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Difunctionalization of alkenes allows the rapid construction of complex molecules with high selectivity and efficiency in organic synthesis. Herein, we first describe a 1,2‐hydroxycarbonylation of alkenes for the preparation of hydroxyl‐functionalized chroman‐4‐ones through the cooperative action of inorganic oxidants and organic acids. The transformation is initiated by the formation of an acyl radical, and then experiences intramolecular 6‐exo‐trig radical cyclization and hydroxylation process. It is notable that the hydroxyl group in the final products originate from organic acids without the use of any transition‐metal catalysts. To further demonstrate the practicality and mechanism of this method, the gram‐scale reaction and a series of control experiments including gas chromatography‐mass spectrometry (GC‐MS) and infrared (IR) absorption spectroscopy experiments were performed, and the corresponding intermediates were successfully captured. [ABSTRACT FROM AUTHOR]

The synergistic systems of photoredox and copper catalyst have already appeared as a novel formation of green synthetic chemistry, which open new avenues for chemical synthesis applications. We describe a novel strategy for the cyclization of alkyne‐tethered α‐bromocarbonyls initiated by the cleavage of C(sp3)−Br bond via the collaboration of photoredox and copper catalyst. The present protocol exhibits mildness using economical copper catalyst and visible‐light at room temperature. The gram‐scale and sunlight irradiation experiments proceeded smoothly to show the practicality of the methodology. It is notable that the newly generated oxygen in the product originates from H2O. [ABSTRACT FROM AUTHOR]

A novel 5-exo-dig/6-endo-trig bicyclization of 1,6-enynes with sulfonyl hydrazides in the aqueous phase using the cheap and available tetrabutylammonium iodide (TBAI)–tert-butyl hydroperoxide (TBHP) combined system is reported. The resulting reaction of diverse nitrogen- and oxygen-polyheterocycles displays high chemical selectivity, high step-economy, and a moderate substrate scope. Moreover, iodosulfonylation can be realized by modulating the structure of the 1,6-enynes. [ABSTRACT FROM AUTHOR]

We describe a photocatalytic decarboxylative cyclization of 1,6-enynes or N -methacryloyl-2-phenylbenzimidazoles for efficient and ecofriendly syntheses of lactams or benzimidazo[2,1- a ]isoquinoline-6(5 H)-ones, respectively, by the use of KI/PPh3 as a redox catalyst system. In this method, N -hydroxyphthalimide esters were used as alkyl-radical precursors to achieve this decarboxylative cyclization without any dyes, transition-metal catalysts, oxidants, or bases. [ABSTRACT FROM AUTHOR]

A method for radical cyclization of N -methacryloyl-2-arylbenzoimidazoles with nitriles, ketones, and tert -butyl nitrite (TBN) for the preparation of benzimidazo[2,1- a ]isoquinolin-6(5 H)-ones with the advantage of mild reaction conditions, excellent functional group compatibility, and broad substrate scope is reported. The present strategy has favorable characteristics: (1) the use of cheap metal catalysis; (2) N -radical-initiated cyclization of N -methacryloyl-2-arylbenzoimidazoles; and (3) rare example of radical C(sp3)–H functionalization in this cyclization. [ABSTRACT FROM AUTHOR]

To investigate the characteristics, source apportionment, and potential source areas of carbonaceous aerosols in Chongqing during winter, PM 2.5 samples were collected from January 2021 to February 2021 in the urban areas of Wanzhou (WZ), Yubei (YB), and Shuangqiao (SQ). The results showed that the average mass concentrations of PM 2.5 , OC, and EC in SQ were (72.6 ±33.3), (18.2 ±8.2), and (4.4 ±1.7) μg·m -3 , respectively, higher than those in WZ[(67.2 ±30.3), (17.2 ±7.4), and (5.1 ±2.4) μg·m -3 ] and YB[(63.4 ±25.7), (15.4 ±6.3), and (4.2 ±1.9) μg·m -3 ]. Compared with that during the clear period, the concentration and fraction of EC in total carbon increased by 103.0% and 8.1%, respectively, in WZ compared to that in other areas during pollution period, whereas the OC/EC ratio was decreased significantly (-10.5%), indicating that the primary emission of carbonaceous aerosols increased significantly during the pollution period. The average mass concentrations of secondary organic carbon (SOC) in SQ and YB were (7.7 ±4.8) μg·m -3 and (6.9 ±2.8) μg·m -3 significantly higher, respectively, than that in WZ[(4.5 ±1.9) μg·m -3 ] during the campaign. This indicated that the secondary transformation had a greater influence on the carbonaceous aerosols in SQ and YB than that in WZ. Furthermore, in contrast to that in WZ, the ratios of SOC/OC were increased with the increase in PM 2.5 concentrations, and significant correlations between SOC concentration and aerosol water content, NO 2 concentration, and the value of NOR were observed in SQ and YB ( P < 0.01), indicating that the increasing of carbonaceous aerosol concentrations might be mainly driven by the SOC with -NO 2 groups produced by aqueous chemical reactions during winter in SQ and YB. The positive definite matrix factor (PMF) results in these urban areas showed that the contribution of biomass/coal combustion source in WZ (47.4%) was significantly higher than that in YB (34.2%) and SQ (38.1%), whereas the gasoline motor vehicle emission and secondary transformation impacts were more significant in YB. The results of the concentration weighted trajectory (CWT) showed that the potential sources of carbonaceous aerosols were mainly the local and northeastern parts of these urban areas (such as Changshou).

