CLATHRATE FORMATION IN (I-C5H11)(4-K)(C4H9)(K)NF-H2O (K=1,2,3) BINARY-SYSTEMS

Phase diagrams of some binary aqueous systems with tetraalkylammonium fluorides are examined. The size of the hydrophobic moiety of the gues t is consecutively varied in the series (i-C5H11)(4-k)(C4H9)(k)NF (k = 0, 1, 2, 3) by replacing bulky isoamyl radicals with n-butyl radicals . Changes in clathrate formation caused by variations of the sizes and forms of guests are analyzed in the series (i-C5H11)(k-4)(C4H9)(k)NF- H2O (k = 0, 1, 2, 3, 4). All tetraisoamylammonium fluoride hydrates ar e more stable than other hydrates of this series. The stability of the compounds increases due to the fact that the isoamyl radicals use the host cavities more effectively than the butyl radicals. In all hydrat es of the series, tetragonal structures-I (TS-I) which were earlier th ought typical only for hydrates of tetrabutylammonium salts, are forme d Hydrates of the orthorhombic system are formed until three isoamyl r adicals have been replaced by butyl radicals. Hydrates with 26-28 wate r molecules (mp 27.4-34.6 degrees C) are the most stable hydrates of t he series, except for i-AmBu(3)NF . 25.9H(2)O, melting 0.3 degrees C l ower than the tetragonal hydrate in the same system. All compounds are defined chemically, and for some of them crystal data are given.