TY - JOUR
T1 - Electrochemical oxidation of amines using a nitroxyl radical catalyst and the electroanalysis of lidocaine
AU - Sato, Katsuhiko
AU - Ono, Tetsuya
AU - Sasano, Yusuke
AU - Sato, Fumiya
AU - Kumano, Masayuki
AU - Yoshida, Kentaro
AU - Dairaku, Takenori
AU - Iwabuchi, Yoshiharu
AU - Kashiwagi, Yoshitomo
N1 - Funding Information:
Funding: This work was supported by JSPS KAKENHI Grant Number JP18K19936 and by the Foundation for Ohu University Joint Research Fund.
Publisher Copyright:
© 2018 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2018/12
Y1 - 2018/12
N2 - The nitroxyl radical of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) can electro-oxidize not only alcohols but also amines. However, TEMPO has low activity in a neutral aqueous solution due to the large steric hindrance around the nitroxyl radical, which is the active site. Therefore, nortropine N-oxyl (NNO) was synthesized to improve the catalytic ability of TEMPO and to investigate the electrolytic oxidation effect on amines from anodic current changes. Ethylamine, diethylamine, triethylamine, tetraethylamine, isopropylamine, and tert-butylamine were investigated. The results indicated that TEMPO produced no response current for any of the amines under physiological conditions; however, NNO did function as an electrolytic oxidation catalyst for diethylamine, triethylamine, and isopropylamine. The anodic current depended on amine concentration, which suggests that NNO can be used as an electrochemical sensor for amine compounds. In addition, electrochemical detection of lidocaine, a local anesthetic containing a tertiary amine structure, was demonstrated using NNO with a calibration curve of 0.1–10 mM.
AB - The nitroxyl radical of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) can electro-oxidize not only alcohols but also amines. However, TEMPO has low activity in a neutral aqueous solution due to the large steric hindrance around the nitroxyl radical, which is the active site. Therefore, nortropine N-oxyl (NNO) was synthesized to improve the catalytic ability of TEMPO and to investigate the electrolytic oxidation effect on amines from anodic current changes. Ethylamine, diethylamine, triethylamine, tetraethylamine, isopropylamine, and tert-butylamine were investigated. The results indicated that TEMPO produced no response current for any of the amines under physiological conditions; however, NNO did function as an electrolytic oxidation catalyst for diethylamine, triethylamine, and isopropylamine. The anodic current depended on amine concentration, which suggests that NNO can be used as an electrochemical sensor for amine compounds. In addition, electrochemical detection of lidocaine, a local anesthetic containing a tertiary amine structure, was demonstrated using NNO with a calibration curve of 0.1–10 mM.
KW - Electrocatalytic oxidation
KW - Lidocaine
KW - Nitroxyl radical
KW - Sensor
KW - TEMPO
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U2 - 10.3390/catal8120649
DO - 10.3390/catal8120649
M3 - Article
AN - SCOPUS:85062534411
SN - 2073-4344
VL - 8
JO - Catalysts
JF - Catalysts
IS - 12
M1 - 649
ER -