Study of ion chromatographic behavior of inorganic and organic antimony species by using inductively coupled plasma mass spectrometric (ICP-MS) detection

An on-line method for the analysis of Sb(III), Sb(V) and trimethylstiboxide (TMSbO) is presented. The separation is performed using ion chromatography (IC) on a strong anion-exchange column with phthalic acid plus 2% acteone at pH 5 as mobile phase. The chromatographic system is coupled to an ICP-MS as detector. The influence of different complexing agents on the chromatographic behavior of the antimony species is studied. Rather stable complexes of Sb(III) seem to be formed with citrate and tartrate under the experimental conditions. TMSbO forms a dianionic species with citrate in contrast to the otherwise monoanionic complex. Received: 31 Juli 1997 / Revised: 8 December 1997 / Accepted: 11 December 1997     

Acidity functions of aqueous fluorinated acid solutions by differential pulse polarography

The acidity functions of aqueous trifluoroacetic and trifluoromethanesulphonic acid mixtures, and aqueous hexafluoropropane-2, 2-diol solutions, have been determined by differential pulse polarography. The apparent shift of the half-wave potential for the ferrocene—ferricinium couple, as the solvent composition is changed, is used to indicate the change in potential of a glass electrode; acidity is measured as the H_GF acidity function. The densities of two of these solvent systems as a function of composition are also reported. Trifluoromethanesulphonic acid—water mixtures represent the strongest aqueous acid solvent system so far studied.     

Novel Access to Furan-3-thiols and Derivatives,Impact Meat-Flavor Compounds

A versatile process for the preparation of a number of 3-thio-substituted furans 1–4 is described. These products have very low odor thresholds and are thus potent flavor compounds. Fur-3-yl thiocyanates 10a , b as well as other S-containing analogues ( 2b , 7a , b , and 8 ) were prepared by a Michael-type addition of thiocyanic acid, thioacetic acid, alakanethiols, and sodium thiosulfate to alkynones 6 or 15 , followed by cyclization (Schemes 3 and 4). The thiocyanates 10a, b were converted to mixed disulfides 3 , symmetric disulfides 4 , thioethers 2 , and thiols 1 , using ‘hard’ or ‘soft’ nucleophiles or reducing agents, respectively (Scheme 6).     

N(SCl)2 ⊕[MoCl5(NSCl)]⊖, ein Chlorthionitrenokomplex von Molybdän(VI)

N(SCl)₂^⊕ [MoCl₅(NSCl)]^?, a Chlorothionitrene Complex of Molybdenum (VI) . The title compound is formed together with MoCl₃(N₃S₂) by the reaction of MoCl₄ or MoCl₅ with (NSCl)₃ in CH₂Cl₂. The black, crystalline compound was characterized by its i.r. spectrum and an X-ray crystal structure determination. N(SCl)₂^⊕[MoCl₅(NSCl)]^? crystallizes in the monoclinic space group P2₁/n with four formula units per unit cell. The lattice constants are a = 716.3, b = 1627.4, c = 1178.9 pm and β = 100.90°. The [MoCl₅(NSCl)]^? ion posseses an almost linear Mo = N = S grouping with bond lengths that can be interpreted as double bonds. Crystal data for AsPh₄[MoCl₅(NSCl)] are reported.     

Formation and Crystal Structure of Stable Five‐coordinate Diorgano Cobalt(III) Complexes

The mer‐octahedral complexes(2‐carbonyl)(4‐Me)(6‐tBu)phenolato[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 1 ) or ‐(1‐carbonyl)(2‐oxo)(1,2‐diphenylethene)[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 2 ) via formal insertion of propynoic acid ethyl ester into Co‐H functions afford pentacoordinate vinylcobalt(III) 3 and 4 , respectively, that are diamagnetic and attain a square pyramidal structure as exemplified by an X‐ray diffraction analysis of 3 .     

A convenient synthesis of 1,3-oxazolidin-4-ones and 1,3-oxazin-4-ones

1,3-Oxazolidin-4-ones and 1,3-oxazin-4-ones were synthesized by formal cyclocondensation of imines with α- or β-hydroxy acids.     

Cyclization Studies with N-Mannich bases of 2-substituted indoles

The synthesis of the indoles 7 , 15 , 16 with a 3-methoxyphenyl group, attached via an α-side chain of 1,2,or 3 CH₂ units, is reported. These compounds, after appropriate protection at C(3), were transformed into the N-[(dimethylamino)methyl]indoles 22 , 23 , and 24 , respectively. When treated with AcCl, these N-Mannich bases gave, in two cases, stable N-(chloromethyl)indoles 25 and 26 . In the presence of SnCl₄, ring closure occurred via electrophilic attack of 1-methylideneindolium ions on the methoxyphenyl group. Formation of seven-membered rings (→ 27 , 28 ) and eight-membered rings (→ 29 ) was found to be a favorable process. Cyclization to six-membered rings did not occur within this series.     

Sila-Analoga des Chlorphenoxamins und des Clofenetamins

Sila-analoguesA 2 andB 2 of two drugs from the benzhydryl ether class, chlorphenoxamine and clofenetamine, were synthesized for the first time by the steps shown in scheme 1. They and their precursors I–VI were characterized by their physical (Table 1) and chemical properties and their structures confirmed by n.m.r., mass and infrared spectrocopy (Tables 2–5). Their physiological effects were investigated and compared with those of the carbon analogues (Chapter 5).

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1. Mitt.:R. Tacke undU. Wannagat, Mh. Chem.106, 1005 (1975).

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Mit Auszügen aus der DissertationR. Tacke, Techn. Univ. Braunschweig 1974.