Special Features of the Interaction between Asymmetric Dimethylhydrazine and Thiocontaining Schungite

The interaction between asymmetric dimethylhydrazine and thiocontaining mineral schungite-III has been studied. Chromatography–mass spectrometry has been used to identify alkyl polysulfides as the products of desorption of asymmetric dimethylhydrazine from schungite surface. The interaction of asymmetric dimethylhydrazine with crystalline sulfur has been investigated in a model system. Dimethyl polysulfides, CH₃S_nCH₃; (dimethylamino)methyl polysulfides, (CH₃)₂NS_nCH₃; and bis(dimethylamino) polysulfides, (CH₃)₂NS_nN(CH₃)₂, with 2 ≤ n ≤ 4 have been detected. Gas-chromatographic retention indices have been determined for the products of the interaction of asymmetric dimethylhydrazine with sulfur and the schungite material.     

Thermodynamic modeling of the behavior of silicon oxide and nitride precursors in the preparation of dielectric layers

The thermodynamic properties of several silicon-containing derivatives of asymmetric dimethylhydrazine were estimated by comparative methods. The CVD diagrams of the deposition of silicon nitride and dioxide from gas media containing these reagents were constructed.     

Polyurethanes based on asymmetric dimethylhydrazine: Synthesis, structure, and properties

New polyurethanes have been synthesized from asymmetric dimethylhydrazine at a nonstoichiometric ratio of the starting reagents. With the use of various methods, the number-average molecular mass of the polymers has been estimated and conclusions concerning their possible structure have been made.     

Catalytic oxidation of unsymmetrical dimethylhydrazine on Pt/SiO<Subscript>2</Subscript>

Specific features of oxidation of unsymmetrical dimethylhydrazine on a Pt-containing catalyst were studied. The temperature dependence of the unsymmetrical dimethylhydrazine conversion was determined, and the main intermediate and final reaction products were identified. Platinum behaves in the process as a multifunctional catalyst participating in dehydrogenation, hydrogenolysis, and oxidation. A new method was suggested for detecting unsymmetrical dimethylhydrazine in air. It consists in catalytic conversion of unsymmetrical dimethylhydrazine and detection of the nitrogen dioxide formed with semiconductor gas sensors. The method was successfully used for detecting unsymmetrical dimethylhydrazine in air at concentrations in the range 0.1–10 mg m^–3.     

Determination of 1,1-dimethylhydrazine and its decomposition products using ion-pair chromatography

The influence of the nature of the ion-pair reagent (IPR) using sodium octylsulfate, octylsulfonate, and dodecylsulfate as an example on the separation of asymmetric dimethylhydrazine (ADMH) and its decomposition products has been investigated using a Synergi Hydro RP column. It has been shown that the use of sodium octylsulfate as an IRP is preferable. The approach to simultaneous determination of hydrazine, methylhydrazine, ADMH, N-nitrosodimethylamine, and tetramethyl-2-tetrazene with detection limits in water matrices of 0.3, 0.7, 0.8, 7, and 1.2 μg/L respectively (sample volume of 100 μL) has been proposed.     

气相色谱/质谱法测定空气中痕量偏二甲肼

建立了气相色谱/质谱法测定空气中痕量偏二甲肼的分析方法。以2-硝基苯甲醛为衍生化试剂,以含有衍生化试剂的甲醇溶液为吸收液,气体发生装置发生的偏二甲肼气样用吸收液直接吸收后,与衍生化试剂在甲醇中发生反应,对气体采样和衍生化反应条件进行了优化,考察了气相色谱/质谱法测定空气中痕量偏二甲肼的加标回收率为75%～92%;检出限(S/N=3)为0.019mg/L。采样2L时,最低检测浓度为9.5ng/m3。当采样流量为0.2L/min时,平均采样效率为99%。本方法灵敏快速,简便易行,可实现对空气中痕量偏二甲肼的检测。     

Transformations of asymmetric dimethylhydrazine in soils

High-performance liquid chromatography and mass spectrometry were used to find that the decomposition of asymmetric dimethylhydrazine (I) in soils occurred with the formation of dimethylamine, formaldehyde dimethylhydrazone, methylhydrazine, trimethylhydrazine, N-nitrosodimethylamine, 1-methyl-1,2,4-triazole, formic acid dimethylhydrazide, 1,5,5-trimethylformazane, 1-methyl-1,6-dihydro-1,2,4,5-tetrazine, N,N-dimethylaminoguanidine, and several other products. High-reliability structure identification was achieved using independent methods, including gas chromatography-mass spectrometry, ¹H and ¹³C NMR, and UV spectroscopy, and by measuring retention times and spectral characteristics after the counter-synthesis of the suggested structures. The products of the decomposition of I potentially capable of forming initial I and characterized by high migration mobility in soils were identified.     

