Gasdurchlässigkeit von mit Hexamethylen-bis-methyloldihydroxyäthylenharnstoff vernetztem Zellglas. II. Vernetzung von Zellglas mit Hexamethylen-bis-methyloldihydroxyäthylenharnstoff und Messung der Gasdurchlässigkeit der vernetzten Folie

The oxygen permeation coefficients of cellophane, crosslinked with hexamethylene-bis-methyloldihydroxyethyleneurea [(CH₂)₆ bis-MDHÄH], were determined. It could be shown, that above all in the very important range of low concentrations, the ?molar barring efficiency”? of this compound is higher than that of all the other crosslinking agents investigated so far. With that the following order for the efficiency, concerning comparable molar concentrations, is valid now: (CH₂)₆--bis-MDHÄH > DMDHÄH ? FA > DMÄH > DMH. Cellophane at 64% relative humidity of gas, which contains 21 percent by weight of (CH₂)₆ bis-MDHÄH, is 12-43 times more impermeable against oxygen than different types of Saran. The course of the curve, showing the dependance of the oxygen permeability on the rel. humidity of gas for this film is very similar to the course of earlier investigated films, crosslinked with other derivatives of methylolureas. Hence it follows, that the crosslinkage with (CH₂)₆ bis-MDHÄH takes place in rather the same morphological areas of the cellulose as the linkage with the other derivatives of urea. Treating cellophane with aqueous solutions of (CH₂)₆ bis-MDHÄH there was found that the crosslinking agent (applied in the range of low concentrations) was taken up by the film in a quantity being proportional to the bath concentration. This is no longer the case when applying comparably high concentrations, in contrast to the earlier investigated other derivatives of urea; now the taking up is less than proportional. This is attributed to the comparably more difficult accessibility of certain morphological areas of the cellophane to the larger and less polar molecules of the (CH₂)₆ bis-MDHÄH. Further there was found after crosslinking the resulting molar barring efficiency being more than a third lower, when cellophane is treated with the same bath concentration of (CH₂)₆ bis-MDHÄH but at pH 8 instead of pH 6,5. This ist attributed to the diminished catalytic activity of the applied MgCl₂. 6H₂O as a crosslinking catalyst, caused by the weak alkaline medium.     

Electrochemical behavior of a new <Emphasis Type="Italic">s</Emphasis>-triazine-based dendrimer

The electrochemical behavior of a new G-2-s-triazine-based dendrimer, 2,4,6-tris-{4-{4,6-bis-{4-{4,6-bis-[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-s-triazin-2-yl}-piperazin-1-yl}-s-triazine, (I), was studied in dimethylsulfoxide solution by cyclic voltammetry, on platinum and graphite electrodes. The electrochemical properties of I were compared with that of one of its precursor, N-{4,6-bis{4-{4,6-bis[(1S,2S)-1,3-dihydroxy-1-(4-nitrophenyl)-prop-2-ylamino]-s-triazin-2-yl}-piperazin-1-yl}-triazin-2-yl}-piperazine), (II), together with that of the starting material, (1S,2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diol (“p-nitrophenylserinol”), (III).     

A new luminescent complex constructed by oxomolybdate and 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid via Mo–N bonds

A new complex namely, [(Mo₂O₆)L]·CH₃OH·3H₂O (1), based on oxomolybdate and 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid (L) was synthesized under hydrothermal condition, which shows a new three-dimensional supramolecular framework with unreported topological structure. In addition, the luminescent and electrochemical behaviors of complex 1 were investigated.     

Metallkomplexkatalysatoren mit Phosphonsäureester-Phosphan-Liganden. I. Carbonylierung von Methanol mit Phosphonsäureester-Phosphan-Rhodiumkomplexen in der Flüssigphase

Metal Complex Catalysts with Phosphonic Ester Phosphine Ligands. I. Carbonylation of Methanol by Phosphonic Ester Phosphine Rhodium Complexes The treatment of technically available 2-(chloroethyl)phosphonic acid dimethylester ( 1 ) with diphenylphosphine and potassium-tert.-butylate affords 2-(diphenylphosphino)ethylphosphonic acid dimethylester ( 2a ) in a simple way. 2a can be used as a hemilabil complex ligand (by phosphine and phosphoryl group.) Rhodium complexes of the type (MeO)₂P(O)CH₂CH₂P(Ph)₂RhL₃ ( 3 ) were obtained from 2a and exhibit excellent catalytic properties in the liquid-phase carbonylation of methanol to acetic acid. Studies on other chelat-ligands did not confirm the exceptional increase of the activity by bisphosphinemonoxyd-ligands and the inhibition of the title reaction by bisphosphine-ligands already published.     

