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: wB97X-D/6-31G*

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			7	-7	allene	propyne	14
C4H6			-40	-51	1,2-Butadiene	1,3-Butadiene	12
C4H6			18	3	1,2-Butadiene	1-Butyne	14
C4H6			-10	-17	1,2-Butadiene	2-Butyne	7
C4H6			-32	-49	Cyclobutene	1,3-Butadiene	17
C4H6			-71	-82	1-Methylcyclopropene	1,2-Butadiene	11
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	5
C4H8			-8	-33	cyclobutane	1-Butene	25
C3H4O2			9	29	2-Propenoic acid	β–Propiolactone	-20
C4H6S			1	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-4
C5H8			31	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	6
C5H8			54	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-10
C5H8			-41	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	11
C5H10			-10	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-5
C5H10			-15	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	14