A simple and efficient method for the direct synthesis of nitriles from aldehydes using ammonium acetate as the nitrogen source has been developed. The reactions were performed with iodine as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant under mild conditions. A variety of aromatic, heteroaromatic, aliphatic and allylic aldehydes could be converted into their corresponding nitriles in good to excellent yields.

A simple synthesis method of nitriles from corresponding aldehydes by electrochemical oxidation was developed with ammonium acetate as the nitrogen source and 4-acetamido- 2,2,6,6-tetramethylpiperidinyl-l-oxy (4-AcNH-TEMPO) as the catalyst. Cyclic voltammetry was performed to investigate the electrocatalytic activity of 4-AcNH-TEMPO for the conversion of benzaldehyde to benzonitrile. On the basis of in situ FTIR data and cyclic voltammetry experiments, a reaction mechanism, involving the redox of 4-AcNH-TEMPO and the generation of intermediate imine during the reaction, was proposed. This electrocatalytic reaction system provided an efficient protocol for synthesis of aromatic nitriles at room temperature with moderate to high yields.

•A novel electrochemical route to generate nitriles from aldehydes under mild conditions using a catalytic amount of TEMPO as the mediator and hexamethyldisilazane as the nitrogen source in the presence of acetic acid has been developed.•A plausible reaction mechanism is proposed based on the cyclic voltammetry, in situ FTIR and the confirmed intermediates.A novel electrochemical route to generate nitriles from aldehydes under mild conditions using a catalytic amount of TEMPO (2,2,6,6-tetramethylpiperidinyl-l-oxy) as the mediator and hexamethyldisilazane as the nitrogen source in the presence of acetic acid has been developed. A variety of aromatic, heteroaromatic and aliphatic aldehydes have been converted to their corresponding nitriles in good to excellent yields. A plausible reaction mechanism is proposed based on the cyclic voltammetry, in situ FTIR and the identification of intermediates.

•Synthesis of 3-sulfenylindoles from indoles and thiols.•Iodine as the catalyst and DMSO as the oxidant.•A wide range of substrates can be used.•Good to excellent yields can be obtained.•Easy operation and metal-free reaction conditions.An iodine-catalyzed regioselective sulfenylation of indoles in the presence of DMSO has been presented. Various indoles can react with aryl thiols or alkyl thiols to afford their corresponding 3-sulfenylindoles in good to excellent yields. The notable features of this protocol include easy operation, metal-free reaction conditions, and excellent functional group tolerance.An iodine-catalyzed regioselective sulfenylation of indoles in the presence of DMSO has been presented. Various indoles can react with aryl thiols or alkyl thiols to afford their corresponding 3-sulfenylindoles in good to excellent yields. The notable features of this protocol include easy operation, metal-free reaction conditions, and excellent functional group tolerance.

The derivative monomer of pyrrole with the side chain nitroxyl radical, 4-(3-(pyrrol-1-yl)propionamido)-2,2,6,6-tetramethylpiperidin-1-yloxy (PyATEMPO) was synthesized. Its corresponding polymer PPyATEMPO was successfully prepared by cyclic voltammetry on Pt electrode in NaClO4/CH3CN solution. The PPyATEMPO electrode showed high electrocatalytic activity for oxidation of benzyl alcohol in the presence of the Lewis base 2,6-lutidine. To further investigation, in situ Fourier transform infrared (FTIR) spectroscopy technique was applied to study the possible electrochemical oxidation mechanism of benzyl alcohol on PPyATEMPO electrode. It showed that the benzyl alcohol was selectively oxidized to benzaldehyde in the action of PPyATEMPO film.

