Catalytic Performance of Zr‐Based Metal–Organic Frameworks Zr‐abtc and MIP‐200 in Selective Oxidations with H2O2

• Published in: Chemistry : a European journal Vol. 27; no. 23; pp. 6985 - 6992
• Main Authors: Maksimchuk, Nataliya V., Ivanchikova, Irina D., Cho, Kyung Ho, Zalomaeva, Olga V., Evtushok, Vasiliy Yu, Larionov, Kirill P., Glazneva, Tatiana S., Chang, Jong‐San, Kholdeeva, Oxana A.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 21-04-2021
• Subjects: alpha,beta-unsaturated ketones; Carvone; Caryophyllene; Catalysis; Chemistry; Epoxidation; Hydrogen peroxide; Ketones; Metal-organic frameworks; Oxidation; Selectivity; Substrates; Zirconium
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202005152

The catalytic performance of Zr‐abtc and MIP‐200 metal–organic frameworks consisting of 8‐connected Zr6 clusters and tetratopic linkers was investigated in H2O2‐based selective oxidations and compared with that of 12‐coordinated UiO‐66 and UiO‐67. Zr‐abtc demonstrated advantages in both substrate conversion and product selectivity for epoxidation of electron‐deficient C=C bonds in α,β‐unsaturated ketones. The significant predominance of 1,2‐epoxide in carvone epoxidation, coupled with high sulfone selectivity in thioether oxidation, points to a nucleophilic oxidation mechanism over Zr‐abtc. The superior catalytic performance in the epoxidation of unsaturated ketones correlates with a larger amount of weak basic sites in Zr‐abtc. Electrophilic activation of H2O2 can also be realized, as evidenced by the high activity of Zr‐abtc in epoxidation of the electron‐rich C=C bond in caryophyllene. XRD and FTIR studies confirmed the retention of the Zr‐abtc structure after the catalysis. The low activity of MIP‐200 in H2O2‐based oxidations is most likely related to its specific hydrophilicity, which disfavors adsorption of organic substrates and H2O2.
An eight‐connected metal–organic framework Zr‐abtc catalyzes a range of H2O2‐based selective oxidations. The significant predominance of 1,2‐epoxide in the epoxidation of carvone and high sulfone selectivity in thioether oxidation point to a nucleophilic oxidation mechanism. With highly reactive alkenes, such as caryophyllene, electrophilic oxidation can also be realized.