Trimythyllead chloride dissociation in aqueous and methanolic solutions

The dissociation constants of (CH₃)₃PbCl at 26°C in water and in methanol have been determined to be 0.51 mol/l and 4.65 x 10 ^-4 mol/l, respectively, from the variations of Pb NMR chemical shifts (by INDOR) with concentration. Chemical shifts to (CH₃)₄Pb have been obtained for (CH₃)₃PbCl, for solvated (CH₃)₃Pb⁺, and for a possible dimer [(CH₃)₃PbCl]₂ formed in methanol.     

Synthesis,storage, and transfer of [210Pb]-(CH3)3PbCl across tomato fruit cuticle

An improved synthetic route to [²¹⁰Pb]-(CH₃)₃PbCl is described in which chelated ²¹⁰Pb²⁺ is methylated to [²¹⁰Pb]-(CH₃)₄Pb with methylmagnesium bromide (CH₃MgBr) in the presence of methyl iodide. Controlled oxidation of the product with anhydrous hydrochloric acid and purification of the crude product by reversed-phase high-pressure liquid chromotography (HPLC) resulted in [²¹⁰Pb]-(CH₃)₃PbCl in 71% radiochemical yield. Whereas storage of the purified product at ?10 °C resulted in complete conversion to Pb²⁺ during one year, storage in 20% acetic acid at 4 °C resulted in less than 15% decomposition during six months. Periodic complexometric extractions to remove ²¹⁰Pb radioactive daughters (²¹⁰Bi, 100% β, E_max = 1.16 MeV; ²¹⁰Po, 100% α, E = 5.305 MeV) from the storage solution did not alter the rate of decomposition. The rate of translocation of [²¹⁰Pb]-(CH₃)₃Pb⁺ across an isolated tomato cuticle was approximately twice the rate of transfer of inorganic lead(II) and was not influenced by the presence of increasing amounts of disodium ethylenediamine-tetra-acetate.     

Kronenetherkomplexe von Blei(II). Die Kristallstrukturen von [PbCl(18-Krone-6)][SbCl6], [Pb(18-Krone-6)(CH3CN)3][SbCl6]2, and [Pb(15-Krone-5)2][SbCl6]2

Crown Ether Complexes of Lead(II). The Crystal Structures of [PbCl(18-Krone-6)][SbCl₆], [Pb(18-Krone-6)(CH₃CN)₃][SbCl₆]₂ und [Pb(15-Krone-5)₂][SbCl₆]₂ . [PbCl(18-crown-6)][SbCl₆] has been prepared in low yield besides [Pb(CH₃)₂(18-crown-6)][SbCl₆]₂ by the reaction of Pb(CH₃)₂Cl₂ with antimony pentachloride in acetonitrile solution in the presence of 18-crown-6, forming pale-yellow crystals. The other two title compounds are formed as colourless crystals by the reaction of PbCl₂ with antimony pentachloride in acetonitrile solutions in the presence of 18-crown-6 and 15-crown-5, respectively. The complexes were characterized by IR spectroscopy and by crystal structure determinations. [PbCl(18-crown-6)][SbCl₆]: Space group P2₁/c, Z = 8, 5 003 observed unique reflections, R = 0.046. Lattice dimensions at - 80°C: a = 1 386.9; b = 1 642.7; c = 2 172.1 pm, β = 92.95°. The lead atom in the cation [PbCl(18-crown-6)]⁺ is surrounded in an almost hexagonal-planar construction by the six oxygen atoms of the crown ether and an axially oriented Cl atom. [Pb(18-crown-6)(CH₃CN)₃][SbCl₆]₂: Space group P1 , Z = 2, 6 128 observed unique reflections, R = 0.076. Lattice dimensions at - 70°C: a = 1 228.0; b = 1 422.9; c = 1 463.2 pm, α = 69.08°; β = 65.71°; γ = 64.51°. In the cation [Pb(18-crown-6)(CH₃CN)₃]²⁺ the lead atom is coordinated by the six oxygen atoms of the crown ether and by the three nitrogen atoms of the acetonitrile molecules. The structure determination is restricted by disorder. [Pb( 15-crown-5)₂][SbCI₆]₂: Space group P6₃/m, Z = 6, 5 857 observed unique reflections, R = 0.059. Lattice dimensions at -70°C: a = b = 2 198.5; c = 1499.4 pm, α = β = 90°, γ = 120°. In the cation [Pb(l5-crown-5)₂]² the lead atom is sandwich-like coordinated by the ten oxygen atoms of the two crown ether molecules. The structure determination is restricted by disorder.     

