Cerium Triflate Research Articles

Cerium triflate as superoxide radical scavenger to improve cycle life of Li[sbnd]O2 battery

Cerium triflate (Ce(CF3SO3)3) is used as a superoxide radical scavenger in the ether-based liquid electrolyte for the LiO2 batteries. The radical scavenging capability of Ce3+ is evaluated both in potassium superoxide + crown solution and the LiO2 batteries. The chemical analyses further demonstrate cerium ions can effectively slow down the decomposition of electrolyte attacked by superoxide radicals. When the capacity is fixed to 1000 mAh g−1 at a current density of 500 mA g−1, the LiO2 battery with 1M LiTFSI-TEGDME electrolyte begins to drop its discharge voltage rapidly to 2.0 V near 40th cycle while the electrolyte with Ce3+ additives is still above 2.0 V after 88 cycles, demonstrating the cycle life of the LiO2 batteries show remarkably improved compared to the LiO2 batteries without any additive into electrolyte.

Influence of cerium triflate and glycerol on electrochemical performance of chitosan electrolytes for electrochromic devices

Polymer electrolytes based on chitosan, glycerol, and cerium triflate are prepared by solution casting technique, and their properties are studied by complex impedance spectroscopy, thermal analysis (DSC and TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The concentration of cerium triflate ranges between 0.00 and 55.72wt%. The DSC results reveal a thermal event between 128 and 145°C indicating a semi-crystalline nature of the samples. The best ionic conducting values of 1.46×10−6 and 8.74×10−5Scm−1 at 30 and 90°C, respectively are registered for the sample containing 33.32wt% of salt. Moreover, it is stated that an increase of glycerol amount promotes an increase of the ionic conductivity up to maximum values of 1.67×10−5 and 4.93×10−4Scm−1 at 30 and 90°C, respectively. SEM images show clusters formation for samples with high salt concentration, and X-Ray studies point a disappearance of large peak at 2θ≈20° and appearance of narrow one at 2θ≈10°, confirming crystalline domains formation. AFM results display the morphological characteristics of samples and 3.72nm was the value obtained for the sample with less roughness.

Fly ash-supported cerium triflate as an active recyclable solid acid catalyst for Friedel–Crafts acylation reaction

An efficient solid Lewis acid, has been synthesized by loading cerium triflate (7 wt%) on the acid activated fly ash with high silica content (81%). The physico-chemical properties of synthesized fly ash-supported cerium triflate catalyst (CFT) were monitored by XRD, FT-IR spectroscopy, FT-IR spectroscopy of the ammonia adsorbed catalyst, SEM-EDAX, TEM, Flame Atomic Absorption Spectrophotometer and TG-DTA study. The increased concentration of silica surface hydroxyl groups on activated fly ash have a major influence on the loading of cerium triflate. The catalytic activity of the catalyst CFT was tested in the acylation of veratrole using acetic anhydride as the acylating agent. The proposed model structure of CFT shows that the triflate species withdraws the electron density from the surface cerium making it electron deficit and generate Lewis acidity on the surface of fly ash as confirmed by NH 3 adsorbed FT-IR spectrum. The activity data indicate that this heterogeneous catalyst is very active, corresponding to high conversion (88%) of veratrole to 3,4-dimethoxyacetophenone. The catalyst could be easily recovered and reused giving similar conversion up to three reaction cycles indicating its stability under experimental conditions. Thus fly ash-supported cerium triflate is a novel and efficient catalyst and is a promising way of bulk utilization of waste fly ash by developing cost effective catalyst system for industrially important Friedel–Crafts acylation reactions.

ChemInform Abstract: Cerium Triflate: An Efficient and Recyclable Catalyst for Chemoselective Thioacetalization of Carbonyl Compounds under Solvent‐Free Conditions.

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Cerium Triflate: An Efficient and Recyclable Catalyst for Chemoselective Thioacetalization of Carbonyl Compounds under Solvent-Free Conditions

A simple and efficient chemoselective thioacetalization of carbonyl compounds has been achieved using Ce(OTf)3 (10 mol-%) as a catalyst under solvent-free conditions. Advantages of the methodology include very short reaction times, excellent yields, the catalytic use of a water tolerant Lewis acid, and simple recovery and reuse of the catalyst.

