The pyrolyses of tri- and tetramethylethylene in the presence of nitric oxide

The pyrolyses of trimethylethylene and tetramethylethylene have been investigated in the presence and absence of nitric oxide. It appears that apart from a unimolecular split, e.g., a disproportionation reaction such as may play an important role in initiation. Nitric oxide had no effect on H₂ production, which is probably a molecular process. There was similar behavior of both compounds in the presence of NO, indicating that the olefinic hydrogen atom does not play a decisive role. Other aspects of the mechanisms are discussed.     

Mechanism of inhibiting action of quinones in oxidizing polymers and model compounds

Quinones (Q) do not affect the liquid-phase oxidation of hydrocarbons and retard the solid-phase oxidation of polymers terminating chains in reactions with alkyl macroradicals. This difference is the result of specific influence of a polymer matrix on the kinetics of free radical reactions. Quinones were found to terminate chains in oxidizing polypropylene containing hydroperoxide groups by the reaction with hydroperoxyl radicals. This is the result of peroxide group's decomposition with hydrogen peroxide production and chain termination in the following reactions: The equilibrium reaction between hydroquinone (QH₂) and quinonimine (QI) was evidenced to proceed as a chain reaction with chain propagation in reactions of •QH with QI and HQI• with QH₂. Analysis of the reactions of quinone with phenols (ArOH) proved that it can be important as an additional way of chain termination in oxidizing polymers and hydrocarbons at elevated temperatures.     

Metastable decompositions of cyclopentanol ions and [C5H10O]+˙ ions with the oxygen on the first carbon

Ionized cyclopentanol and [C₅H₁₀O]+˙ ions with the oxygen on the first carbon lose methyl, ethylene, ethyl, ethane and water in their metastable decompositions. We show by collisionally activated decompositions of the products that the losses of ethyl form CH₃CH₂C?O⁺, the losses of ethylene form , and the losses of methyl probably yield . Deuterium labeling indicates that ethyl loss from ionized cyclopentanol occurs following α-cleavage of the ring, isomerization to the enol isomer of ionized n-pentanal and subsequent isomerization to the 3-pentanone ion.     

Anionic copolymerizations of acrylonitrile with β-propiolactone

Anionic copolymerizations of acrylonitrile (monomer 1) with β-propiolactone (monomer 2) and the structures of the resulting copolymers were studied. The copolymerization with sodium cyanide in N,N-dimethylformamide gave copolymers of the structure I containing acid anhydride linkage in the molecular chains, with the monomer reactivity ratios, r₁ = 1.20, r₂ = 0.00. The copolymerization with potassium hydroxide gave either copolymers of the structure II (r₁ = 0.00, r₂ = 3.64 at 30°C; r₁ = 0.00, r₂ = 5.00 at 40°C) in N,N-dimethylformamide or only β-propiolactone homopolymer in toluene.      

Zur Darstellung von Cyclophosphaten,Cyclophosphatophosphonaten, Diphosphonaten und Diphosphiten in Harnstoffschmelzen

Preparation of Cyclophosphates, Cyclophosphatophosphonates, Diphosphonates, and Di-phosphites in Urea Melts Ammonium cyclotriphosphate (NH₄)P₃O₉, ammonium cyclotetraphosphate [P^IV? P^IV ? O? ]₂, ammonium cyclotriphosphatophosphonates Ammonium organyldiphosphonates And ammonium diphosphites are prepared in high yields on heating acidic phosphates, phosphonates, and phosphites in urea or urea/ammonium nitrate melts. The mechanism of the dehydration of phosphorus compounds containing POH groups in molten urea is discussed.     

Dipolmomente 1, 6-überbrückter [10]- Annulene

The dipole moments of 1, 6-bridged [10]-annulenes of type I (X = CH₂, O, NH) and of bromo derivatives with X = CH₂, O are in agreement with the previously established structure of these compounds if a partial moment of approximately 0,8 D is assigned to the non-planar π-electron system.     

Synthesis and psychotropic properties of furyl- and thienyl-germatranes

Trihalogermyl-furans and -thiophenes were prepared by inserting germanium dibromide (GeBr₂) generated from the dibromogermane(II) dioxanate complex into the carbon-halogen bond of halo-furans and -thiophenes. Their ethanolysis and transesterification by triethanolamine yielded the germatranes which were subjected to psychotropic activity assays. The psychotropic properties of germatranes were found to depend on the type of the heterocycle and on the position of the germatrane moiety.     

