Investigation of the formation of complex reaction products in the gas-phase system O3/NO2/(Z)-2-butene by combination of linear reactors with IR. matrix and microwave Stark Spectroscopy is reported. Besides the polyatomic products observed earlier in the gas-phase ozonolysis of (Z)-2-butene, the following products were identified; N2O5, HNO3, HNO4, CH3NO2, CH3ONO, CH3COONO2 and CH3COO2NO2 (peroxyacetyl nitrate, PAN). Matrix IR. spectra of N2O5, HNO3. CH3COONO, CH3COONO2 required for reference purposes are presented. It is shown that PAN-formation occurs already in the absence of light. A reaction scheme is proposed for explanation of the observed complex NOx-containing products, which assumes methyldioxirane as a central intermediate. Particular reaction steps of the scheme will be discussed, including thermochemical estimates of reaction enthalpies. 相似文献
Product studies using FTIR absorption spectrometry have been performed in a 420 xxx reaction chamber on the 254 nm photolysis of mixtures containing CH3SSCH3 and NO2 at ppm concentrations in 760 Torr of O2/N2 diluent. The results indicate that the CH3S radicals formed by photolysis of CH3SSCH3 react primarily with NO2, forming CH3SO and NO. In the presence of O2 an unstable intermediate whose IR absorption spectrum resembles a peroxynitrate compound is observed. The intermediate has been tentatively assigned to methyl sulfinyl peroxynitrate, CH3S(O)OONO2. Other products include SO2, CH3SNO, CH3SNO2, CH3NO3, CH3SO3H, and HCHO. 相似文献
Photodecomposition of dimethylnitrosamine in the gas phase ( ~ 1 Torr) has been investigated following irradiation into the S1 (nπ*) ← S0 (363.5 nm) and S2 (ππ*) ← S0 (248.1 nm) transitions at room temperature. With a quantum yield of unity, excitation into the S1 state yields the fragments (CH3)2N? and NO which then recombine leaving no photoproducts. The addition of O2 results in only one photoproduct, (CH3)2NNO2. Irradiating into the S2 state, the products CH2?N? CH3, (CH2?N? CH3)3, CH2?NOH, N2O, NO, H2, and N2 were identified by capillary gas chromatography mass spectrometry. In the presence of N2 as a buffer gas the photoproducts are only CH2?N? CH3, (CH2?N? CH3)3, N2O, and H2. For both excitation conditions a mechanism is proposed involving cleavage of the N, N-bond as the main primary photolytic process. 相似文献
In attempts to obtain kinetic and mechanistic data required for an assessment of atmospheric fate of alternative halocarbons containing a CF3 group, reactions of the key free radical intermediates CF3OO and CF3O with several atmospheric compounds (i.e., NO, NO2, alkanes and alkenes) have been studied at 297 ± 2 K in 700 torr of air. Experiments employed the long path-FTIR spectroscopic method for product analysis and the visible (400 nm) photolysis of CF3NO → CF3 + NO as a source for the precursor radical CF3. Numerous labile and stable F-containing molecular products have been characterized based on kinetic and spectroscopic data obtained at sufficiently short photolysis time (≤1 min) to minimize heterogeneous decay on the reactor walls. Major new findings have been made for the reactions involving CF3O radicals. The behavior of CF3O radicals has been shown to be markedly different from that of CH3O radicals, i.e., (1) O2-reaction: no evidence for the F-atom transfer reaction CF3O + O2 → CF2 O + FOO; (2) NO-reaction: addition reaction CH3O + NO (+M) → CH3ONO (+M), but F-transfer reaction CF3O + NO → CF2O + FNO; (3) NO2-reaction: addition reaction for both radicals, but F-transfer reaction CF3 + NO2 → CF2O + FNO2 to a minor extent; (4) alkane-reaction: much faster H-abstraction by CF3O, comparable to HO; (5) alkene-reaction: much faster addition reaction of CF3O, comparable to HO. These results are summarized in this paper. 相似文献
