Photolysis of Heptanal

Abstract

Photolysis of heptanal is investigated from an experimental and theoretical point of view. Photoexcited heptanal is believed to undergo rapid intersystem crossing to the triplet manifold and from there undergoes internal H-abstraction to form biradical intermediates. The favored gamma-H abstraction pathway can cyclize or cleave to 1-pentene and hydroxyethene, which tautomerizes to acetaldehyde. Yields of 1-pentene and acetaldehyde were measured at 62 +/- 7% and 63 +/- 7%, respectively, relative to photolyzed heptanal. Additionally, small quantities of hexanal and hexanol were observed. On the basis of combined experimental and theoretical evidence, the remaining heptanal photolysis proceeds to form an estimated 10% HCO + hexyl radical and 30% cyclic alcohols, particularly 2-propyl cyclobutanol and 2-ethyl cyclopentanol.

Aging of secondary organic aerosol from α-pinene ozonolysis: Roles of hydroxyl and nitrate radicals

“…In the actinic region of UV lights (peak intensity at 350 nm), certain oxygenated organics, such as carbonyls, peroxides, and nitrates, undergo photolysis at this wavelength of light spectrum. Complex photochemical transformations are possible during the photolytic processes (Paulson et al, 2006), which may lead to the addition of functional groups. Finally, OH originating from the photolysis of nitrous acid (HONO) released from the Teflon film may contribute to the increase in volume.…”

Competition Between Cyclization and Unusual Norrish Type I and Type II Nitro-Acyl Migration Pathways in the Photouncaging of 1-Acyl-7-nitroindoline Revealed by Computations

“…The migration of the acyl unit is facilitated by the inherent formation of the stabilized acyl radical, typically formed within classical Norrish 52 type I alpha cleavages of excited carbonyl of ketones (Figure 3, part a). [53][54][55][56] The (Figure 3, part b). 52,56 In order to better understand this migration pathway, we computed the energy for an ethyl group migration (in place of the acetyl) and noted that it was higher in energy (21.3 kcal/mol, Figure 3 part c), Ulg, respectively.…”

“…[53][54][55][56] The (Figure 3, part b). 52,56 In order to better understand this migration pathway, we computed the energy for an ethyl group migration (in place of the acetyl) and noted that it was higher in energy (21.3 kcal/mol, Figure 3 part c), Ulg, respectively. However, according to their reported data (see Table 1 Furthermore, the hydrolysis product (15) and the uncaging product (8) are different in that the former retains the nitro group while the photo uncaging leads to the nitroso.…”

Unusual Norrish Type I and Type II Nitro-Acyl Migration Transition State in the Photo-Uncaging of 1-Acyl-7-Nitroindolines Revealed by Computations

“…54 (Figure 3, part b). 53,57 In order to better understand this migration pathway, we computed the energy for an ethyl group migration (in place of the acetyl) and noted that it was higher in energy (21.7 kcal/mol, Figure 3 part c), despite being positioned in a 1,6-relationship to the nitro oxygen radical. This clearly reflects the stabilizing effect of an acyl radical in the transition state of the 1,6-migration.…”