反应详情

温度

60 °C

To a flask containing 59.30 g (789.92 mmoles) of molten methyl carbamate (85° C. oil bath) was added 260 mg (2.6 mmole) of conc.sulfuric acid. The temperature of the oil bath was then lowered to 60° C., and 14.79 g (93.61 mmoles) of m-DIPEB added dropwise to the reaction mixture. The reaction mixture was stirred 60° C. for 4.5 hours, and 500 mg of anhydrous sodium carbonate added to neutralize the acid catalyst. The mixture was stirred at 60° C. for another 30 minutes and then distilled under the vacuum 95°/30 mm Hg) to recover unreacted methyl carbamate (44.05 g; >90% recovery). GLC analyses of the white residue showed that m-TMXDU and m-TMU were formed in 65% and 24% yields, respectively. The solid was then mixed with 50 g of hexadecane and 1.66 g of heneicosane (GLC internal standard), and the mixture cracked at 265° C. for 4 hours. GLC analyses indicated that α,α,α',α'-tetramethyl meta-xylene diisocyanate (m-TMXDI) (45%), meta-isopropenyldimethylbenzene isocyanate (m-TMI) (10%) and α,α,α',α'-tetramethyl-meta-xylene monourethane monoisocyanate (m-TMXUI) (3%) were formed based on the m-DIPEB.

1. additionwas added 260 mg (2.6 mmole) of conc
2. customwas then lowered to 60° C.
3. stirringThe mixture was stirred at 60° C. for another 30 minutes
4. distillationdistilled under the vacuum 95°/30 mm Hg)
5. customto recover unreacted methyl carbamate (44.05 g; >90% recovery)
6. customm-TMU were formed in 65% and 24%
7. customyields
8. waitthe mixture cracked at 265° C. for 4 hours