Synthesis and nitration of <Emphasis Type="Italic">N,N</Emphasis>´-bis(3-R-furoxan-4-yl)methylenediamines

A Mannich reaction of 4-amino-3-R-furoxans with paraformaldehyde in 10% aqueous H₂SO₄ led to the high yields of N,N′-bis(3-R-furoxan-4-yl)methylenediamines, whose structure (using R = Me as an example) was confirmed by X-ray diffraction study. The N,N′-bis-(3-R-furoxan-4-yl)methylenediamines obtained were nitrated to N,N′-dinitro-N,N′-bis-(3-R-furoxan-4-yl)methylenediamines upon the action of 100% HNO₃ in acetic or trifluoroacetic anhydride.     

Oxidative nitration of the amino group: synthesis of dinitramide and cyanonitramide salts

A convenient preparative method for the synthesis of potassium dinitramide and cyanonitramide salts was developed. The method involves reactions of nitramide or cyanamide with KNO₂ and PhI(OAc)₂ or PhIO in methanol.     

Elastic response of carbon nanotube forests to aerodynamic stresses

The ability to determine static and (hydro)dynamic properties of carbon nanotubes (CNTs) is crucial for many applications. While their static properties (e.g., solubility and wettability) are fairly well understood, their mechanical responses (e.g., deflection under shear) to ambient fluid flow are to a large extent unknown. We analyze the elastic response of single-walled CNT forests, attached to the bottom wall of a channel, to the aerodynamic loading exerted by both laminar and turbulent flows. Our analysis yields analytical expressions for velocity distributions, the drag coefficient, and bending profiles of individual CNTs. This enables us to determine flexural rigidity of CNTs in wind-tunnel experiments. The model predictions agree with laboratory experiments for a large range of channel velocities.     

Formation of nitrone in the reaction ofpara-nitroso-N,N-dimethylaniline with tetracyanoethylene

para-Nitroso-N,N-dimethylaniline reacts with tetracyanoethylene to give [4-(dimethyl-amino)phenylimino]malononitrileN-oxide 1 (65%) in addition to [4-(dimethyl-amino)phenylimino]malononitrile 2 (17%). The structures of the products are confirmed by spectral data and chemical transformations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 617–619, March, 1997.     

Alkylation of 1-hydroxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide

Alkylation of 1-hydroxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide 1 and its silver salt 10 with different alkylating agents (diazomethane, diazoacetone, bromoacetone, α-bromoacetophenone, methyl iodide, methyl vinyl ketone) was studied. Alkylation of compound 1 with diazo compounds and salt 10 with halocompounds results predominantly in O-alkylation products, 1-alkoxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxides. The Michael reaction of compound 1 with methyl vinyl ketone involves the triazole nitrogen atom to give 1-(3-oxobutyl)-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 3,4,6-trioxide. The structures of the compounds synthesized were established by ¹H, ¹³C, ¹⁴N NMR spectroscopy and mass spectrometry.     

Synthesis of 1,2,3,4-tetrazine 1,3-dioxides annulated with 1,2,3-triazoles and 1,2,3-triazole 1-oxides

1,2,3,4-Tetrazine 1,3-dioxides annulated with 1,2,3-triazoles and 1,2,3-triazole 1-oxides have been synthesized by the reaction of 4-amino-5-(tert-butyl-NNO-azoxy)-2-R-2H-1,2,3-triazoles (R=Me, i-Pr, t-Bu) and their 1-oxides (R=H, Me, Et, i-Pr) with the HNO₃/H₂SO₄/Ac₂O system. Their thermal stability, spectroscopic, and X-ray properties have been studied.     

Synthesis of 3,5-disubstituted 1H-1,2,4-triazolium 4-nitroimides

Russian Chemical Bulletin -     

Generation of oxodiazonium ions 1. Synthesis of [1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxides

Methods for the synthesis of [1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxides, which include the reaction of 3-nitramino-4-(R-phenyl)furazans or their O-methyl derivatives with electrophilic agents, have been developed. Unsubstituted [1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxide was synthesized from 3-nitramino-4-phenylfurazan upon the action of phosphorus anhydride or oleum, as well as from O-methyl derivative of 3-nitramino-4-phenylfurazan upon the action of H₂SO₄, MeSO₃H, CF₃CO₂H and BF₃·Et₂O, while 6-, 7-, 8-, and 9-nitro-substituted [1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxides — from the corresponding 3-nitramino-4-(nitrophenyl)furazans upon the action of the H₂SO₄-HNO₃ nitrating mixture. A suggestion has been made that an oxodiazonium ion is formed in these reactions from nitramines or their O-methyl derivatives upon the action of electrophilic agents, which is further involved into the intra-molecular reaction of electrophilic aromatic substitution (S _EAr) with the aryl group. The structure of [1,2,5]oxadiazolo[3,4-c]cinnoline 5-N-oxides was confirmed by ¹H, ¹³C, and ¹⁴N NMR spectra. Theoretical studies by the B3LYP/6-311G(d,p) method of combined molecular system (O-methylated 3-nitramino-4-phenylfurazan + [H₃SO₄]⁺) resulted in calculation of thermodynamic parameters of the sequence of cascade elementary reactions leading to the formation of [1,2,5]oxadiazolo[3,4-c]cinnoline 5-oxide.     

Reactions of CF3-substituted boranes with α-diazocarbonyl compounds

Boranes substituted with a CF₃-group can be generated from methyl boronic esters RB(OMe)₂ and Me₃SiCF₃/KF followed by treatment with Me₃SiCl. These boranes are stable only in coordinating solvents, and due to the increased Lewis acidity of boron, react rapidly with α-diazocarbonyl compounds to give the products of transfer of the organic group from boron. Alkyl, aryl, vinyl, and alkynyl boronic esters can be used in this reaction.     

Asymptotically Optimal Quickest Change Detection in Multistream Data—Part 1: General Stochastic Models

Assume that there are multiple data streams (channels, sensors) and in each stream the process of interest produces generally dependent and non-identically distributed observations. When the process is in a normal mode (in-control), the (pre-change) distribution is known, but when the process becomes abnormal there is a parametric uncertainty, i.e., the post-change (out-of-control) distribution is known only partially up to a parameter. Both the change point and the post-change parameter are unknown. Moreover, the change affects an unknown subset of streams, so that the number of affected streams and their location are unknown in advance. A good changepoint detection procedure should detect the change as soon as possible after its occurrence while controlling for a risk of false alarms. We consider a Bayesian setup with a given prior distribution of the change point and propose two sequential mixture-based change detection rules, one mixes a Shiryaev-type statistic over both the unknown subset of affected streams and the unknown post-change parameter and another mixes a Shiryaev–Roberts-type statistic. These rules generalize the mixture detection procedures studied by Tartakovsky (IEEE Trans Inf Theory 65(3):1413–1429, 2019) in a single-stream case. We provide sufficient conditions under which the proposed multistream change detection procedures are first-order asymptotically optimal with respect to moments of the delay to detection as the probability of false alarm approaches zero.