Organometallic Cerium Complexes from Tetravalent Coordination Complexes

AbstractThe use of tetravalent cerium alkoxides, nitrates, and triflates was studied as a direct route to [CeIV(carbene)] complexes. Protonolysis reactions between 1H‐imidazolium‐ or imidazoline (=4,5‐dihydro‐1H‐imidazole)‐containing alkoxide proligands HL (L=OCMe2CH2[1‐C(NCHCHNiPr)]) and HLS (LS=OCMe2CH2[1‐C(NCH2CH2NiPr)]) and CeIV tert‐butoxide, triflate, and nitrate compounds were studied to target [CeIV(N‐heterocyclic carbene)] complexes (of unsaturated and saturated carbenes, resp.). Instead, tetravalent cerium imidazolium [(OtBu)3Ce(μ‐OtBu)2(μ‐HL)Ce(OtBu)3], or imidazolinium adducts [(OtBu)3Ce(μ‐OtBu)2(μ‐HLS)Ce(OtBu)3] were isolated. However, the salt metathesis of cerium triflate with KL provided a simple route to [CeL4], which was significantly improved if an external oxidant, benzoquinone, was included in the mixture to maintain oxidation‐state integrity. Likewise, the salt metathesis of cerium triiodide with KL and added benzoquinone provided a straightforward route to [CeL4].

Ring-opening polymerization of lactones by rare-earth metal triflates and by their reusable system in ionic liquids

The ring-opening polymerizations (ROPs) of lactones catalyzed by rare-earth metal trifluoromethanesulfonates (triflates) (RE(OTf) 3) were examined. Among various complexes, scandium triflate (Sc(OTf) 3) emerged as an effective catalyst in toluene. The ROP of lactones by Sc(OTf) 3 proceeded in a living fashion, and the number of polymer molecules was controlled by the amount of protic additives such as benzyl alcohol and H 2O. In other words, one molecule of Sc(OTf) 3 catalytically produced a number of polymer molecules (up to 40 molecules) depending on the amount of protic additives. The plausible mechanism was depicted as an activated monomer mechanism. The polylactones with a number-average molecular weight over 25,000 were successfully synthesized. Immobilization of RE(OTf) 3 was investigated in three ionic liquids, and cerium triflate (Ce(OTf) 4) showed relatively high catalytic activity in a biphasic system of 1-butyl-3-methylimidazolium hexafluoroantimonate and toluene in the ROP of ɛ-caprolactone (CL). The ionic liquid containing Ce(OTf) 4 was used, at least three times, in the ROP of CL without losing catalytic activity.

Why has Cerium (III) Triflate been Forgotten Among the Catalysts for the Friedel-Crafts Acylation?

Cerium is the less rare earth; its salts are commercially available and inexpensive. However, screening of lanthanide triflates as Lewis acid catalysts in the Friedel-Crafts acylation of aromatics skipped cerium triflate. Now, catalytic Friedel-Crafts acylations of activated benzenes are performed by using cerium (III) triflate as catalyst. For less activated arenes, addition of lithium perchlorate as co-catalyst is required. In all cases aromatic ketones are obtained in very good yields.

Cerium(III) Triflate versus Cerium(III) Chloride: Anion Dependence of Lewis Acid Behavior in the Deprotection of PMB Ethers.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cerium(III) Triflate versus Cerium(III) Chloride: Anion Dependence of Lewis Acid Behavior in the Deprotection of PMB Ethers

AbstractCerium(III) triflate deprotects p‐methoxybenzyl ethers of simple alcohols better than the cerium(III) chloride/sodium iodide system. It can be used in 1% M instead of equimolecular amounts, giving better yields. Aromatic alcohols rearrange, but the addition of a scavenger overcomes this drawback. Unfortunately, unsaturated alcohols are deprotected with decomposition, probably due to side electrophilic additions to double bonds. A comparison between the mechanisms of cerium triflate and cerium chloride is reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Direct Formation of Tetrahydropyranols via Catalysis in Ionic Liquid.

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Direct formation of tetrahydropyranols via catalysis in ionic liquid

Utilizing a simple homoallyl alcohol and an aldehyde in the presence of a catalytic amount of cerium triflate, the direct stereoselective formation of tetrahydropyranol derivatives in ionic liquid is reported.