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: CID/6-31G*

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-7	-7	allene	propyne	0
C4H6			-42	-49	Cyclobutene	1,3-Butadiene	7
C4H6			46	42	Methylenecyclopropane	1-Methylcyclopropene	4
C3H6O			-110	-110	Oxetane	Propanal	0
C4H8			-18	-33	cyclobutane	1-Butene	15
C3H4O2			24	29	2-Propenoic acid	β–Propiolactone	-5
C4H6S			2	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-2
C5H8			21	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	-4
C5H8			55	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-10
C5H10			-8	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-3
C5H10			-17	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	12