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: BLYP/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-9	-7	allene	propyne	-3
C4H6			-27	-17	1,2-Butadiene	2-Butyne	-10
C4H6			3	-49	Cyclobutene	1,3-Butadiene	53
C4H6			-39	-51	1,2-Butadiene	1,3-Butadiene	12
C4H6			5	3	1,2-Butadiene	1-Butyne	2
C4H6			-67	-82	1-Methylcyclopropene	1,2-Butadiene	15
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	5
C3H6O			-24	-110	Oxetane	Propanal	86
C4H8			41	-33	cyclobutane	1-Butene	73
C3H4O2			-96	29	2-Propenoic acid	β–Propiolactone	-125
C4H6S			-21	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-25
C5H8			36	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	11
C5H8			54	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-11
C5H10			-13	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-8
C5H10			-14	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	15