Tetramethylethylene

Tetramethylethylene is a hydrocarbon with the formula Me₂C=CMe₂ (Me = methyl). A colorless liquid, it is the simplest tetrasubstituted alkene.

Tetramethylethylene

Names
Preferred IUPAC name 2,3-Dimethylbut-2-ene
Identifiers
CAS Number	563-79-1
3D model (JSmol)	Interactive image
ChemSpider	10776
ECHA InfoCard	100.008.422
EC Number	209-263-8
PubChem CID	11250
UNII	7UQ4B3F5JC Y
CompTox Dashboard (EPA)	DTXSID2060339
InChI InChI=1S/C6H12/c1-5(2)6(3)4/h1-4H3 Key: WGLLSSPDPJPLOR-UHFFFAOYSA-N
SMILES CC(=C(C)C)C
Properties
Chemical formula	C6H12
Molar mass	84.162 g·mol−1
Appearance	colorless liquid
Density	0.7075 g/cm3 (20 °C)
Melting point	−74.6 °C (−102.3 °F; 198.6 K)
Boiling point	73.3 °C (163.9 °F; 346.4 K)
Critical point (T, P)	521.0(9) K, 3.4(1) MPa[1]
Solubility in water	insoluble
Solubility	soluble in ethanol, ether, acetone, chloroform[1]
Magnetic susceptibility (χ)	−65.9×10−6 cm3·mol−1[1]
Refractive index (nD)	1.4122 (20 °C)[1]
Thermochemistry[1]
Heat capacity (C)	174.7 J·mol−1·K−1
Std molar entropy (S⦵298)	270.2 J·mol−1·K−1
Std enthalpy of formation (ΔfH⦵298)	−101.4 kJ·mol−1 (liquid) −68.1 kJ·mol−1 (gas)
Enthalpy of fusion (ΔfH⦵fus)	6.45 kJ·mol−1 (at melting point)
Enthalpy of vaporization (ΔfHvap)	32.51 kJ·mol−1 (25 °C) 29.64 kJ·mol−1 (at boiling point)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H304
Precautionary statements	P210, P233, P240, P241, P242, P243, P280, P301+P310, P303+P361+P353, P331, P370+P378, P403+P235, P405, P501
Flash point	−8 °C
Autoignition temperature	401 °C[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

It can be prepared by base-catalyzed isomerization of 2,3-dimethyl-1-butene.^[2] Another route involves direct dimerization of propylene.^[3] It can also be produced by photolysis of tetramethylcyclobutane-1,3-dione.^[4]

Reactions

Tetramethylethylene forms metal-alkene complexes with low-valent metals and reacts with diborane to give the monoalkyborane known as thexylborane.^[5][6]

Oxidation gives pinacol.

It is a precursor to the herbicide fenpropathrin.^[3]