Facile and clean electrochemical synthesis of new acetaminophen derivatives through electrochemical oxidation of acetaminophen in the presence of thiouracil derivatives

The electrochemical oxidation of acetaminophen (1a) is carried out in the presence of thiouracil derivatives (3a–c), as nucleophiles, in an acetate buffer solution (0.15?M, pH 5) mixed with Dimethylformamide (DMF) using cyclic voltammetry and coulometry under a constant potential. The results obtained indicate that N-acetyl-p-benzoquinone-imine derived from acetaminophen participates in a 1,4-Michael-type addition reaction with thiouracils to form the corresponding acetaminophen derivatives (4a–c) in good yields and with high purities using a facile, catalyst-free, and one-pot electrochemical method using three carbon electrodes in an undivided cell under mild conditions. The products obtained were characterized after purification by IR, ¹H NMR, and ¹³C NMR spectroscopies, and by the elemental analysis method.     

Electrochemical synthesis of new catechol derivatives

Electrochemical oxidation of catechols (1a-e) has been studied in the presence of 2-acetylcyclopentanone (3) as a nucleophile in aqueous solutions, using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinones derived from catechols (1a-e), participate in Michael addition reactions with anion of 2-acetylcyclopentanone (3) and via EC mechanism pathway, converted to corresponding catechol derivatives (4a-e). In this work, we derived novel catechol derivatives with good yields based on electrochemical oxidation in aqueous solutions, at carbon electrode in an undivided cell, using environmentally friendly method.     

Electrooxidation of 4-methylcatechol in the presence of barbituric acid derivatives

Electrooxidation of 4-methylcatechol (1) in the presence of 1,3-dimethylbarbituric acid (2a) and 1,3-diethylthiobarbituric acid (2b) as nucleophiles has been studied in detail by cyclic voltammetry and controlled-potential coulometry. The results indicate that 1 can be oxidized to its related o-benzoquinone (1a) and without conversion to its quinone methide tautomeric form, via an ECEC mechanism pathway, is converted to barbiturate derivatives (5a-b). The electrochemical synthesis of 5a-b have been successfully performed in one-pot in an undivided cell.     

Mechanistic study of electrochemical oxidation of 4-tert-butylcatechol: A facile electrochemical method for the synthesis of new trimer of 4-tert-butylcatechol

The electrochemical trimerization of 4-tert-butylcatechol via anodic oxidation of 4-tert-butylcatechol (1) is described. The mechanism of trimerization has been studied in aqueous solution using cyclic voltammetry and controlled-potential coulometry. The electrochemical synthesis of trimer 3a has been successfully performed in an undivided cell in good yield and purity.     

Thin-layer electrochemistry of ferrocenylbenzene derivatives: Intramolecular electronic communication

Three arylferrocene derivatives, ferrocenylbenzene (MFcB), 1,3-diferrocenylbenzene (DFcB), and 1,3,5-triferrocenylbenzene (TFcB), were prepared and their redox properties systematically explored by thin-layer cyclic voltammetry (CV) and differential-pulse voltammetry (DPV). In contrast to conventional CV measurements that produced only a single pair of redox waves for all three compounds, the thin-layer technique discriminated between the multistep electron-transfer processes of DFcB and TFcB. In particular, two and three pairs of symmetric peaks were observed, respectively, when CV curves were recorded at a graphite electrode coated with a DFcB-containing and a TFcB-containing thin film of nitrobenzene and immersed in aqueous sodium perchlorate solution. These results demonstrate that the ferrocenyl moieties attached to the meta-positions of a benzene ring communicate electronically with each other, as a result of their distinct face-to-face orientations.     

A new facile electrochemical method for the synthesis of 4-(pyridine-2-ylthio)benzene-l,2-diols

Electrochemical oxidation of catechols (1a-1c) has been studied in the presence of 2-mercaptopyridine (3) as a nucleophile in water solution using cyclic voltammetry and controlled-potential coulometry. The results revealed that the quinones derived from catechols (1a-1c) participate in Michael addition reaction with 2-mercaptopyridine (3) and converted to the corresponding (pyridine-2-ylthio)benzene-l,2-diol derivatives (4a-4c), via an EC mechanistic pathway. The electrochemical synthesis of compounds 4a-4c has been successfully performed at a carbon rod electrode and in an undivided cell with good yields and high purity.     

