Mechanisms for reactions of halogenated compounds. Part 4.[1] activating influences of ring-nitrogen and trifluoromethyl in nucleophilic aromatic substitution

Rate constants have been measured for the reactions of ammonia with various fluorinated pyridines and diazines in aqueous dioxan at 25°. From the results the activating effects of ring-nitrogen (relative to CH) and of trifluoromethyl (relative to -H) have been determined. Ring-nitrogen activates the system at points $\text{ortho}$-, $\text{meta}$- and $\text{para}$- to the point of substitution, in the ratios $\text{ortho}$- 6.2 × 10⁴, $\text{meta}$- 8.5 × 10², and $\text{para}$- 2.3 × 10⁵. Similarly a trifluoromethyl substituent is activating by a factor of 2.4 × 10³$\text{ortho}$- and 4.5 × 10³$\text{para}$- to the point of substitution.