The osmotic coefficients of acetamide, propionamide and butyramide in water were measured at 293.15, 298.15 and 308.15 K using
the isopiestic method. The activity coefficients were calculated for the aliphatic amides and the pairwise free energy coefficients
for solute-solute interactions were determined according to the McMillan-Mayer theory. The osmotic and activity coefficients
of amides are discussed in terms of solute-solute interactions.
Authors:R. Veeraraghavan, S. Pai, and M. Subramanian
Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP) and N,N-dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) has been studied at various fixed temperatures of 20, 30, 40 and (50±0.1)°C. Results indicate that the equilibrium constants of the organic phase addition reaction (log Ks) with these amides follow their order of basicity (Kh) viz. 4.01 (DBHA, Kh=0.09)<4.05 (DBOA, Kh=0.1)<4.09 (DBDA, Kh=0.13). These values of log Ks (4) are lower than those (5) of HTTA system with these amides, which may perhaps be attributed to the effect of steric hindrance exerted by the uranyl pyrazolone ohelate to the incoming rigid amide molecule. High negative H and negative S values for this system indicate the organic phase reaction to be an addition and not a substitution.
Authors:R. Veeraraghavan, S. Pai, and M. Subramanian
Synergistic extraction of uranyl ion with 2-thenoyltrifluoroacetone (HTTA) and aliphatic amides with varying basicities, viz. dibutyl hexanamide (DBHA), dibutyloctanamide (DBOA) or dibutyldecanamide (DBDA) has been studied at various fixed temperatures of 20, 30, 40 and 50±0.1°C. Results indicate that the equilibrium constants of the organic phase addition reaction (Ks) with these amides follow their order of basicity (Kh) viz. DBHA (0.09)<0.10) H DBOA (0.13) with log Ks values of 4.91, 4.99 and 5.02, respectively. These values are much higher than those with TBP (3.8) or sulfoxides (4) as donors. This may be attributed to the existence of a resonance form of the amide, which has higher electron density on the carbonyl oxygen. The thermodynamic parameters associated with these systems evaluated by the temperature coefficient method indicate that the organic phase addition reaction with all the three amides is stabilized by both enthalpy and entropy changes as against UO
/HTTA/TBP system, where only the enthalpy change contributes to the stabilization.
Authors:S. Suzuki, K. Tamura, S. Tachimori, and Y. Usui
The extraction behavior of heptavalent technetium with cyclic amides inn-dodecane from nitric acid solution was studied. The amides investigated are N-(2-ethyl)hexylbutyrolactam(EHBLA). N-(2-ethyl)hexylvalerolactam(EHVLA),
N-(2-ethyl)hexyl-caprolactam (EHCLA), N-octylcaprolactam(OCLA), a mixture of 3-octyl-N-(2-ethyl)hexylvalerolactam and 4-octyl-N-(2-ethyl)hexylvalerolactam
(3,4,OEHVLA), 2-octyl-N-(2-ethyl)hexylcaprolactam(2OEHCLA), a mixture of 3-octyl-N-(2-ethyl)hexylcaprolactam and 5-octyl-N-(2-ethyl)hexylcaprolactam(3,5,OEHCLA)
and that of 3-octyl-N-octylcaprolactam and 5-octyl-N-octylcaprolactam(3,5,OOCLA). From the results of the distribution ratio
of Tc(VII) as a function of acid concentration, cyclic amides concentration and HTcO4 concentration, the effects of both the ring size of cyclic amide and structure of the substituents attached to different
positions of the cyclic ring on the extraction behavior of Tc(VII) were discussed. A clear steric hindrance was observed.
For applications, 3,4,OEHVLA is proposed as the best extractant for Tc from acidic solution.
Authors:D. Melo, G. Vicentini, L. Zinner, K. Zinner, H. de Souza, M. Batista, A. Garrido Pedrosa, and R. Bezerra
Complexes of neodymium and europium with amides and aminoxides were synthesized and characterized by complexometric analyses
with EDTA, CHN microanalytical procedures, IR absorption spectra, absorption spectra of neodymium complexes, emission spectrum
of europium compounds at 77 K, thermogravimetric analyses in N2 and differential scanning calorimetry (DSC) in N2. Infrared
spectroscopy results revealed that the nitrate molecules are bound to the central ions as bidentate. Thermogravimetric plots
indicated that the decomposition of the complexes occurs in the range 363-1163 K and resulted in the formation of Ln2O3 residues.
Authors:Yu. N. Sazanov, L. A. Shibaev, T. I. Zhukova, N. G. Stepanov, S. A. Dauengauer, and T. M. Bulina
The process of solid-phase cyclodehydration of films cast from solutions of poly(acid amides) (PAA) in dimethylformamide, dimethylacetamide and N-methyl-2-pyrrolidone has been investigated by mass-spectrometric thermal analysis (MTA). It is shown that MTA is a structure-sensitive method making it possible to follow the appearance and changes in the character of ordered structures formed in PAA films. The authors relate these structures to the process of crystallization of complexes of PAA with aprotic polar solvents.
The dissolution enthalpies of glycine in aqueous solutions of acetamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylformamide,
N,N-diethylformamide and N,N-diethylacetamide were measured at 298.15 K. The enthalpic pair interaction coefficients of glycine
zwitterion-amide molecules were determined by using standard solution enthalpies of glycine in water and aqueous solutions
of amides. The additivity of groups concept of Savage and Wood was used to estimate the contribution of each of the functional
groups of the studied amides.
Authors:P. Ruikar, M. Nagar, S. Pai, and M. Subramanian
Extraction of uranium(VI) and plutonium(IV) has been studied with N,N-dibutyl derivatives of hexanamide (DBHA), octanamide (DBOA) and decanamide (DBDA) at various fixed temperatures of 20, 30, 40 and (50±0.1)°C. The equilibrium constants for the uptake of nitric acid (Kh, a measure of their relative basicities) by these amides were evaluated by the usual method. The equilibrium constants for the extraction of uranium as well as plutonium with all the three amides follow their order of basicity (Kh) viz. DBHA (0.09)<DBOA (0.10)<DBDA (0.13) with log K values of 1.31, 1.43 and 1.73 for uranium and 3.55, 3.65 and 4.17 for plutonium, respectively. It has been observed that whereas uranium(VI) is extracted as a disolvate (similar to TBP and sulfoxides), plutonium(IV) has been found to be extracted as a trisolvate. The thermodynamic parameters evaluated by the usual temperature coefficient method indicate that the extraction reactions of uranium as well as plutonium are stabilized by negative enthalpy change only.