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: PBEPBE/6-311G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			13	-7	allene	propyne	20
C4H6			26	3	1,2-Butadiene	1-Butyne	22
C4H6			-5	-17	1,2-Butadiene	2-Butyne	12
C4H6			-38	-51	1,2-Butadiene	1,3-Butadiene	13
C4H6			-44	-49	Cyclobutene	1,3-Butadiene	5
C4H6			-75	-82	1-Methylcyclopropene	1,2-Butadiene	7
C4H6			46	42	Methylenecyclopropane	1-Methylcyclopropene	4
C3H6O			-113	-110	Oxetane	Propanal	-3
C4H8			-20	-33	cyclobutane	1-Butene	13
C3H4O2			27	29	2-Propenoic acid	β–Propiolactone	-2
C4H6S			-2	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-6
C5H8			38	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	13
C5H8			56	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-8
C5H8			-38	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	14
C5H10			-13	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-8
C5H10			-19	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	10