Quaternary ammonium compounds (quats) are used commercially for a variety of applications, many of which are dependent on the counter anion. We have developed a green route for the methylation of tertiary amines to form the quaternary using dimethyl carbonate (DMC). This work explores methods for exchanging the methyl carbonate anion that results from the reaction with DMC. The first attempt via a direct exchange with methoxide or hydroxide (strong base) by precipitation of potassium methyl carbonate in methanol solvent produced poor yields due to solubility of the potassium methyl carbonate in methanol. Other solvents proved to be equally problematic. The next attempt using Dowex 1-X8 anion exchange resin worked well for methoxide, lactate, and benzoate. This multi-step process required conversion of the exchange resin to the appropriate form by reaction with an appropriate salt, rinsing the resin, and finally reacting with the methyl carbonate quaternary. The third attempt via direct reaction of the methyl carbonate with an appropriate acid using a vacuum to drive the reaction to completion also worked well. Direct reaction is the most straight forward method for reaction with acids stronger than hydrogen methyl carbonate. The anion exchange method is required for substituting anions of acids weaker than hydrogen methyl carbonate.