waldonator
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I know that DMAP is a very strong base because the conjugate acid would be stabilized by delocalisation of the +ive charge...but which site is there protonation-the N of the -NMe2 group or the N in the heterocycle? It is a derivative of pyridine but I don't know how to work this out! Thanks
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charco
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(Original post by waldonator)
I know that DMAP is a very strong base because the conjugate acid would be stabilized by delocalisation of the +ive charge...but which site is there protonation-the N of the -NMe2 group or the N in the heterocycle? It is a derivative of pyridine but I don't know how to work this out! Thanks
Both nitrogen atoms will be protonated and each will have a pKb value depending on which is protonated most easily.

There are pros and cons for the amine. It is sterically hindered by the surrounding bulky groups, but the +I effect of two methyl groups boosts the charge density of the lone pair.

The pyridine nitrogen lone pair is easily available and the positive charge is easily conjugated around the ring...

My guess is the ring nitrogen.
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waldonator
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(Original post by charco)
Both nitrogen atoms will be protonated and each will have a pKb value depending on which is protonated most easily.

There are pros and cons for the amine. It is sterically hindered by the surrounding bulky groups, but the +I effect of two methyl groups boosts the charge density of the lone pair.

The pyridine nitrogen lone pair is easily available and the positive charge is easily conjugated around the ring...

My guess is the ring nitrogen.
So much to consider! Thanks a lot
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