Zur Aminolyse von Bis-Imidoylchloriden der Oxalsäure II. Umsetzung mit Diaminen und Aminoalkoholen

On the Aminolysis of Bis-Imidoylchlorides of Oxalic Acid. II. Reaction with Aliphatic Diamines and Aminoalcohols The aminolysis of bis-imidoylchloride 1 derived from oxalic acid with several diamines and aminoalcohols was investigated. At room temperature diamines 2 as well as aminoalcohols 7 give mainly the cyclic amidines 3 and mixed amidine-imidates 8 in moderately up to good yields. While cis-1,2-diaminocyclohexane yields at room temperature the bicyclic amidine 3a , the trans isomer reacts to 3b only when heated for several hours. Depending on the conditions, the racemic 1,2-diaminopropane 2h gives derivatives of pyrazine 3h or the open-chain amidine 5 resulting from an oxidative aromatization and subsequent hydrolysis. Histamine 2i and 1,8-diamino-3,6-dioxaoctane 2p react selectively with 1 to seven- respectively twelve-membered heterocycles 3i and 3p. The mixed aliphatic and aromatic diamines 2n, o show an anomalous behaviour leading to 2,2′-bis-chinazolines 3n, o . In comparison with acyclic oxalic amidines the new cyclic derivatives show less molecular dynamic in their nmr spectra. In some cases, a s-trans-arrangement of the amidine substructure was observed.     

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.     

Zur Aminolyse von Bis-Imidoylchloriden der Oxalsäure. I. Umsetzung mit aromatischen und aliphatischen Aminen

On the Aminolysis of Bis-Imidoylchlorides of Oxalic Acid. Part I. Reaction with Aromatic and Aliphatic Amines The reaction between bis-imidoylchlorides 2 derived from oxalic acid and several aromatic and aliphatic amines was investigated. While primary aromatic amines need a thermical activation by refluxing, primary aliphatic amines give mainly at room temperature the amidines 3 in moderatly up to good yields. Proceeding from enantiomeric pure amines e.g. ( R )- or (S)-1-phenethylamine the new homochiral oxalic amidines 3y and 3z with C₂-symmetry were obtained. Several secondary amines react with the bis-imidoylchloride 2a to give via intramolecular cycloacylation derivatives of isatine. The new synthesized amidines 3 perform systems with a strong molecular dynamic like prototropie and E/Z-interconversion. All new compounds described were characterized by elemental analysis and spectroscopic methods.     

Reaktion von (2-Alkoxy-vinyl)hetero-methiniminiumsalzen mit C-Nukleophilen – ein Zugang zu funktionalisierten Pyryliumsalzen

Reaction of (2-Alkoxy-vinyl)hetero-methiniminium Salts with C-Nucleophiles — an Approach to Functionalized Pyrylium Salts The O-alkylation products 2 of 2-acyl-1-chloro-enamines 1 (X = Cl) or acylketene-S, N-acetales 1 (X = SCH₃) respectively react with cyanoactivated methylene compounds 3 under C,C-bond formation. The reaction products 4 have been converted into functionally substituted pyrylium salts 5 by acidic treatment. Limitations of the synthetic approach are discussed.     

Untersuchungen zum Verlauf der Cyclisierung von Alkylmalonsäure- und β-Amino-crotonsäureestern zu alkylierten Hydroxypyridincarbonsäureestern

Investigations on the Cyclization of Alkylmalonic Acid Esters with β-Aminocrotonic Acid Esters to Alkylated Hydroxypyridine Carboxylic Acid Esters The cyclization of substituted malonic esters with β-aminocrotonic acid alkyl esters yields 2,4- or 4,6-dihydroxy-3-pyridinecarboxylic acid esters, respectively, in dependence on the reaction conditions and the nature of the substituent in the malonic esters. In the presence of alcoholate malonic acid alkyl esters and alkylmalonic acid alkyl esters form 2,4-dihydroxy-3-pyridinecarboxylic acid esters. Under the same conditions nitromalonic acid alkyl esters lead to 4,6-dihydroxy-3-pyridinecarboxylic acid esters, which also arise in the thermal cyclization of malonic acid 2,4,6-trichlorophenyl ester. The structure of the reaction products is determined by the relative nucleophilicity of the cyclization components.     

Energieeffizienzsteigerung in der Prozesswasseraufbereitung – Untersuchungen zu Bildungsmechanismen von Silikatbelägen

Investigations on the formation mechanisms of silicate films on reverse osmosis membranes and their morphological characteristics are presented. Relevant influencing factors on the formation of coatings are considered and the individual mechanisms are described. Furthermore, the essential characterization characteristics for the investigation of silicate coatings are determined, the applied analysis methods are described and an overview of the sample preparation is given.     

Ketofettsäure-Derivate – Ein einfaches Verfahren zu ihrer Herstellung

Keto Fatty Acids – A Simple Procedure for their Preparation Derivatives of keto fatty acids are trace components in many of the naturally occurring oils and fats. After a survey of preparation procedures described in the literature, a simple possibility for the preparation of keto fatty acid derivatives by alkali- or alkaline earth iodides catalyzed rearrangement of epoxidized fatty acid derivatives will be presented. Tests of these compounds as additives in PVC processing showed positive results.     

Beitrag zu den Grundlagen der Lösungs-Kristallisation von Stearinsäure

Contribution to the Fundaments of Solvent Cristallization of Stearic Acid After a short review of the informations available concerning the habit and polymorphism of the three polymorphs of stearic acid, more recent results are discussed. From exact determinations of the solubility of stearic acid in decane, methanol and butanone, it was possible to calculate the stability regions of the three polymorphs. The enthalpies of dissolution as calculated from the solubility were checked by direct solution calorimetry. The determination of the occurrence domains of the polymorphs showed the A and C polymorph to precipitate preferentially at room temperature. It could be shown for the (110) face of stearic acid growing from butanone solutions, that surface diffusion is the rate controlling step. The differences in the growth behaviour between the B and C polymorph are not yet fully understood.     

Tieffarbige Systeme mit Oxalsäurestruktur — eine Strukturkorrektur

Deep Coloured Systems with Oxalic Acid Substructure-a Structural Correction Basing on a recent spectroscopic investigation the structure of earlier described deeply coloured systems derived from oxalic acid imidochlorides and thioacetamide has to be revised. Due to the poor solubility of these systems their spectroscopic characterization led to the misinterpretation as tetramethin-bridged thiazolines 1. By means of ¹H-NOE-Difference-Spectroscopy of newly synthesized derivatives with lipophilic substituents a imidazolin-thion substructure 4 has been found. Such an arrangement of the heteroatoms clearly reflects a 1,3-rearrangement with participation of the oxalic acid system.     

Zur Synthese von Polyfluoralkylestern der Fluorsulfonyl-difluoressigsäure und der α-Trifluormethylfluoressigsäure

On the Synthesis of Polyfluoroalkylesters of Fluorosulfonyl-difluoroacetic Acid and α-Trifluoromethylfluoroacetic Acid .