Self-association of 2-pyrrolidinone. 2. Spectral and dielectric polarization studies of benzene solutions

Abstract

The self-association of 2-pyrrolidinone in benzene has been investigated using infrared and Raman spectroscopy and dielectric polarization measurements. For solutions up to 0.5 M this system is best described as an equilibrium between monomer and cyclic dimer solute species. No evidence for the presence of trimers or other higher n-mers was found. Using a computer fit of the dielectric polarization data a dimerization constant of 33 ± 5 M"1 and dipole moments of 3.91 ± 0.20 D for the monomer and 2.06 ± 0.23 D for the dimer were determined. The Raman spectra confirm that the major associated species is a cyclic dimer. The presence of acyclic dimers cannot be ruled out, but on the basis of all the experimental measurements it is concluded that the concentration must be small, if it exists at all in this solvent.

Thermodynamic, transport, and spectroscopic studies for mixtures of isomeric butanediol and N-methyl-2-pyrrolidinone

“…The volumetric behavior of BTD in NPY is similar to that of diols in DMF but different as compared to diols in PY. This may be due to the fact that PY is self-associated (dimer) [30][31][32][33], however, DMF and NPY are not. NPY, however, is not self-associated by H-bonding, although like DMF, a certain degree of association due to dipole-dipole interactions is expected.…”

Volumetric properties of 2-pyrrolidone with aromatic hydrocarbons at T=(293.15, 303.15, 313.15, 323.15, 333.15, and 343.15)K

“…Owing to the difference in shape, size, and free volume of the two components, the negative V E values at equimolar concentrations of the binary mixtures follow the order: toluene > p-xylene % benzene > m-xylene > o-xylene, figure 6. The molecules of 2-pyrrolidone are associated by intermolecular hydrogen bonding, showing the existence of dimers, trimers and higher oligmers [10,11], the interstitial accommodation of the aromatic hydrocarbon in the empty spaces in the structure of 2-pyyrolidone leads to negative V E values.…”

Molecular interactions of α,ω-alkanediols in pyrrolidin-2-one: Thermophysical and spectroscopic measurements

“…The V E values of a,x-alkanediols in DMF are negative for all the mixtures reveal that DMF interacts strongly with the same diols than with PY in which the disruption of PY dimmers [15,23,24] through breaking of hydrogen bonds result in an increase in volume. Volume loss of these a,x-alkanediols in aqueous media [1,3] is larger than that in PY and this reverse trend in aqueous medium is explained on the basis of occupation of free volume, or cavity in the open ice-like structure of water by diol molecules.…”