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）.
A series of polydimethylsiloxanes containing two primary hydroxyl groups at one single chain end were synthesized by five-step reactions which included esterification, hydroxyl protection, anionic ring-opening polymerization, hydrosilylation and deprotection. The prepared compounds in each step were characterized. The results showed that each step synthesis was successfully carded out and objective products could be achieved.
Meng ZhangJun Ying LiGUO Wei ZhouYuan Juan WuYong Mei XiaTian Duo Li
The urethane reaction of o-hydroxybenzyl alcohol with phenyl isocyanate was monitored with in situ FT-IR.Dibutyltin dilaurate was used as catalyst and its amount effect was investigated.It was found that there was an obvious induction period before reaction began.It was interesting that the time of induction period climbed up and then declined with the increase of dibutyltin dilaurate. When the concentration of dibutyltin dilaurate reached 9.58×10^（-5） mol/L,the induction period disappeared completely and hereafter did not appear any more.Furthermore,the urethane reaction kinetics was studied.When the concentration of dibutyltin dilaurate increased,the reaction rate of phenolic group（k_1） increased sharply,but the reaction rate of alcoholic group（k_2） appeared of little change on the whole.k_1 increased about 20-fold,yet k_2 increased about 2-fold when the concentration of dibutyltin dilaurate varied from 9.58×10^（-6） mol/L to 1.92×10~4 mol/L,which made the value of k_1/k_2 enlarge.
Several new asymmetric substituted dicarbamates were synthesized with a convenient route.Firstly,tolylene-2,4-diisocyanate dimmer was obtained from monomer with tributylphosphine as catalyst.Then,the dimmer reacted with alcohol（R^1OH） to prepare carbamate substituted uretidione.Finally,uretidione ring was opened and the released isocyanate reacted with another alcohol （R^2OH,R^1≠R^2）.
Chao Zhao Peng Fei Yang Shun Ping Wang Jun Ying Li Tian Duo Li
