Thermoanalytical investigation of relative reactivity of some nitrate oxidants in tin-fueled pyrotechnic systems

In order to investigate relative reactivity of different oxidants in solid-state reactions of pyrotechnic mixtures, thermal properties of Sn + Sr(NO₃)₂, Sn + Ba(NO₃)₂, and Sn + KNO₃ pyrotechnic systems have been studied by means of TG, DTA, and DSC methods and the results compared with those of pure oxidants. The apparent activation energy (E), ΔG ^#, ΔH ^#, and ΔS ^# of the combustion processes were obtained from the DSC experiments. The results showed that the nature of oxidant has a significant effect on ignition temperature, and the kinetic of the pyrotechnic mixtures’ reactions, and the relative reactivity of these mixtures was found to obey in the following order: Sn + Sr(NO₃)₂ > Sn + Ba(NO₃)₂ > Sn + KNO₃.     

The oxidation of some enamines with metal oxidants

4-(1-cyclohexen-1-yl)-morpholine, 1-morpholino-styrene and 1-morpholino-2-methyl- styrene were treated with lead tetraacetate. The products obtained were N-acetyl-morpholine, the 2-acetoxy-ketone and in the case of the first substrate its enamine. The 2-morpholino-ketone was also formed in the reactions with 4-(1-cyclohexen-1-yl)-morpholine and 1-morpholino-2-methylstyrene. 4- (1-cyclohexen-1-yl)-morpholine reacted with thallium triacetate and mercuric diacetate, giving very similar results. A mechanistic scheme is discussed, where an intermediate product derived from the addition of two acetoxy groups to the enamine double bond is cleaved via an α-elimination path.     

Reactions of biological oxidants with selenourea: formation of redox active nanoselenium

Reactions of biological oxidizing agents, such as hydroxyl radicals ((*)OH), singlet oxygen ((1)O(2)), hydrogen peroxide (H(2)O(2)), and peroxynitrite (ONOO(-)) with selenourea were studied. The kinetics of the reactions was followed using time-resolved techniques, and the bimolecular rate constants were determined. In all these reactions, under aerated conditions, elemental red selenium was produced as one of the reaction products. The average size of the selenium particles could be controlled and stabilized in the range of 20-100 nm with the addition of bovine serum albumin (BSA) or sodium dodecyl sulfate (SDS). The particles were characterized by dynamic light scattering studies (DLS), which revealed that the size and distribution of the particles depended mainly on the amount of selenourea undergoing oxidation. Other factors such as the nature of the oxidant and the concentration of the stabilizer also are important in stabilizing the particles. Nanoselenium-reduced ABTS(*-) to colorless ABTS(2-) (ABTS = 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) and oxidized dichlorodihydrofluoresecein diacetate (DCFA) to fluorescent dichlorofluorescein (DCF) indicating its ability to participate in redox and free radical reactions. The reactivity of selenium nanoparticles with these systems varied linearly with the surface area of the particles. The studies demonstrate that selenourea undergoes oxidation with both one-electron and two-electron oxidants to produce elemental selenium, which, on stabilization to nanometer size, exhibits size-dependent redox activity.     

Reactions of some chlorohydrins with uracils

Conclusions By the reactions of uracil and 6-methyluracil with chlorohydrins 3-(hydroxyalkyl)- and 1,3-bishydroxyalkyl-uracils were prepared, and their structures were proved.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1327–1329, June, 1968.We thank V. D. Kochkina and S. A. Flegontov for determining the IR spectra.     

Reactions of hexafluorobenzene with some organometallic reagents

The inverse addition of trichloro-2-thienyl-lithium to hexafluorobenzene in THF or ether has given 1,4-bis(trichloro-2-thienyl) tetrafluorobenzene in addition to the tetrakis(trichloro-2-thienyl)difluorobenzene. n-Butyl-lithium with hexafluorobenzene gave mono, bis tris and tetrakis compounds whereas t-BuLi afforded only 1,4-bis(t-butyl)tetrafluorobenzene in excellent yield. Other organolithium and organomagnesium reagents gave the expected products. IR, ¹⁹F NMR and UV spectral data are presented for the several new compounds.     

Reactions of some pyranylidene esters with amines

The reactions of 4-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)-2,6-diphenyl-4H-pyran ( 1 ) with primary amines gave the corresponding 1-substituted 1,4-dihydropyridine derivatives. The related benzo derivative of 1 (12) and primary amines gave 3-substituted 3,4-dihydro-2-phenyl-5H-[1]benzopyrano[3,4-c] pyridine-4,5-dione derivatives. With secondary amines, 12 gave 2-phenyl-4H,5H-pyrano[3,4-c] [1]benzopyrane-4,5-dione, and with isopropylamine, N,N-dimethylhydra-zine, and methanolic potassium hydroxide, 12 gave 4-phenacylcoumarin. Some reaction intermediates were isolated which indicate probable reaction paths. The reactions with amines were extended to a naphtho derivative of 1 (19) and to a thia homolog of 12 (24).     

