Electrochemical Reduction and Azo‐coupling of Ring Chlorinated p‐Dimethylaminobenzenediazonium Salts. Hammett‐CorrelationsThe polarographic half‐wave potentials of ring halogenated 4‐dimethylaminobenzenediazonium salts (6a–6j) can be linearly correlated with the total σ‐constants Σσkorr(E1/2= (0.25 Σσkorr+ 0.33) V; r = 0.995), if for the dimethylamino group of the 3‐ or 3,5‐halogenated derivatives corrected σ′p‐constants are used. The Σσkorr‐values determined can be used to correlate the influence of substituents on the azo‐coupling kinetic