The retention of 1,1-dimethylhydrazine and its decomposition products on alkyl-grafted silica gels under the ion pair chromatography conditions

The influence of eluent composition (the nature and concentration of the ion-pair reagent, medium pH, the concentration of the buffer solution, and the content of acetonitrile) on the retention of asymmetric dimethylhydrazine and its decomposition products on hydrophobized silica gels under the ion pair chromatography conditions was studied. It was shown that, for these sorbates, the influence of ion-pair reagents can be described correctly in terms of stoichiometric models. Empirical dependences of the retention of the components studied on the concentration of the buffer solution and the volume concentration of acetonitrile were determined. Conditions for the separation of the components were suggested. Original Russian Text ? A.D. Smolenkov, S.A. Ponomarenko, O.A. Shpigun, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 3, pp. 565–574.     

Synthesen mit Nitrilen, 21. Mitt.: Anomalien bei der Reaktion von Dicyanolefinen mit Hydrazin

Zusammenfassung Es wird gezeigt, daß bei der Umsetzung von 9-Dicyanmethylen-9,10-dihydro-10-phenanthrenon mit asymm. Dimethylhydrazin dasselbe Hydrazino-(2-oxo-1,2-dihydro-phenanthryliden)-essigsäuredinitril entsteht, wie bei der Umsetzung von unsubstit. Hydrazin. Ein Mechanismus dieser Reaktion, bei welcher es zu einer Ablösung von zwei Methylgruppen kommt, wird an Hand der gaschromatographisch nachgewiesenen Folgeprodukte diskutiert.

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Hydrazino-(2-oxo-1,2-dihydrophenanthrylidene)-acetodinitrile was formed in the reaction of 9-dicyanomethylene-9,10-dihydro-10-phenanthren-one with asymmetric dimethylhydrazine as well as in the reaction with unsubstituted hydrazine. The mechanism of this reaction involving the removal of two methyl groups is discussed on the basis of secondary reaction products detected byGLC.

     

固体吸附-毛细管气相色谱法测定环境空气中的偏二甲肼

采用固体吸附-毛细管气相色谱法测定环境空气中偏二甲肼的含量,色谱峰高与偏二甲肼浓度在0～13．8mg／L范围内线性关系良好,当采样体积为60L时,检出限和测定下限分别为0．37μg／m^3和1．2μg／m^3。低、中、高3种浓度的偏二甲肼标准溶液测定结果（n=6）的相对标准偏差分别为3．5％,2．6％,1．9％,样品加标回收率为84．5％～101．0％。     

Utilization of unsymmetrical dimethylhydrazine in the production of polyurethanes: Synthesis, structure, and properties of new products

Unsymmetrical dimethylhydrazine is used to design novel polyurethane-based film materials, film-forming aqueous dispersions, and closed-cell polyurethane foams.     

Quantification of transformation products of rocket fuel unsymmetrical dimethylhydrazine in air using solid-phase microextraction

Quantification of unsymmetrical dimethylhydrazine transformation products in ambient air is important for assessing the environmental impact of heavy rocket launches. There are very little data of such analyses, which is mainly caused by the low number of analytes covered by the available analytical methods and their complexity. A simple and cost-efficient method for accurate simultaneous determination of seven unsymmetrical dimethylhydrazine transformation products in air using solid-phase microextraction followed by gas chromatography-mass spectrometry was developed. The method was optimized for air sampling and solid-phase microextraction from 20-mL vials, which allows full automation of analysis. The extraction for 5 min by Carboxen/polydimethylsiloxane fiber from amber vials and desorption for 3 min provided the greatest analytes' responses, lowest relative standard deviations, linear calibration (R² ≥ 0.99), and limits of detection from 0.12 to 0.5 μg/m³. Samples with concentrations 500 μg/m³ can be stored at 21 ± 1°C without substantial losses (1–11%) for up to 24 h, while air samples with concentrations 10 and 50 μg/m³ stored for up to 24 h can be used for accurate quantification of only two and four out of seven analytes, respectively. The developed method was successfully tested for the analysis of air above real soil samples contaminated with unsymmetrical dimethylhydrazine rocket fuel.     

Determination of hydrazine, monomethylhydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine by nonaqueous capillary electrophoresis with amperometric detection

The present study is concerned with the application of nonaqueous capillary electrophoresis (NACE) with electrochemical detection (ED) to the separation and quantitative determination of hydrazine (Hy) and its methyl derivatives. The best performance of NACE-ED was found when using 4 mM sodium acetate/10 mM acetic acid/methanol: acetonitrile = 1:2 as the running buffer, with a bare platinum working electrode set at +1.0 V in an end-column amperometric detection cell. The choice and ratio of suitable solvents for the separation and injection media played an essential role for the performance characteristics of the method. The limits of detection for Hy, methylhydrazine, symmetrical dimethylhydrazine, and unsymmetrical dimethylhydrazine were 5, 2, 12, and 1 ng/mL, respectively. This is between one and two orders of magnitude lower than that achieved by previously reported CE-ED methods in aqueous buffer systems in conjunction with various types of chemically modified electrodes. The practical utility of the new NACE-ED methodology is demonstrated in terms of the determination of traces of Hys in spiked environmental samples containing a wide range of explosives and related compounds.     

