764-71-6Relevant articles and documents
A cyclometalated Ir(iii)-NHC complex as a recyclable catalyst for acceptorless dehydrogenation of alcohols to carboxylic acids
Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
, p. 16866 - 16876 (2020/12/18)
In this work, we have synthesized two new [C, C] cyclometalated Ir(iii)-NHC complexes, [IrCp?(C∧C:NHC)Br](1a,b), [Cp? = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C-H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1?:?5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study.
Fatty acid potassium had beneficial bactericidal effects and removed Staphylococcus aureus biofilms while exhibiting reduced cytotoxicity towards mouse fibroblasts and human keratinocytes
Kawahara, Takayoshi,Takita, Miki,Masunaga, Akihiro,Morita, Hayato,Tsukatani, Tadayuki,Nakazawa, Kohji,Go, Daisuke,Akita, Sadanori
, (2019/03/29)
Wounds frequently become infected or contaminated with bacteria. Potassium oleate (C18:1K), a type of fatty acid potassium, caused >4 log colony-forming unit (CFU)/mL reductions in the numbers of Staphylococcus aureus and Escherichia coli within 10 min and a >2 log CFU/mL reduction in the number of Clostridium difficile within 1 min. C18:1K (proportion removed: 90.3%) was significantly more effective at removing Staphylococcus aureus biofilms than the synthetic surfactant detergents sodium lauryl ether sulfate (SLES) (74.8%, p 0.01) and sodium lauryl sulfate (SLS) (78.0%, p 0.05). In the WST (water-soluble tetrazolium) assay, mouse fibroblasts (BALB/3T3 clone A31) in C18:1K (relative viability vs. control: 102.8%) demonstrated a significantly higher viability than those in SLES (30.1%) or SLS (18.1%, p 0.05). In a lactate dehydrogenase (LDH) leakage assay, C18:1K (relative leakage vs. control: 108.9%) was found to be associated with a significantly lower LDH leakage from mouse fibroblasts than SLES or SLS (720.6% and 523.4%, respectively; p 0.05). Potassium oleate demonstrated bactericidal effects against various species including Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Clostridium difficile; removed significantly greater amounts of Staphylococcus aureus biofilm material than SLES and SLS; and maintained fibroblast viability; therefore, it might be useful for wound cleaning and peri-wound skin.
Iridium catalysts for acceptorless dehydrogenation of alcohols to carboxylic acids: Scope and mechanism
Cherepakhin, Valeriy,Williams, Travis J.
, p. 3754 - 3763 (2018/05/23)
We introduce iridium-based conditions for the conversion of primary alcohols to potassium carboxylates (or carboxylic acids) in the presence of potassium hydroxide and either [Ir(2-PyCH2(C4H5N2))(COD)]OTf (1) or [Ir(2-PyCH2PBu2t)(COD)]OTf (2). The method provides both aliphatic and benzylic carboxylates in high yield and with outstanding functional group tolerance. We illustrate the application of this method to a diverse variety of primary alcohols, including those involving heterocycles and even free amines. Complex 2 reacts with alcohols to form the crystallographically characterized catalytic intermediates [IrH(η1,η3-C8H12)(2-PyCH2PtBu2)] (2a) and [Ir2H3(CO)(2-PyCH2PtBu2){μ-(C5H3N)CH2PtBu2}] (2c). The unexpected similarities in reactivities of 1 and 2 in this reaction, along with synthetic studies on several of our iridium intermediates, enable us to form a general proposal of the mechanisms of catalyst activation that govern the disparate reactivities of 1 and 2, respectively, in glycerol and formic acid dehydrogenation. Moreover, careful analysis of the organic intermediates in the oxidation sequence enable new insights into the role of Tishchenko and Cannizzaro reactions in the overall oxidation.
