If the amine is valuable then slightly more than 1equivalent of a 3 degree (tertiary) amine, such as triethylamine orpyridine is added. Triethylammonium and other alkyl ammonium cations have pKa's ~ 10, whereas pyridinium cation has a pKa~5, yet the addition of the weaker base pyridine still suffices to drive the reaction to completion. Explain and write reactions.