The hydroxyl radical reaction rate constant and atmospheric transformation products of 2-butanol and 2-pentanol

The relative rate technique has been used to measure the hydroxyl radical (OH) reaction rate constant of +2-butanol (2BU, CH₃CH₂CH(OH)CH₃) and 2-pentanol (2PE, CH₃CH₂CH₂CH(OH)CH₃). 2BU and 2PE react with OH yielding bimolecular rate constants of (8.1±2.0)×10⁻¹² cm³molecule⁻¹s⁻¹ and (11.9±3.0)×10⁻¹² cm³molecule⁻¹s⁻¹, respectively, at 297±3 K and 1 atmosphere total pressure. Both 2BU and 2PE OH rate constants reported here are in agreement with previously reported values [1–4]. In order to more clearly define these alcohols' atmospheric reaction mechanisms, an investigation into the OH+alcohol reaction products was also conducted. The OH+2BU reaction products and yields observed were: methyl ethyl ketone (MEK, (60±2)%, CH₃CH₂C((DOUBLEBOND)O)CH₃) and acetaldehyde ((29±4)% HC((DOUBLEBOND)O)CH₃). The OH+2PE reaction products and yields observed were: 2-pentanone (2PO, (41±4)%, CH₃C((DOUBLEBOND)O)CH₂CH₂CH₃), propionaldehyde ((14±2)% HC((DOUBLEBOND)O)CH₂CH₃), and acetaldehyde ((40±4)%, HC((DOUBLEBOND)O)CH₃). The alcohols' reaction mechanisms are discussed in light of current understanding of oxygenated hydrocarbon atmospheric chemistry. Labeled (¹⁸O) 2BU/OH reactions were conducted to investigate 2BU's atmospheric transformation mechanism details. The findings reported here can be related to other structurally similar alcohols and may impact regulatory tools such as ground level ozone-forming potential calculations (incremental reactivity) [5]. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 745–752, 1998     

Synthesis and characterisation of trinuclear metal complexes derived from carboxymethyl-substituted sarcophagine macrobicyclic cage amines

The synthesis and single-crystal x-ray structure determination of two new trinuclear metal complexes is detailed. In these we utilise the appended iminodiacetate substituents, in [Co(CH₃)NH(CH₂CO₂H)₂sar]³⁺, to act as a focus for coordination of other metal ions. Thus, we have made complexes of Cu and Ni utilising the basic carbonates of these metals and [Co(CH₃){N(CH₂CO₂H)₂}sar]³⁺ (CoL2) which gave rise to ((CoL2–2H⁺)₂M), M = Cu and Ni. The electrochemical study of the latter was inconclusive and provides the impetus for further study.     

Iodomethane oxidative addition and CO migratory insertion in monocarbonylphosphine complexes of the type [Rh((C6H5)COCHCO((CH2)nCH3))(CO)(PPh3)]: Steric and electronic effects

The chemical kinetics, studied by UV/Vis, IR and NMR, of the oxidative addition of iodomethane to [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)], with R = (CH₂)_nCH₃, n = 1-3, consists of three consecutive reaction steps that involves isomers of two distinctly different classes of Rh^III-alkyl and two distinctly different classes of Rh^III-acyl species. Kinetic studies on the first oxidative addition step of [Rh((C₆H₅)COCHCOR)(CO)(PPh₃)] + CH₃I to form [Rh((C₆H₅)COCHCOR)(CH₃)(CO)(PPh₃)(I)] revealed a second order oxidative addition rate constant approximately 500-600 times faster than that observed for the Monsanto catalyst [Rh(CO)₂I₂]⁻. The reaction rate of the first oxidative addition step in chloroform was not influenced by the increasing alkyl chain length of the R group on the β-diketonato ligand: k₁ = 0.0333 ([Rh((C₆H₅)COCHCO(CH₂CH₃))(CO)(PPh₃)]), 0.0437 ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₃))(CO)(PPh₃)]) and 0.0354 dm³ mol⁻¹ s⁻¹ ([Rh((C₆H₅)COCHCO(CH₂CH₂CH₂CH₃))(CO)(PPh₃)]). The pK_a^′ and keto-enol equilibrium constant, K_c, of the β-diketones (C₆H₅)COCH₂COR, along with apparent group electronegativities, χ_R of the R group of the β-diketones (C₆H₅)COCH₂COR, give a measurement of the electron donating character of the coordinating β-diketonato ligand: (R, pK_a^′, K_c, χ_R) = (CH₃, 8.70, 12.1, 2.34), (CH₂CH₃, 9.33, 8.2, 2.31), (CH₂CH₂CH₃, 9.23, 11.5, 2.41) and (CH₂CH₂CH₂CH₃, 9.33, 11.6, 2.22).     