Four nitrated N‐confused free‐base tetraarylporphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry in nonaqueous media. The examined compounds are represented as NO2(Ar)4NcpH2, where NO2(Ar)4Ncp is the dianion of a tetraaryl N‐confused porphyrin with an inner carbon bound NO2 group and Ar is a p‐CH3OPh, p‐CH3Ph, Ph or p‐ClPh substituent on each meso‐position of the macrocycle. UV/Vis spectra and NMR spectroscopy data indicate that the same form of the porphyrin exists in CH2Cl2 and DMF which is unlike the case of non‐NO2 N‐confused porphyrins. The Soret band of NO2(Ar)4NcpH2 exhibits a 30–36 nm red‐shift in CH2Cl2 and DMF as compared to the spectrum of the non‐NO2 N‐confused porphyrins. The first two reductions and first oxidation of NO2(Ar)4NcpH2 are reversible in CH2Cl2 containing 0.1 M TBAP. The measured HOMO–LUMO gap averages 1.65 V in CH2Cl2 and 1.53 V in DMF, with both values being similar to those of the non‐NO2 substituted compounds. The nitro group on the inverted pyrrole is itself not reduced within the negative potential limit of CH2Cl2 or DMF, but its presence significantly affects both the UV/Vis spectra and redox potentials. 相似文献
Nitromethane is the only presently known organic solvent for highly reactive selenium trioxide (SeO3)4. The stability of the solutions is limited and the beginning of the reaction between both components depends significantly on concentration and temperature. The nitromethane solvate of cyclic triselenium heptoxide Se3O7 · CH3NO2 is the major solid product at the temperature 20–30°C and concentration range 3–20% SeO3. Crystal and molecular structure of this compound was determined by X-ray structure analysis and vibrational spectroscopy. The solvating molecule CH3NO2 is removable from Se3O7 · CH3NO2in vacuo. If reaction temperature does not exceed 10°C, selenium pentoxide (Se2O5)n is formed instead of Se3O7 · CH3NO2. Dinitrosyl triselenate (NO)2Se3O10, nitrosyl hydrogendiselenate NOHSe2O7, nitrosyl hydrogenselenate NOHSeO4, nitrosyl hydrogenselenatoselenite NOHSe2O6 and selenium dioxide (SeO2)n were further identified in the solid reaction products. The selenic and/or oligoselenic acids remains in the nitromethane solution. CO2 and N2O3 were found as gaseous products. 相似文献
Synthesis of Fluoro-λ5-monophosphazenes and Fluoro-1,3-diaza-2λ5,4λ5-diphosphetidines by Means of the Staudinger Reaction 35 Tetrafluoro- and 2 difluorodiaza-diphosphetidines as well as 4 difluoro- and 30 monofluoro-λ5-monophosphazenes were prepared by the Staudinger reaction between tervalent phosphorus fluorides, RnPF3?n (n = 1, 2; R = R2N, (CH2)5N, O(CH2)4N, RO, (CH2O)2, alkyl, aryl) and phenylazides, X? C6H4N3 (X = H, 4-CH3, 4-Cl, 4-Br, 4-NO2, 3-NO2). PF3 does not react with phenylazide The influence of substituents on the structure of the reaction products is discussed. Kinetic measurements allowed to determine the constants λPI of the substituents (CH2)5N, O(CH2)4N and R(C6H5)N (R = CH3, C2H5, n-C4H9). 相似文献
Thermal decomposition of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW, CL-20) and its oxa-analogs containing
four and three nitramine fragments, in the gas phase and in solution predominantly follows the first order kinetics, whereas
in the solid phase it proceeds with acceleration. Replacement of the two nitramine groups in the five-membered cycles of the
molecule CL-20 by oxa groups practically does not affect the rate of decomposition of oxanitroderivatives in the solid phase.
