Differences in physico-chemical properties and behavior of urea and 1,1,3,3-tetramethylurea in the mixture of water with N,N-dimethylformamide at temperature range TÂ =Â (293.15-308.15)Â K

The apparent molar volumes of tetramethylurea (TMU) in the mixture of N,N-dimethylformamide (DMF) and water (W) have been determined within the temperature range: T = (293.15-308.15) K from density measurements. Based on Redlich-Meyer equation partial molar volumes and bV coefficient describing the character of interactions were calculated. The results obtained for TMU showing hydrophobic properties have been compared with the corresponding results for urea that shows hydrophilic properties. This allowed us to analyze the solvation process of the investigated substances as well as to show an opposite behavior of urea in relation to TMU in the mixture DMF + W, particularly in the area of high water content.