Nitrogen-containing Cyclic Compounds Research Articles

Rotational spectroscopy of imidazole: Accurate spectroscopic information for three vibrationally excited states and the heavy-atom isotopologues up to 295 GHz

We report our analysis of the pure rotational spectra of low-lying vibrationally excited states and heavy-atom rare isotopologues of imidazole. To facilitate searches for imidazole in the interstellar medium, we previously described the analysis of the rotational spectrum of the imidazole main isotopologue across the 2–295 GHz range, and we extend this analysis here. Structure optimisation and anharmonic frequency calculations were performed to aid the spectral analysis. Three vibrationally excited states of imidazole were assigned in our room-temperature spectra, with energies up to approximately 670 cm−1 above the vibronic ground state. The vibrational states could act as temperature probes in warmer star-forming regions. The 13C and 15N heavy-atom isotopologues were assigned, which allowed for the structure of imidazole in the gas phase to be determined. Structural comparisons are drawn between the related heterocyclic molecules hydantoin and imidazolidine. An experimental gas-phase structure of the former is also determined in this work. The potential detection of the isotopologues could help deduce formation pathways towards imidazole and other nitrogen-containing cyclic compounds in interstellar space.

Nitrogen-containing cyclic compounds as iminium ion sources for selected reaction monitoring detection of derivatized analytes.

Liquid chromatography-tandem mass spectrometry is one of the most sensitive tools for determination of trace amounts of analytes in metabolomics and proteomics. The highest sensitivity is achieved in selected reaction monitoring detection, which involves fragmentation of the molecular ion between two levels of mass selection. However, fragmentation of some compounds is complicated. Detection sensitivity of such analytes may be increased by derivatizing them with a specific moiety fragmentation of which results in product ion of high abundance. In this work, we reveal the influence of iminium ions' structures on their stability by comparing six nitrogen-containing cyclic compounds as derivatization reagents for tandem mass spectrometric analysis of amino group-containing analyte. Commercially available starting materials (piperidine, 2,6-dimethylpiperidine, 1-methylpiperazine, morpholine, pyrrolidine and 1-cyanomethyl-3-methylimidazolium ionic liquid) were used for the synthesis of corresponding carboxylic acids which were further used for derivatization of the model analyte tryptamine. Liquid chromatographic-mass spectrometric analysis of differently derivatized tryptamine was performed for the evaluation of release and stability of corresponding iminium ions under collision-induced dissociation conditions. As a result, morpholine moiety was shown being the most promising iminium ion source among tested compounds. Possible sub-fragmentation pathways of investigated iminium ions were discussed, and the structures of secondary product ions were proposed.

Comparison of the thermal decomposition processes of several aminoalcohol-based ZnO inks with one containing ethanolamine

Four inks for the production of ZnO semiconducting films have been prepared with zinc acetate dihydrate as precursor salt and one among the following aminoalcohols: aminopropanol (APr), aminomethyl butanol (AMB), aminophenol (APh) and aminobenzyl alcohol (AB) as stabilizing agent. Their thermal decomposition process has been analyzed in situ by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and evolved gas analysis (EGA), whereas the solid product has been analysed ex-situ by X-ray diffraction (XRD) and infrared spectroscopy (IR). Although, except for the APh ink, crystalline ZnO is already obtained at 300°C, the films contain an organic residue that evolves at higher temperature in the form of a large variety of nitrogen-containing cyclic compounds. The results indicate that APr can be a better stabilizing agent than ethanolamine (EA). It gives larger ZnO crystal sizes with similar carbon content. However, a common drawback of all the amino stabilizers (EA included) is that nitrogen atoms have not been completely removed from the ZnO film at the highest temperature of our experiments (600°C).

Determination of Nitrogen-Containing Cyclic Compounds by High Performance Liquid Chromatography and Its Application to Analysis of Motor Bike Gases

Determination of Nitrogen-Containing Cyclic Compounds by High Performance Liquid Chromatography and Its Application to Analysis of Motor Bike Gases

W(CO)5(L)-catalyzed Cyclization of ω-Acetylenic Silyl Enol Ethers for the Preparation of Nitrogen-containing Cyclic Compounds

Abstract Electrophilic alkyne activation of nitrogen-containing 7-siloxy-6-en-1-ynes by W(CO)5(L) allows the preparation of synthetically useful heterocycles. Two types of cyclized products, 5-exo and 6-endo, could be obtained selectively under the appropriate conditions.

