Über basische Aluminiumsalze und ihre Lösungen. X. NMR-Untersuchungen am tridekameren Al-oxo-hydroxo-Kation

Basic Aluminum Salts and their Solutions. X. NMR-Investigations on the Tridecameric Al-Oxo-Hydroxo Cation Using solid-state high resolution ²⁷Al-NMR it is shown that in the basic aluminum chloride with a degree of alkalinity r = OH/Al = 2.5 cations of the [Al₁₃O₄(OH)₂₅(H₂O)₁₁]⁶⁺ type exist. The ¹H-NMR detects besides the constitutional water still an amount of mobile, enclosed H₂O molecules which can be removed by thermal treatment at 104°C. The ²⁷Al spectrum of the aqueous solutions of the chloride shows only one peak at 62.5 ppm which is characteristic for the tridecameric cation. Adding HCl to the solution causes a decomposition to low-molecular species (peak at 0 ppm). Adding NaOH to the aqueous solution of the chloride effects a rearrangement of the tridecameric cations to higher molecular particles which are no more accessible by ²⁷Al-NMR.     

Hetero-cope-umlagerungen -II. Einfache und flexible synthesen für 2-substituierte indole

The reaction of N-phenylhydroxylamine derivatives with electron withdrawing allenes gives o-alkylated anilines, which can further react to form 1,2-disubstituted indoles. 2-Substituted indoles are directly obtainable from reaction with N-phenyl-nitrones.     

Kryoskopische Titrationen als neues Verfahren zur Bestimmung geringer Substanzmengen

Zusammenfassung Es wird ein neues Titrationsverfahren zur Bestimmung geringer Substanzmengen beschrieben, das auf der Verfolgung der Änderung des Gefrierpunkts basiert. Kryoskopische Titrationen werden am Beispiel der Acidimetrie erlautert. Starke und schwache Säuren bzw. Basen lassen sich in 0,01 M Lösungen bei einem Gesamtvolumen von etwa 0,2 ml mit einem Fehler von 1–3% bestimmen. Die Auswertung erfolgt graphisch.

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Cryoscopic titrations—a new method for the determination of small quantities of substances

A new method is described for the determination of small amounts of strong or weak acids or bases. It consists in observing the lowering of the freezing point during titration. Cryoscopic titrations allow the determination of only 0.2 ml of 0.01 N solutions. The error is about 1–3%. Graphical endpoint detection is employed.

     

Kristall- und molekülstruktur vonzwei metallcarbonyl-derivaten des PH3: (CO)3Cr(PH3)3 und (CO)5Cr(PH3)

The structures of two carbonylphosphine complexes of chromium were determined by X-ray analysis. cis-Tricarbonyltriphosphinechromium(0), [(CO)₃(PH₃)₃Cr], crystallizes in space group P2₁/m with a = 6.90± 0.01, b = 11.29±0.02, c = 6.41±0.01 Å, β = 93.80±0.08°, Z=2. The structure was solved by conventional methods and refined by least squares (R₁ = 0.056). The idealized octahedral molecule shows approximate C_3v, symmetry. The mean CrP-distance is 2.346±40.003 Å. Pentacarbonylphosphinechromium, [(CO)₅(PH₃)Cr], crystallizes in spacegroup Pnma with a = 12.23±0.02, b = 11.33±0.02, c = 6.61 ±0.01 Å, Z = 4. Cell dimensions and structural parameters are very similar to those of hexacarbonylchromium(0). In the crystal the PH₃ group is disordered over three mutually cis-positions of the coordination octahedron.     

Chinazolincarbonsäuren. VII. Mitteilung. Ein einfacher Zugang zu (4-Oxo-3,4-dihydrochinazolin-3-yl)-alkansäuren, (4-Oxo-3,4-dihydro-1,2,3-benzotriazin-3-yl)-alkansäuren und deren Estern

Quinazoline Carboxylic Acids. An Easy Route to (4-Oxo-3,4-dihydroquinazolin-3-yl)-alkanoic Acids, (4-Oxo-3,4-dihydro-1,2,3-benzotriazin-3-yl)-alkanoic Acids and their Esters A new route was found for the synthesis of (4-Oxo-3,4-dihydroquinazolin-3-yl)-alkanoic acids ( 8 ) and (4-Oxo-3,4-dihydro-1,2,3-benzotriazin-3-yl)-alkanoic acids ( 6 ) by cyclization of the N-(2-aminobenzoyl)amino acids 5 with HCOOH or HNO₂. 2H-3,1-Benzoxazine-2,4(1H)-diones ( 1 ) reacted with glycine esters to 2 , which were cyclized by HNO₂ to the esters 4 . Ester 4 was hydrolyzed to 6 (X = CH₂). Diones 1 reacted with the most common amino acids (as the ammonium salt of tertiary amine) to amino-alkanoic acids 5 , which were cyclized with orthoformate to 7 or 8 depending on the reaction conditions.     

