Analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride

The synthesis and analytical properties of 1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride are described for the first time. The solubility, spectral characteristics, pK values and reactions with 40 cations and 13 anions are reported.     

Spectrophotometric determination of selenium(IV) with 5,5-dimethyl-1,3-cyclohexanedione

5,5-Dimethyl-1,3-cyclohexanedione (dimedone) reacts in acid aqueous solution with selenium(IV) to give a benzoxaselenol which has an absorption maximum at 313 nm with a molar absorptivity of 4.00 x 10(3) l.mole(-1).cm(-1). The compound is extractable into chloroform, to give a solution with an absorption maximum at 300 nm with a molar absorptivity of 3.77 x 10(3) l.mole(-1).cm(-1). The calibration graph is linear up to 30 ppm selenium, with a detection limit of 0.1 ppm in the final solutions. Of the various other ions tested, only iron(III) interferes at all concentrations but the addition of 1000 ppm fluoride will mask 50 ppm Fe(3+). The method has good reproducibility, with a relative standard deviation of 1.0% for pure solutions. The method has been applied to the analysis of fire-refined copper.     

Rapid spectrophotometric determination of chlorate with dimedone bisthiosemicarbazone monohydrochloride

Summary Dimedone bisthiosemicarbazone monohydrochloride has been examined to evaluate its usefulness as a reagent for rapid and sensitive Spectrophotometric determination of chlorate (0.5–5.0 ppm) by oxidation of the reagent in 70% perchloric acid medium and measurement of the yellow product. The molar absorptivity at 417 nm is 1.86×10⁴ l·mole^–1·cm^–1. The relative standard deviation is 1.6% for 2.5 ppm of chlorate.

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Spektropbotometrische Bestimmung von Chlorat mit Dimedonbisthiosemicarbazon-monocblorhydrat (I)

Zusammenfassung Die Verwendbarkeit von I als Reagens für die rasche und empfindliche spektrophotometrische Bestimmung von 0,5–5,0 ppm Chlorat durch Oxydation von I in 70%iger Perchlorsäure und Messung des gelben Reaktionsproduktes wurde untersucht. Die molare Absorptivität bei 417 nm beträgt 1,86×10⁴ l·mol^–1·cm^–1. Die relative Standardabweichung beträgt 1,6% für 2,5 ppm Chlorat.

     

Mechanistic studies in the attempted synthesis of 5,5-dimethyl-2-isopropylidene-1,3-cyclohexanedione

In contrast to the corresponding cyclopentanedione derivative, 5,5-dimethyl-2-isopropyl-2-phenylsulfinyl-1,3-cyclohexanedione (3) does not undergo the expected cis-elimination of phenylsulfenic acid on warming in CH₂Cl₂ to afford the title compound 1, but instead gives an equimolar mixture of 5,5-dimethyl-2-(1 ′-isopropyl-4′,4′-dimethyl-2′,6′-dioxocyclohexyl)-2-isopropyl-1, 3-cyclohexanedione (9) and S-phenyl benzenethiosulfonate (10). These products result from dimerization of the 4,4-dimethyl-1-isopropyl-2,6-dioxocyclohexylradical (7) andthephenylsulfinyl radical (8), respectively. Diploma Thesis, University of Hamburg, 1990.     

Analytical properties of 5,5-dimetyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride; spectrophotometric determination of chromium(VI) in alloy steels and industrial effluents

The analytical properties of 5,5-dimethyl 1,3-cyclohexanedione dithiosemicarbazone monohydrochloride (5,5-DiMe-1,3-CHDT.HCl) are described. The reagent gives pink coloured solutions with chromium(VI) in acetic medium. The maximum colour intensity is observed in 0.5-2.5 pH range. This colour reaction (molar absorptivity, 1.63 x 10(4) 1 mol(-1) cm(-1) at 360 nm) has been used for the spectrophotometric determination of total chromium in alloy steels and industrial effluents.     

2-Aryl-7,7-dimethyl-5,6,7,8-tetrahydrothieno[3,2-c]azepin-4-ones from 5,5-dimethyl-1,3-cyclohexanedione

A novel synthesis of substituted thieno[3,2-c]azepinones is described. This new approach uses 5,5-dimethyl-1,3-cyclohexanedione (dimedone) as the starting material. Oxime intermediates are obtained in three steps from the aforementioned diketone. Using these intermediates, the title compounds are synthesized in moderate yields.     

