What is the structure of #"hexane"#? How is this structure reflected in its #""^1H# #"NMR spectrum"#?

Question

What is the structure of #"hexane"#?  How is this structure reflected in its #""^1H# #"NMR spectrum"#?

Madison Anderson · Accepted Answer

Well, the molecule is linear to a first approx.....

But in isotropic solution, the molecule is conceived to tumble about. Spectroscopic techniques suggest that can interrogate the molecular symmetry, i.e. #""^1"H"#, and #""^13"C{"""^1"H}"# #"NMR spectroscopies"# reveal that there are three carbon, and three hydrogen environments, with the appropriate #6:4:4# integral ratio, i.e. #H_3C#, and #2xxCH_2#, revealed by integration of the #""^1"H"# #"NMR spectrum"# (and I wish the spectrum were appropriately integrated).

........and the #""^13C{""^1H}# #"NMR spectrum"# gives.....

Both spectra give the required three signals for the #"H"_3"CCH"_2"CH"_2"CH"_2"CH"_2"CH"_3# molecule...As written, and as observed in the spectra, the methyl groups are equivalent, as are the two sets of methylene groups.

And as a general rule, when given an organic molecule to consider, it is usually a good idea to represent it on paper as symmetrically as possible. If something is funny with its preferred conformation, you will soon find out.

Skylar Alexander · Answer

undefined The structure of hexane is a straight-chain alkane with six carbon atoms and 14 hydrogen atoms. In its $^1H$ NMR spectrum, hexane exhibits a single peak because all hydrogen atoms in hexane are equivalent, resulting in only one unique environment for protons. This single peak is observed as a singlet with a chemical shift typically around 0.8 to 1.5 ppm on the $^1H$ NMR spectrum.