The osmotic and activity coefficients of some thioureas in water and in ethylene carbonate

Apparent Molar Volumes and Expansibilities of Thiourea, 1,3-Dimethylurea, and 1,3-Dimethylthiourea in Water at Temperatures from T = (278.15 to 318.15) K and Atmospheric Pressure

“…It is noteworthy also the fact that the given curves (being close to linear) exhibit a weakly pronounced minimum appearing clearly at T = 318 K and shifting probably toward higher molalities as the temperature increases. Figure panels c and d illustrate that (∂ V ϕ,2 /∂ m ) T,p for aqueous 1,3-DMTU and 1,3-DMU are negative in sign and visually comparable in magnitude, although these N,N ′-dimethyl-substituted derivatives differ from each other by both the interacting (mainly, donor-accepting) capability of thionyl and carbonyl as well as amino groups and their structure-packing properties in the hydrated state. − ,, …”

“…In this context, volumetric properties of aqueous urea (U) and some of its N -alkyl-substituted derivatives, as small model bioactive solutes (being predominantly hydrophilic or hydrophobic in nature), have been rather well investigated, − while thiourea (TU) and N -alkylated thioureas have been far less explored. On the basis of the results of heat capacity, isopiestic and enthalpy-related measurements, it was shown that the hydrogen-bonding ability of the functional grouping −N(H)–C(S)–N(H)– can be modulated by the insertion of alkyl substituents. Herewith the “structural topography” of such hydrophobic moieties plays an important role in determining their bonding/hydration as found for U and its N -alkyl-substituted derivatives. ,,, As a consequence, thioureas are widely utilized in the field of molecular recognition, , as well as for the construction of nanostructured materials and pharmaceuticals. , Moreover, taking into account the fact that ureas and thioureas differ in the molecule polarity (dipole moments of the latter were found to be slightly higher), − a comparative analysis of volumetric properties of aqueous U, TU, and their alkyl-substituted derivatives could yield useful information on the interaction of >CO and >CS moieties with the surrounding water molecules.…”

“…1−4 In this context, volumetric properties of aqueous urea (U) and some of its N-alkyl-substituted derivatives, as small model bioactive solutes (being predominantly hydrophilic or hydrophobic in nature), have been rather well investigated, 5−23 while thiourea (TU) and N-alkylated thioureas have been far less explored. On the basis of the results of heat capacity, 24 isopiestic 25 and enthalpy-related 26 measurements, it was shown that the hydrogen-bonding ability of the functional grouping −N(H)−C(S)−N(H)− can be modulated by the insertion of alkyl substituents. Herewith the "structural topography" of such hydrophobic moieties plays an important role in determining their bonding/hydration as found for U and its N-alkyl-substituted derivatives.…”

On the two modes of condensation displayed by thiourea at the mercury-water interface

“…In the pre.sent work, the assumption that = clearly inadéquate, in view of the very high TU concentrations employed. Literature data [24,25] show that aqueous solutions of TU présent négative déviations from ideality, which become particularly important in concentrated solutions. The présence of the supporting electrolyte plays only a limited rôle, as indicated by small sait effects, cven at TU saturation.…”

Volumetric properties of some asymmetrically methyl-N-substituted thioureas in water between (278.15 and 318.15) K at ambient pressure

“…Unlike aqueous thiourea (TU) and its symmetrically methyl-Nsubstituted derivatives, 1,3-dimethyl-2-thiourea (1,3-DMTU) and 1,1,3,3-tetramethyl-2-thiourea (1,1,3,3-TMTU) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the hydration behavior of asymmetrically N-methylated thioureas, 1-monomethyl-2-thiourea (MMTU), 1,1-dimethyl-2-thiourea (1,1-DMTU) and 1,1,3-trimethyl-2-thiourea (1,1,3-TMTU), is far less explored [1,9,13]. Herewith, in these works, the standard molar enthalpies (Δ sol H 2 ∞ ) and heat capacities (Δ sol c p,2 ∞ ) of dissolution were discussed for aqueous MMTU only.…”