Untersuchungen zur intramolekularen C?C-Verknüpfung von Dienen durch Basenkatalyse. III. [1] Cyclisierung von Diallylaminen

Attempts to Intramolecular C C-Connexions of Dienes by Base-catalysis. III. Cyclization of Diallyl Amines Diallyl alkyl amines 1 are isomerized to the corresponding dipropenyl alkyl amines with potassium on alumina catalyst. The trans, trans-isomers are thermodynamically prefered. If the alkyl group in the diallyl alkyl amines is replaced by an electron-attracting group a cyclization to tetrahydropyridines takes place. The base-catalysed isomerization of diallyl ether 3 does not give a cyclic product. Diallyl sulfide 4 can be isomerized to 5-methyl thiacyclohexen-(2) 4a .     

Synthese von Heterocyclen durch C?C-Knüpfung. V. Eine neue Pyridonsynthese

Synthesis of Heterocyclic Compounds by C C-bond Closure. V. A Novel Pyridone Synthesis Under the action of alkali two moles of N-primary alkyl cyanoacetamides 5 condense to form 1-alkyl-5-alkylaminocarbonyl-4,6-diamino-pyridone-2 ( 6 )     

Synthese von Heterocyclen durch C?C-Knüpfung. IV. Heterocyclensynthesen durch intramolekulare Dien-Reaktion

Synthesis of Heterocyclic Compounds by C C-bond Closure. IV. Synthesis of Heterocyclic Compounds by Intramolecular Dienreaction N-2-Cyclohexenyl-N-isopropylcinnamamide 8 cyclizes at 230°C to give the decahydronaphthindolone 9 . N-Alkyl-N-allylcinnamamides 10 analogously form 1 H-hexahydrobenzisoindolones 11 . N-Alkyl-N-allylsorbamides 14 cyclize at 150°C to 1 H-hexahydroisoindolones 15 . 15b yields the cyclic enamide 16 by alkali catalyzed shift of the double bond. Tricyclic lactames 19 and 20 are formed by thermal isomerization of N-cycloalkenylsorbamides 18a and 18b , respectively.     

Photochemie von Aminoketonen. XV. Photochemische Acylgruppenwanderung in N-Tosyl-β-aminovinyl-phenyl-ketonen

Photochemistry of Aminoketones. XV. Photochemical Acyl Migration in N-Tosyl-β-aminovinyl-phenyl-ketones N-Tosyl-β-aminovinyl-phenyl-ketones 1a – i are prepared in good yields from β-chlorovinyl- phenyl-ketones by reaction with the sodium salts of tosyl amides in dry DMF at room temperature. In contrast to the relatively photostable N, N-dialkyl-β-aminovinyl-aryl-ketones the electronically excited 1 give irreversible chemical reactions within a few minutes. Among other not identified photoproducts the α-tosyl-β-aminovinyl-phenyl-ketones 2 were found. From the experimental results it is evident that the migration of the tosyl group prefers a radical-type two step reaction through an intermediate X / Y of a (1,5)-N→O-tosylrearrangement.     

40 Jahre Darstellung von Partikelgrößenverteilungen — und immer noch falsch?

While the quality and variety of particle size measuring instruments have improved dramatically in recent years, both in their accuracy and in their speed of measurement, the representation of the measured data — particularly the density distribution — has generally received little attention from the manufacturers. The depiction of a continuous density distribution by a percentage value on the ordinate makes no sense. Although logarithmic density distributions serve a purpose with distinctly separated bi‐ or multimodal distributions (by analogy with analytical chemical spectra), they can lead to serious interpretation errors in the case of the monomodal distribution. Thus for monomodal distributions either the density distribution q_r(x) should be used or no representation of the density distribution attempted.     

Zur heterogenkatalytischen Oxydation und Ammoxydation von Isobuten. IV. Über die Beeinflussung der heterogenkatalytischen Oxydation von Isobuten zu Methacrolein durch n-Buten

On the Heterogeneous-Catalytic Oxidation and Ammoxidation of Isobutene. IV. Influence of n-Butene on the Heterogeneous-Catalytic Oxidation of Isobutene to Methacroleine The influence of n-butenes 2 on the oxidation of isobutenes 1 to methacroleine 3 has been investigated in presence of a catalyst containing Bi, Mo, P, Fe, Mg, Mn, Si and O. Addition of 2 to the gas mixture increase the selectivity and yield of 3 . This fact can be correlated by decrease of oxygen partial pressure in consequence of the dehydrogenation of 2 to butadiene 4 .     

d-NMR-Untersuchungen der behinderten Rotation am N?C(X)-Bindungsfragment. XIV. 13C-NMR-Spektren von β-Anilinovinyl-phenyl-thioketonen

d-N.M.R. Investigations of the Restricted Rotation at the N C(X) Bonding Fragment. XIV. ¹³C-N.M.R.-Spectra of β-Anilinovinyl-phenyl-thioketones N-phenyl-substituted β-anilinovinyl-phenyl-thioketones ( 1, 2 ) are investigated for restricted rotations about partial double bonds and preferential conformers by ¹H- and ¹³C-n.m.r. spectroscopy. Substituent dependent ¹³C-chemical shift variations and the strength control of the intramolecular hydrogen bridge are discussed.     