Synthesis of trifluoromethyl‐1,2,4‐triazine‐ and trifluoromethylpyrimidine‐fused uracils

A variety of trifluoromethyl‐1,2,4‐triazine‐ and trifluoromethylpyrimidine‐fused uracils ( 9 ), ( 12 ), ( 15 ) and ( 18 ) were synthesized from trifluoroacetaldehyde ethyl hemiacetal or trifluoroacetic anhydride and corresponding uracil derivatives.     

Eine neue einfache Methode zur Entalkylierung von Phosphon- und Phosphinsäureestern

A New Facile Method for the Dealkylation of Phosphonic and Phosphinic Acid Esters The synthesis of phosphonic and phosphinic acid esters of the type is realized by reaction of dialkylphosphonates and O-alkylphosphinates with chlorotrimethylsilane in the presence of catalytical amounts of NH₄Cl and hexamethyldisilazane (HMDZ).     

Electron-impact and thermal fragmentation patterns of some cyclic fluoroethers

The mass spectra of cyclic fluoroethers of the general formula (n = 1 to 4) are reported and discussed. Although these spectra show many similar features, those for which n = 3 and 4 contain intense peaks at m/e 63 which are only of relatively low intensity in the spectra of the other two. A similarity between the electron-impact and thermal fragmentation patterns of these compounds is noted.     

Effect of gegen ion in cationic polymerization and copolymerization of trioxane

p-Chlorophenyldiazonium hexafluorophosphate has been reported to be a superior catalyst for cationic polymerization and copolymerization of trioxane as compared to boron trifluoride dibutyl etherate (BF₃·Bu₂O)¹. In the present investigation the effect of anions derived from elements in Group VA, AsF and SbF, has been ascertained. It has been concluded that p-chlorophenyldiazonium hexafluoroarsenate is also a superior catalyst to boron trifluoride dibutyletherate (BF₃·Bu₂O), while p-chlorophenyl-diazonium hexafluoroantimonate is inferior. Copolymers with the highest polymer yield (>95%) and molecular weight (intrinsic viscosity = 4 to 5) were obtained with Simple dependences on catalyst concentration have been observed to hold for a wide catalyst concentration range ([M]/[C]) = (1 to 20) × 10⁵: For the same relationships hold. However, the polymer yield (75%) and molecular weights (intrinsic viscosity ?1) are considerably lower while the extent of chain transfer is higher. Furthermore, the polymerization proceeds with explosive violence. The quantitative aspects resulting from polymerization, for the most part, can be interpreted in terms of the extent of dissociation of the propagating ions.     

Polymerization of alkoxyallenes by transition-metal catalysts

The structure of polymers obtained by polymerization of methoxyallene and ethoxyallene with transition-metal catalysts depends on the catalyst employed. Rapid polymerization at 0°C through the unsubstituted double bond occurred with π-allylnickel halides, NiCl₂/AlEt₃ and CoCl₂/AlEt₃, yielding polymers with the structure Typical Ziegler–Natta catalysts (TiCl₄, VOCl₃ or FeCl₃ with AIEt₃) gave polymers mainly with the structure although some of the structural units were probably present as well. Polymers having conjugated double bonds were prepared with PdCl₂, [(π-allyl)PdCl]₂, and PdCl₂(C₆H₅CN)₂ as catalysts. Palladium iodide produced polymers with all three of the above structural units present. Polymerization occurred more slowly with these palladium catalysts. A preliminary examination of the effect of variation of solvent, ligand, co-catalyst, and temperature on the rate and structure of the polymers obtained with the palladium catalysts is reported.     

Preparation of silicon-containing polymers. I. Polyimides from dianhydrides and organosilicon diisocyanates

New silicon-containing polyimides have been prepared by the reaction of pyromellitic dianhydride (PMDA) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with organosilicon diisocyanates having the following general structure: where R₁ = R₂ = ? CH₃ and ? C₆H₅. Thermal properties of these polyimides were studied were by TG, DTA, and DTG.     