The electrochemical synthesis of polyaniline/polysulfone composite films and electrocatalytic activity for ascorbic acid oxidation

Polyaniline (PANI)/polysulfone (PSF) composite films with asymmetric porous structure were successfully prepared by electropolymerization. The back face (in contact with the electrode) of the freestanding composite film is green while the outer face is white. The chemical component and the morphology of the surfaces were characterized by FTIR spectra and scanning electron microscopy, respectively. It was shown that replicate films gave reproducible voltammetry in 0.5 M H₂SO₄. The influence of the electrolyte and the acidic concentration on the redox peak currents of polyaniline were investigated in detail. The composite film electrode showed good electrocatalytic activity for ascorbic acid, which the anodic overpotential was evidently reduced compared with that obtained at bare Pt electrode. The diffusion coefficient of ascorbic acid was 1.38 × 10⁻⁶ cm² s⁻¹.     

氯代苯胺的电化学合成进展

详细评述了近２０年国内外电化学法，特别是电化学还原法合成氯代苯胺的进展。     

Electrochemical oxidation of 4-morpholinoaniline in aqueous solutions: Synthesis of a new trimer of 4-morpholinoaniline

Electrochemical oxidation of 4-morpholinoaniline has been studied in various pHs using cyclic voltammetry and controlled-potential coulometry. The electrochemical trimerization of 4-morpholinoaniline is described and its mechanism has been studied in aqueous solution. This method provides a green, reagent-less, and environmentally friendly procedure with high atom economy, for the synthesis of “4-morpholinoaniline-trimer” using a carbon electrode in an undivided cell in good yield and purity.     

The influence of electrodes on the performance of light-emitting electrochemical cells

We demonstrate that the electrochemical properties of the electrode material can have a dramatic impact on the performance of light-emitting electrochemical cells (LECs). Specifically, we report results from planar wide-gap LECs containing a blend of poly(2-methoxy,5-(2′-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV), poly(ethylene oxide) and LiCF₃SO₃ as the active material. We find that Au electrodes are preferable over Al electrodes, since Au-electrode devices exhibit fast turn-on (i.e., p-n junction formation time) and clearly visible light emission during operation at 5 V and 360 K, while Al-electrode devices exhibit slow turn-on (due to a delayed onset of p-doping progression) and no visible light emission. These results are rationalized with a cyclic voltammetry study, which demonstrates that Al is oxidized at a lower potential than the p-doping (oxidation) potential of MEH-PPV, while Au is electrochemically inert over the entire voltage range spanned by the p- and n-doping potentials of MEH-PPV. Consequently, the oxidation charge injected into Al-electrode devices results in a combination of p-doping of MEH-PPV and formation of Al ions. The latter process is undesired since it results in a slow turn-on time and quenched light emission. Finally, we find that planar LECs in a bottom-electrode configuration exhibit a faster turn-on time than identical devices with the electrodes on top of the active material.     

Cyclic voltammetry and scanning electrochemical microscopy studies of the heterogeneous electron transfer reaction of some nitrosoaromatic compounds

The heterogeneous electron transfer reaction for the reduction of some nitroso aromatic derivatives in aqueous-alcoholic medium was studied on both mercury and glassy carbon electrodes (GCE) by using cyclic voltammetry (CV) and scanning electrochemical microscopy techniques (SECM).The nitrosoaromatic derivatives followed a two-electron two-proton mechanism producing a quasi-reversible overall process. This strongly pH dependent mechanism varied from ECCE mechanism at pH < 8.5 to ECEC mechanism at pH > 8.5.The apparent heterogeneous rate constant for the reduction of the nitroso derivatives was calculated using CV or SECM. The rate constant for the electron transfer process depends on the nature of the electrode material. The heterogeneous rate constant on the GCE is almost two orders of magnitude smaller than that on mercury electrode i.e. (3.4 ± 0.3) × 10⁻³ cm s⁻¹ on Hg and (7.0 ± 1.0) × 10⁻⁵ cm s⁻¹ on GCE, for the same nitroso compound and pH.The heterogeneous rate constant values were checked by comparison between experimental and simulated cyclic voltammograms.     

Electrochemical synthesis of polymers with alternate phenothiazine and bithiophene units

An electrochemical and spectroelectrochemical study of a new monomer—N-alkyl-bis(thiophene)phenotiazine have been presented. Electrochemical polymerization of the monomer leads to a polymer with alternate phenothiazine and bithiophene units. Polymerization proceeds after bielectronic oxidation of the molecule. Monoelectronic oxidation gives a stable radical cation with spin located on phenothiazine. Electrochemical properties of the polymer depend on the thickness of the film deposited on the electrode. For thin layers one can observe a characteristic redox couple of phenothiazine oxidation to a radical cation. Analysis of the polymer behaviour and the results of spectroelectrochemical measurements indicate a mixed-type of polymer conductivity.     

