Vapor pressure of ethyl (5-cyano-3,4-diphenyl-6-oxo-1,6-dihydropyridazin-1-yl)acetate by the effusion method

The effusion method was used to determine the vapor pressure of ethyl (5-cyano-3,4-diphenyl-6-oxo-1,6-dihydropyridazin-1-yl)acetate (I) at 13 temperatures, in the range 123-141 /sup 0/C, with a minimum of two results at each temperature. Measured vapor pressures were in the range 10/sup -4/-6 X 10/sup -4/ torr and were expressed by the following equation: log p = 13.40 - (689 1/T), where p is the vapor pressure in torr and T is the absolute temperature. The 95% confidence limits for the constants of the equation are respectively + or - 1.19 and + or - 486. Experimental conditions studied included effusion hole diameter and effusion time. This compound undergoes no phase change below the melting point (about 143 /sup 0/C). All the results are for the crystalline phase below 143 /sup 0/C. Some results by the gas saturation procedure are also included.