Total synthesis of (+)-rishirilide B: development and application of general processes for enantioselective oxidative dearomatization of resorcinol derivatives

A concise synthesis of (+)-rishirilide B (2) is described. This is the first synthesis to be reported for the (+)-enantiomer of rishirilide B (2) as found in nature. The strategy accentuates the valuable combination of a method for o-quinone methide coupling with a method for enantioselective resorcinol dearomatization, which provides a densely functionalized chiral building block. The convergent synthesis illustrates several improvements and refinements to these methods and their supporting chemistries. Among these is the in situ generation of PhI[OTMS]OTf. Combination of this oxidant with phenol 31 constitutes the first example of a diastereoselective oxidative dearomatization of a resorcinol displaying a 2-alkyl substituent. In addition, the preparation of the cyclic sulfone 34 is reported. As a new dimethide precursor expressing a readily cleavable O-benzyl residue, sulfone 34 should prove useful in future endeavors. A protocol using the aluminum amide of dimethylhydrazine for opening and cleavage of a [1,4]-dioxan-2-one is also described. This procedure unmasks the hydroxy dione 36 by jettisoning the chiral directing group. Regioselective O-carbamylation of the 1,3-dione 36 enables the transformation of the remaining carbonyl into the alpha-hydroxy carboxylic acid found in 2. The total synthesis of (+)-rishirilide B (2) requires 15 pots from benzaldehyde 17 and 13 pots from benzaldehyde 32. The final product emerges in yields of 12.5% and 20.3% from compounds 17 and 32, respectively. The longest linear sequence requires eight chromatographies. Important observations leading to the development of the principle asymmetric method are described within the context of the total synthesis.     

Chloro(bromo)vinyl ketones and 2,2-Dichloroacrolein in Reactions with Hydrazines

Reactions of 2,2-dichlorovinyl and 2,2-dibromovinyl ketones with alkylhydrazines afford respectively 1-R-3-alkyl(aryl)-5-chloro- or 5-bromopyrazoles in preparative yields. The dichloroacrolein forms with alkylhydrazines and dimethylhydrazine only the corresponding hydrazones. Quantum-chemical calculations were performed characterizing the structure of the obtained ketones and dichloroacrolein alkylhydrazones, of dichloroacrolein dimethylhydrazone, of 1-alkyl-5-chloropyrazolinium halides, and 1-alkyl-5-chloropyrazoles.     

两种采样方法检测空气中偏二甲肼含量的精密度检验

以自制的偏二甲肼动态配气系统配制已知浓度空气样品为测试环境,采用溶液吸收法采样并简化了G JB2373-1995的分析步骤,使用改进方法与标准方法分别进行实验。用F检验法比较两种方法所对应的两组检测数据,结果表明,两种方法的精密度相当,而溶液吸收法省时、省力。     

Preparation and Deprotection of Aldehyde Dimethylhydrazones

Aldehydes were conveniently protected as dimethylhydrazones by stirring a mixture of the aldehyde, N,N‐dimethylhydrazine, anhydrous magnesium sulfate, and dichloromethane at room temperature. Azeotropic removal of water, formed during the course of the reaction, was not required because anhydrous magnesium sulfate functions as a water scavenger. Deprotection of aldehyde dimethylhydrazones was accomplished by stirring a mixture of the aldehyde dimethylhydrazone and aqueous glyoxylic acid at room temperature. The reaction time for the preparation and deprotection of aldehyde dimethylhydrazones varied with the structure of the aldehyde.     

液体推进剂偏二甲肼自动电位滴定分析方法的建立

设计了Metrohm809型自动电位滴定仪分析液体推进剂偏二甲肼的应用程序,解决了程序设计中滴定模式和终点确定方式选择、滴定速度确定等关键性技术问题,考察了环境温度对分析结果的影响,确定了最佳条件,实现了液体推进剂偏二甲肼的自动电位滴定分析。重复性试验和准确度试验表明,自动电位滴定法分析偏二甲肼具有准确度高、精密度好等优点,测量结果完全符合GJB753-89的要求：     

Palladium‐catalyzed carbonylative cyclization of β‐bromo‐α,β‐unsaturated carboxylic acids with 2,2‐dimethylhydrazine leading to 1‐(dimethylamino)‐1H‐pyrrole‐2,5‐diones

β‐Bromo‐α,β‐unsaturated carboxylic acids are carbonylatively cyclized with 2,2‐dimethylhydrazine under carbon monoxide pressure in THF in the presence of a catalytic amount of a palladium catalyst along with a base to give 1‐(dimethylamino)‐1H‐pyrrole‐2,5‐diones. Copyright © 2014 John Wiley & Sons, Ltd.     

Detection and determination of formaldehyde dimethylhydrazone in mixtures with 1,1-dimethylhydrazine

Small amounts of formaldehyde dimethylhydrazone (FMDH) present as impurity in unsymmetrical dimethylhydrazine (UDMH) give a yellow color (λ_max = 456 nm) on heating with excess of sulphuric acid; the detection limit is 50 μg ml^? FDMH. Differences in the basicity of the two compounds in anhydrous acetic acid and in methanol are used to determine the two compounds in mixtures containing ? 5% (w/w) FDMH.