A simple relationship between the solid density of organic compounds and the liquid density at the triple point is presented as an extension of a previous relationship used internally by the DIPPR 801 database project. The relationship allows estimation of solid density (of the solid phase most stable at the triple point) for organic compounds over a wide range of temperatures with an average uncertainty of approximately 6%.

The interactions of adenosine 5‘-monophosphate (AMP), adenosine 5‘-diphosphate (ADP), and adenosine 5‘-triphosphate (ATP) with protons and with Mg2+ in aqueous solutions have been studied by 1H NMR spectroscopy at 25, 50, and 70 °C. Upfield shifts of H-8 were found in the pH ranges where protonation of phosphate groups occurs for the three nucleotides at all temperatures studied, indicating that AMP, ADP, and ATP adopt an anti conformation at these temperatures. The order of the H-8 upfield shift is AMP > ADP ∼ ATP. The shift decreases slightly at 50 and 70 °C. Chemical shift measurements for the three nucleotides in the presence of Mg2+ give no indication of the existence of an interaction between Mg2+ and the adenine ring in the Mg2+−nucleotide complexes under the experimental conditions of this study. The mechanism of the deshielding effect of phosphate groups on H-8, and the effects of temperature and pH on the intramolecular interaction of these nucleotides are discussed.