Microwave—prompted Reaction of Cinnamonitrile Derivatives with 5,5—Dimethyl—1,3—cyclohexanedione

In the reactions of α-cyanocinnamonitrile or β-cyano-β-carbothoxy styrene with 5,5-dimethyl-1,3-cyclohexanedione in the presence of ammonium acetate under microwave irradiation without solvent,the 2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-7,7-dimethyl-4H-benzo-[b]-pyran derivatives were obtained.However,in the reactions of arylidenecyanoacetamide with 5,5-dimethyl-1,3-cyclohexanedione under the same reaction conditions,the acridine derivatives were obtained.The structures of the products were determined by single crystal X-ray diffraction analysis.     

Spectrophotometric determination of palladium with 5,6-dimethyl-1,3-indanedione-2-oxime

A rapid, sensitive and selective method has been developed for the determination of palladium with 5,6-dimethyl-1,3-indanedione-2-oxime in acetate buffer (pH 5.5). Beer's law is obeyed over the range 0.15-4.17 mug/ml palladium(II). The molar absorptivity at 370 nm is 2.98 x 10(4) 1.mole(-1).cm(-1). The method has been applied for the determination of palladium in synthetic mixtures corresponding to PtIr and Oakay alloys. An interesting feature of the system is the abnormal shape of the Job and molar-ratio plots obtained.     

Anthocyanidins and related compounds—VIII Condensation reactions of flavylium salts with 5,5-dimethyl-1,3-cyclohexanedione in acid solutions

4′-Hydroxyflavylium salts, unsubstituted at position 3, react with 5,5-dimethyl-1,3-cyclohexanedione in acid solutions to yield para-hydroxyphenacyl-5-keto-tetrahydroxanthene derivatives, e.g., Va, isomeric with the flavan derivatives, e.g., IIa, formed at pH 5·8. These flavans isomerize to the tetrahydroxanthenes in both acid and alkaline media.

7-Hydroxy- and 3-methyl-4′-hydroxyflavylium salts yield flavan derivatives, eq. IIIa, IId, when condensed either in acid solutions or at pH 5·8. Isomerization of these flavans to corresponding tetrahydroxyanthenes has not been detected.     

Homolytic telomerization of vinyltrimethylsilane with 5,5-dimethyl-1,3-dioxane

The homolytic telomerization of vinyltrimethylsilane by 5,5-dimethyl-1,3-dioxane follows three principal routes, with the formation of 2- and 4-substituted 5,5-dimethyl-1, 3-dioxanes and a formate ester. The rings in the reaction products (2-trimethylsilylethyl- and 4-trimethylsilylethyl-5,5-dimethyl-1,3-dioxane) exist in the chair conformation. The substituants in the 2- and 4-positions of the dioxane ring occupy equatorial positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1035, August, 1986.     

Spectrophotometric determination of epinephrine and norepinephrine with sodium periodate

A simple and accurate spectrophotometric method is described for the determination of epinephrine (EP), norepinephrine (NE) and their bitartrate salts. The method is based on the development of a red colour (lambda(max) 490 nm) with sodium periodate in aqueous alcoholic medium. The colour is stable for at least 1 hr. The molar reacting ratio of EP or NE to periodate is 1:2. The proposed method is particularly suitable for routine analysis of EP and NE injections. The interference due to the sodium metabisulphite normally used as antioxidant can be overcome by addition of acetone. Results for analysis of bulk drugs and injections agree well with those of official methods.     

Anthocyanidins and related compounds—VII Reactions of flavylium salts with 5,5-dimethyl-1,3-cyclohexanedione at pH 5·8

Phenolic flavylium salts, substituted and unsubstituted at position 3, condense with 5,5-dimethyl-1,3-cyclohexanedione in aqueous methanolic solutions at pH 5·8 to form novel cyclic flavan derivatives of types Xa and XIa.     

Conformation of 5,5-disubstituted 2,2-dimethyl-1,3-dioxanes

It was established by PMR spectral data that in solutions of derivatives of 5-acetoxymethyl-, 5-methyl-, and 5-hydroxymethyl-2,2-dimethyl-1,3-dioxanes with nitrogen-containing substituents (2,4-disubstituted 1,3,5-triazin-6-ylamino, benzamido, and nitro groups) with an N-C₍₅₎ bond the 1,3-dioxane ring exists in the chair conformation with primarily an axial orientation of the nitrogen-containing substituent. Depending on the nature of the substituents attached to the C₍₅₎ atom, the 1,3-dioxane ring may exist either in the stable chair conformation or may undergo rapid inversion of the chair-chair type at 20 °C.The author sincerely thanks A. I. Kol'tsov for his assistance in recording and interpreting the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 468–473, April, 1985.