Propanal → Isocyanate

Participants

Reaction Steps

Propionaldazine is synthesized by the reaction of propionaldehyde with hydrazine hydrate by operating as in Example 1. The cyclooligomerization reaction is then carried out according to the conditions described in Example 1, by causing the azine to react with the butadiene in a ratio of 1/3 in the presence of nickel prepared by the reduction of nickel acetylacetonate (1 at.g. of Ni for 20 moles of azine) and of triphenylphosphine. In 100 ml of tert. butanol, 12.15 g of 3,12-diethyl-1,2-diaza-1,5,9-cyclododecatriene are hydrogenated in 300-ml autoclave, in the presence of 1.3 g of rhodium catalyst deposited at 5% on alumina. The reaction is allowed to proceed for 30 minutes at 45° C. under 130 bars of hydrogen, then for 111/2 hours at 185° C. under 150 bars. The diamine (8.71 g) is phosgenated, in the form of the chlorhydrate, as in Example 1 in order to lead to 9.6 g (yield 90%) of crude isocyanate. The distillation of the latter leads to 1,10-diethyldecane-1,10-diisocyanate, a colorless liquid having a content of 2 NCO groups per mole and the following N.M.R. characteristics of the 13C atom (chemical shifts in relation to CDCl3 at 77 ppm): ##STR12##

Provenance & Evidence