Thiophosphinatokomplexe der Lanthanoiden. I. Dimere Dimethylthiophosphinatokomplexe des LaIII,PrIII, NdIII und ErIII

Thiophosphinate Complexes of Lanthanides. I. Dimeric Dimethylthiophosphinate Compounds of La^III, Pr^III, Nd^III, and Er^III By reaction of Na[(CH₃)₂POS] · 1,5 H₂O with Ln(ClO₄)₃ (Ln ? La, Pr, Nd, Er) neutral dimeric complexes are formed. The crystal and molecular structures of [Pr((CH₃)₂POS)₃(C₂H₅OH)(C₃H₇OH)]₂, [Pr((CH₃)₂POS)₃ · 3 H₂O]₂ · 4 H₂O and [Er((CH₃)₂POS)₃(H₂O)₂]₂ have been determined by single crystal X-ray crystallography. The (CH₃)₂POS^? ions are acting partly as bidentate chelates and partly as monodentate O-donors. The dimers are formed by doubly coordinating oxygen atoms of two ligands. Very strong intramolecular O? H…?S hydrogen bonds exist between noncoordinated S atoms and coordinated water molecules.     

Preparation and spectroscopic studies of some cyclic urea adducts of triphenyl-tin and -lead halides

1,3-Dimethyl-2-imidazolidinone (dimethylethylene urea, DMEU) and 1,3-di- methyl-3,4,5,6-tetrahydro-2(IH)-pyrimidinone (dimethylpropylene urea, DMPU) adducts of the type Ph₃SnX·L (X = Cl, Br and I), Ph₃PbX·L (X = Br, I), 3Ph₃PbCl·2DMEU and 2Ph₃PbCl · DMPU have been prepared and characterized. Assignments are made for ν(CO) and ν(CN) frequencies in the IR, and for skeletal frequencies observed in both the IR and Raman spectra in the range 400 to 100 cm^?1 Infrared measurements show that the adducts are bound through the carbonyl oxygen, and are highly dissociated in dichloromethane solution. ¹H and ¹¹⁹Sn or ²⁰⁷Pb NMR measurements reveal that ligand exchange, fast on the NMR time scale, occurs in solution. Coordination of the ligand causes a large upfield shift in the ¹¹⁹Sn or ²⁰⁷Pb resonances, but Ph₃MI · L have shifts similar to those for the parent iodides, indicating almost complete dissociation. Thermodynamic parameters are reported for the dissociation of Ph₃SnX · DMPU (X = Cl, Br) in CH₂Cl₂ solution.     

由3-二茂铁-2-丁烯酸根和1,10-邻菲啰啉构筑的一维链状铅(II)配位聚合物的合成、晶体结构及电化学性质

Pb(OAc)₂•3H₂O, 3-二茂铁-2-丁烯酸钠以及1,10-邻菲啰啉在甲醇中反应得到了铅的配位聚合物: [Pb(m-OOCCH＝C(CH₃)Fc)(m₂-OOCCH＝C(CH₃)Fc)(phen)]_n (Fc＝(h⁵-C₅H₅)Fe(h⁵-C₅H₄); phen＝1,10-邻菲啰啉). 单晶测试表明: 每个铅离子为六配位, 其中4个氧原子来自4个3-二茂铁-2-丁烯酸根, 另2个氮原子来自邻菲啰啉; 相邻的铅离子通过3-二茂铁-2-丁烯酸根的单齿和双齿氧原子桥连形成了一个无限的一维长链. 研究了标题化合物在DMF溶液中的电化学性能.     

