The chemistry of Deniges test for adrenaline

The phenol groups in adrenaline are activated, step by step, by interaction with sodium acetate. A phenoxide reacts with mercuric chloride (SN2 reaction), giving an organomercurial intermediate. The second phenoxide ion reacts differently because there is a swift internal reaction. The phenolate is connected with the organometallic chain through a double bond, and its electrodotic property gives rise to a concerted mechanism in which an ortho-benzoquinone is formed and the organometallic chain is broken down. Instead of a normal leaving group, elemental mercury and a chloride ion are formed. The red ortho-quinone obtained is in accordance with the red colour observed in the test. There is an analogue fission in an oxygen-mercury-cyanide chain.