Dimethylacetamide (DMAc or DMA) is the organic compound with the formula CH<sub>3</sub>C(O)N(CH<sub>3</sub>)<sub>2</sub>. This colorless, water-miscible, high-boiling liquid is commonly used as a polar solvent in organic synthesis. DMA is miscible with most other solvents, although it is poorly soluble in aliphatic hydrocarbons.

Synthesis and production

DMA is prepared commercially by the reaction of dimethylamine with acetic anhydride or acetic acid. Dehydration of the salt of dimethylamine and acetic acid also furnishes this compound:

: CH<sub>3</sub>CO<sub>2</sub>H·HN(CH<sub>3</sub>)<sub>2</sub> → H<sub>2</sub>O + CH<sub>3</sub>CON(CH<sub>3</sub>)<sub>2</sub>

Dimethylacetamide can also be produced by the reaction of dimethylamine with methyl acetate.

: 550px|frameless|One route to dimethylacetamide

The separation and purification of the product is carried out by multistage distillation in rectification columns. DMA is obtained with essentially quantitive (99%) yield referred to methyl acetate.

Dimethylacetamide is commonly used as a solvent for fibers (e.g., polyacrylonitrile, spandex) or in the adhesive industry. At high doses (400&nbsp;mg/kg body mass daily), dimethylacetamide causes effects on the central nervous system (e.g. depression, hallucinations and delusion).

Dimethylacetamide may be incompatible with polycarbonate or ABS. Devices (e.g. syringes) that contain polycarbonate or ABS can dissolve when coming into contact with dimethylacetamide.

Regulation

In 2011, dimethylacetamide was identified in the EU as a Substance of very high concern (SVHC) because of its reproductive toxicity. In 2014, the European Commission has started an investigation to restrict the use of dimethylacetamide in the EU according to REACH.

In 2015, the CNESST (Committee on Standards, Equity, Health and Safety at Work in Quebec) has adopted a tightened classification of dimethylacetamide:

{| class="wikitable"

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! Description !! Category !! GHS hazard statement

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| Reproductive toxicity || 2|| Suspected of damaging fertility or the unborn child (H361)

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| Specific target organ toxicity – repeated exposure || 2|| May cause damage to organs through prolonged or repeated exposure (H373)

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| Serious eye damage/eye irritation || 2|| Causes serious eye irritation (H319)

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| Acute toxicity – inhalation || 3|| Toxic if inhaled (H331)

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| Specific target organ toxicity – single exposure – narcotic effects || 3|| May cause drowsiness or dizziness (H336)

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| Flammable liquid || 4|| Combustible liquid (H227)

|}

See also

  • N-Methylacetamide
  • Dimethylformamide

References

  • Process flowsheet of Dimethylacetamide Production from Acetic Acid and Dimethylamine
  • CDC – NIOSH Pocket Guide to Chemical Hazards