Chemie der Seltenerdmetalle, 20. Mitt.: Yttriumtartrate im neutralen und alkalischen Bereich

Zusammenfassung Es wurden die Verbindungen HYT ^*·4 H₂O, Y₄ T ₃·14 H₂O, LiYT·4 H₂O, NaYT·5 H₂O, KYT·3 H₂O, RbYT·4 H₂O, CsYT·4 H₂O, NH₄YT·3 H₂O, K₂YTOH·4 H₂O, K₃YT(OH)₂·4 H₂O, K₄YT(OH)₃·3 H₂O, K₅YT(OH)₄·3 H₂O, KYH₄ T ₂·3 H₂O, K₂YH₃ T ₂·5 H₂O, K₃YH₂ T ₂·4 H₂O, KY₂ T(OH)₃·5 H₂O, K₂Y₂ T(OH)₄·5 H₂O isoliert. Die Präparate wurden mit Hilfe von Thermoanalyse, IR-Absorptionsspektren und Röntgenstreuung näher charakterisiert und ihre Löslichkeit in Wasser untersucht.

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Some complexes of Yttrium with tartrates were isolated and the compounds characterised by thermogravimetric analysis, IR-spectroscopy and X-ray diffraction. Solubility in water was examined.

     

The √t law in solid-phase reactions. Analysis of the hypothesis on rate constant distribution

The reaction C₂H₅ + O₂ → C₂H₅O₂ in glassy methanol-d₄ and the H-atom abstraction by CH₃, C₂H₅, and n-C₄H₉ radicals in C₂H₅OH + C₂D₅OH and CD₃CH₂OH + C₂D₅OH glassy mixtures have been studied by electron spin resonance. The analysis of the dependence of the reaction rates on the concentration of O₂ (oxidation) and C₂H₅OH, CD₃CH₂OH (H-atom abstraction) has shown that the √t law is not conditioned by the existence of regions characterized by different rate constants.     

Facile generation of platinum(IV) compounds with mixed labile moieties. Hydrogen peroxide oxidation of platinum(II) to platinum(IV) compounds

Hydrogen peroxide oxidation of platinum(II) compounds containing labile groups such as Cl, OH, and alkene moieties has been carried out and the products characterized. The reactions of [Pt^II (X)₂ (N–N)] (X = Cl, OH, X₂ = isopropylidenemalorate (ipm); N–N 2,2-dimethyl-1,3-propanediamine [(dmpda), N-isopropyl-1,3-propanediamine (ippda)] with hydrogen peroxide in an appropriate solvent at room temperature affords [Pt^IV (OH)(Y)(X)₂(N–N)] (Y = OH, OCH₃). The crystal structures of [Pt^IV(OH)(OCH₃)(Cl)₂(dmpda)]·2H₂O (P-1 bar, a = 6.339(2) Å , b = 9.861(1) Å, c = 11.561(1) Å, a = 92.078(9)°, β = 104.78(1)°, γ=100.54(1)°, V = 684.3(2) ų, Z = 2R = 0.0503) and [Pt^IV(OH)₂(ipm)(ippda)]·3H₂O (C 2/c, a = 27.275(6) Å, b=6.954(2) Å, c = 22.331(4) Å, β = 118.30(2)°, V = 3729(2) ų, Z = 8, R = 0.0345) have been solved and refined. The local geometry around the platinum(IV) atom approximates to a typical octahedral arrangement with two added groups (OH and OCH₃; OH and OH) in a transposition. The platinum(IV) compounds with potential labile moieties may be important intermediate species for further reactions.     

