Eine neue Methode zur Bestimmung des Molekulargewichts von Polymeren durch Ultrazentrifugation

The Lamm differential equation (DG) for the ultracentrifuge was solved for the case δc/δt ≠ 0 experimentally. The concentration gradient in the ultracentrifuge cell was determined by measuring the refractive index increment as well as the UV-absorption. Thus by simultaneously determining sedimentation and diffusion coefficient a new method for absolute molecular weight measurement was obtained.     

3-Amino-4-cyanpyridazine durch Cyclisierung von Nitrilen

3-Amino-4-cyano-pyridazines by Cyclization of Nitriles The reaction of arylglyoxale hydrazones or benzilhydrazone with malononitrile yields the 3-amino-4-cyano-pyridazines 2 which may be converted into substituted 4-amino-pyriimido [4,5-c]pyridazine 3 and 4-amino-isothiazolo[3, 4-c]pyridazines 4 . From ω-hydrazino-acetophenone and malononitrile the 1,2-diaminopyrrole derivative 6 is formed.     

Eine neue Synthese von 4,5-Dihydroxy-pyrazolen

A New Synthesis of 4,5-Dihydroxy-pyrazoles 1-Aryl-pyrazolin-5-ones 1 are converted by Knoevenagel condensation with acetone or by reaction with 2,2-dimethyl-1,3-dioxolane 6 to 1-aryl-4-isopropyliden-pyrazolin-5-ones 2 . The compounds 2 are epoxidized by hydrogen peroxide forming the spiro-epoxides 3 , which can be cleaved to 4,5-dihydroxy-pyrazoles 4 under acidic conditions. 4-Acetoxy-5-hydroxy-pyrazoles 13 are formed directly, when 3 are cleaved in presence of acetic anhydride. The 3,3′,3′-trimethyl-1-(4-nitro-phenyl)-pyrazolin-4-spiro-2′-oxiran-5-one 3b undergoes rearrangement to the 1,3-dioxolo[4,5-c]pyrazole 12 .     

Neuartige Steroidale Orthoester durch intramolekulare Cyclisierung von Ethinylcarbinol-Derivaten mittels Organylhypoioditen

Novel Steroidal Orthoesters by Intramolecular Cyclisation of Ethynylcarbinol Derivatives with Organic Hypoiodites The iodination of the 17β-acetoxy-17-ethynylsteroid 2 using iodine/copper(II)-acetate in combination with the nucleophiles acetic acid, water and methanol is reported. Examples for chemical modification of the products are described. A cyclisation occurs in the case of iodomethoxylation as a formal through-space 1.4-addition of the reagent forming a mixture of 4 isomer iodomethylen-1,3-dioxolanes. The configuration and ratio of the isomers as well as analytical data of this hitherto unknown dioxolane-system are given.     

Eine neue methode zur herstellung von hydroxyterminierten polydienen

It is shown, that hydroxyterminated polydienes of good microstructure and functionality and a narrow molecular weight distribution can be prepared using di-hydroxyethyl-azo-bis-isobutyramide as an initiator. The activation energy of the initiator decay has been determined by volumetric measurement of the nitrogen evolved in this reaction.     

Synthese neuer N-Aroylisothiazol-2-imine und N-Aroylamino-isothiazoliumsalze durch Cyclisierung von thiocyanato-substituierten Hydrazonen

Synthesis of New N-Aroylisothiazole-2-imines and N-Aroylaminoisothiazolium Salts by Cyclisation of Thiocyanato-substituted Hydrazones The synthesis of new N-aroylisothiazole-2-imines ( 4g-n ) as well as the corresponding acceptor-substituted 2-amino-isothiazolium salts ( 6f-n ) by cyclocondensation of thiocyanatovinylaldehyde hydrazones ( 3 ) is reported. The structure of these N-imines was proved by spectroscopic methods. The alternative cyclization route to 1,2,3-thiadiazines ( 8 ) is not observed. The hydrazones ( 3a-e ) could not be cyclized to N-imines, only sulfides ( 5a-c ) were obtained. The reaction of 2-thiocyanatomethylen-cycloheptan-2-one ( 9 ) with benzhydrazides gave the same ring closure to the salts ( 10a,b ). The structure of the N-imine 11b has been confirmed unequivocally by X-ray structure analysis.     

Eine neue Synthese zur Darstellung von organischen Tellurverbindungen unter Verwendung von elektrochemisch erzeugten Polytelluriden

A Novel Synthesis of Organic Tellurium Compounds by the Use of Electrochemically Generated Polytelluride-ions The cathodic polarisation of a tellurium electrode in aprotic solutions gives rise to polytelluride anions, which react with alkylhalides to the corresponding disubstituted ditellurides. By this method of electrosynthesis a number of organic ditellurides can be simply prepared and without danger. Dialkylditellurides of the general formula R-Te-Te-R ( 2a – r ) can be produced with high yields. The reaction with α,ω-dihalides gives heterocycles, which involve one or two tellurium atoms in the ring ( 5a – d , 6 – 8 ). The electrochemical reduction of tellurium in the presence of methyliodid yields trimethyltelluroniumiodid ( 9 ).     

