Dimethyl acetylenedicarboxylate

Dimethyl acetylenedicarboxylate
IUPAC name Dimethyl but-2-ynedioate
Other names DMAD Acetylenedicarboxylic acid dimethyl ester
Identifiers
CAS number	762-42-5 Y
ChemSpider	12440 Y
RTECS number	ES0175000
Jmol-3D images	Image 1
SMILES COC(=O)C#CC(=O)OC
InChI InChI=1S/C6H6O4/c1-9-5(7)3-4-6(8)10-2/h1-2H3 Y Key: VHILMKFSCRWWIJ-UHFFFAOYSA-N Y InChI=1/C6H6O4/c1-9-5(7)3-4-6(8)10-2/h1-2H3 Key: VHILMKFSCRWWIJ-UHFFFAOYAX
Properties
Molecular formula	C6H6O4
Molar mass	142.11 g/mol
Appearance	Colorless liquid
Density	1.1564 g/cm³
Melting point	c
Boiling point	195–198 °C 96–98° at 8 mm Hg
Solubility in water	Insoluble
Solubility in other solvents	Soluble in most organic solvents
Refractive index (nD)	1.447
Structure
Dipole moment	0 D
Hazards
R-phrases	R34
S-phrases	S23 S26 S27 S36/37/39 S45
Main hazards	Toxic gas
Flash point	187 °C; 369 °F; 460 K
Related compounds
Related compounds	Methyl propiolate, Hexafluoro-2-butyne, Acetylene
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

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.

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][4] The acid is then esterified with methanol and sulfuric acid as a catalyst:^[5]

Safety

DMAD is a lachrymator and a vesicant.

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. doi:10.1002/047084289.
2. ↑ Sahoo, Manoj (2007). "Dimethyl Acetylene Dicarboxylate". Synlett 2007: 2142. doi:10.1055/s-2007-984894. 
3. ↑ Bandrowski, E. (1877). "Ueber Acetylendicarbonsäure". Berichte der deutschen chemischen Gesellschaft 10: 838. doi:10.1002/cber.187701001231. 
4. ↑ Abbott, T. W.; Arnold, R. T.; Thompson, R. B., "Acetylenedicarboxylic acid", Org. Synth. ; Coll. Vol. 2: 10 
5. ↑ Huntress, E. H. Lesslie, T. E.; Bornstein, J., "Dimethyl Acetylenedicarboxylate", Org. Synth. ; Coll. Vol. 4: 329