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: B1B95/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-23	-7	allene	propyne	-16
C4H6			34	-49	Cyclobutene	1,3-Butadiene	84
C4H6			-36	-51	1,2-Butadiene	1,3-Butadiene	15
C4H6			-6	3	1,2-Butadiene	1-Butyne	-9
C4H6			-40	-17	1,2-Butadiene	2-Butyne	-23
C4H6			-42	-82	1-Methylcyclopropene	1,2-Butadiene	40
C4H6			48	42	Methylenecyclopropane	1-Methylcyclopropene	7
C3H6O			-6	-110	Oxetane	Propanal	105
C4H8			65	-33	cyclobutane	1-Butene	97
C3H4O2			-110	29	2-Propenoic acid	β–Propiolactone	-139
C4H6S			-17	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-22
C5H8			40	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	15
C5H8			57	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-7
C5H8			-34	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	18
C5H10			-14	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-9
C5H10			13	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	42