Experimental evidence that hydroxyethylcarbamic acid is not a major product of the reaction between hydroxyethylamine and CO2 in the presence of water

The IR spectrum of the mixture obtained in the reaction of hydroxyethylamine and CO2 in the presence of water does not show any significant bands characteristic of the carboxyl group. This fact is a strong evidence to show that hydroxyethylcarbamic acid in its molecular form is not a major product of this reaction. The shapes of the potentiometric titration curves of the reaction mixture with NaOH solution shows that the formation of the zwitterion form of hydroxyethylcarbamic acid as a major product is very unlikely. Both these results, as well as simple considerations of possible equilibria of Brönstedʹs type which may occur in our experiments, indicate that hydroxyethylammonium hydrogen carbonate and not hydroxyethylcarbamic acid should be regarded as the major product of the discussed reaction. Thus, we suggest that during titration of the reaction mixture with NaOH solution the essential reaction is deprotonation of the hydroxyethylammonium ion.