Dimethyl acetylenedicarboxylate

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.

Dimethyl acetylenedicarboxylate

Chemical structure of DMADuak
Ball-and-stick model
Names
Preferred IUPAC name Dimethyl but-2-ynedioate
Other names DMAD Acetylenedicarboxylic acid dimethyl ester
Identifiers
CAS Number	762-42-5 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3248452
ChemSpider	12440 Y
ECHA InfoCard	100.010.999
EC Number	212-098-4
PubChem CID	12980
RTECS number	ES0175000
UNII	7HZA2PL15F
CompTox Dashboard (EPA)	DTXSID0061088
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
SMILES COC(=O)C#CC(=O)OC
Properties
Chemical formula	C6H6O4
Molar mass	142.11 g/mol
Appearance	Colorless liquid
Density	1.1564 g/cm3
Melting point	−18 °C (0 °F; 255 K)
Boiling point	195 to 198 °C (383 to 388 °F; 468 to 471 K) (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
Occupational safety and health (OHS/OSH):
Main hazards	Toxic
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H314
Precautionary statements	P260, P264, P270, P280, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P363, P405, P501
Flash point	187 °C (369 °F; 460 K)
Related compounds
Related compounds	Methyl propiolate, Hexafluoro-2-butyne, Acetylene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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.^[6][7]