title: Shoolery's rule
text: # Shoolery's rule
  
  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 $CH_2$ protons in a $A–CH_2–B$ structure using the formula
  
      $\delta =0.23\,\mathrm {ppm} +S_{\mathrm {A} }+S_{\mathrm {B} }$
  
  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 |
  | - | - |
  | $–CH_3$ | 0.47 |
  | –COOR | 1.55 |
  | –COR | 1.70 |
  | $–C_6H_5$ | 1.83 |
  | –SR | 1.64 |
  | –I | 1.82 |
  | –Br | 2.33 |
  | –OR | 2.36 |
  | –Cl | 2.53 |
  | –OH | 2.56 |
  | –OCOR | 3.13 |
  