Propanediol-1,2 carbonate

Fig. 1. Linear correlation between NMR chemical shifts at infinite dilution of CF3I in various electron pair donor solvents and donicity (DN), referred to CCI3F as external reference. NB, nitrobenzene BN, benzonitrile AN, acetonitrile PDC, propanediol-1, 2-carbonate THF, tetrahydrofuran DMF, dimethylformamide EC, ethylene carbonate TMP, trimethyl phosphate DMA, N,N-dimethylacetamide DMSO, dimethylsulfoxide HMPA, hexamethyl-phosphoric amide.

O) 1—benzoyl fluoride 2—nitromethane 3—nitrobenzene 4—benzo-nitrile S—acetonitrile 6—propanediol-1, 2-carbonate 7—ethylene sulfite 8—Water 9—trimethyl phosphate 10—dimethylformamide 11—N, N-di-methylaoetamide 12—dimethyl sulfoxide 13—hexamethylphosphoric amide. 

HMPA, hexamethylphosphoric amide, DMSO, dimethyl sulfoxide DMF, dimethylformamide TMP, trimothyl phosphate PDC, propanediol-1,2-carbon-ate. 

Selective solvation of various cations was studied in recent years in mixtures of water with solvents such as dioxane, THF, acetonitrile, propanediol-1,2-carbonate and p nridine 76—82). Except for pyridine-water mixtures, cations are preferentially solvated by water. 

Propanediol-1,2-carbonate. . Phenylphosphonic difluoride Phenylphosphonic dichloride... 

The most versatile solvents for the purpose under consideration will have medium donor numbers, no self-ionization producing a certain type of anionic ligands and a reasonable dielectric constant. In particular acetonitrile (DNsbCl5== 14, DEC = 37), propanediol-1,2-carbonate (DNsbcis = DEC = 69) or sulpholane (DNsbCis 14.3, DEC —42) are to be recommended. Numerous bromo-, chloro-, azido-, cyano-, thiocyanato- and other complexes of class (a) metals are readily formed in their solutions. ... 

Certain differences in the properties of acetonitrile and propanediol-1,2-carbonate (both have similar donor numbers) can be attributed to steric influences due to the different sizes and shapes of the solvent molecules. Acetonitrile, being smaller in size and more favourable in shape as a ligand, is a better solvent for many ionic compounds and assists the formation of anionic complexes sometimes more readily than propanediol-1,2-carbonate, although the latter has a higher dielectric constant. 

Propanediol-1,2-carbonate is a very useful solvent of medium donor properties, similar to those of sulpholane or acetonitrile. It has a high dielectric constant so that dissolved compounds, which are ionized, will be extensively electrolytically dissociated. Its stability towards redox reactions is another useful property, and furthermore it is easy to purify and to handle. 

While the acetonitrile molecule is small and rod-like in shape the propanediol-1,2-carbonate molecule is large and bulky, and this may account for a number of differences observed in the two solvents of similar donor number. 

In the vanadyl systems the species existing in PDC-solutions appear to have distorted octahedral structures . The highest chloride-coordinated ion is [VOCU] -, which may be present to some extent in the absence of excess chloride ions, due to some degree of autocomplex formation by vanadium oxydichloride . Likewise the ultimate azidocomplex seems to have the composition [VO(N3)4]2-. It has been concluded from the spectra that all vanadyl species in propanediol-1,2-carbonate are of lower symmetries than the corresponding species in acetonitrile or in dimethyl sulphoxide, and this has been ascribed to stronger 7r-bonding contributions to the V = 0 bond in propanediol-1,2-carbonate . 

The existence of the hexachlorotitanate ion in propanediol-1,2-carbonate is doubtful but the hexaazido-complex is readily formed . ... 

The ferric-systems in propanediol-1,2-carbonate are similar to those in acetonitrile tetrahedral [FeCl]++, FeCU and [FeCl4] are observed in each case ... 

The number of coordination forms found in trimethyl phosphate within a particular system is smaller than in acetonitrile or propanediol-1,2-carbonate. Some of the lower X -coordinated species show high kinetic stabilities. The tendency to form solvate bonds is reflected in autocomplex formation for many systems and in the ionization of manganese(II) bromide and nickel(II) iodide. 

In propanediol-1,2-carbonate no asymmetric units are found since only [MBr4] and [VBr4], respectively were detected. Thus autocomplex formation of the bromides is complete in this solvent. The interaction of propanediol-1,2-carbonate with transition metal cations appears stronger than might be expected from a consideration of its donor number, which is only slightly higher than that of acetonitrile in this latter solvent many more coordination forms are produced. 

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