parts etc the following preparations and examples describe the manner and process of making and using the invention and set forth the best mode contemplated by the inventors of carrying out the invention but are not to be construed as limiting a 100 ml three neck flask which was thoroughly dried was equipped with a stirrer thermometer gas in let tube and an additional funnel the flask was charged with 3 8040 g 0 0202 mole of azelaic acid and the reaction system maintained under a blanket of oxygen free nitrogen in order to exclude air and atmospheric moisture twenty five ml of tetrahydrofuran was added and the azelaic acid dissolved during stirring a solution consisting of 5 0280 g 0 0201 mole of 4 4 39 methylenebis phenylisocyanate dissolved in 3 6 g of tetrahydrofuran was prepared separately and charged to the addition funnel the diisocyanate solution was added to the flask during stirring over a period of 15 minutes at 24 u00b0 25 u00b0 c the solution was stirred and cooled from 25 u00b0 c down to 40 u00b0 c over a period of 4 hours and remained clear and fluid the solution was stripped under a vacuum of 20 25 mm pressure at 0 u00b0 c a white solid was obtained in theoretical yield and further dried at 70 u00b0 80 u00b0 c under 1 mm an infrared spectrum of a kbr pellet of the product displayed the absorption band at 5 57 u03bc for the.