The influence of sequential H/D isotopic substitution in the methanol molecule on its volume characteristics

Literature data and the data obtained in this work on the density of H/D methanol isotopomers (CH 3 OH, CH 2 DOH, CHD 2 OH, CD,OH, CH 3 OD, CH 2 DOD, CHD 2 OD, and CD 3 OD) at 298.15 K were used to calculate the isotope effects on the molar volume of the alcohol with 100% deuterium substitution. Correlation equations that allowed the volume characteristics of a methanol isotopomer to be estimated at the given degree of deuterium substitution were suggested. The contributions to the molar volume of liquid methanol were shown to be nonadditive both when protons were replaced by deuterons in each methanol molecule group and when the methyl radical was sequentially deuterated. The conclusion that hydrogen atoms in the hydrocarbon radical of the alcohol were energetically nonequivalent was substantiated. This nonequivalence predetermined the possibility of formation of weak CH...O bonds in methanolic media.