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: B97D3/6-311+G(3df,2p)

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			14	-7	allene	propyne	21
C4H6			-44	-51	1,2-Butadiene	1,3-Butadiene	7
C4H6			25	3	1,2-Butadiene	1-Butyne	22
C4H6			-69	-49	Cyclobutene	1,3-Butadiene	-20
C4H6			-85	-82	1-Methylcyclopropene	1,2-Butadiene	-3
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	5
C3H6O			-122	-110	Oxetane	Propanal	-11
C4H8			-42	-33	cyclobutane	1-Butene	-9
C3H4O2			42	29	2-Propenoic acid	β–Propiolactone	13
C4H6S			-4	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-8
C5H8			36	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	11
C5H8			60	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-5
C5H8			-44	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	7
C5H10			-10	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-5
C5H10			-33	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-4
C6H8			-2	-3	1,4-Cyclohexadiene	1,3-Cyclohexadiene	0