6415-12-9Relevant academic research and scientific papers
Reactivity of boroxine. Reactions with azomethane and azoethane
Kaldor, Andrew,Pines, Ira,Porter, Richard F.
, p. 1418 - 1423 (1969)
A product of the reaction of boroxine with azomethane and azoethane has been identified as a 1:1 azoalkane-borine addition compound. Structural information based on infrared and nuclear magnetic resonance data indicate that the product has the unsymmetrical configuration (Chemical Equation Presented).
Chromatographic component of identification of the transformation products of 1,1-dimethylhydrazine in the presence of sulfur
Zenkevich,Ul'Yanov,Golub,Buryak
, p. 1106 - 1114 (2014/08/05)
The gas-chromatographic retention indices of the products of 1,1-dimethylhydrazine transformations in the presence of sulfur allows one to confirm and, in ceratin cases, make more exact the results of their gas chromatography-mass spectrometry identificat
Indirect determination of self-exchange electron transfer rate constants
Nelsen, Stephen F.,Ismagilov, Rustem F.,Gentile, Kevin E.,Nagy, Mark A.,Tran, Hieu Q.,Qu, Qinling,Halfen, DeWayne T.,Odegard, Amy L.,Pladziewicz, Jack R.
, p. 8230 - 8240 (2007/10/03)
Second-order rate constants k(ij)(obsd) measured at 25 °C in acetonitrile by stopped-flow spectrophotometry for forty-four electron transfer (ET) reactions among fourteen 0/+1 couples [three aromatic compounds (tetrathiafulvalene, tetramethyltetraselenafulvalene, and 9,10-dimethyl- 9,10-dihydrophenazine), four 2,3-disubstituted 2,3-diazabicyclo[2.2.2]octane derivatives, six acyclic hydrazines, and the bridgehead diamine 1,5- diazabicyclo[3.3.3]undecane] and seventeen compounds and forty-seven reactions from a previous study (J. Am. Chem. Soc. 1997, 119, 5900) [three p- phenylenediamine derivatives, four ferrocene derivatives, and ten tetraalkylhydrazines] are discussed. When all 91 k(ij)(obsd) values are simultaneously fitted to Marcus's adiabatic cross rate formula k(ij)(calcd) = (k(ii)k(jj)K(ij)f(ij))(1/2), ln f(ij) = (ln K(ij))(2/4) ln((kii)k(jj)/Z2), best-fit self-exchange rate constants, k(ii)(fit), are obtained that allow remarkably accurate calculation of k(ij)(obsd); k(ij)(obsd)/k(ij)(calcd) is in the range 0.5-2.0 for all 91 reactions. The average difference without regard to sign, |ΔΔG(+)(ij)|, between observed cross reaction activation free energy and that calculated using the k(ii)(fit) values and equilibrium constants is 0.13 kcal/mol. The ΔG(+)(ii)(fit) values obtained range from 2.3 kcal/mol for tetramethyltetraselenafulvalene(0/+) to 21.8 kcal/mol for tetra-n-propylhydrazine(0/+), corresponding to a factor of 2 x 1014 in k(ii)(fit). The principal factor affecting k(ii)(fit) for our data appears to be the internal vertical reorganization energy (λ(v)), but k(ii)(fit) values also incorportate the effects of changes in the electronic matrix coupling element (V). Significantly smaller V values for ferrocenes and for hydrazines with alkyl groups larger than methyl than for aromatics and tetramethylhydrazine are implied by the observed ΔG(+)(ii)(fit) values.