Zur Biosynthese der Rubratoxine

In order to check the hypothesis that rubratoxin B ( 2 ), a C₂₆-metabolite, is formed biogenetically by head-to-tail coupling of two identical C₁₃-precursors derived from decanoic acid and oxaloacetic acid, two labelled forms of the postulated C₁₃-intermediate 2-((E)-1'-octenyl)-3-[¹⁴C]methyl- and 2-((E)-1'-octenyl)-3-[¹³C]-methylmaleic anhydride ( 10 ), were synthesized. The labelled compounds 10 as well as a number of other ¹⁴C]- and [¹³C]-labelled potential precursors were administered to growing cultures of Penicillium rubrum STOLL . Significant incorporation rates of acetate (as intact units) and malonate were observed. Propionate was incorporated after decarboxylation. Succinate exhibited the highest rate of incorporation. The results are in agreement with the assumption that the C₁₀-chain is formed by the fatty acid pathway and the C₃-unit via the tricarboxylic acid cycle. After administration of 10 randomization of the label was observed. Thus the question whether compound 10 is a biogenetic intermediate remains unanswered.     

Pseudohalide‐Induced Moisture Tolerance in Perovskite CH3NH3Pb(SCN)2I Thin Films

Two pseudohalide thiocyanate ions (SCN^?) have been used to replace two iodides in CH₃NH₃PbI₃, and the resulting perovskite material was used as the active material in solar cells. In accelerated stability tests, the CH₃NH₃Pb(SCN)₂I perovskite films were shown to be superior to the conventional CH₃NH₃PbI₃ films as no significant degradation was observed after the film had been exposed to air with a relative humidity of 95 % for over four hours, whereas CH₃NH₃PbI₃ films degraded in less than 1.5 hours. Solar cells based on CH₃NH₃Pb(SCN)₂I thin films exhibited an efficiency of 8.3 %, which is comparable to that of CH₃NH₃PbI₃ based cells fabricated in the same way.     

Electrochemical properties of electrolyte for lead fluoroborate redox flow battery prepared with recovered lead

The electrochemical properties of electrolyte for soluble lead flow battery(SLFB) are a key factor for the improvement of its performance. Pb(BF₄)₂ in which Pb²⁺ ions are highly soluble is cheaper and more stable than conventional Pb(CH₃SO₃)₂. This paper presents the electrochemical properties of HBF₄ and Pb(BF₄)₂ prepared with recovered lead for the electrolytes of SLFB. The density difference of reagent grade and recovered lead electrolytes is less than 0.05 g/cm³ and their viscosities increase up to 132 %, 120 %, respectively when concentration of Pb(BF₄)₂ changes from zero to 2.0 mol·dm⁻³. The conductivity of 1.5 mol·dm⁻³ electrolyte prepared with recovered lead has a peak when concentration of HBF₄ is less than 1.0 mol·dm⁻³. The results of cyclic voltammetry, linear sweep voltammetry and constant current charge/discharge test showed that impurities of recovered lead exert insignificant influences on the Pb²⁺/Pb and Pb²⁺/PbO₂ reactions. These results are promising to apply recovered lead to SLFB.     

248. Methylation reactions of 30-oxa-(14)-cytochalasanes

For synthetic studies the protection of the hydroxyl groups of phomin (cytochalasin B) ((7S,22R,26R)-7,26-dihydroxy-22-methyl-30-oxa-[14]cytochalasa-6(18), 19^t 27^t-trien-1,29-dion) ( 1 ), the dodecahydro-derivative 2 , and the dihydro-derivative 4 by methylation was investigated. Treatment of 1 with CH₃I/Ag₂O gave the iminoether 6 . The reaction of 4 with CH₂N₂/BF₃ led to the di-O-methyl derivative 8 and to the N-methyl-di-O-methyl derivative 9 , whereas 2 was transformed to the N-methyl-di-O-methyl compound 10 and to the iminoether 11 . NaBH4 reduction of 3 yielded not only 4 but also the epimeric dihydro derivative 5 .     

