Untersuchungen über Perylen und seine Derivate, 67. Mitt.: Mehrkernige Aromaten durch Diensynthesen mit Perylen

Zusammenfassung Perylen (1) reagiert mit p-Benzochinon zu Naphtho[1,2,3,4-ghi]perylen-1,4-chinon3 a und Tetranaphtho[2,1,8-uva: 1, 8 7-cde:2, 1, 8-jkl: 1, 8, 7-nop]pentacen-9,20-chinon5a, mit Naphthochinon zu Anthra[1,2,3,4-ghi]perylen-9,14-chinon4a.5 a entsteht auch aus3 a und1. Alle drei Chinone lassen sich in ihre Grundkohlenwasserstoffe3, 5 bzw.4 überführen, jedoch nur3 a und4 a reduzierend acetylieren. Bei der Umsetzung des Diacetylderivats von3 a mit Maleinsäureanhydrid (MSA) und Chloranil entsteht Benzo[a]coronen-9,12-chinon-3,4-dicarbon-säureanhydrid (6), aus dem Anthraperylen (4) Naphtho[2,3-a]-coronen-3,4-dicarbonsäureanhydrid (7) bzw. dessenMSA-Addukt7 a.

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Reaction of perylene (1) with p-benzoquinone gives3 a and5 a, with naphthoquinone4 a is formed.5 a is also obtainable from1 and3 a. The quinones3 a, 4 a and5 a can be reduced to the corresponding hydrocarbons; however, only3 a and4 a undergo reductive acetylation. Reaction of the diacetyl derivative of3 a with maleic anhydride and chloranil leads to the anhydride6, whereas from4 the anhydride7 resp. its maleic anhydride adduct7 a is formed.

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Mit 5 Abbildungen

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Teile aus der DissertationF. Wiedemann, Univ. Graz, März 1959 bis November 1961.     

Lithium 2,2,6,6-tetramethylpiperidide-mediated alpha- and beta-lithiations of epoxides: solvent-dependent mechanisms

Lithium 2,2,6,6-tetramethylpiperidide (LiTMP)-mediated alpha- and beta-lithiations of epoxides are described. LiTMP displays a markedly higher reactivity than does lithium diisopropylamide, consistent with literature reports. Detailed rate studies of LiTMP/THF and LiTMP/Me(2)NEt mixtures reveal similar rates but significant mechanistic differences. LiTMP-mediated alpha-lithiation of cis-cyclooctene oxide with subsequent oxacarbenoid formation and transannular C-H insertion proceeds via monosolvated dimers in both THF and Me(2)NEt. LiTMP-mediated beta-lithiation of 2,3-dimethyl-2-butene oxide affords the corresponding allylic alcohol via a monosolvated monomer in THF and a monosolvated dimer in Me(2)NEt. We discuss how the solvent-dependent aggregation of LiTMP markedly influences the rate profile. The reaction transition structures are examined with density functional computations.     

Rhodium-catalyzed direct C-H addition of 4,4-dimethyl-2-oxazoline to alkenes

A new method for the preparation of 2-substituted oxazolines by rhodium-catalyzed coupling of alkenes with 4,4-dimethyl-2-oxazoline is reported. The oxazoline products are obtained in good yield with excellent selectivity for the linear product. A variety of alkene substitution patterns and functional groups are tolerated. This procedure represents an attractive alternative to hydroesterification because it does not involve the manipulation of CO gas.     

Kinetics and Mechanism of Oxidation of 1-Phenylsemicarbazide by Peroxydisulphate

Kinetics of oxidation of 1-phenylsemicarbazide (PSC) by peroxydisulphate ion (PDS) have been carried out where by the pseudo first order condition was verified at large excess of PDS concentration. The rate of the reaction was followed spectrophotometrically, The stoichiometry was found to be 1:1 where 1-phenylazoformamide is the oxidation product. The effect of acidity on the rate of oxidation was investigated for different temperatures. The parameters of activation ΔG*, ΔH* and ΔS* were computed for both hydrogen ion depedent and hydrogen ion independent reaction pathes. A free radical mechanism was proposed.     

Investigation of minerals and of lunar samples (14163, 14258) by simultaneous thermal and X-ray analysis

Two methods for density determination are compared for test solutions of different apparent relative density (0.9778–1.0648). In case of the conventional method a comparative variation range of ±0.0003 has been found for three test solutions by cooperative experiment. In case of one test solution (liqueur wine) ±0.00042 has been obtained. The automatized digital method described permits the calculation of the density ? or the apparant relative density D′ ₂₀ ²⁰ from the resonance frequency of a flexural oscillator filled with the solution and excited to undamped oscillation by high frequency. The comparative variation range 3σ of this method was <5×10^?5 for three test solutions and standard solutions. For liqueur wine it was 7.8×10^?5. The mean values of the test solutions by the automatized method are within the single standard deviation of the pyknometric mean values. Both values are comparable. The digital method is recommended as reference method. It avoids subjective personal errors and makes possible the measurement of about 20 test solutions per hour.     

