[fran008]

I was reading in my biology book that some chemicals like HNO2 can covalently alter the nucleotide bases in DNA. The book gives the example of HNO2 which reacts with cytosine and deaminates it converting the amino group into a keto group. But isnt this false? Doesnt HNO2 form a diazonium salt with an aromatic ring and then that diazonium salt can react with OH-, Cl-,CN- or whatever?

[movies]

It could also just oxidize the amine to an imine which would then be hydrolyzed to a ketone.

[Arsenic]

I was reading in my biology book that some chemicals like HNO2 can covalently alter the nucleotide bases in DNA. The book gives the example of HNO2 which reacts with cytosine and deaminates it converting the amino group into a keto group. But isnt this false? Doesnt HNO2 form a diazonium salt with an aromatic ring and then that diazonium salt can react with OH-, Cl-,CN- or whatever?

[fran008]

Why is the phenol formed deprotonated? This does not always happen ey?

[Arsenic]

there is no phenol formation,the mechanism is like a Keto-enol tautomerism,
the mechanism was not entirely shown.