Why does bromination occur exclusively at the allylic position? Allylic H 360 kJ/mol(87 kcal/mol) H H Alkyl 400 kJ/mol (96 kcal/mol)- Vinylic 445 kJ/mol (106 kcal/mol) 2004 Thomson-Brooks/Cole H H R R H-C. R-C. R-C. RC H H H R Vinylic Methyl Primary < Secondary Tertiary Allylic (1) (2) (3) Less Stability More stable stable e2004 Thomson-Brooks/Cole Why does bromination occur exclusively at the allylic position?