Electrochemical Reduction of Acetonylacetone in Hydrochloric Acid

The electrochemical reduction of acetonylacetone on a mercury cathode in aqueous hydrochloric acid medium has been studied. It has been shown that the electroactive species is the protonated form of acetonylacetone. The experimental results indicate -that the rate of electrochemical reduction is dependent upon the preceding chemical protonation step and/or adsorption of the electroactive species. The electrolysis at controlled potential (- 1.2 V vs. S. C. E .) yielded the following products : acetaldehyde; acetone, acetic acid, 2,5-hexanediol and 2,5-dimethyltetrahydrofuran. Possible mechanistic routes leading to the formation of these products are discussed

Electrochemical Synthesis of Keto and Enol Forms of Tetraketones of the Type 3,4-Diaroyl-2,5-hexanedione by Oxidative Dimerization of Aroylacetones

Tetraketones of the type 3,4-diaroyl-2,5-hexanedione: Ar = CsH;-, p-CHs-CsH4-, 3,4-(CHsh-CsHs-, p-CHaO-CsH4-, p- Cl-CsH4-, p-Br-C6H4- and 2-C4H3S- were prepared in good yield by oxidative anodic dimerization of aroylacetones. Electrochemical oxidation was carried out at constant current (4-5 A) in cylindrical cell without diaphragm with Pt-gauze anode and Ni-cathode. Depending on the method used (A or B) and depending on the properties of the electrolysed aroylacetones, dimer-products were isolated as stable keto or enol tautomers. Electrolysis in 80°/o aqueous methanol (Method A) gave keto or enol tautomers, while electrolysis in absolute methanol (Method B) yielded only enol tautomers

Electrochemical Synthesis of Keto and Enol Forms of Tetraketones of the Type 3,4-Diaroyl-2,5-hexanedione by Oxidative Dimerization of Aroylacetones

Tetraketones of the type 3,4-diaroyl-2,5-hexanedione: Ar = CsH;-, p-CHs-CsH4-, 3,4-(CHsh-CsHs-, p-CHaO-CsH4-, p- Cl-CsH4-, p-Br-C6H4- and 2-C4H3S- were prepared in good yield by oxidative anodic dimerization of aroylacetones. Electrochemical oxidation was carried out at constant current (4-5 A) in cylindrical cell without diaphragm with Pt-gauze anode and Ni-cathode. Depending on the method used (A or B) and depending on the properties of the electrolysed aroylacetones, dimer-products were isolated as stable keto or enol tautomers. Electrolysis in 80°/o aqueous methanol (Method A) gave keto or enol tautomers, while electrolysis in absolute methanol (Method B) yielded only enol tautomers

Ferrocene Compounds. IX. Voltammetric Studies on the Oxidation of Some Ferrocene Derivatives

Oxidation potentials for ferrocene and a series of mono- (II- VII) and bridged diferrocenyl derivatives (VIII-XIV) have been determined by rotating disk electrode voltammetry and cyclic voltammetry using a platinum electrode in acetonitrile solution. The diffusion coefficients of monoferrocenyl derivatives, ranging from (0.74 to 2.38) X 10-5 cm2 s-1, were evaluated. Analysis of the\u27 results obtained for bridged diferrocenyl derivatives has shown that their oxidation potentials are sensitive to structural and electronic effects

Electrochemical Reduction of Intermediates in the Vitamin B6 Production. III. Reduction of Some Substituted Pyridones

Earlier papers in this series1\u272 treated the selective preparative reduction of substituted pyridines with four reactive functional groups (- N02 , -CH20CH3 , -CN and -Cl). This paper treats the electrochemical reduction of some substituted pyridones with three reactive functional groups (-N02 , -CH20CH" and -CN)

Electrochemical Reduction of Intermediates in the Vitamin B6 Production. II. Reduction of 2-Methoxymethyl-3-nitro-4-methyl- 5-cyano-6-chloropyridine

