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: B1B95/6-31G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-9	-7	allene	propyne	-2
C4H6			50	3	1,2-Butadiene	1-Butyne	47
C4H6			-9	-17	1,2-Butadiene	2-Butyne	8
C4H6			-38	-51	1,2-Butadiene	1,3-Butadiene	13
C4H6			-31	-49	Cyclobutene	1,3-Butadiene	18
C4H6			-89	-82	1-Methylcyclopropene	1,2-Butadiene	-7
C4H6			71	42	Methylenecyclopropane	1-Methylcyclopropene	29
C3H6O			-99	-110	Oxetane	Propanal	11
C4H8			22	-33	cyclobutane	1-Butene	55
C3H4O2			17	29	2-Propenoic acid	β–Propiolactone	-12
C4H6S			-1	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-5
C5H8			37	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	12
C5H8			56	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-8
C5H8			-41	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	11
C5H10			-13	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-8
C5H10			-10	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	19