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/cc-pVDZ

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			17	-7	allene	propyne	24
C4H6			29	3	1,2-Butadiene	1-Butyne	26
C4H6			-1	-17	1,2-Butadiene	2-Butyne	16
C4H6			-44	-51	1,2-Butadiene	1,3-Butadiene	7
C4H6			-66	-49	Cyclobutene	1,3-Butadiene	-17
C4H6			-92	-82	1-Methylcyclopropene	1,2-Butadiene	-10
C4H6			47	42	Methylenecyclopropane	1-Methylcyclopropene	5
C3H6O			-122	-110	Oxetane	Propanal	-12
C4H8			-38	-33	cyclobutane	1-Butene	-6
C3H4O2			39	29	2-Propenoic acid	β–Propiolactone	10
C4H6S			-2	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-6
C5H8			-42	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	9
C5H10			-12	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-6
C5H10			-39	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-10