Question
How can one determines whether there is a free rotation around a carbon-carbon triple bond?
Answers
drwls
That could be determined spectroscopically if it occurred, but it doesn't happen according to what I have been able to determine online.
Dr Russ
I am not sure how even spectoscopically you could determine if rotation had occurred as ethyne is a member of the
D(infinity h ) point group. Similarly in a cyclic or linear molecule containing a C-C triple bond there is free rotation around the adjacent C-C single bonds so the group roatates as a whole.
The spectra of acetylene (ethyne) are complex. If you have access to an academic library there is a recent paper by Lyulin et al who have studied the line spectra of acetylene in great detail. The paper is:
"Line parameters of acetylene in the 1.9 and 1.7 ìm spectral regions", O.M. Lyulin et al, Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 109, Issue 10, July 2008, Pages 1856-1874.
D(infinity h ) point group. Similarly in a cyclic or linear molecule containing a C-C triple bond there is free rotation around the adjacent C-C single bonds so the group roatates as a whole.
The spectra of acetylene (ethyne) are complex. If you have access to an academic library there is a recent paper by Lyulin et al who have studied the line spectra of acetylene in great detail. The paper is:
"Line parameters of acetylene in the 1.9 and 1.7 ìm spectral regions", O.M. Lyulin et al, Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 109, Issue 10, July 2008, Pages 1856-1874.