Properties and structure of water and hexamethylphosphortriamide mixtures

Volumetric properties of (water+hexamethylphosphoric triamide) from (288.15 to 308.15)K

“…Note that, besides of the above-mentioned works [19,30,31], the temperature dependences of density for HMPT have been also studied by Kolker et al [38] {from (283.15 to 328.15) K, through 15 K}, and by authors [39] {between (288.15 and 318.15) K, with a step of 10 K} as well. However, the uncertainty in data obtained is by far higher in the latter case, being 1 Á 10 À4 g Á cm À3 .…”

“…Most studies have been carried out either at one temperature (298.15 K) [25][26][27][28] or for the HMPT/water-rich composition range [22,29]. We have found only three papers which report densities and/or excess molar volumes for the (water + HMPT) over a wider temperature range [19,30,31]. Herewith, if Chebib et al [31] report data at (283.…”

“…Herewith, if Chebib et al [31] report data at (283. 15, 298.15, 308.15, and 318.15) K, the results of Kessler et al [19] and Gal and Persin [30] concern only three temperatures, between (288.15 and 308.15) K and (298. 15 and 328.15) K, respectively.…”

“…The organic component molecules in these mixtures do not act as H-bonding donors, however, they are electron lone-pair donors capable of forming the strong hydrogen bonds with water molecules [7,10,[13][14][15][16]. Among such binary mixtures, a {water + hexamethylphosphoric triamide (HMPT)} is the liquid system, the component molar volumes of which differ each other one order of magnitude, and the organic component as a net solvent has a number of wideused distinctive characteristics [16][17][18][19][20][21][22][23]. In particular, noteworthy is the fact that the values of Gutmann's electron-donating number, DN SbCl 5 , and molecular dipole moment, l, for HMPT ($38.8 kcal Á mol À1 and 5.54 D, respectively) cannot be compared with those neither for any other aprotic dipolar solvent nor for water ($18.0 kcal Á mol À1 and 1.83 D, respectively) [16,17,24].…”

“…Meanwhile, though HMPT is completely miscible with water [19,[25][26][27][28][29][30][31], the volumetric properties of this liquid system have been studied quite scantily by now. A survey of the literature shows that very few precise densimetric measurements have been made for the binary mixtures of water with HMPT.…”