Glycosylidene Carbenes. Part 6. Synthesis of alkyl and fluoroalkyl glycosides

The syntheses of glycosides from the diazirine 1 and a range of alcohols under thermal and/or photolytic conditions are described. Yields and diastereoselectivities depend upon the pK_HA values of the alcohols, the solvent, and the reaction temperature. The glycosidation of weakly acidic alcohols (MeOH, EtOH, i-PrOH, and t-BuOH, 1 equiv. each) in CH₂Cl₂ at room temperature leads to the glycosides 2–5 in yields between 60 and 34% (Scheme 1 and Table 1). At ?70 to ?60°, yields are markedly higher. In CH₂Cl₂, diastereoselectivities are very low. In THF, at ?70 to ?60°, however, glycosidation of i-PrOH leads to α-D -/β-D - 4 in a ratio of 8:92. More strongly acidic alcohols, such as CF₃CH₂OH, (CF₃)₂ CHOH, and (CF₃)₂C(Me)OH, and the highly fluorinated long-chain alcohols CF₃(CF₂)₅(CH₂)₂OH ( 11 ) and CHF₂(CF₂)₉CH₂OH ( 13 ) react (CH₂Cl₂, r.t.) in yields between 73 and 85% and lead mainly to the β-D -glucosides β-D - 6 to β-D - 8 , β-D - 12 , and β-D - 14 (d.e. 14–68%). Yields and diastereoselectivities are markedly improved, when toluene, dioxane, 1,2-dimetoxyethane, or THF are used, as examined for the glycosidation of (CF₃)₂C(Me)OH, yielding (1,2-dimethoxyethane, 25°) 80% of α-D -/ β-D - 8 in a ratio of 2:98 (d.e. 96%; Table 4). In EtCN, (CF₃)₂C(Me)OH yields up to 55% of the imidate 10 . Glycosidation of di-O-isopropylideneglucose 15 leads to 16 (CH₂Cl₂, r.t.; 65%, α-D / β-D = 33:67). That glycosidation occurs by initial protonation of the intermediate glycosylidene carbene is evidenced, for strongly acidic alcohols, by the formation of 10 , derived from the attack of (CF₃)₂MeCO^? on an intermediate nitrilium ion (Scheme 4), and for weakly acidic alcohols, by the formation of α-D - 9 and β-D - 9 , derived by attack of i-PrO^? on intermediate tetrahydrofuranylium ions. A working hypothesis is presented (Scheme 3). The diastereoselectivities are rationalized on the basis of a protonation in the σ plane of the intermediate carbene, the stabilization of the thereby generated ion pair by interaction with the BnO? C(2) group, with the solvent, and/or with the alcohol, and the final nucleophilic attack by RO^? in the π plane of the (solvated) oxonium ion.     

PHOTOFRAGMENTATION OF HYDROXYACETONE, 1.3-DIHYDROXYACETONE, AND 1.3-DICARBOXYACETONE IN AQUEOUS SOLUTION. AN EPR STUDY

Abstract —On photoexcitation, hydroxyacetone undergoes a Norrish-type-1 fragmentation to yield CH₃CO and CH₂OH. CH₂OH is identified by its EPR spectrum. The existence of CH₃CO is inferred from the presence of diacetyl and acetaldehyde in irradiated solutions. Above pH 5, in addition to CH₂OH, the cis and trans forms of the hydroxyacetone enediol radical anion, CH₃C(O^-)=C(O***)H, are detected. 1.3-Dihydroxyacetone is photodecomposed to HOCH₂C?O and C?H₂OH. The former radical decarbonylates to yield CH₂OH and CO. At 254 nm the overall quantum yield of CO production is 0.75. Above pH 5, in addition to CH₂OH, the cis and trans forms of the 1.3-dihydroxyacetone enediol radical anion, HOCH₂C(O^-)C(O***)H, are observed. Electronically excited hydroxyacetone and 1.3-dihydroxyacetone react exclusively by C-C fragmentation, and no H-abstraction from H-donors is observed. In contrast, electronically excited 1.3-dicarboxyacetone shows H-abstraction from H-donors in competition with C-C fragmentation. In the absence of H-donors, fragmentation resulting in CH₂CO₂^- and ^-O₂CCH₂C?O occurs followed by decarbonylation of ^-O₂H₂C?O. At 254 nm the quantum yield of CO production is 0.02. In the presence of H-donors, H-abstraction, yielding HO₂CCH₂C(OH)CH₂CO₂, predominates.     

