N,N′,N′′,N′′′‐Tetraethylterephthalamidinium bis(tetrazolate)

The crystal structure of the title 2:1 salt of tetrazole and a substituted terephthal­amidine, C₁₆H₂₈N₄²⁺·2CHN₄^?, contains an infinite network of hydrogen bonds, with short N?N distances of 2.820 (2) and 2.8585 (19) Å between the tetrazolate anion and the amidinium cation. Involvement of the lateral N atoms of the tetrazole in the hydrogen bonding appears to be a typical binding pattern for the tetrazolate anion.     

Mass spectra of some tetrasubstituted 4,4′-biisoxazoles and 4,4′-methylendiisoxazoles

The behaviour of some tetrasubstituted 4,4′-biisoxazoles and 4,4′-methylendiisoxazoles under electron impact has been investigated by means of high and low resolution mass spectrometry. The determination of metastable transitions and accurate masses of important fragment ions has led to the construction of fragmentation schemes. Specific skeletal rearrangement processes are discussed and it is proposed that they proceed through azirine and oxazole intermediates.     

Unusual mass spectrometric fragmentation of N,N′-diethyl-N,N′-diphenylurea

The electron impact mass spectrum of N,N′-diethyl-N,N′-diphenylurea contains the ion m/z 164 which is of low abundance at normal energy of ionizing electrons but prominent at 15-20eV. The mechanism of its formation has been revealed by means of labelled compounds. It is rationalized in terms of an unusual formation of styrene lost as a neutral molecule.     

N‐Benzoyl‐N′,N′‐dibutylselenourea and its palladium(II) complex

The crystal and molecular structures of N‐benzoyl‐N′,N′‐dibutylselenourea (HL), C₁₆H₂₄N₂OSe, and the corresponding complex bis(N‐benzoyl‐N′,N′‐dibutylselenoureato‐κ²Se,O)palladium(II), [Pd(C₁₆H₂₃N₂OSe)₂], are reported. The selenourea molecule is characterized by intermolecular hydrogen bonds between the selenoamidic H atom and the Se atom of a neighbouring molecule forming a dimer, presumably as a consequence of resonance‐assisted hydrogen bonding or π‐bonding co‐operativity. A second dimeric hydrogen bond is also described. In the palladium complex, the typical square‐planar coordination characteristic of such ligands results in a cis‐[Pd(L‐Se,O)₂] complex.     

Intramolecular cyclization of N′-chloroacetylsalicylhydrazide

Treatment of N′-chloroacetylsalicylhydrazide (I) with sodium hydroxide in dimethylformamide produces an intramolecular cyclization. Of all theoretically possible reactions, only one proceeds to give 5,6-dihydro-2-o-hydroxyphenyl-4H-1,3,4-oxadiazin-5-one (II). No formation of the 1,4,5-benzoxadiazocin-3,6-dione (III) is detected. The structure of II, as well as of its acetylation, methylation and hydrolysis derivatives are discussed.     

Accelerating effects of N‐aryl‐N′,N′‐dialkyl ureas on epoxy‐dicyandiamide curing system

This report focuses on epoxy‐dicyandiamide (DICY) curing system accelerated by N‐aryl‐N′,N′‐dialkyl urea, aiming at clarifying the accelerating mechanism and the relationship between accelerating effect and molecular structure of the accelerators. Nine N‐aryl‐N′,N′‐dialkyl ureas were synthesized and investigated with measurements of differential scanning calorimetry, thermo gravimetric/differential thermal analysis and NMR spectroscopy. The results revealed that the ureas released the corresponding secondary amines by the thermal dissociation in the presence of epoxide, which led to the formation of tertiary amines that catalyze the addition reaction of DICY to epoxide. Moreover, a tendency that the ureas able to release more compact amines exhibited higher acceleration effects was discovered. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

[N,N′‐Bis(3‐aminopropyl)ethylenediamine‐κ4N,N′,N′′,N′′′](trithiocyanurato‐κ2N,S)zinc(II) ethanol solvate

In the crystal structure of the title compound, [N,N′‐bis(3‐­amino­propyl)­ethyl­enedi­amine‐κ⁴N,N′,N′′,N′′′][1,3,5‐triazine‐2,4,6(1H,3H,5H)‐tri­thionato(2−)‐κ²N,S]­zinc(II) ethanol sol­vate, [Zn(C₈H₂₂N₄)₂(C₃HN₃S₃)]·C₂H₆O, the Zn^II atom is octa­hedrally coordinated by four N atoms [Zn—N = 2.104 (2)–2.203 (2) Å] of a tetradentate N‐donor N,N′‐bis(3‐­amino­propyl)­ethyl­enedi­amine (bapen) ligand and by two S and N atoms [Zn—S = 2.5700 (7) Å and Zn—N = 2.313 (2) Å] of a tri­thio­cyanurate(2−) (ttcH²⁻) dianion bonded as a bidentate ligand in a cis configuration. The crystal structure of the compound is stabilized by a network of hydrogen bonds.     

N,N,N′,N′‐Tetrasubstituted Piperazinium Salts of Perfluorinated Acids

Well crystallized diquaternary piperazinium salts of perfluorocarboxylic acids can be prepared by thermal rearrangement of a primary product obtained from the appropriate fluorinated acid chloride and N,N‐dialkylamino‐ethanol. The mechanism of the ring closure step is discussed. The synthetic strategy easily gives access to structurally different piperazinium perfluorocarboxylates. The title compounds show surface activity and can be regarded as ionic amphiphiles.     

Mass spectra of some 2-(4′-butyl-3,′5′-dimethylpyrazol-1′-yl)-6-substituted benzothiazoles

The fragmentation of the title compounds on electron impact has been studied and the major processes interpreted. The base peak invariably appears at [M ? 43]⁺ whose origin from the butyl chain has been traced with the help of metastable ion studies and accurate mass measurements. Loss of methyl cyanide, involving the decomposition of the pyrazole moiety, is observed only from the fragment ions.