Determination of Relative Stability of Urea Complexes from X-Ray Powder Diffraction Data

UREA INCLUSION COMPOUNDS OF n-ALKYL BROMIDES AND IODIDES

“…Since all the starting inaterials are liquids, the X-ray powder pattern of the crystalline products obtained after treatment with a urea-methanol solutioil must be either that of uncoinplexed urea (tetragonal) between these two since the spacing a t 3.08-4.02 A* is the most intense spacing characteristic of tetragonal (4) (uncomplexed) urea and the spacing a t 4.104.11 (Table I) (Table 11) is the most intense spacing characteristic of the (hexagonal) urea inclusion compound (4). From these spacings which indicate the relative concentration of free urea and the complex, it was concluded that n-heptylbrornide is the shortest bromoalkane tested which unequivocally gives a complex (Table I).…”