Absolute rate constants for the reactions ofOHradicals withCH3CH2OH, CF2HCH2OHandCF3CH2OH

Summary Pulsed laser photolysis with resonance fluorescence monitoring of OH radicals was applied at T = 300±2 K to obtain the rate constants of k₁= (3.38±0.60)x10^-12, k₂= (2.52±0.44)x10^-13and k₃ = (1.06±0.30)x10^-13cm³molecule^-1s^-1with 2σprecision given for the overall reactions OH + CH₃CH₂OH (1), OH + CF₂HCH₂OH (2) and OH + CF₃CH₂OH (3), respectively. k₂is the first direct kinetic data for the reaction of OH radicals with CF₂HCH₂OH reported in the literature.</o:p>     

Light production in alkaline mixtures of reducing agents and dimethylbiacridylium nitrate.

Abstract— Kinetic studies were made of light production and 0₂ absorption elicited by treatment of dimethylbiacridylium hydroxide [D(OH)₂] with reducing agents in alkaline aqueous solutions. D(OH)2 addition stimulated O₂ uptake which proceeded with zero-order kinetics until nearly all of the O₂ or of the D(OH)₂ was converted to end products. At the termination of the reactions with fructose as reductant the D(OH)₂ was converted to methylacridone and to dimethylbiacridene each compound accounting for approximately one-half the D(OH)₂ consumed. O₂ was reduced to H₂O₂. With hydroxylamine as the reducing agent the emitted light intensity was related to the first power of the D(OH)₂ concentration and the rate of O₂ uptake to the square root of the D(OH)₂. The disappearance of D(OH)₂ in these circumstances was by a first order or pseudo-first order rate. Fructose as a reducing agent by contrast resulted in an O₂ uptake nearly independent of D(OH)₂ concentration over a range from 1 × 10^-5M-1 × 10^-4M, while the light intensity and disappearance of D(OH)₂ followed a one-half order rate. O₂ uptake was by zero order kinetics and the oxidation of fructose proceeded at the same rate as was found with ferricyanide as oxidant. The kinetics, quantum yields and temperature dependence of the fructose reactions were compared with similar reactions employing H₂O₂ as the light eliciting reagent. The results are interpreted as indicating that D(OH)₂ acts as a chain initiator in a manner analogous to better known, radical producing compounds found to accelerate hydrocarbon autooxidations.     

Decomposition of zinc (1-hydroxyethylidene)diphosphonate induced by aliphatic amines and ammonia. Molecular structures of ammonium (1-hydroxyethylidene)diphosphonates

A suspension of sparingly soluble zinc (1-hydroxyethylidene)diphosphonate ZnH₂L?2H₂O (H₄L = MeC(OH)[P(O)(OH)₂]₂) is rapidly transformed into an aqueous solution when treated with ammonia or aliphatic amines (hexamethylenediamine, triethylamine, tert-butylamine, di-n-butylamine) containing no hydrophilic groups ?OH and ?(OCH₂CH₂)_n?. The dissolution effect is due to the decomposition of the coordination polymer giving ammonium derivatives. Dehydrated dry powders of the corresponding ammonium compounds based on triethylamine, tert-butylamine, or di-n-butylamine rapidly dissolve in water to form transparent colorless solutions, whereas hexamethylenediamine and ammonia derivatives are poorly soluble. (1-Hydroxyethylidene)diphosphonic acid forms ammonium salts with hexamethylenediamine, triethylamine, and tert-butylamine. The molecular structures of these compounds are considered.

     

Inorganic coordination polymers. XIV. Chromium(III) phosphinate perfluorocarboxylate polymers

A series of polymers, {Cr(OH)(OPRR′O)[OOC(CF₂)_nCF(CF₃)₂]}_x has been prepared and studied. The polymers with R = R′ = C₆H₅ are soluble in CCl₂FCClF₂, whereas those with R = CH₃ and R′ = C₆H₅ and with R = R′ = C₈H₁₇ are insoluble in all solvents. Attempts to prepare similar materials without hydroxyl groups gave the polymers {Cr(OH)_r(OPRR′O)_p[OOC(CF₂)_nCF(CF₃)₂]_q}_x with 0 < r < 1. The latter polymers are much more tractable than the former; however they are also less thermally stable. The perfluoro-carboxylate groups in these materials can either be chelating or bridging, depending on the other ligands present.     

