transport conditions worldwide. No heated storage or winterization is required, even in northern European or North American winter environments.
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