Amines, aromatic electrochemical

Galceran, M. T., Pais, P., and Puignas, L., High-performance liquid chromatographic determination of ten heterocychc aromatic amines with electrochemical detection, J. Chromatogr. A, 655, 101-110, 1993. 

Scheme 2.10 S5mthesis of functionalized aromatic primary amines by electrochemical C-H amination...

Electropolymerization is also an attractive method for the preparation of modified electrodes. In this case it is necessary that the forming film is conductive or permeable for supporting electrolyte and substrates. Film formation of nonelectroactive polymers can proceed until diffusion of electroactive species to the electrode surface becomes negligible. Thus, a variety of nonconducting thin films have been obtained by electrochemical oxidation of aromatic phenols and amines Some of these polymers have ligand properties and can be made electroactive by subsequent inincorporation of transition metal ions... 

Reynolds R, Line LL, Nelson RF (1974) Electrochemical generation of carbazoles from aromatic amines. J Am Chem Soc 96(4) 1087-1092... 

Zanoni MVB, Stradiotto NR (2005) Electrochemical behaviour of aromatic amines protected by nitrobenzenesulfonyl group. Electroanalysis 7(4) 365-369... 

Dvorak V, Nemek I, Zyka J (1967) Electrochemical oxidation of some aromatic amines in acetonitrile medium II. benzidine, N,N,N ,N -tetramethylbenzidine, and 1,4-phenylene-diamine derivatives. Microchem J 12 324-349... 

On occasion such reductive deprotection processes can be quite selective. Electrochemical reduction of A,A -di-p-toluenesulfonyl-A-t-butoxycarbonyl derivatives of aliphatic and aromatic diamines selectively removed the p-toluenesulfonyl group attached to a primary amine site63. Yields on the mono-protected products are fair to high selective deprotection of the corresponding A,A -dibenzoyl derivatives occurred in yields >92%. 

Accordingly, many reactions can be performed on the sidewalls of the CNTs, such as halogenation, hydrogenation, radical, electrophilic and nucleophilic additions, and so on [25, 37, 39, 42-44]. Exhaustively explored examples are the nitrene cycloaddition, the 1,3-dipolar cycloaddition reaction (with azomethinylides), radical additions using diazonium salts or radical addition of aromatic/phenyl primary amines. The aryl diazonium reduction can be performed by electrochemical means by forming a phenyl radical (by the extrusion of N2) that couples to a double bond [44]. Similarly, electrochemical oxidation of aromatic or aliphatic primary amines yields an amine radical that can be added to the double bond on the carbon surface. The direct covalent attachment of functional moieties to the sidewalls strongly enhances the solubility of the nanotubes in solvents and can also be tailored for different... 

It should be noted that the electrochemical measurements (corrosion potential and conductivity) for the two novolac epoxies cured with an aromatic amine from different sources showed good agreement, although the tensile adhesion and weight gain values were not as reproducible. 

Barek et al. have reported on the determination of AT-nitroso compounds, azo compounds, heterocychcs, aromatic nitro compounds, heterocychc amines and even benzyl chloride using electrochemical methods such as voltammetry and polarog-raphy. The nitro and AT-nitroso compounds work particularly well in reductive mode [47, 48]. For appropriate analytes, adsorptive stripping voltammetry and anodic stripping voltammetry can give orders of magnitude lower detection hmits than are available from HPLC with electrochemical detection [48]. 

A -nitroso cpds, azo cpds, heterocyclics, aromatic nitro cpds, heterocyclic amines Environment analysis SPE Electrochemical methods [47]... 

A typical electrochemical reaction for an aromatic amine (benzidine) is shown in Figure 2. Most of the HPLC/EC work to date has been conducted using carbon working electrodes and thus the oxidative mode of the detector has been exploited (e.g. for benzidine) to the greatest extent. However, platinum and mercury have been used successfully for electroreducible species such as metal ions =/ and parathionC .). ... 

In a similar way it is possible to perform the amination of aromatics by indirect electrochemical reduction of hydroxylamine using a combination of the Cu /Cu and redox pairs Thus, aniline and toluidine are formed from benzene... 

Technically interesting are the indirect electrochemical oxidations of benzylic alcohols (Table 11, No. 15-18) benzaldehyde dimethylacetals (Table 11, No. 19) and alkyl aromatic compounds (Table 11, No. 20, 21) It could be proven that benzylic alcohols are oxidizable using tris(2,4-dibromophenyl)amine as mediator not only in acetonitrile in a divided cell but also in methanol in an undivided cell... 

Since proton addition is known (3, 4) to be a rate-determining step in the chemical reduction of aromatic and olefinic double bonds in the alkali-amine system, the effect of adding a proton donor (ferf-butyl alcohol) on current efficiency in the electrochemical reduction of 1-decene was investigated. 

A recent development31 is the preparation of metal polymer complexes directly on the electrode via the electrochemically induced polymerization of the metal complex. Ruthenium(II) and osmium(II) complexes with ligands containing aromatic amines, e.g. 3- or 4-aminopyridine or 5-amino-1,10-phenanthroline, are electrochemically polymerized to yield a film of the metal polymer on the electrode surface. The polymerization involves free radicals, which are formed via the initial oxidation of the metal complex to a radical cation and subsequent reaction of the radical cation with a base to yield the free radical. 

LCEC systems are used for a wide variety of applications, many of which have been published [1,32]. Space does not permit a thorough review however, it is possible to generalize by considering the classes of compounds that have most frequently been studied phenols, aromatic amines, thiols, quinones, and nitro compounds. By analogy with liquid chromatography with UV detection (LCUV), it is frequently desirable to obtain an electrochemical spectrum of a compound to assess Its suitability for LCEC. Cyclic voltammetry (CV) is the electrochemical equivalent of spectroscopy (Chap. 3). It is useful to carry out CV experiments in several possible mobile phases, since electrochemical reactions can be very dependent on the medium. 

---