Shoolery's rule, which is named after
James Nelson Shoolery, is a good approximation of the
chemical shift
In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is the resonant frequency of an atomic nucleus relative to a standard in a magnetic field. Often the position and number of chemical shifts are diagnostic of the structure of ...
δ of
methylene group
In organic chemistry, a methylene group is any part of a molecule that consists of two hydrogen atoms bound to a carbon atom, which is connected to the remainder of the molecule by two single bonds. The group may be represented as , where the '< ...
s in
proton nuclear magnetic resonance
Proton nuclear magnetic resonance (proton NMR, hydrogen-1 NMR, or 1H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of a substance, in order to determine the struct ...
. We can calculate shift of the CH
2 protons in a A–CH
2–B structure using the formula
:
where 0.23 ppm is the chemical shift of
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
and the empirical adjustments are based on the identities of the A and B groups:
Shoolery's rule is a particular instance of a general class of rules of the form
:
,
with two substituents on methylene resulting in two parameters
and
.
References
External links
Organic Spectroscopy: Principles and Applications page 206
Nuclear magnetic resonance
{{NMR-stub