Intermittency in the Navier-Stokes dynamics

Intermittency effects in high Reynolds number turbulence (Re10³–10⁶) are calculated from the Navier-Stokes equation in Fourier-Weierstrass approximation. First, the probability density functions (PDF) of scale resolved turbulent signals is found to be Gaussian for large scales, whereas for smaller scales the PDF changes (in agreement with experiment) to a more and more stretched exponential type. This is due to intermittent small scale fluctuations which are caused by the competition between turbulent energy transfer downscale and viscous energy loss. Second, we calculate the moments of ther-averaged energy dissipation rate _r (x) and theirr-scaling exponents (m/3). Our results well agree with experiment and numerical simulations of the full Navier-Stokes equations ((2)=0.29±0.02). We analytically show that the common identification between the (m/3) and the corrections (m) to classical scaling of the velocity structure functions (Kolmogorov's refined similarity hypothesis) is doubtful, because even Gaussian ₁ u ₁-PDFs (characterizing non intermittent flow) lead to (m/3)0.     

Furylvinylhalogenides,XII: Reactions of β-chloro-α-cyano-β-(5-nitrofur-2-yl)-acrylic acid derivatives with malonic acid derivatives

Summary Reactions of -chloro--cyano--(5-nitrofur-2-yl)-acrylic acid derivatives with malonic acid derivatives in the presence of collidine yield the allyl anions3a–d. The pyridines4, 8 or9 are formed by cyclization of3 under acidic conditions. The 2-chloropyridine4a reacts with nucleophiles under substitution. The treatment of ethyl dichloropropionate1b with C-H-acidic compounds provided the cyclopropanes11 or12, the configurations of which were determined by¹³C-NMR spectroscopy. The results of the X-ray structure analysis of8c are discussed.

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Furylvinylhalogenide, 12. Mitt.: Reaktionen von -Chlor--(5-nitrofur-2-yl)--cyanacrylsäurederivaten mit Malonsäurederivaten

Zusammenfassung Die Umsetzung von -Chlor--cyan--(5-nitrofur-2-yl)-acrylsäurederivaten mit Malonsäurederivaten in Gegenwart von Collidin führt zu Allylanionen3a–d. Unter sauren Bedingungen cyclisiert3 zu den Pyridinen4, 8 oder9. Das 2-Chlorpyridin4a reagiert mit Nukleophilen unter Substitution. Setzt man den Dichlorpropionsäureester1b mit C-H-aciden Verbindungen in Gegenwart von Collidin um, so werden die Cyclopropane11 bzw.12 gebildet, deren Konfigurationen mit Hilfe der¹³C-NMR-Spektroskopie bestimmt wurden. Die Ergebnisse der Röntgenkristallstrukturanalyse von8c werden diskutiert.

     

Limit theorems for probability measures on simply connected nilpotent lie groups

LetX ₁,X ₂,... be i.i.d. random variables with values in a simply connected nilpotent Lie groupG. Assume the laws of to be weakly convergent to a probability measure onG, _n Aut(G), and (k _n)_n strictly increasing in. In this paper we want to characterize the possible limit laws. We obtain that every limit law is continuously embeddable and we prove a kind of functional limit theorem. Further, we study the connections between two different concepts of stability (resp. semistability) and limit laws. Finally, we describe the various domains of attraction of measures (resp. of convolution semigroups).     

A Regio‐ and Diastereoselective Anodic Aryl–Aryl Coupling in the Biomimetic Total Synthesis of (−)‐Thebaine

The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)‐reticuline. For decades, chemists have sought to mimic this coupling by using stoichiometric oxidants. However, all approaches to date have suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regio‐ and diastereoselective anodic coupling of 3′,4′,5′‐trioxygenated laudanosine derivatives is presented, which finally enables electrochemical access to (?)‐thebaine.