7556-83-4Relevant articles and documents
SN2 and E2 Branching of Main-Group-Metal Alkyl Intermediates in Alkane CH Oxidation: Mechanistic Investigation Using Isotopically Labeled Main-Group-Metal Alkyls
Ess, Daniel H.,Gunsalus, Niles Jensen,Hashiguchi, Brian G.,Konnick, Michael M.,Koppaka, Anjaneyulu,Park, Sae Hume,Periana, Roy A.
, p. 1907 - 1916 (2020/06/08)
The main-group-metal alkyl compounds trialkyltin and dialkylthallium have been utilized to investigate the mechanism of functionalization of monoalkyl thallium and lead species, proposed to be putative intermediates in alkane (RH) functionalization, formed via CH activation of alkanes (methane, ethane, and propane) using electrophilic Tl(III) and Pb(IV) in trifluoroacetic acid (HTFA). Two different organometallic transalkylation methods were used to generate the putative intermediates in situ. The results herein strongly support a mechanism of CH activation to generate a main-group-metal alkyl intermediate which undergoes reductive functionalization to generate the products, R-TFA, and the reduced metal salt. In the case of ethane there are two products, ethyl trifluoroacetate (EtTFA) and 1,2-bis(trifluoroacetoxy)ethylene glycol (EG(TFA)2), observed in the reaction mixture that are proposed to form in parallel from a common intermediate, EtTl(TFA)2. The alkyl transfer studies herein strongly support the simultaneous formation of both species from this intermediate. Furthermore, studies conducted using regiospecifically isotopically labeled diethylthallium salts strongly support an SN2 functionalization from EtTl(TFA)2 to give EtTFA (and reduced Tl(TFA)) and an E2 elimination (also from EtTl(TFA)2) to generate ethylene, which instantly reacts with an additional 1 equiv of Tl(TFA)3 to generate EG(TFA)2.
OXIDATION OF ALKANES TO ALCOHOLS
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Page/Page column 12; 13; 14, (2014/09/03)
The invention provides processes and materials for the efficient and cost- effective functionalization of alkanes, such as methane from natural gas, to provide esters, alcohols, and other compounds. The method can be used to produce liquid fuels such as methanol from a natural gas methane-containing feedstock. The soft oxidizing electrophile, a compound of a main group, post- transitional element such as Tl, Pb, Bi, and I, that reacts to activate the alkane C- H bond can be regenerated using inexpensive regenerants such as hydrogen peroxide, oxygen, halogens, nitric acid, etc. Main group compounds useful for carrying out this reaction includes haloacetate salts of metals having a pair of available oxidation states, such as Tl, Pb, Bi, and I. The inventors herein believe that a unifying feature of many of the MXn electrophiles useful in carrying out this reaction, such as Tl, Pb, and Bi species, is their isoelectronic configuration in the alkane -reactive oxidation state; the electrons having the configuation [Xe]4f145d10, with an empty 6s orbital. However, the iodine reagents have a different electronic configuration.
Ortho-Phenylene bridged palladium bis-N-heterocyclic carbene complexes: Synthesis, structure and catalysis
Munz, Dominik,Poethig, Alexander,Tronnier, Alexander,Strassner, Thomas
, p. 7297 - 7304 (2013/07/11)
A series of ortho-phenylene bridged palladium bis-NHC complexes has been synthesized. Complexes with imidazolium and benzimidazolium derived NHCs and methyl-/benzyl-wingtips are reported. Bis(benz)imidazoles with a doubly brominated ortho-phenylene bridge could be obtained by an electrophilic substitution reaction. The structure of the complexes could be confirmed by three solid-state structures. All catalysts have been tested in the catalytic functionalisation of propane. The catalytic activity is highly dependent on the ligand, whereas ligand effects on the regioselectivity (n/iso) are much smaller.
