A nitrosamine photooxidation reaction is shown to generate a peroxy intermediate by experimental physical-organic methods. The irradiation of phenyl and methyl-substituted nitrosamines in the presence of isotopically labeled 18-oxygen revealed that an O atom was trapped from a peroxy intermediate to trimethylphosphite or triphenylphosphine, or by nitrosamine itself, forming two moles of nitramine. The unstable peroxy intermediate can be trapped at low temperature in postphotolyzed solution in the dark. Chemiluminescence was also observed upon thermal decomposition of the peroxy intermediate, that is, when a postphotolysis low-temperature solution is brought up to room temperature. A DFT study provides tentative information for cyclic nitrogen peroxide species on the reaction surface.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/acs.jpca.7b02414 | DOI Listing |
Bioresour Technol
January 2025
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China; Key Laboratory of Guangxi Biorefinery, Guangxi University, Nanning 530004, China. Electronic address:
Limonene dioxide (LDO) is essential for manufacturing bio-based polycarbonate and non-isocyanate polyurethanes. Herein, we report a strategy for the chemoenzymatic epoxidation of (R)-(+)-limonene to LDO with high selectivity using Rhizopus oryzae whole cells. The presence of sufficient excess acid in the system is essential, in addition to overcoming the hydrolysis of the intermediate product, 1,2-limonene oxide, to accomplish the double epoxidation of limonene.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
Department of Chemistry, KU Leuven, Celestijnenlaan, 200F, Leuven 3001, Belgium.
In this study, we revisited the mechanism of isoprene oxidation by OH radicals, focusing on the formation of hydroperoxyaldehydes (HPALDs) in the reactions following O-addition at the α-position to ,'-OH-allyl radical products of the 1,6-H shift of the 1st-generation -δ-OH-isoprenylperoxy radicals. Utilizing high-level quantum chemical calculations and a master equation approach, we provide theoretical confirmation that the formation of δ-HPALDs dominates by far and show that production of β-HPALDs by the mechanism proposed by Wennberg (, 2018, , 3337-3390) is negligible. Besides the dominance of the δ-HPALD formation channel, our investigation also reveals a novel though minor reaction channel resulting in the formation of an allylic δ-hydroperoxy acid and OH radical.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
In pursuit of advancing the electrooxidation of amines, which is typically encumbered by the inertness of C(sp)-H/N(sp)-H bonds, our study introduces a high-performance electrocatalyst that significantly enhances the production efficiency of vital chemicals and fuels. We propose a novel electrocatalytic strategy employing a uniquely designed (NiCo)Se-R electrocatalyst, which is activated through Se-O exchange and electron orbital spin manipulation. This catalyst efficiently generates M species, thus enabling the activation of lattice oxygen and streamlining the electrooxidation of amines.
View Article and Find Full Text PDFEnviron Sci Technol Lett
September 2024
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Organic alkoxy (RO) and peroxy (RO) radicals are key intermediates in multiphase atmospheric oxidation chemistry, though most of the study of their chemistry has focused on the gas phase. To better understand how radical chemistry may vary across different phases, we examine the chemistry of a model system, the 1-pentoxy radical, in three phases: the aqueous phase, the condensed organic phase, and the gas phase. In each phase, we generate the 1-pentoxy radical from the photolysis of -pentyl nitrite, run the chemistry under conditions in which RO radicals react with NO, and detect the products in real time using an ammonium chemical ionization mass spectrometer (NH CIMS).
View Article and Find Full Text PDFSci Adv
September 2024
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Secondary organic aerosol (SOA), atmospheric particulate matter formed from low-volatility products of volatile organic compound (VOC) oxidation, affects both air quality and climate. Current 3D models, however, cannot reproduce the observed variability in atmospheric organic aerosol. Because many SOA model descriptions are derived from environmental chamber experiments, our ability to represent atmospheric conditions in chambers directly affects our ability to assess the air quality and climate impacts of SOA.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!