Solvation and self-association of water in propylene carbonate

Abstract

The experimental error (±25% average) is somewhat larger than in other nmr rate studies due to the relatively large viscosity of the solutions at the lower temperatures and due to the relatively small chemical shift differences between the cis and trans isomers.

Solid-State NMR Study of MCM-41-type Mesoporous Silica Nanoparticles

“…Also shown, in Figure , are the structures of surface OH groups and water in several configurations considered in this work. Table includes the chemical shifts reported in the literature for water in various hydrogen-bonded environments. − …”

On the Molecular Mechanism of H2O Diffusion into Polyimides: A Vibrational Spectroscopy Investigation

“…The difference between these values, Δν̄, (−58 cm -1 ) measures the H-bonding energy. We may convert Δν̄ to kilocalories for comparison with ice and for assuming a direct proportionality between the stretching frequency and the H-bond energy. ,, Knowing that, for ice, the enthalpy of formation per H-bond is approximately −6 kcal/mol 49-51 and that Δν̄ for ice and water vapor is 3305−3707 = − 402 cm -1 , we get (− 6 kcal/mol)(−58 cm -1 )/(−402 cm -1 ) = −0.9 kcal/mol. This value is to be compared with those reported in the literature relative to the enthalpy of formation of the H-bond between the proton-donor−proton-acceptor pairs water−acetaldeyde (Δ H 0 = −3.6 kcal/mol), water−dioxane (Δ H 0 = −3.5 ± 0.2 kcal/mol), water− N , N -dimethylacetamide (Δ H 0 = −3.0 kcal/mol), water−acetone 56 (Δ H 0 = −2.4 kcal/mol), and water−propylene carbonate 53 (Δ H 0 = −1.2 kcal/mol).…”

“…49,50,53 Knowing that, for ice, the enthalpy of formation per H-bond is approximately -6 kcal/mol [49][50][51] and that ∆ν j for ice and water vapor is 3305-3707 ) -402 cm -1 , we get (-6 kcal/mol)(-58 cm -1 )/(-402 cm -1 ) ) -0.9 kcal/mol. This value is to be compared with those reported in the literature relative to the enthalpy of formation of the H-bond between the proton-donor-proton-acceptor pairs water-acetaldeyde 54 (∆H 0 ) -3.6 kcal/mol), water-dioxane 55 (∆H 0 ) -3.5 ( 0.2 kcal/mol), water-N,N-dimethylacetamide 56 (∆H 0 ) -3.0 kcal/ mol), water-acetone 56 (∆H 0 ) -2.4 kcal/mol), and waterpropylene carbonate 53 (∆H 0 ) -1.2 kcal/mol). It is apparent that the ∆H 0 we have estimated for the water-polyimide system is of the same order of magnitude than those of low molecular weight analogs and is about half that of a water-ketone interaction.…”

Acid-base equilibriums of some acids in propylene carbonate

“…Advantages are that PC is nonpoisonous, has a high dielectric constant (which makes it a popular solvent for electrochemical studies), but is about log(ca/cs) Figure 2. Relation between log (Ca/Cs) and paH in PC (1) phenol, Cs = 2.6 X 10-3 M; (2) acetic acid, Cs = 2.93 X 1CT3 M; (3) benzoic acid, Cs = 2.71 X 1( 3 M; (4) salicylic acid, (O) Cs = 2.85 X 3 M, (•) Cs = 4.11 X 1CT3 M 10 times a stronger base than AN. A disadvantage is that standard solutions of strong acids are not stable in PC as is also the case in AN and Act.…”