Catalysts 3-Methyl-1 -phenyl-3-phospholene- 1-oxide

Rosthauser et al. (4) used l-methyl-3-phospholene-l-oxide to prepare and isolate oligomeric diisocyanates containing dicarbodiimides using 4,4 -diphenyl-methane diisocyanate. Diisocyanates containing dicarbodiimides were also prepared by Takahashi et al. (5) using 3-methyl-l-phenyl-2-phospholene-l-oxide as the reaction catalyst. 

Polycarbodi-imides have been prepared from isocyanates using 1-phenyl-3-methyl-2-phospholene-l-oxide as catalyst. ... 

The reaction is usually carried out at high temperatures (of about 200°C) in a polar solvent, such as tetramethylene sulfone, and the polyamide formation can be accelerated by the addition of l-phenyl-3-methyl-2-phospholene 1-oxide as catalyst. However, in the case of a two-step process, the reaction time of the first step must be carefully controlled, since the catalyst can also play a role in the formation of carbodiimides from two terminal isocyanate groups [36], These carbodiimides can then further react and lead to crosslinking [36], In most cases [34-39], the polymers are prepared with 4,4 -methylene bis(phenyl-isocyanate) (MDI), using adipic acid, isophtahc acid, azelaic acid, or a mixture of two of them (in order to accelerate the solubilization of the polyamide phase in the solvent) and a polyether based on tetramethylene oxide, ethylene oxide, or a mixture of propylene oxide and ethylene oxide. 

To address this concern uretonimine-modified isocyanates with improved low-temperature properties were prepared using 4,4 -diphenylmethane diisocyanate catalyzed with 3-methyl-l-phenyl-3-phospholene-l-oxide. The formation of uretonimine was consistently higher than uretdione formation using this catalyst. The uretonimine-modified isocyanate can be stored at temperatures substantially lower than ambient temperature while still remaining liquid. In addition it is soluble in melted 4,4 -diphenylmethane diisocyanate. 

A reactor was charged with 93.80% 4,4 -diphenylmethane diisocyanate, 6.20% 2,4 -diphenylmethane diisocyanate, and 3-methyl-1 -phenyl-3-phospholene-1 -oxide (6 ppm) as catalyst and then heated for 6 hours at 110°C. Trifluoromethanesulfonic acid (50 ppm) was then added to quench the reaction. The mixture was then cooled to 50°C and the product isolated having a 29.5% isocyanate content. 

An efficient method for preparation of aromatic and aliphatic carbodiimides involves the reaction of an Isocyanate with 3-methyl-1-phenyl-S-phospholene-1-oxide, the most readily prepared catalyst of Us type. ... 

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