1,2,3,4-四氢喹啉类化合物合成与应用的研究进展

1,2,3,4-四氢喹啉类化合物是治疗心血管病药物和染料的中间体。综述了1,2,3,4-四氢喹啉类化合物合成及应用的研究进展,分析比较了氢化反应、Diels-Alder反应、多步反应、多组分反应、多米诺反应等合成方法的优缺点,讨论了1,2,3,4-四氢喹啉类化合物在药物化学和染料合成领域的应用现状,并对其研究前景进行了展望：发展具有原子经济性合成方法及光学纯1,2,3,4-四氢喹啉类化合物的合成及应用。     

(S)-对羟基苯基乳酸衍生物的合成进展

光学纯的(S)-对羟基苯基乳酸衍生物是合成新型抗糖尿病药物和混杂多肽的有价值的关键中间体。综述了合成(S)-对羟基苯基乳酸衍生物的各种方法,并分析了各种合成方法的优缺点。     

几种新型杯[4]芳烃衍生物的合成

以对叔丁基苯酚为起始原料,通过缩合、一步取代反应合成了对叔丁基杯[4]芳烃的衍生物,两步取代反应合成了对叔丁基杯[4]芳烃的衍生物。用FT-IR,^1HNMR,FAB-MS对产物的结构进行了表征。     

Different synthesis methods allow to tune the permeability and permselectivity of dopamine–melanin films to electrochemical probes

Different methods to prepare melanin films by dopamine oxidation are compared with respect to their permeability to electrochemical probes being either neutral or carrying a positive or a negative charge. To examine charge-dependence of the permeability differently charged probes of similar size (hexaamineruthenium, ferrocenemethanol and hexacyanoferrate) are employed. We deliberately not investigated the permeability of metal cations through the melanin films owing to their possible complexation by the catechol groups of melanin. The films prepared by solution oxydation methods (O₂ or Cu²⁺ as oxidants) are impermeable to hexacyanoferrate as soon as their thickness reaches 5–10 nm but remain permeable to hexaamineruthenium and ferrocenemethanol up to thickness reaching 25–40 nm before becoming also impermeable. The melanin films prepared by electrochemical deposition display a marked difference; they remain permeable to hexacyanoferrate up to 35 nm in thickness and to hexaamineruthenium and ferrocenemethanol up to the maximal thickness that can be reached by this deposition method. When the maximal film thickness of 45 nm is reached the film becomes also impermeable to these two redox probes. These results are explained on the basis of structural differences of the melanin films at the molecular level. The permselectivity of the melanin coatings is related to their negative surface charge density at the working pH of 7.5.     

3,4,5-三甲氧基苯甲酸衍生物的合成与结构表征

由没食子酸合成３，４，５－三甲氧基苯甲酰氯 ，然后 与醇和酚反应 ，合成了８个 ３,４，５－三甲氧基苯甲酸 类化合物。通过元素分析、ＩＲ ，１Ｈ ＮＭ Ｒ 和 Ｍ Ｓ 对其结构进行表征，并对 它们的裂解途径进行了探讨。     

液晶中间体环己酮衍生物合成及应用进展

环己酮衍生物在液晶显示材料中占有非常重要的地位。综述了近年来广泛应用的6种环己酮衍生物液晶中间体,即4-烷基环己酮,4-(反式-4-烷基环己基)环己酮,4-(4-烷基苯基)环己酮,4-[2-(反式-4-烷基环己基)乙基]环己酮,单乙二醇缩-1,4-环己二酮及单乙二醇缩-4,4’-双环己二酮,反式-6-烷基-2-十氢萘酮的合成方法及其在液晶合成中的应用进展。     

电化学氧化法制取烟酸的研究进展

介绍了直接电氧化法和间接电氧化法制取烟酸的原料及相应的电极反应,同时对直接电氧化法制取烟酸的电解槽、电极材料、离子交换膜及支持电解质等的研究进展进行了评述。直接电氧化法多采用Pt、PbO2和PbO2/Ti为阳极,Pb和Ni为阴极,离子交换膜为隔膜,电流效率可达70%。     

新型胆固醇侧部衍生物的合成研究

对胆固醇的双键进行环氧化,然后分别用4-溴丁酸、5-溴戊酸和6-溴己酸进行开环氧化,将柔性链键接到胆固醇的腰上,再分别与甲基丙烯酸钾进行反应,得到了3个新型的含柔性链腰接胆固醇的甲基丙烯酸酯衍生物单体,从而为合成新型的含胆固醇衍生物的聚合物研究奠定了基础。