Dimethyl acetylenedicarboxylate explained

Dimethyl acetylenedicarboxylate (DMAD) is an organic compound with the formula CH₃O₂CC₂CO₂CH₃. It is a di-ester in which the ester groups are conjugated with a C-C triple bond. As such, the molecule is highly electrophilic, and is widely employed as a dienophile in cycloaddition reactions, such as the Diels-Alder reaction. It is also a potent Michael acceptor.^{[1] [2]} This compound exists as a colorless liquid at room temperature. This compound was used in the preparation of nedocromil.

Preparation

Although inexpensively available, DMAD is prepared today as it was originally. Maleic acid is brominated and the resulting dibromosuccinic acid is dehydrohalogenated with potassium hydroxide yielding acetylenedicarboxylic acid.^[3] The acid is then esterified with methanol and sulfuric acid as a catalyst:

Safety

DMAD is a lachrymator and a vesicant.

Notes and References

1. Stelmach, J. E.; Winkler, J. D. "Dimethyl Acetylenedicarboxylate"in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. .
2. Sahoo . Manoj . Dimethyl Acetylene Dicarboxylate . Synlett . 2007 . 13 . 2142–2143 . 2007 . 10.1055/s-2007-984894. free .
3. Bandrowski . E. . Ueber Acetylendicarbonsäure . Berichte der Deutschen Chemischen Gesellschaft . 10 . 838–842 . 1877 . 10.1002/cber.187701001231.