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: QCISD/6-311G**

formula	sketch		Energy (kJ mol-1)		Name		difference
	A	B	calculated	experiment	A	B
C3H4			-8	-7	allene	propyne	-1
C4H6			-48	-49	Cyclobutene	1,3-Butadiene	2
C4H6			-78	-82	1-Methylcyclopropene	1,2-Butadiene	5
C4H6			45	42	Methylenecyclopropane	1-Methylcyclopropene	3
C4H6			-47	-51	1,2-Butadiene	1,3-Butadiene	4
C4H6			0	3	1,2-Butadiene	1-Butyne	-3
C4H6			-19	-17	1,2-Butadiene	2-Butyne	-2
C3H6O			-119	-110	Oxetane	Propanal	-9
C4H8			-24	-33	cyclobutane	1-Butene	9
C5H8			-46	-52	1,2-Butadiene, 3-methyl-	1,3-Butadiene, 2-methyl-	5