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: B3LYP/LANL2DZ

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			8	-7	allene	propyne	15
C4H6			-10	-17	1,2-Butadiene	2-Butyne	7
C4H6			-48	-51	1,2-Butadiene	1,3-Butadiene	4
C4H6			19	3	1,2-Butadiene	1-Butyne	16
C4H6			-69	-49	Cyclobutene	1,3-Butadiene	-20
C4H6			-111	-82	1-Methylcyclopropene	1,2-Butadiene	-28
C4H6			62	42	Methylenecyclopropane	1-Methylcyclopropene	20
C3H6O			-105	-110	Oxetane	Propanal	5
C4H8			-32	-33	cyclobutane	1-Butene	0
C3H4O2			48	29	2-Propenoic acid	β–Propiolactone	19
C4H6S			8	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	4
C5H8			37	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	12
C5H8			66	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	2
C5H8			-49	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	3
C5H10			-10	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-5
C5H10			-48	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-19