Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. XXV [1]. Über den Einfluß von MgCl2 auf Aceton bzw. Aceton-Wasser-Gemische

Studies on systems of salts and mixed solvents. XXV. Effect of MgCl₂ on acetone and acetone-water mixtures In the sphere of the system Na⁺, K⁺, Mg⁺⁺/Cl^?//acetone-water being rich in acetone and especially with high intensity in the boundary system MgCl₂-acetone the formation of condensation products of acetone depending on temperature and time is observed. These reaction products, like e. g. 4-methyl-3-pentene-2-cene (mesityl oxide) and diacetone alcohol dye the solutions yellow to brown and influence the salt solubilities. MgCl₂ acts catalytically in form of Lewis acid on the aldol condensation of the acetone. As new solid phases MgCl₂ · 6 diacetone alcohol and MgCl₂ · 3 acetone are observed in the systems to be investigated.     

Thermische Zersetzung und Lösungskalorimetrie von Ammoniumsamariumbromiden

Thermal Decomposition and Solution Calorimetry of Ammonium Samarium Bromides The ternary pure phases on the line SmBr₃—NH₄Br in the thermodynamically equilibrium have been synthesized by solid state reactions and characterized by X‐ray powderdiffraction. The existence of a new phase (NH₄)₃SmBr₆ was demonstrated beside the known phases (NH₄)₂SmBr₅ and NH₄Sm₂Br₇. The decomposition equilibria of the ammonium samarium bromides have been investigated by total pressure measurements and the thermodynamical data of the solid phase complexes derived from the decompostion functions. The standard enthalpies of solution in 4n HBr (aq.) of the ternary phases, SmBr₃ and Sm₂O₃, were measured and on the basis of these values and known data the standard enthalpies of ammonium samarium bromides were derived. The phase diagram is constructed on the basis of DTA measurements. Data from total pressure measurements: ΔH((NH₄)₃SmBr_{6, f, 298}) = —400, 0 ± 6, 5 kcal/mol S°((NH₄)₃SmBr_{6, f, 298}) = 146, 9 ± 8 cal/K · mol ΔH((NH₄)₂SmBr_{5, f, 298}) = —340, 6 ± 5, 0 kcal/mol S°((NH₄)₂SmBr_{5, f, 298}) = 106, 0 ± 6 cal/K · mol Δ(NH₄Sm₂Br_{7, f, 298}) = —479, 4 ± 6, 0 kcal/mol S°(NH₄Sm₂Br_{7, f, 298}) = 119, 5 ± 7 cal/K · mol Data from solution calorimetry: ΔH(SmBr_{3, f, 298}) = —204, 4 ± 1, 8 kcal/mol ΔH((NH₄)₃SmBr_{6, f, 298}) = —400, 7 ± 3, 2 kcal/mol ΔH((NH₄)₂SmBr_{5, f, 298}) = —339, 6 ± 2, 6 kcal/mol ΔH(NH₄Sm₂Br_{7, f, 298}) = —475, 6 ± 4, 4 kcal/mol     

Reaktionsprodukte aus 3-Dimethylamino-2, 2-dimethyl-2H-azirin und Phthalohydrazid bzw. Maleohydrazid

Reaction Products from 3-Dimethylamino-2,2-dimethyl-2H-azirine and Phthalohydrazide or Maleohydrazide 3-Dimethylamino-2, 2-dimethyl-2H-azirine (1) reacts in dimethylformamide at room temperature with the six-membered cyclic hydrazides 2, 3-dihydrophthalazin-1, 4-dione (2) and 1, 2-dihydropyridazin-3, 6-dione (15) to give the zwitterionic compounds 3 and 16 , respectively (Scheme 1 and 7). The mechanism of these reactions is outlined in Scheme 1 for compound 3 (cf. also Scheme 8). The first steps are thought to be similar to the known reactions of 1 with the NH-acidic compounds saccharin and phthalimide (cf. [1]). Instead of ring expansion to the nine-membered heterocycle i (X=CONH, Scheme 8), a proton transfer followed by the loss of water gives 3 (Scheme 1). The structure of the zwitterionic compounds 3 and 16 is deduced from spectral data and the reactions of these compounds (see Schemes 2, 3, 4, 6 and 7). Methylation of 3 yields the iodide 4 , which is hydrolysed easily to the 2-imidazolin-5-one derivative 5 (Scheme 2). Hydrolysis of 3 under basic conditions leads to the amide 6 , which undergoes cyclization to 7 at 220–230° (Scheme 3). The analogous cyclization has been realized under acidic conditions in the case of 17 (Scheme 7). Catalytic reduction of 3 yields the tertiary amine 14 (Scheme 6), whereas the reduction with sodium borohydride leads to a mixture of 14 and the 2-imidazoline derivative 13 . The alcohol 11 , corresponding to the amine 14 , is obtained by sodium borohydride reduction of the 2-imidazolin-5-one 7 or of the amide 6 (Scheme 3). This remarkably easy reaction of 7 shows the unusual electrophilicity of the lactamcarbonyl group in this compound. The reduction of 6 to 11 is understandable only by neighbouring group participation of N (2′) in the dihydrophthalazine residue.     

