Lithiated Derivative Research Articles

Electrochemical lithiation/delithiation kinetics and capacity of phosphate tungsten bronze and its chemically pre-lithiated derivatives in aqueous solutions

Monophosphate bronze (PW8O26, WPB) was synthesized by low-temperature (650 °C) heating of 12-tungstophosphoric acid (WPA). Its lithiated derivative with a low lithium content (Li3-WPB) was synthesized by heating lithium salt of WPA at 650 °C. Its lithiated derivative with a high lithium content was synthesized by mechanochemical lithiation of Li3WPB (Lin-WPB) (n > 3), followed by heat treatment at 650 °C. X-ray powder diffraction analysis confirmed that the bronze structure changed with the increase of the incorporated lithium content. These bronzes were investigated from the aspect of lithiation/delithiation kinetics in an aqueous saturated LiNO3 electrolyte solution. By cyclic voltammetry, both the kinetics of intercalation/deintercalation and the coulombic capacity were found to decrease with the increase of initial lithium content, in agreement with literature data for electrochemically lithiated tungstophosphate bronzes. Monoclinic lithium-free bronze PW8O26, as the most promising material, was subjected to a further detailed galvanostatic investigation coupled with the LiFe0.95V0.05PO4/C composite as a cathode material in an aqueous battery. In comparison to its behavior in an organic electrolyte, a considerably lower initial capacity of the bronze electrode was measured. However, its cyclic stability was much better in an aqueous than in an organic electrolyte.

Trimethylsilyldiazomethane in the preparation of diazoketones via mixed anhydride and coupling reagent methods: a new approach to the Arndt–Eistert synthesis

Reaction of trimethylsilyldiazomethane with a mixed anhydride derived from a carboxylic acid by the action of ethyl chloroformate, yields the corresponding diazoketone in high yield. Subsequent Wolff rearrangement of the diazoketone leads to the homologated ester. Reaction of trimethylsilyldiazomethane with carboxylic acid–dicyclohexylcarbodiimide mixtures leads to the formation of diazoketone and trimethylsilylmethyl ester in equimolar ratio via an acid anhydride intermediate. The N-hydroxysuccinimide ester of the acid does not react with trimethylsilyldiazomethane or with its more reactive lithiated derivative.

Synthesis of [14C]‐labelled tolrestat(N‐[[5‐(trifluoromethyl)‐6‐methoxy‐1‐naphthalenyl]‐[14C]thioxomethyl]‐N‐methylglycine; AY‐27, 773)

Abstract[14C]‐Tolrestat(N‐[[5‐(trifluoromethyl)‐6‐methoxy‐1‐naphthalenyl]‐[14C]‐thioxomethyl]‐N‐methylglycine; [14C]AY‐27, 773), a new aldose reductase inhibitor, was prepared by incorporating [14C]carbon dioxide. The intermediate, 6‐methoxy‐5‐trifluoromethyl‐[1–14C]‐naphthoic acid, prepared by carbonation of the corresponding lithiated derivative, was condensed with sarcosine methyl ester hydrochloride, converted to the thioamide and hydrolyzed. [14C]Tolrestat, having a specific activity of 52.7 μCi/mg was obtained in 26% overall yield from [14C]barium carbonate and had a radiochemical purity of 97%.

Ein spiro-bicyclisehes Phosphor-ylid und sein korrespondierendes Phosphoniumkation / A Spiro-bicyclic Phosphorus Yhde and its Corresponding Phosphonium Cation

Abstract The spiro-bicyclic ylide (4) has been synthesized from 1-methyl - phosphorinane (5) via a phosphonium salt precursor [(CH2)5P⊕(CH3)-(CH2)4Br⊖Bre (6) which is cyclized with KH. Two other isomeric ylides (4 a , b) are detected in the reaction mixture by NMR spectroscopy. 4 is characterized by IR, MS, 1H, 13C and 31P NMR spectroscopy, and through conversion into the corresponding phosphonium cation [(CH2)5P(CH2)5]+ (7). A lithiated derivative (8) is obtained in the metalation reaction with LiCH3.