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Tolylene-2,4-diisocyanate(2,4-TDI) 1 reacts with methanol through two simultaneous paths in the polyurethane reaction,which involve two different intermediates-tolylene-4-carbamatic-2-isocyanate 2 and tolylene-2-carbamatic-4-isocyanate 3,and the final product is tolylene-2,4-dicarbamate 4.The-CH_3 chemical shifts in benzene ring in compounds 1,2,3 and 4 can be easily tested and well distinguished,through which those four compounds are quantified and their kinetics are investigated.It shows that four rate constants for the tolylene-2,4-diisocyanate-methanol reaction in CCl_4 at 50℃are k_1=9.6×10~(-2)h~(-2)mol~(-2)min~(-1), k_2=1.4×10~(-2)h~(-2)mol~(-2)min~(-1),k_3=4.0×10~(-3)h~(-2)mol~(-2)min~(-1),k_4=1.4×10~(-3)h~(-2)mol~(-2)min~(-1).(k_1 is the reaction rate constant from compounds 1 to 2;k_2 is the reaction rate constant from compounds 1 to 3;k_3 is the reaction rate constant from compounds 3 to 4;k_4 is the reaction rate constant from compounds 2 to 4).
Tolylene-2,4-diisocyanate (2,4-TDI) 1 reacts with methanol through two simultaneous paths in the polyurethane reaction, which involve two different intermediates-tolylene-4-carbamatic-2-isocyanate 2 and tolylene-2-carbamatic- 4-isocyanate 3, and the final product is tolylene-2,4-dicarbamate 4. The-CH_3 chemical shifts in benzene ring in compounds 1,2,3 and 4 could be easily tested and well distinguished, through which those four compounds are It is illustrated that the four rate constants for the tolylene-2,4-diisocyanate-methanol reaction in CCl_4 at 50 ° C are k_1 = 9.6 × 10 ~ (-2) h ~ (-2) mol ~ ( -2) min ~ (-1), k_2 = 1.4 × 10 ~ (-2) h ~ (-2) mol ~ (-2) min ~ (-1), k_3 = 4.0 × 10 ~ (-3) h ~ (-2) mol ~ (-2) min ~ (-1) and k_4 = 1.4 × 10 ~ (-3) h ~ (-2) mol ~ (-2) min ~ the reaction rate constant from compounds 1 to 2; k_2 is the reaction rate constant from compounds 1 to 3; k_3 is the reaction rate constant from compounds 3 to 4; k_4 is the reaction rate constant from compounds 2 to 4).