Acetylene hydrochlorination over tin nitrogen based catalysts: effect of nitrogen carbon-dots as nitrogen precursor

The catalysts comprising the main active compounds of Sn-Nx were synthesized using trichlorophenylstannane ((C₆H₅)Cl₃Sn), nitrogen carbon-dots (NCDs), and activated carbon (AC) as starting materials, and the activity and stability of catalysts was evaluated in the acetylene hydrochlorination. According to the results on the physical and chemical properties of catalysts (TEM, XRD, BET, XPS and TG), it is concluded that NCDs@AC can increase (C₆H₅)Cl₃Sn dispersity, retard the coke deposition of (C₆H₅)Cl₃Sn/AC and lessen the loss of (C₆H₅)Cl₃Sn, thereby further promoting the stability of (C₆H₅)Cl₃Sn/AC. Based on the characterization results of C₂H₂-TPD and HCl adsorption experiments, we proposed that the existence of Sn-N_x can effectively strengthen the reactants adsorption of catalysts. By combing the FT-IR, C₂H₂-TPD and Rideal-Eley mechanism, the catalytic mechanism, in which C₂H₂ is firstly adsorbed on (C₆H₅)Cl₃Sn to form (C₆H₅)Cl₃Sn-C₂H₂ and then reacted with HCl to produce vinyl chloride, is proposed.     

氮中二氧化氮气体标准物质的研制

采用称量法制备并计算定值,研制(10～5000)μmol.mol-1氮中二氧化氮气体标准物质。考察了气体标准物质随贮存时间和钢瓶压力变化的稳定性,将制备的气体标准物质与GBW 08180进行比对验证,结果表明研制的气体标准物质定值的扩展不确定度优于3%(k=3),有效期限为12个月。     

Asymmetric nitrogen

The¹H NMR spectra ofO-derivatives of 1-hydroxy-2,2-bis(trifluoromethyl)aziridine containing such substituents as EtO₂CCH₂, (R/S)-RO₂CCH(Me) (R=Me, Prⁱ, or Bu^t), (R/S)-H₂NC(O)CH(Me), and (R)-H₂NC(O)CH(Me) were analyzed. Both of the diastereomerically pure amides of the latter type were isolated. The validity of the¹H NMR criteria, which were suggested for the determination of absolute configurations of diastereomers ofN-alkoxyaziridines, was confirmed by X-ray diffraction study of the (R,R)-amide.     

Asymmetric nitrogen

Reactions of the Tröger base (1) with HgBr₂ and Mel proceed with the participation of only one N atom. According to the data of X-ray diffraction analysis, the complex [(±)-1]₂·HgBr₂ crystallizes in the achiral space groupP _n . Unlike the complex [(+)-1]₂·HgBr₂, methiodide of (+)-1 in MeOH undergoes racemization at 20°C. The virtual spin-spin coupling constants⁴ J _HH observed for the base (C ₂ symmetry) are transformed into the “usual” constants in the case of the desymmetrized methiodide system.     

Synthesis of heterocycles from molecular nitrogen as a nitrogen source

Nitrogen fixation is a very attractive process. We succeeded in nitrogen fixation using a TiCl₄‐ or Ti(O‐i‐Pr)₄‐Li‐TMSCl system. Nitrogen fixation proceeds at room temperature under 1 atmosphere pressure of nitrogen to give a mixture of titanium nitride complex 12 , titanium nitrogen complex 13 , and N(TMS)₄. Using the titanium nitrogen complexes 1 , various heterocycles were synthesized from the corresponding ketocarbonyl compounds. Nitrogen in air could be fixed using this method. The total syntheses of lycopodine and monomolin I were achieved from nitrogen in air as the nitrogen source. On the other hand, transmetalation of the nitrogen moiety of titanium nitrogen complexes 1 to a palladium complex was realized, and the non‐substituted anilines could be synthesized from ArX and N₂ in the presence of the palladium catalyst. Furthermore, amide could be synthesized from ArX, CO, and N₂ using the palladium catalyst.     

Reactions of nitrile oxides with nitrogen oxides. 2. Reactions with nitrogen monoxide and nitrogen sesquioxide

We have studied the reactions of aromatic nitrile oxides with nitrogen monoxide and nitrogen sesquioxide. It was shown that nitrogen monoxide removes an oxygen atom from the nitrile oxide with formation of the corresponding nitrile and nitrogen dioxide. The reaction products with nitrogen sesquioxide are formed as a result of reactions of the nitrile oxide with nitrogen monoxide and nitrogen tetroxide.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1623–1625, July, 1990.     

