[Mpatas]

Why pyridinium salts are easier to reduce than pyridine?

[orgopete]

Let's look at this from a broad perspective. If reduction reactions were generally additions of electrons, then would it be easier to add electrons to pyridine or a pyridinium salt?

[Babcock_Hall]

@OP, It is a forum rule that you must show your attempt before we can help you.  By the way, do you have any examples in mind from organic or biochemistry?

[Mpatas]

Yeah i reduced pyridine with 1 bar of hydrogen pressure ate RT in the presence of HCl and using PtO2. What i believe is that the  in situ formation of the pyridinium salt reduces the aromaticity of the system making reduction easier.

[mjc123]

Pyridine is protonated on the lone pair orthogonal to the pi system, without disrupting the aromaticity. Pyridinium ion is isoelectronic with benzene.

[Mpatas]

Thanks for you answer but do you have any suggestions?

[Babcock_Hall]

Having eliminated aromaticity as the answer, how is the pyridinium ion different from pyridine?