[Howtohelp23]

I came across a molecule in my practice questions. It is a 2 carbon carboxylic acid, but the alpha C has a nitrogen attached to it. This nitrogen is itself attached to 2 methyl groups, and a -SH group.

The four groups attached to the N are: -CH3 -CH3 CH2COOH -SH


With 4 bonds to substituents (and a + formal charge), I figured it was a tertiary amine. I got the Q wrong and the explanations called this a Quaternary amine. I recognize that the nitrogen atom is Quaternary, but since only 3 of the 4 groups attached to the N are carbons (the last is sulfur), can I still count this as a Quaternary amine? Does a sulfur group count as an R group?

[Corribus]

Yes, it counts. So does a hydrogen.