Über die Reaktion von Trimethylamin mit Antimon(V)-chlorid

Inhaltsübersicht. Trimethylamin und Antimon(V)-chlorid bilden keinen Dornor-Acceptor Komplex. In Abhängigkeit vom Molverhältnis reagieren die Komponenten zu (CH₃)₃NCl⁺SbCl₆^– (I) bzw. zu (CH₃)₃NH+X^– und (CH₃)₂N=CH₃⁺X^– (X^– = SbCl₆^–, SbCI₄^–, Sb₃CI₁₄^3– und CI^–). I kann in (CH₃)₃NH⁺SbCl₆^– und (CH₃)₂N=CH₂+SbCl₆^– zerfallen. The Reaction of Trimethylamine with Antimony (V) Chloride Abstract. Trimethylamine and antimony(V) chloride forms no donor-acceptor-complex. In dependence of the molar ratio the compounds reacts to (CH₃)₃NCl⁺SbCl₆^– (I) resp. to (CH₃)₃NH+X^– and (CH₃)₂N=CH₃⁺X^– (X^– = SbCl₆^–, SbCI₄^–, Sb₃CI₁₄^3– and CI^–). I can decompose into (CH₃)₃NH⁺SbCl₆^– and (CH₃)₂N=CH₂+SbCl₆^–.     

Structure, 31P and 13C chemical shift anisotrophy of (CH3)3P, (CH3)3PO, (CH3)3PS and (CH3)3PSe as determined by liquid crystal NMR spectroscopy

The ¹³P and ¹³C spectra of the triply ¹³C labelled molecules (CH₃)₃P, (CH₃)₃PO, (CH₃)₃PS and (CH₃)₃PSe oriented in a nematic phase are reported. The CPC bond angles have been measured. The ¹³P chemical shift tensor shows a large anisotropy except in the case of (CH₃)₃P. The abnormal large value observed for the PSe bond length suggests a large anisotropy of the ¹J(PSe) spin coupling.     

Synthesis,crystal structures and electrochemical properties of group 6 metal carbonyl anion complexes

A series of [M(CO)₅I]⁻ and [M₂(CO)₁₀I]⁻ anion complexes have been synthesized by the photochemical reaction of PhCH₂N(CH₃)₃I or FcCH₂N(CH₃)₃I (Fc=ferrocenyl) with M(CO)₆ (M = Cr, Mo or W), and characterized by elemental analyses, i.r., ¹H-n.m.r. and ¹³C-n.m.r. spectra in the case of the molybdenum and tungsten complexes. These complexes exhibit considerably different electrochemical behavior, when investigated by cyclic voltammetry. The crystal structures of [PhCH₂N(CH₃)₃][Cr(CO)₅I] and [FcCH₂N(CH₃)₃][W₂(CO)₁₀I] have been determined by X-ray diffraction, indicating that only weak contacts maybe exist between anions and cations by the I...H bond in the former, and there are no direct interactions between anions and cations in the latter.     

Synthesis,Structural Characterization and Reactivity of Two New Triangular Molybdenum Cluster Compounds：Mo3T37—[S2CN（CH2CH2OH）2]3I and Mo3Te4Y3[S2P（^iPrO）2]3I（Y3=1.43Te＋1.57S）

Two triangular molybdenum‐tellurium clusters, Mo₃Te₇‐[S₂CN (CH₂CH₂OH₂]₃I (1) and Mo₃Te₄Y₃[S₂P(ⁱPrO)₂]₃I (Y₃ = 1. 43Te+ 1.57S) (2), were obtained from the reaction of K · HOdtc [HOdtc = S₂CN(CH₂CH₂OH)₂] or K·ⁱPr₂dtp (ⁱPr₂dtp = S₂P[OCH(CH₃)₂]₂) with a mixed product of elements Mo, Te(S) and I₂ at high temperature. The structures of the two compounds were determined by X‐ray crystallography study. Crystal data are, (1): monoclinic, P2₁/n, a = 1.6256(3), b = 1.3264(2), c = 1.8808(4) nm, β=96.923°, V = 4.025.9 (14) nm³, D_cal = 3.050g·cm‐³, Z = 4, and (2): monoclinic, P2₁/n, a = 1.4564(2), b = 2.3917(4), c = 1.5094(3) nm, β = 114.35(2)°, V = 4.0259(14) nm³, D_cal = 2.449 g·cm^?3 and Z = 4. Single crystal analyses show that 1 consists of discrete Mo₃Te₇[S₂CN(CH₂CH₂OH)₂]₃I connected into three‐dimensional framework via hydrogen bonds, while 2 forms a linear chain via Te(S)—I interaction.     