Acylierung von tautomeriefähigen C-Amino-azolen mit Amidin- bzw. Guanidinstruktur

Acylation of Tautomerizable C-Amino-Azoles with Amidine or Guanidine Structure Amino-azoles can react with electrophiles to give different regioisomers. Stable ringacylated isomers were isolated at low temperatures and under neutral conditions. Acyl migrations are obtained at higher temperatures and under basic conditions to form the thermodynamic stable isomers. The different isomers can be characterized by mean of ¹H-NMR, ¹³C-NMR, IR and mass spectrometry. The results obtained enable us to correct some confusions in the literature about the regioselectivity of the acylation of amino-azoles.     

Über die strukturanalystische Anwendung von „anomalen”︁ Multipletts in off-resonance entkoppelten 13C-NMR-Spektren von ?CH  CH?Fragmenten

On the Structural Analytical Application of „Anomalous”︁ Multiplets in Off-resonance Decoupled ¹³C NMR Spectra of  CH  CH Fragments The theoretical background of “anomalous” splitting of signals of molcular fragments  CHCH in off-resonance decoupled ¹³C NMR spectra is described. The use of these splitting phenomena on the determination of vicinal H,H and geminal C,H coupling constants is demonstrated using simple examples. The possibilities to determine the configuration of double bonds are shown by other examples from the field of natural constituents chemistry.     

Säurekatalysierte Umsetzungen von Aromaten mit Alkanen und Cycloalkanen. VI. Alkylierungen mit niederen Alkanen (C3?C5)

Acid-catalyzed Reactions of Aromatic Hydrocarbons with Alkanes and Cycloalkanes. VI. Alkylations with Lower Alkanes (C₃ C₅) Benzene and toluene are alkylated in the presence of HF/SbF₅, CF₃SO₃H/SbF₅, HBr/AlBr₃ or CF₃SO₃H/AlBr₃ by propane, n- and isobutane or n- and isopentane to products of complex composition, using a special apparature where the gases are circulated. The results of these experiments are compared with corresponding results in an autoclave. The reaction products of benzene with isobutane were analyzed, qualitatively and quantitatively, by gas-liquid chromatography and mass spectrometry.     

Darstellung von organischen Dikationen durch Protonierung von Iminiumsalzen. – NMR-spektroskopische Bestimmung der Topomerisierungsbarrieren im Bis(dimethylamino)-dimethylammonio-carbeniumion

Preparation of Organic Dications by Protonation of Iminium-Salts. – NMR-Spectroscopic Evaluation of the Topomerisation Barriers in the Bis(dimethylamino)-dimethylammonio-carbeniumion 1,3-Bis(dimethylamino)-2-aza-2-propenylium-chloride ( 4a ) is protonated by inorganic acids as HCl, HBr, HI, H₂SO₄, HBF₄ and HClO₄ to give the corresponding 1,3-bis(dimethylamino)-2-azapropan-1,3-diylium-salts ( 7a – f ) which are isolated and characterized by elemental analysis and their ¹H-NMR-spectra. N, N, N′, N′, N″, N″-Hexamethylguanidinium-chloride ( 5a ) can be protonated only by super acid systems e.g. HFSO₃/SbF₅. The dication thus formed presents 3 topomerisation barriers. Two of them are explained as restricted rotations, whereas the third is assumed to be a frozen torsional vibration.     

Electrochemical properties of amorphous Li<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>V<Subscript>2</Subscript>O<Subscript>5−<Emphasis Type="Italic">y</Emphasis></Subscript> thin film deposited by r.f.-sputtering

The electrochemical properties of amorphous vanadium pentoxide (V₂O₅) thin films deposited by reactive r.f.-sputtering were investigated using galvanostatic charge/discharge cycling and galvanostatic intermittent titration technique (GITT). As x in Li _x V₂O_5−y increased (x = 0–2.0), the electromotive force of the lithium (Li)∣1 M LiClO₄–propylene carbonate∣Li _x V₂O_5−y cell decreased gradually without a potential plateau or an abrupt potential reduction, demonstrating that an irreversible structural change did not occur in the entire Li content. Chemical diffusivity of the Li ion in the Li _x V₂O_5−y thin film measured using GITT was determined to be 4 × 10⁻¹³–7 × 10⁻¹⁴ cm² s⁻¹ in the Li content range investigated.