Synthesis,structure and magnetic properties of a tetranuclear Mn(II) complex with carbohydrazone based ligand

A new tetranuclear complex of Mn(II), [Mn₄(L)₂(CH₃OH)₂(μ-N₃)₄(N₃)₂] ∙ 2(CH₃OH) (1), was synthesized and characterized by spectroscopic methods, single-crystal X-ray diffraction analysis and TGA analysis where HL is bis-[(E)-N′-(phenyl(pyridin-2-yl)methylene)]carbohydrazide. Single crystal X-ray analysis reveals that 1 has a Mn₄ core in which Mn(II) ions are connected by azide and enolate oxygen atoms. IR spectroscopy and X-ray analysis indicate that the carbohydrazone is coordinated to the metal cores as a mononegative ligand in the enol form. The magnetic behavior of 1 was investigated between 2 and 295 K and indicated that the magnetic coupling mediated via azide bridge is ferromagnetic whereas the enolate oxygen mediates antiferromagnetic coupling that leads to overall antiferromagnetic behavior.     

Darstellung von Isocyanatderivaten der aliphatischen Diäther

On the Preparation of Isocyanatoderivatives of Aliphatic Diethers A method for the preparation of some isocyanates of aliphatic diethers of the general formula: CH₃(NCO) O [CH₂]ⁿ O CH(NCO)CH₃ 2a – e , where n = 1–5 has been reported. The syntheses conditions, properties, as well as the conversion of the obtained diisocyanates into the new urea derivatives were described.     

The synthesis,using microwave irradiation and characterization of novel,organosoluble metal-free and metallophthalocyanines substituted with flexible crown ether moieties

Cyclotetramerization of a phthalonitrile derivative to the metal-free phthalocyanine was accomplished in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene at reflux under an argon atmosphere. Ni(II), Zn(II), Co(II), Cu(II) phthalocyanines with four, peripheral 4-[methyleneoxy(12-crown-4)] groups were synthesized from 4-[{(12-crown-4)-yl}methyleneoxy]phthalonitrile in the presence of the anhydrous, divalent metal salts (NiCl₂, Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The green phthalocyanines were soluble in common organic solvents such as CHCl₃, CH₂Cl₂, CH₃COCH₃, THF, DMF and DMSO. The structures of the target compounds were confirmed using elemental analysis, IR, ¹H NMR, ¹³C NMR, UV–vis and MS spectral data.     

Structure–property relationship in copolyesters. I. Preparation and characterization of ethylene terephthalate–hexamethylene terephthalate copolymers

Poly(ethylene terephthalate)-containing ethylene and hexamethylene residues in the polymer backbone were prepared by melt condensation reaction of dimethyl terephthalate (DMT) and diffrent quantities of ethylene glycol (EG) and 1,6-hexane diol (H) in the initial monomer feed. Several polyester samples were prepared by varying the mol % of 1,6-hexane diol with respect to ethylene glycol in the initial monomer feed. These included 0.0 (PET), 2.5 (H₁), 5.0 (H₂), 7.5 (H₃), 10.0 (H₄), 12.5 (H₅), 15.0 (H₆), 17.5 (H₇), 20.0 (H₈), 50.0 (H₉), 80.0 (H₁₀), and 100.0 (H₁₁), respectively. The polymers were characterized by recording IR spectra and intrinsic viscosity measurements. The relative thermal stability of the polymers was evaluated by dynamic thermogravimetry in air. An increase in mol % of 1,6-hexane diol resulted in a decrease in melting points and thermal stability of copolymers. PET and copolyesters were spun to fibers by using the melt-spinning technique. The fibers were drawn to draw ratios 2,3,4, and 5. In case of copolymes, tensile strength decreases slightly with increasing mol % of H whereas % elongation increases. The moisture regain and dye uptake in copolyesters was treatly enhanced as compared to PET.     

