Cryoscopic and spectroscopic studies of mixtures of HNO3 and BF3

A cryoscopic study of mixtures of HNO3 and BF3 reveals the existence of a compound HNO3. 2BF3 (melting point 53° C). Mixtures of composition HNO3. 1/2BF3, HNO3. BF3, HNO3. 2BF3 and HNO3. 1/2SO3 were studied spectroscopically. In liquid HNO3. 1/2BF3 and HNO3. BF3 the reaction HNO3 + BF3 → NO+2 + BF3OH‐ takes place to a more or less considerable extent. In HNO3. 2BF3 no clear indication for the presence of NO2+ ions is found. HNO3. 2BF3 probably is an addition compound comparable with those described by Baumgarten c.s. for BF3 with a number of sulphates or pyrophosphates. In liquid HNO3. 1/2SO3 a considerable amount of NO2+ and HSO4 ions are present.