57266-69-0Relevant articles and documents
Electrocatalytic dechlorination of chloropicolinic acid mixtures by using palladium-modified metal cathodes in aqueous solutions
Ma, Hongxing,Xu, Yinghua,Ding, Xufen,Liu, Qi,Ma, Chun-An
, p. 762 - 772 (2016)
In China, chloropicolinic acid (ClPA) mixtures comprising 3,5,6-trichloropicolinic acid, 3,6-dichloropicolinic acid (3,6-D), 3-ClPA, and 6-ClPA are discharged as organic wastes at a rate of approximately 300 tons per year. In this work, we developed an aqueous phase electrocatalytic hydrogenation (ECH) system based on Pd catalyst to dechlorinate the ClPA mixtures into picolinic acid (PA) at room temperature. Firstly, we evaluated the influence of cathode support and Pd loading on the catalytic performance of cathodes, as well as the effects of operating parameters on the intermediate product selectivity and dechlorination efficiency of the ECH process with 3,6-D as the target compound. Secondly, we analyzed the ECH dechlorination mechanism of 3,6-D with regard to the surface condition of cathode and catholyte pH, and the rate-limiting step of the dechlorination process was also discussed. Finally, we assessed the practicability of the ECH system to dechlorinate the ClPA mixtures into PA by using a plate-and-frame cell. Results demonstrated that Pd/Ni foam cathodes with Pd loading of 2.25-3.6 mg cm-2 exhibited the optimum ECH dechlorination performance, and the basic aqueous solution and high 3,6-D concentration favored the ECH process. The ClPA mixtures with 47 g L-1 concentration (the total concentration of ClPAs was approximately 250 mM) can be selectively dechlorinated into PA with 99% yield, 76.3% current efficiency, and 2.47 kW h kg-1 PA specific electric energy consumption at a current density of 208 A m-2 in a 1.25 M NaOH aqueous solution.
Directed lithiation of unprotected pyridinecarboxylic acids: Syntheses of halo derivatives
Lazaar, Jalal,Rebstock, Anne-Sophie,Mongin, Florence,Godard, Alain,Trécourt, Fran?ois,Marsais, Francis,Quéguiner, Guy
, p. 6723 - 6728 (2007/10/03)
Deprotonation of all isomeric lithium pyridinecarboxylates and subsequent trapping with hexachloroethane or iodine afforded straightforward access to chloro- and iodopyridinecarboxylic acids, respectively. Starting from lithium 5-bromonicotinate, the introduction of an iodine atom at C4 and further halogen migration allowed the potential of this method to be extended to the synthesis of more elaborate derivatives.
Application of organolithium compounds in organic synthesis. Part 19. Synthetic strategies based on aromatic metallation. A concise regiospecific synthesis of 3-halogenated picolinic and isonicotinic acids
Epsztajn,Plotka,Grabowska
, p. 1075 - 1086 (2007/10/03)
The synthesis of the halogenated picolin- and isonicotinalides (3) and (4) via metallation (n-BuLi) of the anilides (1) and (2) and then the reaction of the generated bis-lithiated anilides with halogenating agents (CCl3-CCl3, CH2Br-CH2Br, I2) followed by subsequent acidic hydrolysis of (3) and (4), as a way of regiospecific transformation of picoline and isonicotine acids into their C3-halogenated derivatives, is described.