Substitution of the nitro group in one of oxa-nitroderivatives by R = H, NO, COCH3, CH2N(NO2)CH3 differently affects the rate of decomposition. For R = H the rate of decomposition increases; when R = COCH3, CH2N(NO2)CH3, it decreases; for R = NO, the rate of decomposition remains constant. For the studied compounds the activation parameters
of thermal decomposition are determined in the solution, the gas phase, and the solid phase. In general, the reactivity of
nitramines depends on the length of the weakest bond N-NO2, which is affected by the conformation of the nitro group. 相似文献
The reactions of the Mannich reagent Et3SiOCH2NMe2 ( 1 ) with a variety of anilines (mono-substituted RC6H4NH2, R=H, 4-CN, 4-NO2, 4-Ph, 4-Me, 4-MeO, 4-Me2N; di-substituted R2C6H3NH2, R2=3,5-(CH3)2, 3,5-(CF3)2; tri-substituted R3C6H2NH2, R3=3,5-Me2-4-Br and a “super bulky” aniline (Ar*NH2) [Ar*=2,6-bis(diphenylmethyl)-4-tert-butylphenyl]) led to the formation of a range of products dependent upon the substituent. With electron-withdrawing substituents, previously unknown diamines, RC6H4NH(CH2NMe2) [R=CN ( 2 a ), NO2 ( 2 b )] and R2C6H3NH(CH2NMe2) [R2=3,5-(CF3)2 ( 2 c) ] were formed. Further reaction of 2 a , b , c with 1 yielded the corresponding triamines RC6H4N(CH2NMe2)2 (R=CN ( 3 a ), NO2 ( 3 b ) and R2C6H3N(CH2NMe2)2, R2=3,5-(CF3)2 ( 3 c ). The new polyamines were characterized by NMR spectroscopy, and for 2 a , 2 c , and 3 c , by single crystal XRD. In the case of electron-donating groups, R=4-OMe, 4-NMe2, 4-Me, 3,5-Me2, 3,5-Me2-4-Br, and for R=4-Ph, the reactions with 1 immediately led to the formation of the related 1,3,5-triazines, R=4-MeO ( 5 a ), 4-Me2N ( 5 b ), 4-Me ( 5 c ), 3,5-Me2 ( 5 d ), 3,5-Me2-4-Br ( 5 e ), 4-Ph ( 5 f ), 4-Cl ( 5 g ). The “super bulky” aniline rapidly produced a single product, namely the corresponding imine Ar*N=CH2 ( 4 ) which was also characterized by single crystal XRD. Imine 4 is both thermally and oxidatively stable. All reactions are very fast, thus based upon the presence of Si we are tempted to denote the reactions of 1 as examples of “Silick” chemistry. 相似文献
Picosecond multiphoton ionization of (NO)mArn clusters produced in a supersonic expansion of NO/Ar gas mixtures has been studied using time-of-flight mass spectrometry. Two-photon ionization with 266 nm photons show that dilute gas mixtures (1% NO/Ar) yield clusters limited to m≤7, but with as many as 37 argon atoms. Magic numbers are observed for NO+Ar12, NO+Ar18, (NO)2+Ar17, NO+Ar22, and (NO)2+Ar21 and are understood in terms of solvation of the NO+ and (NO)2+ by argon in icosahedral arrangements. Four-photon ionization with 532 nm light produces dissociation of the clusters to yield only NO+Arn with n up to 54. This distribution exhibits an additional magic number at n=54, consistent with the completion of a second solvation sphere about the NO+. The known wavelength dependence for photodissociation of (NO)2+ and (NO)3+ and comparison of MPI spectra obtained with 266, 355, and 532 nm light indicate that the dissociation is occurring in the cluster ions. 相似文献
Solvent-free Synthesis of Tetramethylammonium Salts: Synthesis and Characterization of [N(CH3)4]2[C2O4], [N(CH3)4][CO3CH3], [N(CH3)4][NO2], [N(CH3)4][CO2H], and [N(CH3)4][O2C(CH2)2CO2CH3] A general procedure to synthesize tetramethylammonium salts is presented. Several tetramethylammonium salts were prepared in a crystalline state by solvent-free reaction of trimethylamine and different methyl compounds at mild conditions: [N(CH3)4]2[C2O4] (cubic; a = 1 114.8(3) pm), [N(CH3)4][CO3CH3] (P21/n; a = 813.64(3), b = 953.36(3), c = 1 131.3(4) pm, β = 90.03(1)°), [N(CH3)4][NO2] (Pmmn; a = 821.2(4), b = 746.5(3), c = 551.5(2) pm), [N(CH3)4][CO2H] (Pmmn; a = 792.8(7), b = 791.7(3), c = 563.3(4) pm) and [N(CH3)4][O2C(CH2)2CO2CH3] (P21; a = 731.1(2), b = 826.4(3), c = 1 025.2(3) pm, β = 110.1(1)°). The tetramethylammonium salts were characterized by IR-spectroscopy and X-ray diffraction. The crystal structures of the methylcarbonate and the nitrite are described. 相似文献
