Deuterium isotope differences in 2-propanone, (CH 3) 2CO/(CD 3) 2CO: a high-pressure sound-speed, density, and heat capacities study

Abstract

A new high-pressure, non-intrusive ultrasonic microcell [J. Chem. Thermodyn. 36 (2004) 211–222] was used to carry out sound-speed measurements in deuteriated 2-propanone (acetone-d 6) in broad ranges of temperature (288 < T/K < 338) and pressure (0.1 < p/MPa < 160). To the best of our knowledge, there are no data regarding speed of sound of acetone-d 6. ( p, ρ, T) data for acetone-d 6 were also determined but in a narrower T, p range (298 to 333 K; 0.1 to 60 MPa). In this interval, several thermodynamic properties were thus determined, such as: isentropic ( κ s) and isothermal ( κ T) compressibility, isobaric thermal expansivity ( α p), isobaric ( c p) and isochoric ( c v) specific heat capacity, and the thermal pressure coefficient ( γ v). Comparisons with our data for acetone-h 6 enabled us to establish the magnitude and sign of deuterium isotope effects for identical properties. These effects are a consequence of distinct vibrational mode frequencies in an isotope-invariant force constants’ field. Molar heat capacities and their isotope effects were theoretically determined by employing an Einstein-like model for the vibrational frequencies of acetone-h 6 and acetone-d 6.