Y. Shi et al.
species for activation of methanol. Step B is insertion of CO2 into an Ni–O bond
with formation of 3. At the same time, addition of methanol to the cumulene forms
o-methylisourea 5 that may further interact with 3 to form 4. The last step is
conversion of 4 into DMC and urea 6 with regeneration of the catalyst. The urea 6
can also be reconverted into DCC [21].
Conclusions
In summary, we have developed a new catalytic system for formation of DMC from
methanol and CO2. The experimental results show that NiL2–DCC had excellent
catalytic activity, because the catalytic system, containing a small amount of NiL2,
promoted facile formation of DMC under moderate conditions (80 °C, 1.0 MPa)
with an acceptable yield. The NiL2 could be easily synthesized, recovered simply,
and consecutively reused. The reaction described in this article may further be
developed for application to the synthesis of DMC.
Acknowledgments This work was supported by the National Natural Science Foundation of China (nos
20972124, 21272184), the Shaanxi Science and Technology Co-ordination Innovation Engineering
Project (No. 2011K12-77), the Special Science Research Foundation of Education Committee in Shaanxi
Province (No. 12JK0584), and the Xi’an City Science and Technology Project (No. CXY1123-1).
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