Reactions of triethylgermylpentafluorobenzene with some electrophilic agents

Triethylgermylpentafluorobenzene C₆F₅GeEt₃ reacts with CF₃SO₃H, HSO₃Cl, Me₃SiOSO₂Cl, chlorine, bromine, Cl₂/AlCl₃, or Br₂/AlBr₃ with cleavage of the C_aryl Ge bond. Cesium fluoride promotes electrophilic degermylation of C₆F₅GeEt₃, possibly via the intermediate formation of a tetraorganylfluorogermanate.     

Reactions of salicylaldehyde with some conjugated olefins

Some condensation reactions of salicylaldehyde with various conjugated olefins, 1a, 1b, 1c, 2a, 2b, 2c , and 3 , were studied. In the condensations with 1a, 1b , and 1c gave 2,2-dimethyl-2H-chromene derivatives via “3–2 cyclization”, while the condensations with 2a, 2b, 2c , and 3 gave 2-methyl-2H-chromen-2-yl)acetic acid derivatives via “3–4 cyclization”.     

Reactions of some nitrosoperfluoroalkanes with trimethylsilyl phosphites

Nitrosotrifluoromethane or nitrosopentafluoroethane reacted with trimethylsilyl diethyl or tris(trimethylsilyl) phosphite to give phosphato-fluorocarbimino- or phosphato-trifluoroacetimino-phosphonates and fluorotrimethylsilane. Some intermediate compounds could be detected by NMR spectroscopy, namely, diethyl (N-trimethylsiloxy-N-trifluoromethyl)- or diethyl (N-trimethylsiloxy-N-pentafluoroethyl)amidophosphate and difluorocarbimino diethyl phosphate. © 1996 John Wiley & Sons, Inc.     

Reactions ofP-cyanospirophosphoranes with some thiols and alcohols

5-Cyano-2,3,7,8-tetrarnethyl-1,4,6,9-trioxathia-5-phosphaspiro[4.4]nonane reacts with thiols and secondary alcohols only in the presence of Et₃N.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 946–947, May, 1994.     

Reactions of some nitrofluoroaromatics with the methanethiolate anion

Previous studies on the reactions of simple fluoroaromatics, C₆F_xH_6?x′ with sodium methanethiolate in an ethylene glycol/pyridine solvent mixture have shown that at least two fluorine atoms remained C₆F₅H + SMe^? → C₆F₂H(SMe)₂ on the aromatic ring. When the reactions of simple nitrofluoroaromatics, C₆F_xH_yNO₂ were studied under the same conditions stepwise replacement of all the aromatic fluorines was observed. This clearly demonstrates the activating effect of the nitro group in these reactions, and is in marked contrast to the deactivating effect of the amino group observed previously in analogous reactions of the fluoroaniline. Details of these reactions will be discussed. In one case the expected substitution was not observed and an azoxybenzene was formed.

The methylthio group can readily be oxidized, but

simple reduction of the nitrogroup to an amino group was not feasible.All the new compounds isolated have been characterized by chemical analysis and mass spectroscopy. The structures have been determined by NMR spectroscopy usually proton and/or fluorine, but in cases of ambiguity the carbon-13 spectra have also been examined.     

Reactions of some fluoroaromatics with the ethoxide anion

The reactions of sodium ethoxide in ethanol with various fluoroaromatics, C₆F_6?nH_n, C₆F_5?nH_nNO₂, C₆F₅X (X = CF₃, C₆F₅, COCH₃, CH₂Br), C₆Cl₆ and $\text{m}$H₂C₆Cl₄ have been studied. Partial substitution of the aromatic halogen was observed. The new products have been characterized by elemental analysis, NMR (H?1 and F?19), infrared and mass spectroscopy.     

Reactions of zero-valent platinum complexes with some diacetylenes

The complexes[Pt(C₂H₄)L₂] (L = PPh₃ or PMePh₂) react with 1,4-diphenyl-buta-1,3-diyne to give, successively, mono- and di-platinum compounds [Pt-(PhC₄Ph)L₂] and [Pt₂(PhC₄Ph)L₄]. Hexa-2,4-diyne and [Pt(C₂H₄)(PPh₃)₂] react similarly. In the di-platinum compounds both acetylenic linkages are η²-bonded to platinum atoms, as also occurs in the complex [Pt₂{HC₂(CH₂)₂C₂H}(PPh₃)₄] obtained from hexa-1,5-diyne. Reaction of [Pt₃(CN-t-Bu)₆ with 1,4-diphenylbuta-1,3-diyne and hexa-2,4-diyne affords di-platinum complexes, shown by spectroscopic studies to have structures containing diplatinacyclobutene rings.