Pentavalent nitrogen

Conclusions The limitations imposed by the octet rule on the valence of nitrogen (and oxygen) are not necessary: pentacovalent nitrogen really does exist.Translated from Izvestiya Akademii NaukSSSR, Seriya Khimicheskaya, No. 9, pp. 1931–1933, September, 1979.     

Asymmetric nitrogen

The molecular structure of 3-methyl-1-((S)-1-tosylprolyl)1,2-diazacyclohex-2-ene, the product of the reaction of 5-methyl-1,6-diazabicyclo[3.1.0]hexane with (S)-N-tosylproline chloride, has been established by X-ray structural analysis. The pyrrolidine cycle has a half-chair conformation with the pyramidal nitrogen atom; the tosyl and pseudo axial carbamoyl groups havetrans orientations. The diazacyclohexene cycle has an envelope conformation with folding along the C(7)...C(9) line. The stereochemistry of the transition state of the above-mentioned reaction is discussed.For the previous communication, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 500–503, March, 1995.     

Asymmetric nitrogen

The possibility of tranferring chirality from nitrogen to carbon by a three-step transformation of racemic dimethyl 1-methoxyaziridine-2,2-dicarboxylate into 3-amino-2-chloromethyl-2-methoxyaminopropan-1-ol was demonstrated. The first representative of 1-silyloxyaziridines,viz., dimethyl 1-(tert-butyldimethylsilyloxy)aziridine-2,2-dicarboxylate, was synthesized by acidolysis or thermolysis of triazoline, obtained by the reaction oftert-butyldimethylsilyloxime of dimethy mesoxalate with CH₂N₂     

The influence of nitrogen sources on nitrogen doped multi-walled carbon nanotubes

A range of nitrogen doped carbon nanotubes (N-CNTs) was produced by a nebulised floating catalyst method at 850 °C using a mixture of toluene and 1-8% nitrogen containing reagents (a range of amines and amides). The carbon nanotube (CNT) products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), CHN analysis as well as Raman spectroscopy. Differences due to the different N containing reagents were noted but in general all reagents gave aligned CNTs that at low concentration (1%) were longer and wider than those produced without nitrogen. Increased N content in the reactant mixture gave doped tubes that became shorter and showed more disorder. Treatment of the N-CNTs with nitric acid (microwave, 30 min) gave samples that were chemically modified by the acid (loss of alignment, narrower tubes and more facile oxidation). It appears in general that the amount of N in the nitrogen containing reagent is more important than the source and type of the N atoms used as revealed by trends in the morphology (diameter, length) of the N-CNTs produced.     

S-demethylation of nitrogen heterocycles

When 3-chloro-4,5-diaminopyridazine ( 2 ) was treated with sodium methylmercaptide in refluxing N,N-dimethylformamide, two heterocycles were formed and isolated, neither of which was the expected 3-methylthio-4,5-diaminopyridazine ( 3 ). A thorough spectral analysis of these heterocycles showed them to be 4-methylthioimidazo[4,5-d]pyridazine ( 5 ) and imidazo[4,5-d]pyridazine-4-thione ( 6 ). N,N-Dimethylformamide was found to provide the one carbon unit required for the formation of 5. The origin of 6 was shown to be a result of S-demethylation of 5. S-Demethylation of 3 could also be effected with sodium methylmercaptide in methyl sulfoxide without the occurrence of annulation. In methyl sulfoxide the process of demethylation was accelerated and occurred at lower temperature.     

Improved diffusion methods for nitrogen and 15nitrogen analysis of Kjeldahl digests

Simple methods are described that permit the use of either H3BO3 indicator solution or acidified filter disks to collect NH3 liberated by treatment of Kjeldahl digests with NaOH. These methods incorporate modifications to improve reliability, analytical capacity, and convenience. A semimicro digest was diluted to 25 mL with deionized water, and a 10 mL aliquot, containing up to 4 mg N (150 microg N for diffusions into acidified disks), was transferred to a shell vial, which was placed inside a 473 mL (1 pint) Mason jar containing 10 mL 10N NaOH. The NH3 liberated by overturning the vial was collected after 12 to 48 h at ambient temperature, or after 4 h at 45 to 50 degrees C on a hotplate, for quantitative and/or isotope-ratio analyses. With either H3BO3 indicator solution or acidified filter disks, recovery of diffused N was quantitative. Isotope-ratio analyses of diffused N from 15N-labeled chemical, plant, and soil samples were within 3% of analyses using steam distillation.