13C-NMR-chemische Verschiebungen von Polymethinen. Elektronenstruktur und Lösungsmitteleinfluss

The ¹³chemical shifts of simple polymethines (cyanines and merocyanines) show the very pronounced charge alternation in these compounds. The ¹³C shifts of polar merocyanines are also susceptible to solvent polarity, which in this case has a strong influence upon the electron structure.     

Löslichkeiten und Aktivitätskoeffizienten von H2S in Elektrolytmischungen

From solubility measurements on hydrogen sulfide in aqueous solutions of the composition [H⁺] = HM, [Na⁺] = (I — H) M = A M, [Cl^?] = I M at 25°C, the molar and molal activity coefficients of H₂S have been calculated. The activity coefficients of H₂S in the electrolyte mixtures have been found to be additive functions of the activity coefficients in the individual electrolyte solutions at the same ionic strength. This result is predicted by the internal pressure theory of salt effects on non-electrolyte activity coefficients, provided that the volume change upon mixing two electrolyte solutions of the same ionic strength is zero.     

Zur Photochemie von 1H- und 2H-Indazolen in saurer Lösung

On the Photochemistry of 1H- and 2H-Indazoles in Acidic Solution It is shown that 1H- and 2H-indazoles (cf. Scheme 2) on protonation (0, 1N H₂SO₄ in water or alcoholic solution) give analogous indazolium ions (see Fig. 1 and 2) which on irradiation undergo heterolytic cleavage of the N (1), N (2) bond whereby aromatic nitrenium ions in the singlet ground state are formed (cf. Scheme 13). If the para position of these nitrenium ions is not occupied by a substituent (e.g. a methyl group) they are readily trapped by nucleophiles present (e.g. water, alcohols, chloride ions) to yield the corresponding 5-substituted 2-amino-benzaldehydes or acetophenones (cf. Schemes 4–10). Photolysis of indazole ( 4 ) and 3-methyl-indazole ( 5 ) in 0,75N H₂SO₄ in alcoholic solutions gives in addition minor amounts of the corresponding 3-substituted 2-amino-benzaldehydes and acetophenones, respectively (cf. Schemes 6 and 8 and Table 2). Phenylnitrenium ions carrying a methyl group in the para position give in aqueous sulfuric acid mainly the reduction products, i.e. 2-amino-5-methyl-benzaldehydes (cf. Schemes 11 and 12 and Table 3). In methanolic sulfuric acid, in addition to the reduction products, 6-methoxy substituted benzaldehydes are found (cf. Schemes 11 and 12 and Table 3) which are presumably formed by an addition-elimination mechanism (cf. Scheme 18). It is assumed that precursors of the reduction products are the corresponding nitrenium ions in the triplet ground state. Singlet-triplet conversion of the nitrenium ions may become efficient when addition of nucleophiles to the singlet nitrenium ions is reversible (cf. Scheme 22) thus, enhancing the probability of conversion or when conjugation in the singlet nitrenium ions is disturbed by steric effects (cf. Scheme 20) thus, destabilizing the singlet state relative to the triplet state.     

Darstellung von Alkalichlorowolframaten(V) aus WCl6 in chloridhaltigen Lösungsmitteln

Preparation of Compounds AWCl₆ from WCl₆ in Cl^?-containing Solvents In Glyme, ACN or CH₂Cl₂ WCl₆ is reduced by Cl^? to WCl₆^?. From those solutions compounds AWCl₆ can be isolated with A = Cs (Glyme, ACN), A = Rb, K, NH₄(ACN) and A = N(C₂H₅)₄ (CH₂Cl₂). By concentrating of glyme-solutions a precipitate of A₂WCl₆ is formed by disproportionation. In methanol/HCl also solvolysis to oxo-compounds of W⁶⁺ takes place as function of the H⁺-concentration. With N(C₂H₅)₄Cl not only chlorotungstates but also methoxy- and oxo-spezies of W⁵⁺ can be isolated.     

Untersuchungen über die Löslichkeit von Molybdatophosphaten. I. Löslichkeit von Chinoliniummolybdatophosphat

Studies on the Solubility of Molybdatophosphates. I. Solubility of Quinolinium Molybdatophosphate The solubility of quinolinium molybdatophosphate was determined radiochemically under conditions of the gravimetric determination of phosphate in hydrochloric acid as well as in nitric acid media. The residue concentration of phosphate variies in the range of 10^?8 to 10^?9 mol/I. The dependence of the solubility on the reagent concentration and on the concentration of solution components was investigated and discussed variing the pore width of the filters used for separating the precipitate. The accuracy and the precision of the determination of phosphate was not influenced in practice by the solubility.     