Effect of carbon deposition over carbonaceous catalysts on CH<Subscript>4</Subscript> decomposition and CH<Subscript>4</Subscript>-CO<Subscript>2</Subscript> reforming

An investigation was made using a continuous fixed bed reactor to understand the influence of carbon deposition obtained under different conditions on CH₄-CO₂ reforming. Thermogravimetry (TG) and X-ray diffraction (XRD) were employed to study the characteristics of carbon deposition. It was found that the carbonaceous catalyst is an efficient catalyst in methane decomposition and CH₄-CO₂ reforming. The trend of methane decomposition at lower temperatures is similar to that at higher temperatures. The methane conversion is high during the initial of stage of the reaction, and then decays to a relatively fixed value after about 30 min. With temperature increase, the methane decomposition rate increases quickly. The reaction temperature has significant influence on methane decomposition, whereas the carbon deposition does not affect methane decomposition significantly. Different types of carbon deposition were formed at different methane decomposition reaction temperatures. The carbon deposition Type I generated at 900°C has a minor effect on CH₄-CO₂ reforming and it easily reacts with carbon dioxide, but the carbon deposition Type II generated at 1000°C and 1100°C clearly inhibits CH₄-CO₂ reforming and it is difficult to react with carbon dioxide. The results of XRD showed that some graphite structures were found in carbon deposition Type II.     

Über neue Pyrazolverbindungen. IV Darstellung und Cyclisierungsverhalten einiger akzeptorsubstituierter N-(Pyrazol-3-yl)-thioharnstoffe

New Pyrazol Derivatives. IV. Preparation and Cyclization of Some Acceptor-Substituted N-(Pyrazol-3-yl)-thioureas . 3-Aminopyrazol-4-carboxylic acid derivatives ( 1 , 2 ) were transformed by reaction with different isothiocyanates R²NCS to N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 , 6 ). Ethyl 3-amino-1-benzylpyrazol-4-carboxylate reacts with CSCl₂ to form ethyl 1-benzyl-3-isothiocyanatopyrazol-4-carboxylate ( 3 ) which yields with amines the corresponding N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 ). As a byproduct in the reaction with CSCl₂ N,N^. -di-(pyrazol-3-yl)-thiourea ( 4 ) is formed. With hydrazine or phenylhydrazine N-(pyrazol-3-yl)-thiosemicarbazides ( 7a , b ) are obtained. The thioureas ( 5 , 6 ) can be cyclized in basic solution to 4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidin-4-on-6-thiones ( 8 ) which on alkylation form 6-alkylthio-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-ones ( 9 ). Methyl-N-(pyrazol-3-yl)-N^.-benzoylisothiourea ( 10 ) reacts with ethylamine to form N-benzoyl-N^. -ethyl-N^‥-(pyrazol-3-yl)-guanidine derivative ( 11 ) which on treatment with NaH in dimethylformamide yields 6-benzoylamino-5-ethyl-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-one ( 12 ). By treatment with sulfuric acid the N-(pyrazol-3-yl)-thiourea derivatives ( 5 , 6 ) form new 6-amino substituted pyrazolo[3,4-d][1,3]thiazin-4-ones ( 13 ).     

Synthesis of well-defined poly[(2-β-D-glucopyranosyloxy)ethyl acrylate] by atom transfer radical polymerization

The ‘living’ radical polymerization of 2-(2′,3′,4′,6′-tetra-O-acetyl-β-D -glucopyranosyloxy)ethyl acrylate (AcGEA) by atom transfer radical polymerization (ATRP) is reported. It has been found that the polymerization kinetics are first-order, the molecular weights increase linearly with conversion, and the molecular weight distribution remains narrow when the polymerization conversion is below 70%. Well-defined P(AcGEA) was obtained, and the O-protecting acetyl groups of P(AcGEA) were quantitatively removed by reacting with dilute CH₃ONa solution in CHCl₃/CH₃OH to afford well-defined poly[(2-β-D -glucopyranosyloxy)ethyl acrylate] (PGEA). © 1999 Society of Chemical Industry     

Zur Kenntnis der katalytischen Dimerisation von Acrylsäurederivaten mit Hilfe von Palladium-Komplexen. III. Reaktionen von β-Palladioacrylestern und deren Beziehung zur Katalytischen Reaktion