Gas-Phase Reactions of (CH3)2N Radicals with NO and NO2
Lazarou, Yannis G.,Kambanis, Kyriakos G.,Papagiannakopoulos, Panos
, p. 2110 - 2115 (2007/10/02)
The absolute rate constants for the reactions of (CH3)2N radicals with NO and NO2 were determined in the gas phase and at room temperature by using the very low pressure reactor (VLPR) technique.The rates were k(CH3)2N + NO = (8.53 +/- 1.42) x 1E-14 Cm3 molecule-1s-1 and k(CH3)2N + NO2 = (9.08 +/- 1.36) x 1E-13 cm3 molecule-1s-1.The reaction with NO2 proceeds via two competitive pathways: the recombination patway (CH3)2N + NO2 -> (CH3)2NNO2, with a rate constant k2a = (3.18 +/- 0.48) x 1E-13 cm3molecule-1s-1, and the oxidation patway (CH3)2N + NO2 -> (CH3)2NONO* -> (CH3)2NO + NO, with a rate constant k2b = (6.36 +/- 0.74) x 1E-13 cm3molecule-1s-1.The oxidation pathway is ca. 2.2 times faster than the recombination one, and the ratio k2a/k2b = 0.45 +/- 0.15.Conventional transition state theory analysis indicates that the involved transition states are loose, with the NN or bond lengths equal to ca. 2.5 Angstroem.
Absolute Rates of Recombination and Disproportination of Dimethylaminyl Radicals
Lazarou, Yannis G.,Papagiannakopoulos, Panos
, p. 9133 - 9140 (2007/10/02)
The absolute rate constants for the recombination (kr) and disproportionation (kd) reactions of dimethylaminyl radicals were determined at room temperature with the very low pressure reactor (VLPR) technique.The obtained values were kr = (1.70 +/- 0.19) x 1E-12 cm3 molecule-1 s-1 and kd = (4.19 +/- 0.52) x 1E-12 cm3 molecule-1 s-1, and the ratio kd/kr was 2.32 +/- 0.26.The transition-state geometries for both recombination and disproportination reactions are loose, with the N...N bond length ca. 3.5 Angstroem and the N...H...C distance ca. 4.4 Angstroem.In the recombination TS, the four C-N...N bending modes are ca. 90 cm-1 and play a significant role in the formation of the N-N bond in tetramethylhydrazine.In the disproportionation TS, the two (in-plane and out-of-plane) vibrational modes of the metathetic hydrogen are ca. 110 cm-1 and are essential in the formation of the N-H bond in dimethylamine.
Kinetic Effects of an Unusually Large Neutral to Radical Cation Geometry Change. Slow Electron-Transfer Reactions between Alkylhydrazines
Nelsen, Stephen F.,Rumack, Daniel T.,Meot-Ner (Mautner), Michael
, p. 1373 - 1379 (2007/10/02)
High pressure mass spectrometry was used to measure the kinetics for electron transfer between 54 pairs of tetraalkylhydrazines containing acyclic and f-ve- to seven-membered cyclic and bicyclic rings.Rate constants for electron transfer vary between 18 and 0.03 x 10-11 cm3molecule-1s-1 at 550 K.Variable-temeprature mesuremeants were made on five pairs over a 77-120 deg range.The (Me2N)2(1+), (EtMeN2)2 pair gave Ea=2.7 kcal/mol.The association energy for (Me2N)2 was measured at ΔH0=-13.0 kcal/mol near room temperature.These data are combined to estimate an energy separation of about 15.7 kcal/mol between associated (Me2N)2(1+)/(EtMeN)2 dimer complex and the transition state for electron transfer.The observed Bronsted α value of about 0.5 suggests a large barrier to electron transfer, and the kinetics suggests that the components largely retain their original structures in the associated complex, but that significant distortion is required to reach the transition-state geometry.The effect of alkyl group changes on the electron-transfer rate and comparison of these data with solution experiments are discussed.
Ureas as Amine Substrates for Hydrazine and Alkylhydrazine Synthesis - Base-assisted Chlorination of Urea by Dimethylchloramine as a Route for Hydrazine and Teramethylhydrazine Synthesis
Prakash, Hari
, p. 764 - 767 (2007/10/02)
Base-assisted chlorination of urea by dimethylchloramine is reported.It has been shown that dimethylchloramine prefers to abstract H-atom from urea, but unlike the oxidative coupling of sulphamide by chloramine via the formation of aminium radical, chlorination of urea occurs and tetramethylhydrazine forms as a result of the coupling of the dimethylamino radicals.Fairly good yields of hydrazine are obtainable in methanol, promising a feasible route for the hydrazine fuel preparation in alcohols.
