Formamide → HCID 131710587, compound

Participants

Reaction Steps

About 10 parts of a hydrogenation catalyst which consists of finely divided nickel on kieselguhr as a carrier are added to about 972 parts of 1,6-hexamethylene diisocyanate and about 600 parts by volume of anhydrous toluene in a 3-liter autoclave of VA steel equipped with a stirrer. When the autoclave has been purged several times with nitrogen, it is charged with hydrogen and the pressure is adjusted to about 100 atmospheres at a temperature of about 120° C. Hydrogenation is carried out for about 5 hours at this temperature, the pressure dropping to about 78 atmospheres during the process. During this reaction time, about 1 NCO equivalent is reduced to isocyanato-hexylformamide by 1 mol of hydrogen, and this formamide reacts with the excess hexamethylene diisocyanate to form N-formyl-bis-(isocyanatohexyl)urea. When the pressure in the autoclave has been released, the catalyst is filtered off, the toluene is removed under vacuum by means of a water pump and the solution of the reaction product is freed from excess hexamethylene diisocyanate by thin layer distillation at about 0.2 mm Hg and about 140° C. About 321 parts of a pale yellow diisocyanate which has an NCO content of about 24.8% are obtained. According to an osmotic molecular weight determination, this has an average molecular weight of 340. According to the percent NCO content, elementary analysis and IR spectroscopic data, the polyisocyanate consists of about 85% of N-formyl-bis-(isocyanatohexyl) urea and about 15 percent of higher homologues of N-formyl-tris-(isocyanatohexyl)-biuret.

Provenance & Evidence