71805-64-6Relevant academic research and scientific papers
Comparative study of the pyrolysis, photoinduced electron transfer (PET), and laser-jet and 185-nm photochemistry of alkyl-substituted bicyclic azoalkanes
Adam, Waldmar,Denninger, Uwe,Finzel, Ralf,Kita, Fumio,Platsch, Herbert,Walter, Herbert,Zang, Gerald
, p. 5027 - 5035 (2007/10/02)
The gas-phase pyrolysis, photoinduccd electron transfer (PET), and laser-jet 185-nm photochemistry of 2,3-diazabicyclo[2.2.1]hept-2-ene (1a), syn-7-methyl-2,3-diazabicyclo[2.2.1]hept-2-ene (syn-1b), anti-7-methyl-2,3-diazabicyclo[2.2.1]hept-2-ene (anti-1b), 1,4-dimethyl-2,3-diazabicyclo[2.2.1]hept-2-ene (1c), 7,7-dimethyl-2,3-diazabicyclo[2.2.1]hept-2-ene (1d), syn-7-(1-methylethyl)-2,3-diazabicyclo[2.2.2]hept-2-ene (syn-1e) were investigated and the results of their product studies compared with one another. Pyrolysis and conventional direct and benzophenone-sensitized 350-nm photolysis of the azoalkanes 1 yielded the bicyclo[2.1.0]pentanes 2 and negligible amounts of cyclopentenes 3. PET and benzophenone-sensitized laser-jet and 185-nm photolysis of the azoalkanes 1 led to significant quantities of cyclopentene derivatives 3, a bekavior that is attributed to radical cation-type 1,3-cyclopentadiyl intermediates, which subsequently suffer hydrogen or alkyl migration. The polar character of the radial cation D?+ is clearly demonstrated by the Wagner-Meerwein rearrangement into 2,3-dimethylcyclopentene (3′d) in the PET and 185-nm photolysis of azoalkane 1d. When the corresponding 1,3-cyclopentadiyl D?? was generated in the pyrolysis of 5,5-dimethylbicyclo[2.1.0]pentane (2d), the 3,3-dimethyl-1,4-pentadiene (4d) was obtained as the exclusive reaction product; instead of methyl migration, fragmentation into the 1,4-diene took place. The PET chemistry of the stereochemically labeled azoalkanes syn- and anti-1b revealed that the radical cations D?+ have a puckered geometry, because a stereochemical memory effect was observed for the cyclopentene products 3. Specifically, the pseudoaxial substituent at the stereolabled center migrates with preference, which speaks for a coplanar arrangement for the rearrangement in D?+. The common and distinct mechanistic features of the denitrogenation process of the various thermal and photochemical activation modes will be discussed.
UV LASER PHOTOCHEMISTRY: EVIDENCE FOR "THROUGH-BOND COUPLING" EFFECTS IN THE LIFETIMES OF 2,2-DIMETHYL-1,3-CYCLOPENTADIYL TRIPLET DIRADICALS.
Adam, Waldemar,Guenther, Erhard,Haessel, Peter,Platsch, Herbert,Wilson, R. Marshall
, p. 4407 - 4410 (2007/10/02)
The 2,2-dimethyl substituted 1,3-diradicals 5a-c posses significantly shorter triplet lifetimes (τT) than the parent 1,3-cyclopentadiyl 3, which is being rationalized on the basis of changes in the "through-bond" coupling and thus singlet-triplet energy splitting between the radical sites.
Thermal and Photochemical Reactions of Bicyclic Azoalkanes in Concentrated Sulfuric Acid
Adam, Waldemar,Miranda, Miguel A.
, p. 5498 - 5500 (2007/10/02)
Thermolysis of bicyclic azo compounds 1a-d in concentrated sulfuric acid affords ethylene (trapped as ethyl sulfate) and pyrazoles 3 in marked contrast to thermolysis of the nonprotonated azoalkanes, for which only loss of nitrogen (N2) is observed.
