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: B3LYP/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-20	-7	allene	propyne	-14
C4H6			-38	-17	1,2-Butadiene	2-Butyne	-21
C4H6			18	-49	Cyclobutene	1,3-Butadiene	67
C4H6			-38	-51	1,2-Butadiene	1,3-Butadiene	13
C4H6			-6	3	1,2-Butadiene	1-Butyne	-9
C4H6			-58	-82	1-Methylcyclopropene	1,2-Butadiene	24
C4H6			49	42	Methylenecyclopropane	1-Methylcyclopropene	7
C3H6O			-12	-110	Oxetane	Propanal	98
C4H8			55	-33	cyclobutane	1-Butene	87
C3H4O2			-101	29	2-Propenoic acid	β–Propiolactone	-130
C4H6S			-17	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-21
C5H8			34	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	9
C5H8			52	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-12
C5H10			-13	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-8
C5H10			-3	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	26