Cyclic voltammetry and in situ FTIR were employed to study the electrochemical hydrodebromination (EHB) mechanism of 2,5-dibromobenzoic acid (2,5-DBBA) in NaOH solution. Compared with titanium and graphite electrodes, silver electrode exhibited a high electrocatalytic activity for the hydrodebromination reaction of 2,5-DBBA. On the basis of in situ FTIR data, EHB reaction of 2,5-DBBA on Ag cathode might be represented as a sequence of electron additions and bromine expulsions. Firstly, from potential at approximately −1100 mV, 2,5-DBBA received an electron to form 2,5-DBBA radical anion, which lost a bromine ion in the 2-position to form 3-bromobenzoic acid (3-BBA) free radical. Then the free radical received a proton to give 3-BBA. Finally, 3-BBA further took off another bromine ion to produce benzoic acid free radical and the end product benzoic acid was obtained by receiving another electron and a proton with the potential shifting to more negative values.Research highlights► Silver is a good catalyst for the hydrodebromination of 2,5-dibromobenzoic acid. ► 3-Bromobenzoic acid as main intermediate product. ► The finally product is benzoic acid. ► In situ FTIR is useful to study the electrochemical hydrodebromination mechanism.

A facile approach to improve the electrocatalytic properties of Pt nanoparticles (nm-Pts) has been developed. nm-Pts are deposited on substrate electrode Pt sheet using cyclic voltammetry in sulfuric acid containing H2PtCl6 to get nm-Pt electrode, and then are modified with polypyrrole in an ionic liquid 1-ethylimidazolium trifluoroacetate (PPy-HEImTfa) to obtain the electrode PPy-HEImTfa/nm-Pt. The electrocatalytic performance of PPy-HEImTfa/nm-Pt towards the oxidation of formaldehyde in acidic solution has been studied by cyclic voltammetry and in situ FTIR spectroscopy. Results show that PPy-HEImTfa/nm-Pt exhibits high electrocatalytic activity and stability, as compared with nm-Pt electrode or PPy-HEImTfa modified with nm-Pts (nm-Pt/PPy-HEImTfa) under the similar preparation conditions. In situ FTIR spectroscopic measurements confirm that PPy-HEImTfa film on the surface of nm-Pts help to catalyze the oxidation of the adsorbed CO and reduced the poisoning effect of CO on nm-Pt catalyst.Highlights► Pt nanoparticles are modified with polypyrrole in 1-ethylimidazolium trifluoroacetate. ► The electrocatalytic activity towards formaldehyde oxidation is improved. ► The poisoning effect of CO on the electrode is reduced. ► Cyclic voltammetry and in situ FTIR spectroscopy are used.

The electrochemical hydrodechlorination reaction from starting material 3,4,5,6-tetrachloropicolinic acid (3,4,5,6-TCP) to the end product 3,6-dichloropicolinic acid (3,6-DCP) was investigated by cyclic voltammetry and in situ Fourier transform infrared spectroscopy (in situ FTIR). Compared with copper and glassy carbon, Ag cathode showed a high electrocatalytic activity for the irreversible reduction process of 3,4,5,6-TCP in NaOH aqueous solution. In situ FTIR results suggested that electrochemical hydrodechlorination took place in the 4- or 5-position of 3,4,5,6-TCP on Ag cathode after receiving an electron to get mixed trichloropicolinic acid free radical, which could receive another electron and give 3,5,6-trichloropicolinic acid (3,5,6-TCP) and 3,4,6-trichloropicolinic acid (3,4,6-TCP) at the potential more positive than −1000 mV afterwards. Finally, 3,5,6-TCP and 3,4,6-TCP were further dechlorinated to produce 3,6-dichloropicolinic acid (3,6-DCP) at the potential more negative than −1000 mV. Further studies of preparative electrolysis experiments by constant current electrolysis were carried out. The results were in good agreement with those from in situ FTIR investigations.

A Bronsted acidic ionic liquid 1-ethylimidazolium trifluoroacetate (HEImTfa) was prepared with high yield and used as a novel electrolyte for electropolymerization of aniline. HEImTfa played an important role in increasing the electrochemical polymerization rate of aniline. Scanning electron microscopy results showed that polyaniline prepared in HEImTfa (PAN–HEImTfa) was composed of significantly regulated nano-structures, which was smooth and homogeneous with a perfect-adhesion to Pt matrix. The electrocatalytic activity of PAN–HEImTfa for oxidation of formic acid was quite high and stable.