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: mPW1PW91/6-31G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			11	-7	allene	propyne	18
C4H6			-43	-51	1,2-Butadiene	1,3-Butadiene	9
C4H6			24	3	1,2-Butadiene	1-Butyne	21
C4H6			-9	-17	1,2-Butadiene	2-Butyne	8
C4H6			-55	-49	Cyclobutene	1,3-Butadiene	-5
C4H6			-98	-82	1-Methylcyclopropene	1,2-Butadiene	-16
C4H6			61	42	Methylenecyclopropane	1-Methylcyclopropene	19
C3H6O			-112	-110	Oxetane	Propanal	-2
C4H8			-21	-33	cyclobutane	1-Butene	12
C3H4O2			44	29	2-Propenoic acid	β–Propiolactone	16
C4H6S			8	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	4
C5H8			38	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	13
C5H8			61	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-3
C5H8			-43	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	9
C5H10			-13	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-8
C5H10			-30	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-1