On the Knowledge of the Catalytic Dimerization of Acrylic Acid Derivatives by Palladium Complexes. III Reactions of β-Palladio Acrylates and Their Relation to the Catalytic Reaction Complexes of the type L₂PdCl(CH  CHCOOCH₃) (L₂ = 2 PPh₃ or Ph₂PCH₂CH₂PPh₂) were decomposed to dimethyl muconate by pyrolysis or by substraction of the phosphine ligands with (CH₃CN)₂PdCl₂ in acetonitrile. The last mentioned reaction gave Δ³-dimethyl dihydromuconate in the presence of hydrochloric acid. Δ³-Dimethyl dihydromuconate was also formed by decomposition of (Ph₂PCH₂CH₂PPh₂) PdCl (CH  CHCOOCH₃) with HBF₄ in acetonitrile, but the analogous reaction in methyl acrylate as solvent gave Δ²-dimethyl dihydromuconate. Thus, we have simulated the formation of the two main products of the catalytic dimerization of methyl acrylate with palladium(II)chloride in a stoichiometric manner. Mechanisms with hydride and carbene intermediates are discussed.     

Säurestärke und Komplexbildung von Curcuminoiden

Acidity and Complex Formation of Curcuminoids The stoichiometric acid dissociation constants of curcumin 1a and derivatives as well as the stoichiometric stability constants of the Cu(II)- and Ni(II)-complexes of these substances have been determined by pH-potentiometric titrations in dioxane-water mixture. The influence of different substituents on the pK_a-values and the stability constants is discussed. The complexing properties of the  CO CH₂ CO structural element of the ligands are not significantly changed when the phenyl group is substituted by the styryl group. Solid CuL₂-complexes have been characterized. The coordination of the ester group in the tricarbonyl ligand systems 4 was excluded by i.r. spectroscopy.     

Selektiv S-geschützte Cysteinpeptide. IV. Zur Synthese von Cysteinpeptiden unter Verwendung der S-Ethylthio-Schutzgruppe. II

Selectively S-Protected Cysteine Peptides. IV Synthesis of Cysteine Peptides Using the S-Ethylthio Protecting Group. II Studying the problems of the selective sulphur protection in cysteine peptides, a model octapeptide from the sheep insulin A-chain was prepared by conventional synthesis using the S-ethylthio and the S-diphenylmethyl group. As consequence of the small acid stability of S-ethylthio protected cysteine peptides, the corresponding compounds were synthesized using the strong acid labile 2-(p-biphenylyl)-iso-propyloxycarbonyl(Bpoc) and the 2-phenyl-iso-propyloxycarbonyl(Ppoc) amino protecting group, respectively. Therefore a new synthesis of N-protected S-alkylthio cysteine derivatives 5 via N-unprotected compounds 4 was developed starting from S-guanylthio cysteine dihydrochloride 3 . The synthesis of the octapeptide Boc-Cys(SEt)-Cys(Dpm)-Ala-Gly-Val-Cys(SEt)-Ala-Leu-OBu^t 1 was carried out with the fragments Boc-Cys(SEt)-Cys(Dpm)-Ala-Gly-OH and TFA · H-Val-Cys(SEt)-Ala-Leu-OBu^t 12 by means of the DCCI/HOOBt coupling method. 12 was synthetisized step by step from the carboxyterminal end. The S-ethylthio group was completely stable during all synthetic steps including the deprotection of the N^α-Bpoc and N^α-Ppoc group, respectively. The cyclocystine octapeptide 2 , Boc-Cys-Cys(Dpm)-Ala-Gly-Val-Cys-Ala-Leu-OBu^t, was produced by treatment of 1 with an excess of HS CH₂ CH₂ OH followed by oxidation with I CH₂ CH₂ I.     

The effect of the perturbation of hydrogen bonding on the Zn(II) coordination geometry: synthesis and structure of [Zn(BIP)(H2O)2](ClO4)2 (BIP=1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propane)

A polydentate ligand comprising imidazole donor 1,3-bis[(4-methyl-5-imidazol-1-yl)ethylideneamino]propane (BIP) was synthesized, and the crystal structure of its Zn(II) complex [Zn(BIP)(H₂O)₂](ClO₄)₂ has been reported, in which the Zn(II) atom adopts a distorted octahedral coordination geometry with the equatorial positions occupied by four nitrogen atoms of BIP and the axial positions by two aqua molecules. The effect of hydrogen bonding of the aqua ligand on the coordination geometry is discussed.     

