1、组会汇报,文献汇报,李满 04/15/2016,文献汇报,1,Inorg. Chem., 2015, 54, 5043-5052,文献汇报,2,R. A. Baillie and P. Legzdins, Acc. Chem. Res., 2014, 47, 330340 L. Que et al., J. Am. Chem. Soc., 2003, 126, 472473 M. J. Burk and R. H. Crabtree, J. Am. Chem. Soc., 1987, 109, 80258032 S. Kraft et al., J. Am. Chem. Soc., 2011,
2、 133, 18321848,文献汇报,3,(1) the combination of a catalyst responsible for CH activation with a cocatalyst responsible for dioxygen activation, (2) transition-metal catalysts, which react with both hydrocarbons and molecular oxygen, (3) the introduction of very robust main-group element catalysts for C
3、H functionalization chemistry.,D. Munz and T. Strassner, Inorg. Chem., 2015, 54, 5043-5052,Three strategies:,Strategy 1,4,D. Munz and T. Strassner, Inorg. Chem., 2015, 54, 5043-5052,Strategy 1,5,M. Muehlhofer, T. Strassner, W. A. Herrmann, Angew. Chem. Int. Ed., 2002, 41, 17451747,Strategy 1,6,D. Mu
4、nz and T. Strassner, Angew. Chem. Int. Ed., 2014, 53, 24852488 D. Munz and T. Strassner, Chem. Eur. J., 2014, 20, 1487214879 D. Munz, D. Meyer, T. Strassner, Organometallics, 2013, 32, 34693480,Halogens like chlorine or bromine appear to be good candidates for efficient redox catalysts because they
5、are strong enough oxidants for CH functionalization chemistry and are well-known to be capable of generating transition-metal complexes in high oxidation states like palladium(IV) or copper(III) by a nonradical two-electron process (Scheme 3).,Strategy 1,7,D. Munz, D. Meyer, T. Strassner, Organometa
6、llics, 2013, 32, 34693480,Strategy 1,8,D. Meyer and T. Strassner, J. Organomet. Chem., 2015, 784, 8487,Strategy 1,9,D. Meyer and T. Strassner, J. Organomet. Chem., 2015, 784, 8487 T. Strassner et al., Organometallics, 2006, 25, 5409-5415,If 11 is an intermediate in the catalytic cycle it should be a
7、s active as 8 in the methane activation (Scheme 1). We therefore tested 11 under our standard conditions (see Methane activation for experimental details) and found a comparable activity (TON 22) as in the case of 8 (TON 24) 19.,Strategy 1,10,D. Meyer and T. Strassner, J. Organomet. Chem., 2015, 784
8、, 8487,Strategy 1,11,D. Meyer, A. Zeller and T. Strassner, J. Organomet. Chem., 2012, 701, 5661,Strategy 1,12,R. A. Periana et al., Science, 1998, 280, 560564,Because oleum is produced by the aerobic oxidation of sulfur dioxide in the presence of a vanadium(V) catalyst (contact process), the partial
9、 oxidation of methane could be coupled to this cooxidation using sulfur trioxide as the redox mediator. Similar to the catalytic processes in HOFTA,68,165,177 however, a drawback is the formation of the byproduct water, which renders the development of an economic process challenging. This might hav
10、e kept the authors from demonstrating the possibility for an aerobic cooxidation procedure.,Strategy 2,13,D. Munz and T. Strassner, Inorg. Chem., 2015, 54, 5043-5052,Strategy 2,14,A. B. McQuarters, M. W. Wolf, A. P. Hunt, N. Lehnert, Angew. Chem. Int. Ed., 2014, 53, 47504752,Strategy 2,15,T. Strassn
11、er et al., Eur. J. Inorg. Chem., 2013, 21, 36593663 I. I. Moiseev et al., J. Chem. Soc., Chem. Commun., 1991, 938939,The cobalt-catalyzed oxidation of methane to methyl trifluoroacetate by molecular oxygen in trifluoroacetic acid has been studied in detail. Yields of up to 50% based on methane were
12、obtained. Deactivation by precipitation of the cobalt catalyst could be prevented by the addition of trifluoroacetic anhydride. According to an energy-dispersive X-ray analysis, this precipitate contained mainly cobalt fluorides (ca. 20 atom-% cobalt) (cf. CoF2). TFA2O removes water from the reactio
13、n mixture. The observation of CC bond scission processes in the reaction with propane points toward a reaction mechanism involving radicals.,Strategy 3,16,D. Munz and T. Strassner, Inorg. Chem., 2015, 54, 5043-5052,Strategy 3,17,D. Munz and T. Strassner, Angew. Chem. Int. Ed., 2014, 53, 24852488 D.
14、Munz and T. Strassner, Chem. Eur. J., 2014, 20, 1487214879,We could observe that the presence of sodium bromide also led to the formation of minor amounts of propyl trifluoroacetate with NaVO3 under 4 bar of molecular oxygen and 6 bar of propane without the addition of any transition-metal catalyst
15、(Scheme 9). Considering the previous reports on the activation of methane by supposedly Br+ and I+ species and that such types of catalytic systems should be extraordinarily robust with regard to demanding reaction conditions, the development of appropriate and more efficient aerobic cooxidation pro
16、tocols for methane should become feasible in the near future.,Strategy 3,18,R. A. Periana et al., Angew. Chem. Int. Ed., 2014, 53, 1049010494,Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) comp
17、lex in nonsuperacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (99%). In the case of ethane, greater than 0.5M EtTFA can be achieved.,Strategy 3,19,R. A. Periana et al., Angew. Chem. Int. Ed., 2014, 53, 1049010494,Calculations identified two low-energy III
18、I-Et functionalization pathways (Figure 3), which explains the lack of direct observation of the intermediate 6.,Strategy 3,20,T. B. Gunnoe et al., J. Am. Chem. Soc., 2014, 136, 83938401,We describe an efficient system for the direct partial oxidation of methane, ethane, and propane using iodate sal
19、ts with catalytic amounts of chloride in protic solvents. In HTFA (TFA = trifluoroacetate), 20% methane conversion with 85% selectivity for MeTFA have been achieved. The addition of substoichiometric amounts of chloride is essential, and for methane the conversion increases from 20%. The reaction al
20、so proceeds in aqueous HTFA as well as acetic acid to afford methyl acetate. The system is selective for higher alkanes: 30% ethane conversion with 98% selectivity for EtTFA and 19% propane conversion that is selective for mixtures of the mono- and difunctionalized TFA esters.,Strategy 3,21,T. B. Gu
21、nnoe et al., J. Am. Chem. Soc., 2014, 136, 83938401,Strategy 3,22,T. B. Gunnoe et al., J. Am. Chem. Soc., 2014, 136, 83938401,It is possible that chloride bonds with the active iodine-based reagent to provide an electronic modulation for the CH bond-breaking step and/or the CO bond-forming step. The exact identity of the active iodine species is the subject of ongoing studies.,Strategy 3,23,J. T. Groves, T. B. Gunnoe et al., Dalton Trans., 2015, 44, 52945298,Conclusion,24,D. Munz and T. Strassner, Inorg. Chem., 2015, 54, 5043-5052,
