Shoolery's rule
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Shoolery's rule, which is named after James Nelson Shoolery, is a good approximation of the chemical shift δ of methylene groups in proton nuclear magnetic resonance. We can calculate shift of the CH2 protons in a A–CH2–B structure using the formula
where 0.23 ppm is the chemical shift of methane and the empirical adjustments S are based on the identities of the A and B groups:
Substituent | S / ppm |
---|---|
–CH3 | 0.47 |
–COOR | 1.55 |
–COR | 1.70 |
–C6H5 | 1.83 |
–SR | 1.64 |
–I | 1.82 |
–Br | 2.33 |
–OR | 2.36 |
–Cl | 2.53 |
–OH | 2.56 |
–OCOR | 3.13 |
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 .[1]
References
[edit]- ^ Schaller, Renate; Arnold, Cédric; Pretsch, Ernö (1995-08-18). "New parameters for predicting 1H NMR chemical shifts of protons attached to carbon atoms". Analytica Chimica Acta. 312 (1): 95–105. doi:10.1016/0003-2670(95)00106-A. Retrieved 2024-02-06.
External links
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