Reactivity of selected volatile organic compounds (VOCs) toward the sulfate radical (SO4−)

Rate constants for a series of alcohols, ethers, and esters toward the sulfate radical (SO₄^?) have been directly determined using a laser photolysis set‐up in which the radical was produced by the photodissociation of peroxodisulfate anions. The sulfate radical concentration was monitored by following its optical absorption by means of time resolved spectroscopy techniques. At room temperature the following rate constants were derived: methanol ((1.6 ± 0.2) × 10⁷ M^?1 s^?1); ethanol ((7.8 ± 1.2) × 10⁷ M^?1 s^?1); tert‐butanol ((8.9 ± 0.3) × 10⁵ M^?1 s^?1); diethyl ether ((1.8 ± 0.1) × 10⁸ M^?1 s^?1); MTBE ((3.13 ± 0.02) × 10⁷ M^?1 s^?1); tetrahydrofuran (THF) ((2.3 ± 0.2) × 10⁸ M^?1 s^?1); hydrated formaldehyde ((1.4 ± 0.2) × 10⁷ M^?1 s^?1); hydrated glyoxal ((2.4 ± 0.2) × 10⁷ M^?1 s^?1); dimethyl malonate (CH₃OC(O)CH₂C(O)OCH₃) ((1.28 ± 0.02) × 10⁶ M^?1 s^?1); and dimethyl succinate (CH₃OC(O)CH₂CH₂C(O)OCH₃) ((1.37 ± 0.08) × 10⁶ M^?1 s^?1) where the errors represent 2σ. For the two latter species, we also measured the temperature dependence of the corresponding rate constants. A correlation of these kinetics with the bond dissociation energy is also presented and discussed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 539–547, 2001     

Dihalogen(organylthio)alane,darstellung und eigenschaften

The reactions of the aluminium halides AlCl₃, AlBr₃, and AlI₃ (I, II, III) with the trimethylsilylorganylsulfides (CH₃)₃ SiSCH₃, (CH₃)₃ SiSC₂H₅, and (CH₃)₃ SiSPh (IV, V, VI), as well as the lead bis(thiolates) Pb(SCH₃)₂, Pb(SC₂H₅)₂, Pb(S-i- C₃H₇)₂, and Pb(SPh)₂ (XV, XVI, XVII, XVIII) and the redox reactions between III and the organic disulfides CH₃SSCH₃ and PhSSPh (XXIX, XXX) have been investigated. In benzene solution the reactions of I, II and III with IV, V and VI yield the 1:1 adducts, the aluminium trihalide · trimethylsilylorganylsulfides VII–XIV. By heating under vacuum these adducts form the corresponding organylthioaluminium dihalides. These compounds are obtained as well by the reaction of I, II, and III with XV, XVI, XVII and XVIII. The redox reactions between III and the disulfides XXIX and XXX also lead to the corresponding organylthioaluminium diiodides.The spectra and some physical and chemical properties of the new compounds are described.     

Reduction of aliphatic bromoesters: Reactivity of the electrochemically generated carbanion (CH2COOEt)− on substrates such as β-, γ- and δ-bromoesters

The reactivity of the carbanion (CH₂CO₂Et)^?, obtained from CH₂(Br)CO₂Et (I) by means of electrochemical reduction, on substrates such as CH₂(Br)CH₂CO₂Et (II), CH₂(Br)(CH₂)₂CO₂Et (III) and CH₂(Br)(CH₂) ₃CO₂Me (IV), was studied in dimethylformamide solutions by means of polarography, cyclic voltammetry and coulometry at mercury and vitreous carbon electrodes. Evidence was found for coupling (diethyl glutarate (CH₂)₃(CO₂Et)₂ and diethyl adipate (CH₂)₄(CO₂Et)₂) and elimination reaction (ethyl acrylate CH₂CHCO₂Et and ethyl cyclopropancarboxylate $\text{CH}{}_2\text{CH}{}_2\text{C}$HCO₂Et) compounds. In addition, the electrochemical reduction of the single esters (I)–(IV) was reported. The dependence of the percentage ratio among the various products obtained on the potential, the proton donor presence and the nature of the ester were investigated.