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 °F
Related compounds
Related compounds	Methyl propiolate, Hexafluoro-2-butyne, Acetylene
Y acetylenedicarboxylate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Dimethyl acetylenedicarboxylate (DMAD) is the organic compound with the formula CH₃O₂CC₂CO₂CH₃. This ester, which exists as a liquid at room temperature, is highly electrophilic. As such, DMAD, as it is commonly called in the laboratory, is widely employed as a dienophile in cycloaddition reactions, such as the Diels-Alder reaction. It is also a potent Michael acceptor.^[1][2]

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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0010 ; Coll. Vol. 2: 10 
5. ^ Huntress, E. H. Lesslie, T. E.; Bornstein, J., "Dimethyl Acetylenedicarboxylate", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0329 ; Coll. Vol. 4: 329