Photochemische Reaktionen von Arylglycidethern

Photochemical Reactions of Arylglycidyl Ethers The absorption, fluorescence and phosphorescence spectra, respectively, of arylglycidyl ether 1 correspond to those of other alkyl aryl ethers. Also the photolysis product distribution (λ = 254 nm) is in agreement with a normal ether photolysis. Furthermore, photoinduced epoxy ring opening takes place giving homopolyaddition oligomers and in methanolic solution also CH₃OH addition products. These reactions can be explained using the model of bichromophoric molecules with the ArO-chromophore as donor and the epoxy ring as acceptor. The calculations based on this model are in agreement with the experimental data. In the aromatic nucleus halogene substituted 1 were dehalogenated with high quantum yield (0.25 in the case of bromo substituted compound 1g ). The quantum yields of the ArO-C-bond scission are about 0.08 independently of the aromatic ring substituents. As indicated by sensitization and quenching experiments, respectively, with aromatic hydrocarbons the photo reactions proceed via S₁ state. It was found that phenol quenches the photodegradation of 1 very efficiently. Excited methyl phenyl glycerol ether 5a reacts with phenyl glycidylether 1a in its ground state producing oligomers.     

Eine neue Gruppe vom Nereistoxin abgeleiteter Verbindungen - Synthese von Bis-dimethylamino-tris-disulfanen

A New Group of Compounds Derived from Nereistoxin - Synthesis of Bis-dimethylamino-tris-disulfanes The reaction of organo-thiosulfates, BUNTE-salts, with mercaptans is a convenient synthesis of disulfanes. Similarly bis-BUNTE-salt 7 and tert. butyl mercaptan give bis-disulfane 5c [ 9 ]. By treating 7 with several aliphatic mercaptans we found the formation of the tris-disulfanes 8a – d in preparative amounts in addition to the bis-disulfanes 5a – d expected. This reaction was investigated. The preparation of the compounds 8 is described and a proposal is given for a mechanism of the formation of 8 as a thiol-disulfide-interchange.     

Entwicklung von Öl-Schaumbädern - Eine neue Klasse von Badezusatzmitteln

Development of Oil Foaming Bathes - A New Range of Bathing Additives After a short historical review concerning the origin of bathing additives in general and the enormous increase in popularity of this kind of products possible disadvantages and a corresponding consumer behaviour are exhibited. Afterwards as a suitable consequence recent developments in the field of oil foaming bathes are regarded in detail.     

Synthese von Heterocyclen durch C-C-Knüpfung. II. Katalytische Cyclisierung von N-Alkyl-N-allyl-acrylamiden und N.N-Diallyl-carbonsäureamiden

Synthesis of Heterocycles by C C-Bond Formation. II. Catalytic Cyclization of N-Alkyl-N-allyl-acrylamides and N,N-Diallyl Carbonic Acid Amides N-Alkyl-N-allyl-acrylamides 2 cyclize in the presence of PdCl₂ to 1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones 4 and 1-alkyl-4-methyl-3-methylene-pyrrolidin-2-ones 5 . Compounds 4 predominate in the mixture. With RhCl₃, ring closure gives comparable amounts of lactams 4 and 7 (1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones) besides some product of allyl elimination. N. N-Diallyl carboxylic amides 3 form cyclic enamides (1-acyl-3,4-dimethyl-2-pyrrolines, 9 ) on the action of PdCl₂ besides the products 10 of allyl elimination. RhCl₃ effects cyclization of 3 to form 1-acyl-3-methyl-4-methylene-pyrrolidines 11 besides some 9 . The acid amide groups of compounds 9 and 11 are shown by n.m.r. spectroscopy to exist as rotamers.     

Radikalische Cyclisierung von Petroselinsäure

Free-Radical Cyclization of Petroselinic Acid Petroselinic acid was cyclized via methyl 2-iodopetroselinate ( 13 ) with tributyltin hydride to give methyl trans- and cis-2-dodecyl-1-cyclopentanecarboxylate ( 14 ). The atom-transfer method with hexabutylditin resulted in the formation of bicyclic γ-lactones 16 and methyl trans-2-(1′-iodododecyl)-1-cyclopentanecarboxylate (trans- 17 ). The same products were obtained with the new initiator system SnCl₂/AgOAc. This method showed, if compared with the other methods, the shortest reaction time, the highest yield and stereoselectivity combined with a very simple work-up procedure and the use of less toxic chemicals.