- Facile sulfur-assisted carbonylation of diaminoresorcinol with carbon monoxide
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4,6-Diaminoresorcinol, which is a raw material of ZYLON (PBO fiber), has an instability in air atmosphere. Therefore, very stable benzo[1,2-d:5,4-d']bis- 2(3H)-oxazolone recognized a useful equivalent of 4,6-diaminoresorcinol during the stages of production, storage, and transportation. By combining the sulfur-assisted carbonylation of 4,6-diaminoresorcinol dihydrochloride with carbon monoxide and triethylamine under 0.1 MPa at 20°C for 4 h in DMF with the oxidation of resulting hydrogen sulfide salt with molecular oxygen for 2 h, benzo-[1,2-d:5,4-d']bis-2(3H)-oxazolone was obtained in a quantitative yield. Also, carbonylation of 2,5-diaminohydroquinone dihydrochloride and 2,5-diamino-1,4-benzenedithiol dihydrochloride was smoothly performed to give benzo[1,2-d:4,5-d']bis-2(3H)-oxazolone and benzo[1,2-d:4,5-d']bis-2(3H)- thiazolone, respectively, in good to excellent yields under similar reaction conditions. Furthermore, 2,6-dimercaptobenzo[1,2-d:5,4-d']bisoxazole, which is another equivalent of 4,6-diaminoresorcinol, was obtained in excellent yield by the thiocarbonylation of 4,6-diaminoresorcinol dihydro-chloride with carbon disulfide in the presence of 1-methylpyrrolidine at 20°C for 24 h in DMF.
- Mizuno, Takumi,Nakai, Takeo,Mihara, Masatoshi,Ito, Takatoshi
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- UREA DERIVATIVES AND THEIR USE AS CURATIVES AND CURATIVE ACCELERATORS FOR RESIN SYSTEMS
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Bisorthohydroxy aromatic urones and their use as curatives and cure accelerators in resin systems particularly epoxy resin systems provide formulations with good outlife, low curing temperatures and desirable glass transition temperatures after curing, they are particularly useful in prepregs used in the production of components for the aerospace and wind turbine industries.
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(2022/02/28)
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