Chemodivergent tandem radical cyclization offers exciting possibilities for the synthesis of structurally diverse cyclic compounds. Herein, we revealed a chemodivergent tandem cyclization of alkene-substituted quinazolinones under metal- and base-free conditions, this transformation is initiated by alkyl radicals produced from oxidant-induced α-C(sp 3 )-H functionalization of alkyl nitriles or esters. The reaction resulted in the selective synthesis of a series of mono- and di-alkylated ring-fused quinazolinones by modulating the loading of oxidant, reaction temperature, and reaction time. Mechanistic investigations show that the mono-alkylated ring-fused quinazolinones is constructed by the key process of 1,2-hydrogen shift, whereas the di-alkylated ring-fused quinazolinones is mainly achieved through crucial steps of resonance and proton transfer. This protocol is the first example of remote second alkylation on the aromatic ring via α-C(sp 3 )-H functionalization and difunctionalization achieved by association of two unsaturated bonds in radical cyclization., (© 2023 Wiley-VCH Verlag GmbH.)

In order to further improve the accuracy of fine particulate matter (PM 2.5 ) source apportionment results, a hybrid source apportionment approach (CTM-RM) combining the capabilities of a receptor model (RM) and chemical transport model (CTM) was developed. The CTM-RM method was evaluated and applied according to a typical PM 2.5 pollution process from January 21 to 27, 2019 in Chongqing. The average value of square prediction error based on CTM-RM was 84.58% lower than that of CAMx/PSAT during the campaign. Compared with that of CAMx/PSAT, the fractional error of PM 2.5 and its chemical component concentrations decreased by 15.69%-92.86%. Furthermore, the temporal and spatial variations in PM 2.5 source impacts could be obtained using the CTM-RM method in Chongqing. The average adjustment factor ( R ) values were 1.39±0.38 (agriculture sources), 1.54±0.48 (industrial sources), 1.01±0.13 (power sources), 1.02±0.58 (residential sources), 0.86±0.59 (transportation sources), and 0.58±0.67 (other sources) in the main urban areas of Chongqing. Additionally, the cumulative distribution functions of R were found to be distinct among the six sources. The residential and industrial sources were the main sources of PM 2.5 , with contributions of 46.23% and 28.23%, respectively. In contrast to that of the other sources, the transportation source impacts of PM 2.5 (8.62%) increased significantly from the clear period to pollution period ( P <0.001), indicating that the increase in PM 2.5 concentrations was mainly driven by vehicular emissions during the pollution period in the main urban areas of Chongqing. The fitting functions between the initial simulated concentrations and R values of each source in the main urban areas of Chongqing could be used to evaluate PM 2.5 concentrations at 47 air quality monitoring stations in Chongqing, and the correlation between the refined simulated concentrations and measured concentration of PM 2.5 was significant ( r =0.82, P <0.001). Compared with that during the clear period, the increases in the percentages of industrial source impacts of PM 2.5 in Northeast Chongqing and residential source impacts of PM 2.5 in Southeast Chongqing were 17.20% and 9.15% higher, respectively, than that in other areas during the pollution period. By contrast, the increasing percentage of transportation source impacts of PM 2.5 in the main urban areas of Chongqing (66.39%) and Western Chongqing (84.16%) from the clear period to the pollution period were higher than that in other areas. The results of CTM-RM on January 26 indicated that the residential source impacts in Northeast Chongqing (64.56%) were higher than those in other areas, and the industry source impacts of PM 2.5 were primarily observed in the main urban areas of Chongqing and Western Chongqing, with contributions of 25.26% and 21.20%, respectively.

Based on the basic information of the Second National Pollution Source Census and the VOCs source profiles of industrial industries, we established the speciated emission inventory of major industrial sources in Chongqing in 2017, estimated their ozone formation potential (OFP), and identified the key control species of industrial VOCs and their sources. The results showed that the total VOCs emission from industrial sources and their OFPs were 144.12 kt and 477.34 kt, respectively. Automobile manufacturing, equipment manufacturing, plastic manufacturing, and chemical raw materials and chemical products were all industries that contributed significantly to VOCs emissions and OFP, with VOCs emissions of 37.18, 33.09, 19.47, and 18.14 kt and OFP of 191.43, 153.69, 27.21, and 57.51 kt, respectively. Aromatics were the components with the largest contribution to VOCs emissions and OFP, accounting for 62.55% of the total VOCs emissions and 82.15% of the total OFP, mainly from metal surface coating and petrochemical industries. The major reactive species of industrial source VOCs were m/p -xylene, toluene, ethylbenzene, o -xylene, and propylene, with OFP of 130.47, 103.37, 46.37, 42.83, and 28.26 kt, respectively, cumulatively accounting for 71.11% of the total OFP. In terms of spatial distribution, the emission intensity of VOCs and O 3 pollution degree in all districts and counties of Chongqing were relatively consistent; the high value points of VOCs emissions and OFP were mainly distributed in the main urban area and the western area, and the sources of VOCs emission in the main urban area and western area were mainly in metal surface coating and the petrochemical industry, respectively.