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Compare the basic strengths of above two compounds.

In the first compound (1,2-dihydropyrazine), the lone pair of one N will participate in resonance but the lone pair of other N will not, similarly in pyridine, lone pair will not participate in resonance. I think that since the first compound atleast has $2$ nitrogens (and only one in pyridine), it should be slightly more basic than pyridine, but I came to know that it's the other way round. So how do we compare their basic strengths and what are their $\mathrm{p}K_\mathrm{b}$ values?

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    $\begingroup$ The additional nitrogen in 1,2-dihydropyrazine rather pulls the electrons towards itself since it is a electronegative atom causing decrease in basic nature. $\endgroup$
    – Desai
    Jan 6 at 21:31
  • $\begingroup$ pKb(pyridine) = 8.77 at 25°C [CRC HANDBOOK for Physics & Chemistry; 2004 - Edition 8] $\endgroup$
    – Desai
    Jan 6 at 21:36
  • $\begingroup$ Related : alfa.com/en/pyrazines/?page=2 $\endgroup$
    – Desai
    Jan 6 at 21:43
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What I would do is I would compare their acid strengths. Due to inductive forces, deprotonating the 1,2-dihydropyrazine would result in a more stable compound than that in pyridine--the nearby nitrogen (electronegative) will share the burden of the negative charge. Therefore, 1,2-dihydropyrazine is more acidic and thus is less basic.

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