The kinetics of the acetaldehyde pyrolysis have been studied at temperatures from 450° to 525°C, at an acetaldehyde pressure of 176 torr and at 0 to 40 torr of added nitric oxide. The following products were identified and their rates of formation measured: CH4, H2, CO, CO2, C2H4, C2H6, H2O, C3H6, C2H5CHO, CH3COCH3, CH3COOCH?CH2, N2, N2O, HCN, CH3NCO, and C2H5NCO. Acetaldehyde vapor was found to react with nitric oxide slowly in the dark at room temperature, the products being H2O, CH3COOCH3, CO, CO2, N2, NO2, HCN, CH3NO2, and CH3ONO2. The rates of formation of N2 and C2H5NCO depend on how long the CH3CHO-NO mixture is kept at room temperature before pyrolysis; the rates of formation of the other products depend only slightly on the mixing period. The pyrolysis of “clean” CH3CHO–NO mixtures (i.e., the results extrapolated to zero mixing time, which are independent of products formed in the cold reaction) are interpreted as follows: (1) There are two chain carriers, CH3 and CH2CHO, their concentrations being interdependent and influenced by NO in different ways: the CH3 radical is both generated and removed by reactions directly involving NO, whereas CH2CHO is generated only indirectly from CH3 but is also removed by direct reaction with NO. (2) An important mode of initiation by NO is its addition to the carbonyl group with the formation of which is converted into ; this splits off OH with the formation of CH3NCO or CH3 + OCN. (3) Important modes of termination are The steady-state equations derived from the mechanism are shown to give a good fit to the experimental rate versus [NO] curves and, in particular, explain why there is enhancement of rate by NO at higher CH3CHO pressures and, at lower CH3CHO pressures, inhibition at low [NO] followed by enhancement at higher [NO]. The cold reaction is explained in terms of chain-propagating and chain-branching steps resulting from the addition of several NO molecules to CH3CHO and the CH3CO radical. In the “unclean” reaction it is found that the rates of N2 and C2N5NCO formation are increased by CH3NO2, CH3ONO, and CH3ONO2 formed during the cold reaction. A mechanism is proposed, involving the participation of α-nitrosoethyl nitrite, CH3CH(NO)ONO. It is suggested that there are two modes of behavior in pyrolyses in the presence of NO: (1) In the paraffins, ethers, and ketones, the effects are attributed to the addition of NO to a radical with the formation of an oxime-like compound. (2) In the aldehydes and alkenes, where there is a hydrogen atom attached to a double-bonded carbon atom, the behavior is explained in terms of addition of NO to the double bond followed by the formation of an oxime-like species. 相似文献
The thermal decomposition of nitropropane (CH3CH2CH2NO2) has been investigated at the CBS-QB3 level of theory. The pyrolysis of CH3CH2CH2NO2 mainly includes the simple bond ruptures mechanism, hydrogen abstraction processes, isomerization and secondary reactions. As a result, for the simple bond ruptures mechanism, the formation of \({\text{CH}}_{3} {\text{CH}}_{2} {\text{CH}}_{2}^{\cdot} +\,^{\cdot}{\text{NO}}_{2}\) products is dominant with the energy barrier of 49.77 kcal mol?1. The process of H atom on the β–CH2 abstracted by one O atom of NO2 moiety in CH3CH2CH2NO2(CH3CH2CH2NO2 → CH3CH=CH2 + HONO) needs to overcome lower energy barrier than that of the rate-determining step (one of H atom on the α-CH2 and γ-CH3 abstracted of reaction) of the other hydrogen abstraction reactions. Therefore, we predict that the corresponding alkenes and HONO are the main products in the hydrogen abstraction reaction of nitroparaffin. Besides, the channel of the CH3CH2CHO + HNO formations (CH3CH2C(α)H2NO2 → CH3CH2C(α)H2ONO → CH3CH2CHO + HNO), occurring through the H atom of C(α) abstracted by the N atom of NO2 moiety after the isomerization reaction from CH3CH2CH2NO2 to CH3CH2CH2ONO, is favorable in the isomerization secondary reactions. Rate constants and branching ratios are estimated by means of the conventional transition state theory with zero curvature tunneling over the temperature range of 400–1500 K. The calculation shows that the overall rate constant in the temperature of 400–1500 K is mainly dependent on the competitive channels of formations of CH3CH=CH2 + HONO and \({\text{CH}}_{3} {\text{CH}}_{2} {\text{CH}}_{2}^{\cdot} +\,^{\cdot}{\text{NO}}_{2}\) The three-parameter expression for the total rate constant is fitted to be ktotal = 1.74 × 10?13T8.20exp(17038.7/T) (s?1) between 400 and 1500 K. 相似文献