ION-MOLECULAR INTERACTIONS AND THE EQUILIBRIUM COMPOSITION IN THE L-1-METHYL-2-PYRROLIDONE-1,1,2,2-TETRACHLOROETHANE SYSTEM ACCORDING TO IRSPECTROSCOPY DATA

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions o f HCl in 1-methyl-2-pyrrolidone (N-MP) (0-43.4% HCl) were studied in t he 900-4000 cm(-1) range. Spectra were recorded for the N-MP-HCl-1,1,2 ,2-tetrachloroethane (TCE) ternary system at a TCE : N-MP ratio of 1 : 1. Depending on the ratio between the components, complexes of the co mposition N-MP HCl (C-1), N-MP . 2HCl (C-2), and 2N-MP . HCl (C-3) are formed in the system. Complex C-1 has a quasiionic structure, (CH2)(3 )N(Me)CO...H...Cl, formed by a strong quasisymmetrical H-bond between the carbonyl O atom and the C1 atom. The addition of an N-MP molecule to complex C-1 yields complex C-3, in which the quasiionic character o f the bond between N-MP and HCl is retained. When excess HCl is presen t, the quasiionic structure is destroyed, the N-MP molecule is protona ted, and the Cl- anion interacts with HCl to give an ion with a strong symmetrical H bond (Cl...H...Cl)(-). Complex C-2 is an ion pair.