Quenching of I(2P½) by R-OH compounds. Influence of the alkyl group on the quenching efficiency

The deactivation of I(²P_½) by R-OH compounds (R = H, C_nH_2n+1) was studied using time-resolved atomic absorption at 206.2 nm. The second-order quenching rate constants determined for H₂O, CH₃OH, C₂H₅OH, n-C₃H₇OH, i-C₃H₇OH, n-C₄H₉OH, i-C₄H₉OH, s-C₄H₉OH, t-C₄H₉OH, are respectively, 2.4 ± 0.3 × 10⁻¹², 5.5 ± 0.8 × 10⁻¹², 8 ± 1 × 10⁻¹², 10 ± 1 × 10⁻¹², 10 ± 1 × 10⁻¹², 11.1 ± 0.9 × 10⁻¹², 9.8 ± 0.9 × 10⁻¹², 7.1 ± 0.7 × 10⁻¹², and 4.1 ± 0.4× 10⁻¹² cm³ molec⁻¹ s⁻¹ at room temperature. It is believed that a quasi-resonant electronic to vibrational energy transfer mechanism accounts for most of the features of the quenching process. The influence of the alkyl group and its role in the total quenching rate is also discussed. © 1997 John Wiley & Sons, Inc.     

Reinvestigation of Sr2[Cu(OH)6]

During an investigation of the SrO–CuO–P₂O₅–H₂O system, single crystals of distrontium hexahydroxidocuprate(II), Sr₂[Cu(OH)₆], were obtained by the hydrothermal method. The blue prismatic crystals of Sr₂[Cu(OH)₆] adopt the same structure type as Ba₂[Cu(OH)₆], Sr₂[Zn(OH)₆] and Ba₂[Zn(OH)₆]. The Cu atoms, located at (0, 0, ) (site symmetry ), form mutually isolated and highly elongated Cu(OH)₆ octahedra, which are interconnected to slightly distorted Sr(OH)₆ trigonal prisms, forming a layered structure. The location of H atoms from difference Fourier maps and their refinement allowed the precise determination of a three‐dimensional hydrogen‐bonding network in which all hydroxide O atoms are involved. In addition, the hydrogen‐bonding topologies in Sr₂[Cu(OH)₆] and other similar hexahydroxidometallates with the general formulae M1[M2(OH)₆], M1₂[M2(OH)₆] and M1₃[M2(OH)₆] were analysed in detail.     

Photoaffinity labelling of chymotrypsin. Synthesis of photorecognizable ligands]

The syntheses of m-azido-L-phenylalanine, p-azido-o-nitro-L-phenylalanine, Z · Ala-Ala-Xxx · OH, and Z · Ala-Ala(β-³H)-Xxx · OH, with Xxx – Phe, Phe(p-NO₂), Phe(p-N₃), Phe(m-N₃), and Phe(p-N₃, o-NO₂) are described. The tripeptides with substituted phenylalanine residues are reversible inhibitors of chymotrypsin in the dark, and irreversible ones in the light. Photoaffinity labelling of chymotrypsin has been reported by the authors in FEBS Letters 46, 347 (1974).     

Mechanisms of polymer-supported catalysis. 5. Solvation of quaternary onium ions in polystyrene gels by 13C-NMR spectroscopy

¹³C-NMR linewidths and spin-lattice relaxation times have been determined for soluble and crosslinked polystyrenes containing quaternary phosphonium and ammonium ions. Solubilities and NMR linewidths show that the solvating abilities toward tri-n-butylphosphonium ions are CDCl₃ > CH₃OH > D₂O > benzene, toluene, toward the trimethylammonium ions, CH₃OH > CDCl₃ > D₂O > toluene, and toward the nonpolar polymer backbone, CDCl₃, benzene > toluene > CH₃OH > D₂O.     

矿化剂对水热法改性氢氧化镁晶体的影响

近几年来,氢氧化镁作为一种无机阻燃剂由于其具有制备条件相对温和,生产工艺简单且产品与自然环境友好等特点,在研究及生产活动方面备受关注且得到了长足的发展[1～4].目前采用氢氧化钠法进行反应一水热制备高分散阻燃级氢氧化镁的工艺路线已经比较成熟[5～8].然而,不利的是,氢氧化钠偏高的价格导致了产品的制造成本较高.而采用石灰法制备氢氧化镁阻燃剂具有价格低廉的特点,引起了人们的关注.     

