: B rist ol ▁City ▁F . C . ▁man agers ▁Category : Year ▁of ▁death ▁missing ▁Category : Sc ott ish ▁football ▁man agers ▁Category : M idd les br ough ▁F . C . ▁w art ime ▁guest ▁players <0x0A> </s> ▁The ▁Z in cke ▁reaction ▁is ▁an ▁organ ic ▁reaction ▁in ▁which ▁a ▁py rid ine ▁is ▁transformed ▁into ▁a ▁py rid in ium ▁salt ▁by ▁reaction ▁with ▁ 2 , 4 - d init ro - ch lor ob enz ene ▁and ▁a ▁primary ▁am ine , ▁named ▁after ▁The odor ▁Z in cke . ▁ ▁The ▁Z in cke ▁reaction ▁should ▁not ▁be ▁confused ▁with ▁the ▁Z in cke - Su hl ▁reaction ▁or ▁the ▁Z in cke ▁nit r ation . ▁Furthermore , ▁the ▁Z in cke ▁reaction ▁has ▁nothing ▁to ▁do ▁with ▁the ▁chemical ▁element ▁z inc . ▁ ▁Re action ▁mechanism ▁The ▁first ▁reaction ▁is ▁the ▁formation ▁of ▁the ▁N - 2 , 4 - d init ro phen yl - py rid in ium ▁salt ▁( 2 ). ▁ ▁This ▁salt ▁is ▁typically ▁isolated ▁and ▁pur ified ▁by ▁rec ry st all ization . ▁ ▁Upon ▁he ating ▁a ▁primary ▁am ine ▁with ▁the ▁N - 2 , 4 - d init ro phen yl - py rid in ium ▁salt ▁( 2 ), ▁the ▁addition ▁of ▁the ▁am ine ▁leads ▁to ▁the ▁opening ▁of ▁the ▁py rid in ium ▁ring . ▁ ▁A ▁second ▁addition ▁of ▁am ine ▁leads ▁to ▁the ▁disp lacement