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: QCISD/6-31G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-4	-7	allene	propyne	3
C4H6			-76	-82	1-Methylcyclopropene	1,2-Butadiene	7
C4H6			-49	-51	1,2-Butadiene	1,3-Butadiene	2
C4H6			-48	-49	Cyclobutene	1,3-Butadiene	1
C4H6			5	3	1,2-Butadiene	1-Butyne	2
C4H6			45	42	Methylenecyclopropane	1-Methylcyclopropene	4
C3H6O			-116	-110	Oxetane	Propanal	-6
C4H8			-24	-33	cyclobutane	1-Butene	9
C4H6S			0	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-4
C5H8			27	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	2
C5H8			62	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-3
C5H8			-48	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	4
C5H10			-7	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-2
C5H10			-24	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	5