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: HF/SDD

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-9	-7	allene	propyne	-3
C4H6			-83	-49	Cyclobutene	1,3-Butadiene	-33
C4H6			-55	-51	1,2-Butadiene	1,3-Butadiene	-4
C4H6			-0	3	1,2-Butadiene	1-Butyne	-3
C4H6			-127	-82	1-Methylcyclopropene	1,2-Butadiene	-45
C4H6			-28	-17	1,2-Butadiene	2-Butyne	-11
C4H6			73	42	Methylenecyclopropane	1-Methylcyclopropene	32
C3H6O			-114	-110	Oxetane	Propanal	-4
C4H8			-42	-33	cyclobutane	1-Butene	-9
C3H4O2			85	29	2-Propenoic acid	β–Propiolactone	56
C4H6S			16	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	11
C5H8			29	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	3
C5H8			71	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	6
C5H8			-55	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	-3
C5H10			-6	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-1
C5H10			-55	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-26