Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Tautomer energy comparison

using model chemistry: BLYP/cc-pV(T+d)Z

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			13	-7	allene	propyne	20
C4H6			-76	-49	Cyclobutene	1,3-Butadiene	-27
C4H6			-41	-51	1,2-Butadiene	1,3-Butadiene	10
C4H6			-4	-17	1,2-Butadiene	2-Butyne	13
C4H6			-97	-82	1-Methylcyclopropene	1,2-Butadiene	-15
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	6
C3H4O2			47	29	2-Propenoic acid	β–Propiolactone	18
C5H10			-11	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-6
C5H10			-43	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-14