Abstract:

The effect of solvents on the crystal structure of pure stearic acid crystd. from them was studied using x-ray and DTA. The latent heat of the phase transition, $Δ$Ht, was measured for the two well-defined forms B and C. X-ray diffractograms are the means for the identification of crystal modifications. However, only qual. information about the compn. present in the mixt. is inferred from the relative peak intensities. DTA of the phase transitions at 54° (for B) and 64° (for A) furnishes quant. data for each component present in the mixt. Values of 0 and 4.9 cal g-1 for the phase transition enthalpies were measured for the pure C form and B form, resp. Intermediate values were found for mixts. of C and B. The interplay between the crystn. conditions (type of solvent, cooling rate, and flow regime) dictates the formation of various crystal structure modifications. [on SciFinder(R)]