Question

Diazoniumsalts, Azoarnes, Nitrosamine

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Hello, our prof provided us with some slides under the topic "Diazoniumsalts, Azoarnes, Nitrosamine" and the following image is inside the slides. I didnt understand what is going on there. does that reaction have a name ? so that ı can find some video lectures on clutchprep or links on the internet to stduy for it