Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Experimental Barriers to Internal Rotation for CH₃COCH₂CH₃ (2-Butanone)

Atoms in torsion 1 are 1, 2, 3, 4
The rotor type is CH₂CH₃

Atoms in torsion 2 are 9, 4, 3, 2
The rotor type is CH₃
methyl on ethyl

Atoms in torsion 3 are 6, 1, 2, 3
The rotor type is CH₃
methyl on CO

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