Kryometrische Untersuchungen. IV. Lösungen von oxidischen Mo6+- und Cr6+-Verbindungen in geschmolzenem K2Cr2O7 und KNO3

The depression of freezing point of molten K₂Cr₂O₇ and KNO₃ as solvents was measured after addition of small concentrations of the following compounds: to K₂Cr₂O₇: MoO₃, CrO₃, (NH₄)₂CrO₄, K₂MoO₄, Na₂MoO₄, Li₂MoO₄, and Na₂Mo₂O₇, respectively; to KNO₃: CrO₃, (NH₄)₂Cr₂O₇ K₂Cr₂O₇, K₂CrO₄ and MoO₃, (NH₄)₆(Mo₇O₂₄) · 4 H₂O, K₂Mo₂O₇, K₂MoO₄, Na₂MoO₄ and Li₂MoO₄, respectively. It could be concluded from the measured values of the freezing point depression if a reaction between solvent and solute took place.     

Selenostannate aus wäßriger Lösung Darstellung und Struktur von Na4Sn2Se6 · 13 H2O

Selenostannates from Aqueous Solution, Preparation and Structure of Na₄Sn₂Se₆ · 13 H₂O The dimeric anion Sn₂Se₆^4? is prepared by reaction of SnSe₂ with alkali metal selenide in a 1:1 molar ratio. The orange-red hydrated sodium salt Na₄Sn₂Se₆ · 13 H₂O is characterized by a complete X-ray structure analysis and by its vibrational spectrum. The compound is triclinic (P1 ) with a = 7.106(2), b = 10.330(2), c = 19.009(4) Å, α = 78.60(2), β = 85.66(2), γ = 72.85(2)° (?130°C), Z = 2. It contains isolated Sn₂Se₆^4? anions consisting of two edge-sharing tetrahedra [Sn? Se 2.456(1)–2.589(1) Å] which are in contact to the hydrated Na⁺ ions within an extensive hydrogen bridge system. Raman-active vibrations are observed at 260, 202, 188, 116, 93, and 78 cm^?1.     

Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. XXXIV. 27Al- und 1H-NMR-spektroskopische Untersuchungen an Lösungen des Systems AlCl3-Wasser-N,N-Dimethyl- formamid

Studies on Systems of Salts and Mixed Solvents. XXXIV. ²⁷Al and ¹H N.M.R. Spectroscopic Investigations of AlCl₃-Water-N,N-Dimethylformamide Solutions Al³⁺ ions exist in aqueous solutions as well as in DMF solutions in a sixfold coordination; the coordination of DMF exclusively occurs via the oxygen atom. Because of the small shift difference between the pure aqueous and the pure DMF solution at the ²⁷Al n.m.r. spectra no separated signals were found corresponding to the species with mixed coordination. From the changes of the Al chemical shifts and of the linewidths in dependence of the solvent composition a selective solvation process is suggested. At the ¹H n.m.r. spectra for the formyl and methyl protons of DMF separated signals appear for the molecules of the first coordination sphere and of the bulk, respectively. From this the number of directly coordinated DMF molecules can be determined. Up to a DMF content of about x = 0.45 DMF is preferentially coordinated, after that a change of selectivity takes place and accordingly water is preferred at the first coordination sphere.     

Extraktion von Alkali- und Erdalkalimetallpikraten aus wässerigen Lösungen in Methylenchlorid durch ungeladene azyklische Ionophoren. Quantitative Interpretation

Extraction of alkali and alkaline earth metal picrates from water into methylene chloride. Quantitative interpretation The ligands N, N, N′, N′-tetraphenyl-3, 6-dioxaoctanediamide (1) , (?)-(R, R)-N, N′di [(ll - ethoxycarbonyl) undecyl] - N, N′, 4, 5-tetramethyl-3, 6-dioxaoctanediamide (2) , and N, N′-diheptyl-N, N′, 5,5-tetramethyl-3,7-dioxanonanediamide (3) , reported earlier as components for liquid membrane electodes with selectivity for Ba²⁺ (1) , Ca²⁺ (2) and Li⁺ (3) , were used to study models for the extraction of alkali and alkaline earth metal picrates from water into methylene chloride. The composition of the extracted complexes of alkaline earth cations with 1 and 2 proved to be mono- and diassociated with the picrate anion. The extraction selectivity observed for 1, 2 , and 3 towards different cations paralleled the potentiometric selectivity factors obtained for liquid membrane electrodes with 1, 2 , and 3 as membrane components.     

Homogene Lösungskatalyse. Über die Hemmwirkung von La3+-Ionen im H2O2-Zerfall in homogener Lösung

The inhibitor action of La³⁺ ions on the H₂O₂ decomposition has been proved in NaHCO₃ containing solution.