Proton transfer

[SysBio]

Hi everyone,

 

Can someone please explain to the best of their ability:

WHAT does "proton transfer" mean?

 

There are no reactions that protons actually jump from one molecule to the next, are there? I thought only electrons move?

[coke]

I think when they say proton, they mean H+ ion (which is basically a proton)...

 

Of course as you understand, such a highly positively charged particle is not just going to stay ionized by itself in water... its going to find some electrons on some other molecule and try to stick to it... i.e. H2O + H+ > H3O+

NH3 + H+ > NH4+

 

Apparently it's a bit more complicated than that, but wiki says its used to create very high purity H3O+, so i think that's close enough.

[Kaeroll]

I think when they say proton, they mean H+ ion (which is basically a proton)...

 

Of course as you understand, such a highly positively charged particle is not just going to stay ionized by itself in water... its going to find some electrons on some other molecule and try to stick to it... i.e. H2O + H+ > H3O+

NH3 + H+ > NH4+

 

Apparently it's a bit more complicated than that, but wiki says its used to create very high purity H3O+, so i think that's close enough.

At a basic level, in aqueous media, protons exist as the hydroxonium ion [math]H_{3}O^{+}[/math], which I understand goes through a huge number of (not fully understood) dynamic processes.

 

To address the OP's question, there are reactions that 'just' move a proton from one molecule to the next. You must understand, this does not refer to nuclear transmutation - these reactions don't involve plucking a proton from, say, a carbon nucleus to form an isotope of boron. Simple acid equilibria are good illustrations:

[math]CH_{3}CO_{2}H + H_{2}O \Updownarrow CH_{3}CO^{-}_{2} + H_{3}O^{+}[/math]

This is simply the dissociation of acetic acid, but is an example of a reaction in which the net result is simply proton transfer.

 

Proton transfer is more commonly used to refer to an elementary step within a mechanism, wherein a proton is 'shuttled' from one part of a molecule to another, or from one molecule to another.

[SysBio]

thanks for the resopnses...

 

ok I think I get the point...it refers to reactions involving transfer of hydrogen ions....and there ARE reactions where hydrogen is transferred from one molecule to the next

 

thanks