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: MP2/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-104	-7	allene	propyne	-98
C4H6			11	-49	Cyclobutene	1,3-Butadiene	60
C4H6			-45	-51	1,2-Butadiene	1,3-Butadiene	6
C4H6			-90	3	1,2-Butadiene	1-Butyne	-94
C4H6			-117	-17	1,2-Butadiene	2-Butyne	-100
C4H6			-49	-82	1-Methylcyclopropene	1,2-Butadiene	33
C4H6			25	42	Methylenecyclopropane	1-Methylcyclopropene	-17
C3H6O			-64	-110	Oxetane	Propanal	46
C4H8			35	-33	cyclobutane	1-Butene	68
C3H4O2			-79	29	2-Propenoic acid	β–Propiolactone	-108
C4H6S			-11	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-15
C5H8			26	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	1
C5H8			57	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-8
C5H8			-38	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	14
C5H10			-11	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-5
C5H10			-21	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	8