Synthesis and characterization of 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles

The synthesis of a new set of selenadiazoles, 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles ( 4 ) derived from 2‐[4‐methyl‐4‐nitro‐1,3‐diarylpentylidene]‐1‐hydrazinecarboxamide ( 3 ) has been reported. THF has been found to be the solvent of choice for this reaction. Structural features of 3 and 4 have been analyzed by NMR and X‐ray techniques.     

Structural changes in polymers of diethyl succinylsuccinate(1,4-diethoxycarbonyl-2,5-dihydroxy-1,4-cyclohexadiene) with diamines at high temperatures

The structural changes of the polymers having the following structures: at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure: The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction.     

Fluorsulfonylstickstoffverbindungen

The reactions of fluorosulfonylurea derivatives with phosphorus pentachloride in carbon tetrachloride leads to and . These compounds are easily fluroinated by arsenic trifluoride to the corresponding fluorosulfonyl derivatives. It was shown that PCl₅ is reliable for the fluorine-chlorine exchange. Isocyanate esterchlorides as well as carbonyl-fluoride derivatives react with compounds which have an active hydrogen atom. By this way were prepared: . By hydrolysis of , is probably formed as the first reaction product. The acid could be trapped with tetraphenylphosphoniumchloride as a well-cristalline salt. Fluorosulfonyl isocyanate reacts with aldehydes to the following compounds: FSO₂N ? CHCH₃, FSO₂N ? CHC₂H₅, FSO₂N ? CH? CH(CH₃)₂ and FSO₂N ? CHC₆H₅. The physical and chemical properties as well as IR and NMR spectra of the compounds are described and, in part, compared and discussed.     

Le Spectre de L'Alcool Propargylique en Fonction du pH. Un Exemple de Transferts Protoniques Complexes sur un Diacide Organique

Dimethyl sulphoxide (DMSO) is used as a solvent to investigate the kinetic acidity of very weak organic diacids by ¹H d.n.m.r. An inspection of the spectrum of propargyl alcohol as a function of the pH allows the assignment of various proton transfer mechanisms:      

Durch Nachbargruppenbeteiligung induzierte (1,2)-Chlorwasserstoff-Eliminierung aus ionisiertem 2-(β-Chloräthyl)- benzoesäuremethylester

By using deuterium labelled compounds and collisional activation spectra the mechanism of the unusually intensive HCl elimination from 2-(β-chloroalkyl)benzoic acid methyl ester as well as the structure of the product ion have been elucidated. It can be shown that the structure of the stable ion (lifetime τ～10?5 s) is best represented by 2-vinyl benzoic acid methyl ester whereas the reactive ion (lifetime τ<10^?6 s) at least partially rearranges to a cyclic ion. The hydrogen chloride elimination from 2-(β-chloroalkyl)benzoic acid is apparently a simple 1,2 process. A closer examination reveals that the reaction represents a further example of an unusual neighbouring group participation of the ester function.     

Cyclization by the intermediates of phenylthio- and phenoxy carbamoyl. Formation of azasuccinic anhydrides and their polycondensation products. Intervention of the carbamoyl pyridinium cation

The N-(p-nitrophenoxy-carbonyl) derivatives of glycine, DL -alanine and DL -leucine are transformed by the action of pyridine into azasuccinic, 3-methyl-2-azasuccinic and 3-isobutyl-2-azasuccinic anhydride, respectively. These cyclisations occur probably via the intermediate N-carbamoyl-pyridinium cation , the rate of cyclisation seems to depend on the concentration of the intermediate in the form of the dipolar ion , i.e. the ionised carboxyl is necessary for the reaction. In γ-collidine the cyclisation occurs very slowly; this is attributed to the slowness due to steric hindrance of the production of N-carbamoyl-γ-collidinium cation and its instability. The azasuccinic anhydrides mentioned polycondense, yielding the corresponding polyglycine, poly-DL -alanine and poly-DL -leucine. This reaction too is catalysed by pyridine; it can also be effected by γ-collidine, but the efficacity of the latter in comparison with pyridine is even less than in the catalysis of the cyclisation described above. N-(p-nitrophenoxy-carbonyl)-glycine reacts with lysozyme in the presence of pyridine; several glycine residues are introduced into the enzyme molecule, the product being insoluble and poorly active.