How is this reaction correct? I have studied until now that with $\ce{Br2}$ only anti-addition takes place.

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  • 8
    $\begingroup$ Please don’t ever draw alkynes with a bond angle that isn’t 180°. $\endgroup$
    – orthocresol
    Sep 19 at 12:48
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    $\begingroup$ What is $\ce{M}$ in $\ce{M2O\bond{-}}$ group on your diagram? It also would be nice if you could add chemical names and fix issues with molecular geometry. $\endgroup$
    – andselisk
    Sep 19 at 21:43