Pentaerythrityltetramine: A precipitant for nitric acid

I&EC 150

William S. Anderson, Harry J. Hyer, John E. Sundberg, and Thomas P. Rudy. United Technologies Corporation (Retired), 5987 Peacock Ridge Rd. #115, Rancho Palos Verdes, CA 90275
Nitric acid combines with pentaerythrityltetramine, C(CH2NH2)4, to form a tetranitrate of exceptionally low solubility: 2% in ice water and less than 0.1% in dilute nitric acid. The low solubility in water reflects the strength of the dense, crosslinked network of N...H+...O hydrogen bonds in the C(CH2NH3+)4(NO3-)4 crystal. This tetranitrate is a stronger acid than most amine nitrates and is known to release four moles of HNO3 vapor when heated as a thin film. (Caution: the tetranitrate detonates if mishandled.) The high nitrate ion content of C(CH2NH3+)4(NO3-)4, its low solubility, high density and high acidity suggest that a C(CH2NH2)4-based, closed-loop HNO3 precipitation-and-recovery process could be developed for treating waste nitric acid.