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/cc-pVDZ

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			13	-7	allene	propyne	19
C4H6			24	3	1,2-Butadiene	1-Butyne	21
C4H6			-45	-51	1,2-Butadiene	1,3-Butadiene	6
C4H6			-86	-82	1-Methylcyclopropene	1,2-Butadiene	-4
C3H6O			-117	-110	Oxetane	Propanal	-7
C3H4O2			38	29	2-Propenoic acid	β–Propiolactone	9
C4H6S			-0	4	Thiophene, 2,5-dihydro-	Thiophene, 2,3-dihydro-	-5
C5H8			36	25	1,3-Pentadiene, (E)-	1,4-Pentadiene	11
C5H8			62	64	1,3-Pentadiene, (E)-	1,2-Pentadiene	-2
C5H8			-44	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	8
C5H10			-32	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	-3
C5H10			-11	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-6