Computational Chemistry Comparison and Benchmark DataBase Release 18 (October 2016) Standard Reference Database 101 National Institute of Standards and Technology
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Relative enthalpies of isomers - Comparison of 298.15K enthalpies (kJ mol^-1)

Isomers of C₄H₆

index	Species	CAS number	Name	Relative experimental enthalpy (kJ mol-1)	sketch
a	CH2CHCHCH2	106990	1,3-Butadiene	0.0
b	CH3CCCH3	503173	2-Butyne	36.0
c	C4H6	822355	Cyclobutene	47.5
d	CH2CCHCH3	590192	1,2-Butadiene	53.1
e	CHCCH2CH3	107006	1-Butyne	56.0
f	C4H6	6142730	Methylenecyclopropane	91.3
g	C4H6	157335	Bicyclo[1.1.0]butane	107.9
h	C4H6	3100047	1-Methylcyclopropene	134.4