Karminsäure

Carminic acid was isolated from dried Dactylopius coccus Costa (Dactylopiidae) and chromatographically purified. All analytical spectra were recorded and are reproduced either in the main part or in the supplementary material. The NMR‐ and mass‐spectra have been interpreted and compared with theoretical calculations of the ¹³C chemical shifts. The project is a follow up of the recent book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

Die Dodecavanadophosphorsäure

Dodecavanadophosphoric Acid The dodecavanadophosphoric acid was obtained as a violetred, crystalline solid by evaporating its aqueous solution which was prepared from Li₂H₅[PV₁₂O₃₆] solution by means of cation exchange. Chemical analysis, NaOH titration and infra-red spectroscopy were used to characterize the acid.     

Doppelt und dreifach funktionalisierte,enantiomerenreine C4-Synthesebausteine aus β-Hydroxybuttersäure, Äpfelsäure und Weinsäure

Enantiomerically Pure Synthetic Building Blocks with Four C-Atoms and Two or Three Functional Groups from β-Hydroxy-butanoic, Malic, and Tartaric Acid The pool of chiral, non-racemic electrophilic building blocks, which are available from simple natural products in both enantiomeric forms is enlarged by the epoxides 3, 5 , and 10 , by the tosylate 12a , and by the aldehydes 18 (cf. symbols A-D , 14 , and Scheme 1). Key steps of the conversions leading from hydroxyacids to the building blocks are: epoxide-opening by triethylborohydride ( 1 → 2a ) and tosylate reduction ( 12a → 12b ); the Mitsunobu inversion ( 2a → 4a ); the reduction of (R, R)-tartaric ester to (R)-malic ester by NBS (N-bromosuccinimide) opening of the benzaldehyde acetal 8 and tin hydride reduction ( 6c → 7c ); the enantiomer enrichment of optically active ethyl β-hydroxy-butanoate through the crystalline dinitrobenzoate 21b . Detailed procedures are given for large scale preparations of the key intermediates. The enantiomeric purities of the building blocks are secured by correlations.     

Über Chalkogenolate. 81. Untersuchungen über N-Hydroxydithiocarbamidsäure 3. Ester der N-Hydroxydithiocarbimidsäure und -carbamidsäure

On Chalcogenolates. 81. Studies on N-Hydroxy Dithiocarbamic Acid. 3- Esters of N-Hydroxy Dithiocarbimic Acid and Dithiocarbamic Acid The reaction between hydroxylamine, carbon disulfide, and alkyl halide leads to the corresponding ester of N-hydroxy dithiocarbimic acid HO? N?C(SR)₂ with R = CH₃, C₂H₅; R₂ = ? CH₂? CH₂? . The phenyl ester of N-hydroxy dithiocarbamic acid HO? NH? CS(SC₆H₅) has been prepared by reaction of hydroxylammonium chloride with the phenyl ester of chlorodithioformic acid. N-Methyl hydroxylammonium chloride reacts with carbon disulfide and alkyl iodide to form the corresponding ester of the dithiocarbamic acid HO? N(CH₃)? CS(SR) with R = CH₃, C₂H₅. The unstable compounds have been characterized by different methods.     

Nickelphosphankomplexe der Mercaptoessigsäure

Nickel Complexes of Mercaptoacetic Acid The reaction of [Cp°₂Zr(OOCCH₂SH‐κ¹O)(OOCCH₂SH‐κ²O, O′)] (Cp° = C₅EtMe₄) with [NiCl₂(PMe₂Ph)₂] or [NiCl₂(dppe)] (dppe = PPh₂CH₂CH₂PPh₂) in the presence of NEt₃ yields the tetranuclear Zr^IV/Ni^II complex [{Cp°₂Zr(κ¹O‐OOCCH₂S‐κ²O′, S)(κ²O, O′‐OOCCH₂S‐κ¹S)Ni(PMe₂Ph)}₂] ( 1 ) and the chelate complexes [Ni(OOCCH₂S‐κ²O, S)L₂] [L = PMe₂Ph ( 2 ), L₂ = dppe ( 3 )]. 2 and 3 are also accessible from [NiCl₂(PMe₂Ph)₂] or [NiCl₂(dppe)] and mercaptoacetic acid in the presence of NEt₃ in quantitative yield. The structure of 2 is dynamic in solution, whereby a complex with three‐coordinate nickel atom is formed. 2 and 3 were characterized spectroscopically (¹H, ¹³C, ³¹P NMR and IR) and by crystal structure determination.     

Tetrafluoro-orthoperjodsäure und Joddioxidtrifluorid

Of the new iodine(VII) compounds HOIOF₄ and IO₂F₃ the preparation and chemical and physical properties are reported. According to the ¹⁹F nuclear magnetic resonance spectra, both exist in two non-separable isomeres. HOIOF₄ is a very strong acid. IO₂F₃ forms yellow needles, which are not wetted by water. Both are very strong oxidising species. IO₂F₃ is probably the first trigonal-bipyramidal molecule with two simultaneously existing isomeres.     

Synthesen der Nonactinsäure

Two stereoselective syntheses of nonactic acid I, the building block of the macrotetrolide antibiotic nonactin are described. The characteristic cis-configuration of the 2,5-substituents on the tetrahydrofuran ring of I is obtained in the first synthesis by catalytic hydrogenation of the furan derivative X. This key intermediate possesses the carbon skeleton and correct distribution of oxygen functions for conversin into nonactic acid. It is synthesized by an electrophilic substitution of 2-acetonylfuran (VI) with the N-cyclohexyl-N-propenyl nitrosonium ion (V) generated from the corresponding α-chloronitrone (VII) and silver fluoroborate, followed by hydrolysis and oxidation of the aldehyde group. The second synthesis starts with a diol already having the correct configuration of the side chain that contains the hydroxyl group. For this purpose threo-1-octen-5,7-diol (XV) is synthesized from acetylacetone in two steps. Oxidative cleavage of the terminal double bond of this threo-diol yields an aldehyde which is converted by a Wittig reaction, with the carbanion, obtained from diethyl α-methoxycarbonylethyl phosphonate, into the open chain intermediate, 2-methyl-6,8-dihydroxy-2-nonenoic acid methylester (XVIII). Base-catalyzed cyclisation of this α,β-unsaturated dihydroxy ester yields the methyl ester of nonactic acid (I) as the main product.     

Ester der Imidodiphosphorsäure

Imidodiphosphoric Acid Esters Imidodiphosphoryl tetrachloride reacts with aliphatic alcohols (C₁–C₃) as well as with sodium phenolate to form tetraalkylesters or tetraphenylesters of the imidodiphosphoric acid, resp. The tetraalkylesters (alkyl = methyl, ethyl, n-propyl) are also formed by reaction of trichlorphosphazene phosphoryldichloride, Cl₃P?N? POCl₂, with the corresponding alcohols. The purification of the esters can be reached by destillation of their silyl derivatives followed by desilylation. The esters are associated by intermolecular O…?H…?O hydrogen bonds.