Verbindungen der Seltenerdelemente mit α-4-Dimethylaminobenzoinoxim

Zusammenfassung Es wurden VerbindungenLnCl₃·H₂ DBox ^* (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) und La₂(DBox)₃·6 CH₃OH, Pr₂(DBox)₃·6 CH₃OH, Nd₂(DBox)₃·3 C₂H₅OH, Sm₂(DBox)₃· ·3 C₂H₅OH, Gd₂(DBox)₃·3 C₂H₅OH, Tb₂(DBox)₃·2 C₂H₅OH, DyH(DBox)₂·2 C₂H₅OH, HoH(DBox)₂·2 C₂H₅OH, ErH(DBox)₂, YH(DBox)₂·H₂O isoliert. Diese wurden mittels Thermoanalyse und Röntgenstreuung untersucht sowie ihre IR-Absorptionspektren gemessen und diskutiert.

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Compounds of rare earth elements with -4-dimethylaminobenzoinoxime

The compoundsLnCl₃·H₂ DBox ^* (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) and La₂(DBox)₃·6 CH₃OH, Pr₂(DBox)₃·6 CH₃OH, Nd₂(DBox)₃·3 C₂H₅OH, Sm₂(DBox)₃·3 C₂H₅OH, Gd₂(DBox)₃· ·3 C₂H₅OH, Tb₂(DBox)₃·2 C₂H₅OH, DyH(DBox)₂·2 C₂H₅OH, HoH(DBox)₂·2 C₂H₅OH, ErH(DBox)₂ and YH(DBox)₂·H₂O were isolated, and studied by thermoanalysis and X-ray diffraction. Their IR absorption spectra were recorded and are discussed.

     

Electron transfer. 121. Oxidations by Rhodium-Bound Superoxide

The violet superoxo complex, [(H₂O)₄(OH)Rh^III(O₂)Rh^III(OH)(H₂O)₄]³⁺, formed by treatment of (Rh^II)₂⁴⁺ with O₂ in HClO₄, is converted to a le^? reduction product, the corresponding μ-peroxo complex, by the reductants I^?, IrCl₆^3?, and the trinuclear aquamolybdenum(III) cation, (Mo^III)₃. Each reaction is first-order in both redox partners, and the le^? reduction by IrCl₆^3? is followed by a much slower conversion to a peroxide-free complex. Among the rapid reductions of the superoxo derivative examined here and in a previous study, only that by IrCl₆^3? is accelerated by increases in acidity; the rate law for this reaction features both an acid-independent and a [H⁺]-proportional component, the latter stemming from partial conversion of the oxidant to its conjugate acid (pK_A < ?1.0). Rate laws for reductions by other metal-center reagents generally exhibit inverse-[H⁺] terms, reflecting deprotonation of the reductant. All reductions thus far observed involving this superoxo species appear to be outer-sphere. Treatment of acid-independent rate constants within the framework of the Marcus model, allows estimates of the self-exchange rate, k₁₁, for the (Rh^III)₂-bound superoxo-peroxo couple. Because values of k₁₁ calculated from the several reductions span a range of 10^4.5, reductions of the superoxo complex cannot be taken to conform satisfactorily to the Marcus treatment, being in this respect comparable to the systems VO(OH)^+/2+, Mn^2+/3+, Eu^2+/3+, and Ti(OH)^2+/3+, each of which exhibits similar divergences. The wide range of calculated self-exchange rates appears to invalidate an earlier suggestion that reduction of the superoxo complex by Fe²⁺ proceeds primarily through a bridged path. © 1994 John Wiley & Sons, Inc.     