A New Method for the Preparation of Nitrogen-containing Cyclic Compounds from p-Nitrobenzenesulfonamide and Alkyl Bis(diphenylphosphinite)s by Oxidation–Reduction Condensation Using 1-Azidoadamantane

Abstract A new and efficient method was established for the preparation of nitrogen-containing cyclic compounds from p-nitrobenzenesulfonamide, bisphosphinites, and 1-azidoadamantane in good yields under neutral conditions.

溶媒抽出法を用いる高速液体クロマトグラフィー／紫外分光光度検出による環境水中の含窒素環状化合物の分析法

溶媒抽出法を用いる高速液体クロマトグラフィー／紫外分光光度検出による環境水中の含窒素環状化合物の分析法

Conversion of Imines into C,N-Dimagnesiated Compounds and Trapping with Electrophiles. One-Pot Access to 1-Azaspirocyclic Framework

Under selected conditions, the Zr-catalyzed reaction of EtMgCl with imines produces C,N-dimagnesiated compounds, which can be further trapped with electrophiles. The overall transformation provides a new route to bifunctional or cyclic nitrogen-containing compounds. Particularly, 1-azaspirocyclic γ-lactams, pyrrolidines and azetidines can be obtained in this way.

Modifications of surface properties of nickel/silica catalysts by nitrogen-containing compounds II. Piperidine, 3,5 dimethyl piperidine and pyridine

The interactions of piperidine, 3,5-dimethylpiperidine and pyridine with a reduced Ni/SiO 2 sample have been studied as a function of the temperature, using magnetic measurements, infrared spectroscopy and catalytic activity changes in the hydrogenation of 1,3 butadiene. The three cyclic nitrogen-containing compounds (CNCC) are adsorbed at room temperature without cracking of the molecule: the bond number (number of nickel atoms demagnetized by the adsorption of one adsorbate molecule) is equal to 2,4 and 6 for piperidine, 3,5-dimethylpiperidine and pyridine respectively. For the first two CNCC, the increase of the adsorption temperature considerably increases the bond number; at 373 K, it reaches values of 12 for piperidine and 24 for 3,5-dimethylpiperidine. These values show that a complete cracking of the two molecules does not occur. In the case of pyridine adsorption, a constant bond number close to 7 was observed in the 298–373 K temperature range. Regeneration of the poisoned catalysts was performed by vacuum treatments at increasing temperature. During this process the insertion of nitrogen and carbon atoms in the metal lattice has been evidenced. Regeneration under flowing hydrogen was more efficient than treatment under vacuum. Concerning the hydrogenation of 1,3-butadiene, the addition of CNCC leads to a decrease of the catalytic activity associated with an increase of the selectivity for partial hydrogenation. By contrast with the introduction of ammonia, these effects are permanent, i.e., changes in catalytic activity and selectivity are maintained even after the removal of the CNCC from the feed. The increase in the selectivity in partial hydrogenation of 1,3-butadiene was explained by an electron enrichment of the metallic sites in the presence of cyclic nitrogen-containing compounds.

Synthesis of Nitrogen-containing Cyclic Compounds. CXXIV. Synthesis of Imidazopyridine Derivatives. (3)

Synthesis of Nitrogen-containing Cyclic Compounds. CXXIV. Synthesis of Imidazopyridine Derivatives. (3)

Synthesis of Nitrogen-containing Cyclic Compounds. CXV. Synthesis of Imidazopyridine Derivatives. (2).

Synthesis of Nitrogen-containing Cyclic Compounds. CXV. Synthesis of Imidazopyridine Derivatives. (2).

Sulphonamides. IV. The Reaction of N-Heterocyclic Amines with Sulphonyl Halides

The hypothesis is advanced that the reaction of sulphonyl halides with amino-derivatives of nitrogen-containing cyclic compounds occurs on the ring-nitrogen (which is the more basic), followed either by reaction of the amino-group with another molecule of sulphonyl halide, or by migration of the sulphonyl group from the ring to the ammo-nitrogen. Several apparently anomalous cases of this reaction are explained.