posted on 2024-03-11, 05:05authored byYingying Pan, Hongrui Tian, Zhiping Zheng
Selective
oxidation of sulfides to sulfoxides is of great
significance
in the synthesis of pharmaceuticals, desulfurization of fuels, and
detoxification of sulfur mustard chemical warfare agents. Designing
selective catalysts to achieve the efficient transformation of sulfides
to sulfoxides is thus highly desired. Herein, we report three transition
metal-complex-functionalized polyoxovanadates, [Zn2(BPB)2][V4O12]·0.5BPB·H2O (1), [Ni(BPB)(H2O)][V2O6]·2H2O (2), and [Co(HBPB)2][V4O12] (3) (BPB = 1,4-bis(pyrid-4-yl)benzene)),
and explore their applications for selective oxidation of sulfides
using H2O2 as an oxidant. All three compounds
were catalytically effective for the oxidation of methyl phenyl sulfide
to methyl phenyl sulfoxide, with 1 being best-performing
with complete conversion and a selectivity of 96.7%. In the selective
oxidation of a series of aromatic and aliphatic sulfides to corresponding
sulfoxides, 1 also showed satisfactory performance; in
particular, the chemical warfare agent stimulant 2-chloroethyl ethyl
sulfide can be completely and selectively oxidized to the nontoxic
2-chloroethyl ethyl sulfoxide within 20 min at room temperature. Catalyst 1 can be recycled and reused at least six times with uncompromised
performance. The perfect performance of 1 is attributed
to the synergistic effect of coordinatively unsaturated V and Zn sites
in bimetallic oxide, as revealed by comparative structural and catalytic
studies.