Konfigurative Zuordnung über sterisch definierte Epoxidringe. VIII. Glycidonitrile. I. Synthese von 4-Aryl-1-oxaspiro(2,5)octan-2-nitrilen und 4-Aryl-1-oxaspiro(2,5)octan-2-carbonsäureestern

Determination of Configurations by the Aid of Sterically Corresponding Epoxides. VIII. Glycidic Nitriles. I. Synthesis of 4-Aryl-1-oxaspiro(2,5)octane-2-nitriles and 4-Aryl-1-oxaspiro(2,5)octane-2-carboxylic Acid Methyl Esters The condensation of 2-aryl-cyclohexan-1-ones ( 1–5 ) with ClCH₂CN or ClCH₂CO₂CH₃ at 80°C in the presence of NaH and in dimethoxyethane yields the corresponding glycidic nitriles and the glycidic esters, respectively. The configuration and the preferred conformation of the two isomeric 1-oxaspiro-[2,5]octane derivatives ( 12 A and 12 B ) formed have been determined by ¹H-n.m.r. spectroscopy. Some earlier results from BOEKELHEIDE and SCHILLING and from SCHWARTZMAN and WOODS have been corrected.     

Spiroheterocyclic system. Part IV: Novel azo dye sulpha drugs of spiroheterocyclic naphthenes

Novel azo-dyes have been synthesized by diazotization of 4-amino benzene-4′-(substituted heterocyclo) sulphonamide derivatives and coupling with 1-oxa-4-thia-spiro[4,4]nonan-2-one (I) and/or with l-oxa-4-thia-spiro[4,5]decan-2-one (I′) in acid medium to give the corresponding 3-azo-(4′-substituted benzenesulphonamido)-l-oxa-4-thia-spiro[4,4]nonan-2-one (II-IX) and/or l-oxa-4-thia-spiro[4,5]decan-2-one (II′-IX′] as spiro-ligands. Treatment of these ligands with metal salts of iron (Fe³⁺), copper (Cu²⁺) and mercury (Hg²⁺) as chlorides in ethanolic solution furnished the corresponding metal chelates (II_a-c-IX_a-c) and/or (II′_a-c-IX′_a-c). The compounds were tested in vitro for antimicrobial activity to study the structure-activity relationship.     

Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Über die Verwendung von Glyoxal-bis(tert.-butylnitron) als Spin-Trap

On the Use of Glyoxal Bis (t-Butyl Nitron) as a Spin Trap Nitroxides derived from glyoxal bis(t-butyl nitrone), GBBN , have been studied by e.s.r. spectroscopy. Well resolved e.s.r. spectra exhibiting extra hyperfine splitting by magnetic active nuclei in γ-position have been recorded for the spin adducts of alkyl, as well as ^.N₃ and ^.CH₂Cl radicals. Enhanced stability was found for the spin adducts of halogen atoms. However, a wider application of this spin trap is limited by the strong superposition of the e.s.r. signals of different radical spin adducts which is directly related to almost identical conformations of these nitroxides.     

New Insight into Dearomatization and Decarbonylation of Antitubercular 4H-Benzo[e][1,3]thiazinones: Stable 5H- and 7H-Benzo[e][1,3]thiazines

8-Nitro-4H-benzo[e][1,3]thiazinones (BTZs) are potent in vitro antimycobacterial agents. New chemical transformations, viz. dearomatization and decarbonylation, of two BTZs and their influence on the compounds’ antimycobacterial properties are described. Reactions of 8-nitro-2-(piperidin-1-yl)-6-(trifluoromethyl)-4H-benzo[e][1,3]thiazin-4-one and the clinical drug candidate BTZ043 with the Grignard reagent CH₃MgBr afford the corresponding dearomatized stable 4,5-dimethyl-5H- and 4,7-dimethyl-7H-benzo[e][1,3]thiazines. These methine compounds are structurally characterized by X-ray crystallography for the first time. Reduction of the BTZ carbonyl group, leading to the corresponding markedly non-planar 4H-benzo[e][1,3]thiazine systems, is achieved using the reducing agent (CH₃)₂S ⋅ BH₃. Double methylation with dearomatization and decarbonylation renders the two BTZs studied inactive against Mycobacterium tuberculosis and Mycobacterium smegmatis, as proven by in vitro growth inhibition assays.