2-Methoxymethyl-3-nitro-4-methyl-5-cyano-6-chloropyridine (I) was reduced on a mercury-pool in an electrolytic cell with a diaphragm. A mixture of acetic and hydrochloric acid was used as catholyte and diluted hydrochloric acid as anolyte. Compound I was reduced at - 0.5 V to 2-methoxymethyl-3-amino-4-methyl- 5-cyano-6-chloropyridine (II) (yield 67-820/o). Compound II was reduced at - 0.9 V to 2-methoxymethyl-3-amino-4-methyl-5- cyanopyridine (Ill) (yield 54-83-0/o). Compound III was reduced at -1.1 V to 2,4-dimethyl-3-amino-5-cyanopyridine (IV) (yield 48-660/o Compound IV was reduced at constant current density to 2,4-dimethyl-3-amino-5-aminomethylpyridine (V) (yield 82,40/o). Polarographic waves of I, II, and III are defined and character of limiting currents was determined according to the usual criteria

Electrochemical Reduction of Intermediates in the Vitamin B6 Production. II. Reduction of 2-Methoxymethyl-3-nitro-4-methyl- 5-cyano-6-chloropyridine

2-Methoxymethyl-3-nitro-4-methyl-5-cyano-6-chloropyridine (I) was reduced on a mercury-pool in an electrolytic cell with a diaphragm. A mixture of acetic and hydrochloric acid was used as catholyte and diluted hydrochloric acid as anolyte. Compound I was reduced at - 0.5 V to 2-methoxymethyl-3-amino-4-methyl- 5-cyano-6-chloropyridine (II) (yield 67-820/o). Compound II was reduced at - 0.9 V to 2-methoxymethyl-3-amino-4-methyl-5- cyanopyridine (Ill) (yield 54-83-0/o). Compound III was reduced at -1.1 V to 2,4-dimethyl-3-amino-5-cyanopyridine (IV) (yield 48-660/o Compound IV was reduced at constant current density to 2,4-dimethyl-3-amino-5-aminomethylpyridine (V) (yield 82,40/o). Polarographic waves of I, II, and III are defined and character of limiting currents was determined according to the usual criteria

Reaction Products of 2, 7-Diaroyl-4,5-Fulvenotropones with Hydrazine Hydrate

6\u27 -Hydroxy-8~( a-hydrazonoarylmethyl)ful veno(2\u27 ,3\u27 -5,6)-1,2-diazaazulenes (IIIa, Ar==tolyl; IIIb, Ar==phenyl; IIIc, Ar==thienyl) were obtained as reaction products of corresponding 2,7-diaroyl-4,5-fulvenotropones with hydrazine hydrate. The structure of the obtained compounds are discussed on the basis of their infrared, mass and 1H nuclear magnetic resonance spectra

Electrochemical Reduction of Intermediates in the Vitamin B6 Production. III. Reduction of Some Substituted Pyridones

Earlier papers in this series1\u272 treated the selective preparative reduction of substituted pyridines with four reactive functional groups (- N02 , -CH20CH3 , -CN and -Cl). This paper treats the electrochemical reduction of some substituted pyridones with three reactive functional groups (-N02 , -CH20CH" and -CN)

Electrochemical Reduction of Intermediates in the Vitamin B6 Production. I. Reduction of 2-Methyl-3-nitro-4-methoxymethyl- 5-cyano-6-chloropyridine

2-Methy 1-3-ni tro-4-metoxymethy 1-5-cyano-6-chloropyridine (I) was reduced on a mercury-pool cathode in an electrolytic cell fitted with a diaphragm. The catholyte consisted of a mixture of acetiC acid and hydrochloric acid and the anolyte was dilute hydrochloric acid. At a potential of - 0.5 V vs. SCE. compound I was reduced to 2-methy 1-3-amino-4-methoxymethy 1-5-cyano-6-chloropyridine (II). Compound II was reduced at a potential of -1.1 V vs. SCE. to give 2,4-dimethyl-3-amino-5-cyanopyridine (Ill). Compound III was reduced at constant current density to 2,4-dimethyl-3-amino- 5-aminomethylpyridine (IV). The influence of several factors (depolarizer concentration, electrolyte concentration and temperature) on yield of products was examined in each step. Polarograms were recorded with compounds I, II and III, and the character of limiting currents was assessed using the usual criteria