Thermal and Raman-spectroscopic analysis of Maya Blue carrying artefacts, especially fragment IV of the Codex Huamantla

Maya Blue, a pigment composed of very low concentrations of natural indigo and the clay mineral palygorskite, is one of the most brilliant blue dyes, intensively used for more than 2000 years in Mesoamerica. It is extremely stable against environmental attacks and was applied by the Indians for inside and outside mural paintings, ceramics, textiles and for colouring their famous codices. In the present paper it was studied as a powder (compared with modern synthetic indigo) and as colour on tissues, a Maya clay head, and fragment IV of the famous Codex Huamantla. Investigations using Raman spectroscopy in the visible and near-infrared range showed a high degree of correspondence among all Maya Blue-carrying samples and a good agreement with synthetic indigo. Additional spectral lines may be explained by a transformation of the planar indigo molecule when binding to the palygorskite lattice. Thermal investigations of the original “amatl” paper of the codex and of recent paper from fig-trees showed a high similarity and thus proved that this tree was chosen for paper making by Mayas, Aztecs and other Indian tribes. This was also true for the codex.     

Thermomechanical analysis of quartz,glasses and woods

The expansion and viscoelastic behavior of natural and synthetic materials changes during thermal treatment. Thermomechanical analysis (TMA) is the method to determine these mechanical properties directly as a function of time and temperature. Depending on the selected measuring mode either the expansivity (dilatometry), the viscous flow or the elastic behaviour can be investigated. Young's modulus is calculated from flexure and compression measurements.To show some of these possibilities quartz, various glasses and woods have been analysed. The solid transition of– quartz revealed a minimum of the modulus of elasticity during the transition. Flexure measurements of wood samples during degradation show the different elastic regions.

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Zusammenfassung Das Ausdehnungs- und viskoelastische Verhalten natürlicher und synthetischer Materialen verändert sich bei Wärmebehandlungen. Das Verfahren zur Bestimmung dieser mechanischen Eigenschaften als eine Funktion von Zeit und Temperatur ist die thermomechanische Analyse (TMA). In Abhängigkeit vom gewählten Meßverfahren können Ausdehnungsvermögen (Dilatometrie), Reibungsströmung oder das elastische Verhalten untersucht werden. Das Elastizitätsmodul wird aus Biegungs- und Kompressionsmessungen ermittelt.Um einige dieser Möglichkeiten aufzuzeigen, wurden Quarz, verschiedene Gläser und Hölzer analysiert. Die Feststoffumwandlung -ß-Quarz zeigt während der Umwandlung ein minimales Elastizitätsmodul. Biegungsmessungen an Holzproben zeigen bei Zersetzung verschiedene elastische Regionen.

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Dedicated to Prof. Dr. H. J. Seifert on the occasion of his 60^th birthday     

Large Ferrierite Crystals as Models for Catalyst Deactivation during Skeletal Isomerisation of Oleic Acid: Evidence for Pore Mouth Catalysis

Large zeolite crystals of ferrierite have been used to study the deactivation, at the single particle level, of the alkyl isomerisation catalysis of oleic acid and elaidic acid by a combination of visible micro‐spectroscopy and fluorescence microscopy (both polarised wide‐field and confocal modes). The large crystals did show the desired activity, albeit only traces of the isomerisation product were obtained and low conversions were achieved compared to commercial ferrierite powders. This limited activity is in line with their lower external non‐basal surface area, supporting the hypothesis of pore mouth catalysis. Further evidence for the latter comes from visible micro‐spectroscopy, which shows that the accumulation of aromatic species is limited to the crystal edges, while fluorescence microscopy strongly suggests the presence of polyenylic carbocations. Light polarisation associated with the spatial resolution of fluorescence microscopy reveals that these carbonaceous deposits are aligned only in the larger 10‐MR channels of ferrierite at all crystal edges. The reaction is hence further limited to these specific pore mouths.     

Sc3+-catalyzed aldol-type additions of N-benzoylcyclopropanecarboxamides via iodide-mediated ring-opening: stereoselective synthesis of gamma-lactams

A new catalytic aldol-type addition of cyclopropanecarboximides to aldehydes via iodide-mediated ring-opening is presented. The reaction was found to be catalyzed at 0 degrees C using either a Sc(OTf)3/NaI system or ScI3. Stereoselective formation of alpha,alpha-disubstituted enolates occurred in situ. gamma-Lactams bearing alpha-carbonyl quaternary stereocenters were obtained in 97-57% yield and dr = 90:10-80:20 after ring closure.     

Eine kleine Ver?nderung am Pyknometer

Ohne Zusammenfassung