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: mPW1PW91/STO-3G

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-23	-7	allene	propyne	-16
C4H6			36	-49	Cyclobutene	1,3-Butadiene	85
C4H6			-37	-51	1,2-Butadiene	1,3-Butadiene	14
C4H6			-7	3	1,2-Butadiene	1-Butyne	-10
C4H6			-41	-17	1,2-Butadiene	2-Butyne	-25
C4H6			-45	-82	1-Methylcyclopropene	1,2-Butadiene	37
C4H6			49	42	Methylenecyclopropane	1-Methylcyclopropene	8
C3H6O			-5	-110	Oxetane	Propanal	105
C4H8			71	-33	cyclobutane	1-Butene	103
C3H4O2			-112	29	2-Propenoic acid	β–Propiolactone	-141
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
C5H8			-29	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	23
C5H10			-14	-5	1-Butene, 2-methyl-	2-Butene, 2-methyl-	-9
C5H10			12	-29	Cyclopropane, 1,1-dimethyl-	1-Butene, 2-methyl-	41