Dimethylformamide


Dimethylformamide is an organic compound with the formula 2NCH. Commonly abbreviated as DMF, this colourless liquid is miscible with water and the majority of organic liquids. DMF is a common solvent for chemical reactions. Dimethylformamide is odorless, but technical-grade or degraded samples often have a fishy smell due to impurity of dimethylamine. Dimethylamine degradation impurities can be removed by sparging degraded samples with an inert gas such as argon or by sonicating the samples under reduced pressure. As its name indicates, it is a derivative of formamide, the amide of formic acid. DMF is a polar aprotic solvent with a high boiling point. It facilitates reactions that follow polar mechanisms, such as SN2 reactions.

Structure and properties

As for most amides, the spectroscopic evidence indicates partial double bond character for the C-N and C-O bonds. Thus, the infrared spectrum shows a C=O stretching frequency at only 1675 cm−1, whereas a ketone would absorb near 1700 cm−1.
DMF is a classic example of a fluxional molecule.
The ambient temperature 1H NMR spectrum shows two methyl signals, indicative of hindered rotation about the C-N bond. At temperatures near 100 °C, the 500 MHz NMR spectrum of this compound shows only one signal for the methyl groups.
DMF is miscible with water. The vapour pressure at 20 °C is 3.5 hPa. A Henry's law constant of 7.47 × 10−5 hPa m3 mol−1 can be deduced from an experimentally determined equilibrium constant at 25 °C. The partition coefficient log POW is measured to −0.85. Since the density of DMF is similar to that of water, significant flotation or stratification in surface waters in case of accidental losses is not expected.

Reactions

DMF is hydrolyzed by strong acids and bases, especially at elevated temperatures. With sodium hydroxide, DMF converts to formate and dimethylamine. DMF undergoes decarbonylation near its boiling point to give dimethylamine. Distillation is therefore conducted under reduced pressure at lower temperatures.
In one of its main uses in organic synthesis, DMF was a reagent in the Vilsmeier–Haack reaction, which is used to formylate aromatic compounds. The process involves initial conversion of DMF to a chloroiminium ion, +, known as a Vilsmeier reagent, which attacks arenes.
Organolithium compounds react with DMF to give, after hydrolysis, aldehydes.

Production

DMF was first prepared in 1893 by the French chemist Albert Verley, by distilling a mixture of dimethylamine hydrochloride and potassium formate.
DMF is prepared by combining methyl formate and dimethylamine or by reaction of dimethylamine with carbon monoxide.
Although currently impractical, DMF can be prepared from supercritical carbon dioxide using ruthenium-based catalysts.

Applications

The primary use of DMF is as a solvent with low evaporation rate. DMF is used in the production of acrylic fibers and plastics. It is also used as a solvent in peptide coupling for pharmaceuticals, in the development and production of pesticides, and in the manufacture of adhesives, synthetic leathers, fibers, films, and surface coatings.
As a cheap and common reagent, DMF has many uses in a research laboratory.
Reactions including the use of sodium hydride in DMF as a solvent are somewhat hazardous; exothermic decompositions have been reported at temperatures as low as 26 °C. On a laboratory scale any thermal runaway is quickly noticed and brought under control with an ice bath and this remains a popular combination of reagents. On a pilot plant scale, on the other hand, several accidents have been reported.
On the 20 of June 2018, the Danish Environmental Protective Agency published an article about the DMF's use in squishies. The density of the compound in the toy resulted in all squishes being removed from the Danish market. All squishies were recommended to be thrown out as household waste.

Toxicity

The acute LD50 is 2.2–7.55 g/kg. Hazards of DMF have been examined.