Dimethylformamide
N,N-Dimethylformamide (DMF), with the chemical formula C₃H₇NO and CAS number 68-12-2, is a versatile organic compound commonly used as an aprotic polar solvent in industrial and laboratory applications.[1][2] It appears as a clear, colorless to pale yellow liquid with a faint fishy or amine-like odor, a molecular weight of 73.09 g/mol, a boiling point of 153 °C, a melting point of -61 °C, a density of 0.944 g/mL at 20 °C, and complete miscibility with water and most organic solvents.[1][3][2] DMF has a flash point of 58 °C (136 °F), making it flammable, with vapors heavier than air that can travel to ignition sources and flash back.[4][3] As one of the most widely used industrial solvents, DMF plays a key role in the manufacture of synthetic fibers (such as acrylic and polyurethane), films, surface coatings, and adhesives, where it dissolves vinyl-based polymers and facilitates processing.[5][6] It is also employed in organic synthesis as a reaction medium, in peptide and pharmaceutical production, electrolytic processes, petroleum refining, and as a component in paint removers and cleaning agents.[6][7] Industrially, DMF is primarily synthesized through the carbonylation of dimethylamine with carbon monoxide in the presence of a catalyst, such as sodium methoxide in methanol, yielding high-purity product on a large scale.[8] Despite its utility, DMF poses significant health and safety risks; it is toxic by inhalation, dermal absorption, and ingestion, acting as a potent liver toxin that can cause acute hepatic damage, abdominal pain, and nausea upon short-term exposure.[1][7] Chronic exposure is associated with reproductive toxicity, including birth defects and developmental issues, leading to its classification as a Category 1B reproductive toxicant, as well as potential liver and kidney damage.[1][6] Environmentally, DMF is persistent in water and soil, with moderate biodegradation, and its release can contribute to aquatic toxicity, prompting regulatory limits in wastewater discharges.[5]Molecular Structure and Properties
Chemical Structure
Dimethylformamide, systematically named N,N-dimethylformamide, has the molecular formula C₃H₇NO and the condensed structural formula (CH₃)₂NCHO. This structure consists of an amide functional group where the nitrogen atom is bonded to two methyl groups and a formyl moiety (–CHO), distinguishing it from simpler formamides such as formamide (HCONH₂) or N-methylformamide (HCONHCH₃). The IUPAC nomenclature emphasizes the N,N-substitution to highlight its specific isomeric form among substituted formamides, as the two methyl groups on nitrogen prevent tautomerism or other positional isomerism typical in less substituted analogs. The amide group in dimethylformamide adopts a planar configuration due to resonance delocalization between the carbonyl π-bond and the nitrogen lone pair, resulting in partial double-bond character for the C–N linkage and a shortened C=O bond. This resonance stabilization restricts rotation about the C–N bond, with a measured rotational barrier of approximately 88 kJ/mol, contributing to the molecule's overall planarity around the amide core. Spectroscopic studies, including X-ray crystallography and microwave spectroscopy, confirm key bond lengths: the C=O bond measures about 1.20 Å, indicative of its partial single-bond influence from resonance, while the C–N bond is elongated to roughly 1.35 Å compared to a typical single C–N bond (1.47 Å), reflecting the double-bond character.[9][10]Physical and Thermodynamic Properties
Dimethylformamide (DMF) is a colorless, hygroscopic liquid at room temperature, exhibiting a faint fishy odor characteristic of low-molecular-weight amides.[3] Its molecular weight is 73.09 g/mol.[5] DMF demonstrates a wide liquid range, with a melting point of -61 °C and a boiling point of 153 °C at standard pressure.[11] The density is 0.944 g/cm³ at 25 °C, and the refractive index is 1.430 at 20 °C.[12] These properties render DMF stable under ambient conditions but prone to slow hydrolysis in the presence of moisture.| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 153 °C | 760 mmHg | https://macro.lsu.edu/howto/solvents/dmf.htm |
| Melting point | -61 °C | - | https://www.sigmaaldrich.com/IQ/en/product/mm/103034 |
| Density | 0.944 g/cm³ | 25 °C | https://www.sigmaaldrich.com/US/en/product/sial/227056 |
| Refractive index | 1.430 | 20 °C | https://www.sigmaaldrich.com/US/en/product/mm/102375 |
| Flash point | 58 °C | Closed cup | https://www.inchem.org/documents/icsc/icsc/eics0457.htm |