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/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-9	-7	allene	propyne	-2
C4H6			23	-49	Cyclobutene	1,3-Butadiene	72
C4H6			-39	-51	1,2-Butadiene	1,3-Butadiene	12
C4H6			7	3	1,2-Butadiene	1-Butyne	4
C4H6			-28	-17	1,2-Butadiene	2-Butyne	-11
C4H6			-51	-82	1-Methylcyclopropene	1,2-Butadiene	31
C4H6			48	42	Methylenecyclopropane	1-Methylcyclopropene	7
C3H6O			-17	-110	Oxetane	Propanal	93
C4H8			58	-33	cyclobutane	1-Butene	91
C3H4O2			-110	29	2-Propenoic acid	β–Propiolactone	-138
C4H6S			-22	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-27
C5H8			38	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	13
C5H8			55	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-10
C5H8			-29	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	22
C5H10			-15	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-9
C5H10			4	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	33