Complex Formation in the Region of Metal Hydrolysis and M(OH)2 Precipitation. A Glass Electrode Potentiometric and Polarographic Study of Cd–(AMPSO)x–(OH)y and Zn–(AMPSO)x–(OH)y Systems

The interaction between cadmium or zinc and AMPSO was investigated by DCP and GEP, at fixed total ligand to total metal concentration ratios and various pH values, at 25.0 °C and 0.1 M KNO₃ ionic strength. For Cd–(AMPSO)_x–(OH)_y system, CdL and CdL(OH) species, were identified, with stability constants values set to (as log β): 2.1±0.1 and 6.2±0.2, respectively. For Zn–(AMPSO)_x–(OH)_y system, the proposed final model with stability constants set to (as log β) is: ZnL=2.5±0.1 and ZnL(OH)₂=12.9±0.2. For both systems, the fact that AMPSO deprotonation occurs in the metal hydrolysis and M(OH)₂ precipitation and the complexes formed are not too strong added a real challenge to data interpretation.     

Photoinduced Oxidation Reaction of Benzotrifluoride with OH Radical by the Laser Flash Method

The optical transient and kinetics characterizations of the transients formed in the reaction of OH with benzotrifluoride (BTF) were performed by a laser flash photolysis technique. The results indicated that the formation of π‐type adduct of C₆H₅(OH)CF₃ was the major reaction channel, and the δ‐type adduct of C₆H₅CF₃OH formation was an additional minor process in the oxidation reaction of BTF attacked by OH radicals yielded from the photolysis of H₂O₂. Addition of OH to the CF₃ group led to the fluoride ion elimination to yield α,α‐difluorophenylcarbinol (C₆H₅CF₂OH). Trifluoromethylphenol (HOC₆H₄CF₃) of meta‐, para‐ and ortho‐substituted isomers resulted from the addition of OH to the BTF aromatic ring.     

Synthesis and structure of the first molybdenum compound of N,O,N-hydroxybis(2-pyridyl)methanolato (η 3-dpkO,OH). The structure of [Mo(O)2(μ-O)(η 3-dpkO,OH)]2 · 2dmso

When di-2-pyridyl ketone (dpk) was allowed to react with [Mo(CO)₆] in toluene under reflux in air [Mo(O)₂(μ-O)(η ³-dpkO,OH)]₂ where η ³-dpkO,OH is N,O,N-hydroxybis(2-pyridyl)methanolato was isolated. Infrared and ¹H-NMR spectral data measured on solutions of the isolated compound indicate the absence of the carbonyl groups and the presence of coordinated η ³-dpkO,OH, terminal and bridging oxo-groups and elemental analysis confirmed the formulation of the product as [Mo(O)₂(μ-O)(η ³-dpkO,OH)]₂. Crystals of [Mo(O)₂(μ-O)(η ³-dpkO,OH)]₂·2dmso obtained from a dimethyl sulfoxide (dmso) solution of [Mo(O)₂(μ-O)(η ³-dpkO,OH)]₂ are in the monoclinic P2₁/c space group. X-ray structural analysis confirmed the identity of [Mo(O)₂(μ-O)(η ³-dpkO,OH)]₂ and shows a dioxomolybdenum oxo-bridged dimer with two terminal oxygen atoms and one tridentate N,O,N-dpkO,OH occupying the coordination sites of the high-valent molybdenum(VI) in a pseudo-octahedral coordination geometry. The molecular packing shows parallel stacks of [Mo(O)₂(μ-O) (η ³-dpkO,OH)]₂·2dmso and disclose an extensive network of non-covalent interactions within each stack.     

Sila-Riechstoffe und Riechstoff-Isostere, 13. Mitt.Grimmsche Hydridisostere im Bereich der Duftstoffklasse des Linalools

Summary Substitution of the (CH₃)₂CH=CH group by (CH₃)₂C=N in linalool as well as by the (CH₃)₂CH-CH₂ group in linalool and in sila-linalool does not lead to noticeable changes of their scent qualities. On the contrary, substitution of the OH group at the tertiary C atom by NH₂ or CH₃ — hydride isosteric to OH according toGrimm — affords fishy or etheric instead of the original flowery smells thus indicating a transition to different basic classes of odor. Similar results were obtained with the linalool-like scents of benzyldimethylcarbinol and phenylethyldimethylcarbinol. Therefore the theory ofAmoore, after which only shape and size of molecules are ruling their odor qualities, must be called in question.