Self-diffusion and volumetric measurements for N-methylformamide and N,N-dimethylformamide at temperatures from 240 to 313 K and pressures up to 300 MPa

Abstract

(p, V, T) data for N,N-dimethylformamide (DMF) and N-methylformamide (NMF) have been obtained at 288.15, 298.15 and 313.15 K for pressures up to 280 MPa, together with densities at 0.1 MPa at those temperatures. Self-diffusion coefficients for N,N-dimethyl-1[²H₁]formamide (DDMF) and NMF are reported at the same temperatures and pressures up to 300 MPa, with some additional data for NMF at 278.69 K and pressures up to 149 MPa and for DDMF at 0.1 MPa at seven further temperatures in the range 240–308 K. Isothermal compressibilities, isobaric expansivities and internal pressures have been evaluated from the (p, V, T) data. Anomalous behaviour observed previously for formamide seems to be present for both liquids, although the anomalous properties do not persist to as high a pressure. The self-diffusion coefficients have been interpreted in terms of a modified rough hard-spheres theory.