Kinetics of Radical Reactions between Methyl, Acetyl and Dimethylamino Radicals Formed in the Flash Photolysis of N,N-Dimethylacetamide in the Gas Phase.

Seetula, Jorma A.; Blomqvist, K.; Kalliorinne, Kaarlo; Koskikallio, Jouko; Urso, Fabio; Suzuki, Iwao; Tokii, Tadashi; Zingaro, Ralph A.

doi:10.3891/acta.chem.scand.40a-0658

Cited by 12 publications

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“…In general, our rate constant values are lower by an order of magnitude, except the disproportionation rate which is equal with a previous value. 10 The total reaction rate is in good agreement with a previous value obtained by thermolysis or photolysis of tetramethyl-2-tetrazene in solution.91" Finally, the obtained k¿/ kr value is higher than 1, which is in agreement with previous values of =1.2 in the gas phase83 and 1.44 in the liquid phase96 but in disagreement with an extrapolated value of 0.6 in the gas phase.11…”

Section: Discussionsupporting

confidence: 86%

Absolute rates of recombination and disproportionation of dimethylaminyl radicals

Lazarou¹,

Papagiannakopoulos²

1993

J. Phys. Chem.

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Section: Discussionsupporting

confidence: 86%

Absolute rates of recombination and disproportionation of dimethylaminyl radicals

Lazarou¹,

Papagiannakopoulos²

1993

J. Phys. Chem.

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“…Table I summarizes the results of prior studies of primary photochemical pathways in amides. [1][2][3][4][5][6][7][8] While these early studies provide an invaluable starting point for further investigations, most of the experiments were conducted using solution-phase reactants, making the analysis of primary processes challenging. Also, the illumination source in most of these experiments was a mercury-arc lamp, accessing the n* transition centered around 225-235 nm.…”

Section: Introductionmentioning

confidence: 99%

Electronic accessibility of dissociation channels in an amide: N,N-dimethylformamide photodissociation at 193 nm

Forde

Butler

Abrash

1999

The Journal of Chemical Physics

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Measurement of the photofragment velocity and angular distributions from the photodissociation of N,N-dimethylformamide at 193 nm in its nb * absorption evidences three competing dissociation channels: HCON͑CH 3 ͒ 2 →HCO(X 2 AЈ)ϩN͑CH 3 ͒ 2 (X 2 B 1); HCO(X 2 AЈ)ϩN͑CH 3 ͒ 2 (Ã 2 A 1); and HCONCH 3 ϩCH 3. ͑H atom eliminations are not probed.͒ These products are formed in a ratio of 0.15Ϯ0.04:0.49Ϯ0.09:0.36Ϯ0.07, determined by use of trimethylamine as a calibrant molecule. Nitrogen-carbonyl bond fission occurs on a rapid time scale with an angular distribution of the dissociation products given by ␤ϭ1.2Ϯ0.2. Excited state N͑CH 3 ͒ 2 products are formed quasidiabatically from the initial planar geometry, whereas symmetry-breaking vibrations allow one-electron matrix elements to couple the initial electronic configuration to the ground state N͑CH 3 ͒ 2 ϩHCO channel. Competition of nitrogen-methyl bond fission is evidence of the strong coupling between the nb * excitation and the nitrogen-methyl reaction coordinate; ab initio calculations confirm that the electronic excitation is not localized on the N-CϭO moiety. We also include here an advance report of the excited state energy of the N͑CH 3 ͒ 2 (Ã 2 A 1) radical, which is found to be 1.59 eV.

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“…Primary photoreaction of acetoin quantitatively undergoes Norrish type I homolytic˛-cleavage from its n * excited triplet state, giving an acetyl radical and an˛-hydroxyethyl radical. 25 The acetyl radical may secondarily decompose into a methyl radical and CO. 13 Probably, the radical CH 3 C(O)C( ž )…”

Section: Methodsmentioning

confidence: 99%

“…4 It seemed that the spectrum shown in Fig. 10 12,13 Sequentially, the acetyl radical decomposes into a methyl radical and carbon monoxide (CO) and the dimethylcarbamoyl radical into a dimethylamino radical and CO. 13 As the N-methyl hydrogen is more easily abstracted, 17d the radical ž CH 2 N(CH 3 C(O)CH 3 15b,16a,17d,e can be generated by hydrogen-atom abstraction from an N-methyl of DMA. It is well established that NO reacts favorably with the methyl radical to produce nitrosomethane, which proves to be a reactive spin trap in solution.…”

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confidence: 99%

EPR study of nitroxides formed from the reaction of nitric oxide with photolyzed amides

Wang

Jin

2003

Magnetic Reson in Chemistry

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Free radicals generated from UV irradiation of simple aliphatic amides in anaerobic and nitric oxide (NO)-saturated liquid mixtures or solutions gave EPR spectra of nitroxides. The application of isotopic effects to EPR spectra and the generation of radicals by transient radical attack on substrate molecules or by photolysing amine or acetoin were used to help identify photochemically produced radicals from the amides. The aliphatic amides used were formamide, acetamide and their N-methyl-or deuteriumsubstituted derivatives. Transient radicals used to attack the amides via hydrogen-atom abstraction were generated from the initiator AIBN or AAPH. The observation of various nitroxides indicates the reactivity of NO for trapping acyl, carbamoyl and other carbon-centered radicals. Possibly mechanistic pathways diagnosed with this trap are proposed.

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Kinetics of Radical Reactions between Methyl, Acetyl and Dimethylamino Radicals Formed in the Flash Photolysis of N,N-Dimethylacetamide in the Gas Phase.

Cited by 12 publications

References 0 publications

Absolute rates of recombination and disproportionation of dimethylaminyl radicals

Absolute rates of recombination and disproportionation of dimethylaminyl radicals

Electronic accessibility of dissociation channels in an amide: N,N-dimethylformamide photodissociation at 193 nm

EPR study of nitroxides formed from the reaction of nitric oxide with photolyzed amides

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