# Betaine HCl solution at neutral pH

I was trying to make a $$2\text{M}$$ solution at $$\text{pH}\, 7.5$$ of Betaine $$\ce {HCl}$$. I started by weighing out the appropriate amount of Betaine $$\ce {HCl}$$, added some water and started stirring. At this point, the $$\text{pH}$$ of the solution was $$\sim1-2$$.

I went on to titrate the solution with $$\ce {NaOH}$$. At about $$\text{pH}$$ $$3-4$$ the betaine $$\ce {HCl}$$ was completely dissolved. as I added more base, I noticed that the solution began to warm up and give off a some sort of a "plasticy" smell and foamed a little bit. This began to happen at around $$\text{pH}$$ $$5.5-5.7$$.

It seems to me that the Betaine $$\ce {HCl}$$ is somehow reacting at high $$\text{pH}$$. I was wondering if someone can explain what may be happening to the Betaine $$\ce {HCl}$$.

• Trimethylamine is quite a good leaving group – Waylander Mar 2 at 18:41
• @Waylander That has nothing to do here. Helloo, this is hydrochloride! – Mithoron Mar 2 at 18:53