Carbonyl Compounds Research Articles

Ein‐Topf‐Synthese von 1,3‐Cyclohexadienen durch Birch‐Reduktion in Gegenwart von Carbonylverbindungen

Ein‐Topf‐Synthese von 1,3‐Cyclohexadienen durch Birch‐Reduktion in Gegenwart von Carbonylverbindungen

Construction of Acyclic Quaternary Carbon Stereocenters via Enantioselective Nickel Catalysis†

Comprehensive SummaryThe construction of acyclic quaternary carbon stereocenters, which are ubiquitous in many bioactive compounds, pharmaceuticals and natural products, has been a long persuit in synthetic organic chemistry. Among numerous methods, enantioselective nickel‐catalysis has attracted incremental attention in recent years. This review summarizes the recent development in the asymmetric strategies, research progress, mechanistic investigations for the generation of acyclic quaternary carbon stereocenters via enantioselective nickel catalysis. Key ScientistsIn 2006, the Zhou group and RajanBabu group realized the nickel‐catalyzed enantioselective hydrovinylation of α‐substituted styrenes and ethylene to construct acyclic quaternary carbon stereocenters (QCSs) by using spiro‐ and binaphthyl phosphoramidite ligands, respectively. In 2016, Watson developed a nickel‐catalyzed Suzuki‐Miyaura arylation to generate acyclic QCSs via chirality transfer reaction. In 2017, the Feng and the Fu group developed nickel‐catalyzed enantioselective conjugated/Michael additions to build acyclic QCSs, respectively. In 2020, the Fang group made the first success in the construction of QCSs by nickel‐catalyzed hydrocyanation of alkenes and allenes. In 2021, Gregory C. Fu and co‐workers disclosed a nickel‐catalyzed enantioselective α‐functionalization of carbonyl compounds that could form acyclic QCSs. At the same time, the Shi group constructed chiral acyclic QCSs via nickel‐catalyzed functionalization of alkenes. In 2023, Kleij and co‐workers applied a new strategy for Ni‐catalyzed regio‐ and enantioselective homoallylic coupling to construct acyclic QCSs. In the same year, Tao and co‐workers demonstrated a novel strategy that is dinickel‐catalyzed enantioselective α‐alkylation of carbonyl compounds with alkyl iodides.

Synthesis of Multisubstituted 2,3-Allenamides via Palladium-Catalyzed Carbonylation of Propargylic Esters.

2,3-Allenamides are an important class of unsaturated group-substituted carbonyl compounds. A palladium-catalyzed aminocarbonylation of propargyl acetates with amines for the synthesized tri-/tetrasubstituted 2,3-allenamides has been developed. A broad range of tri-/tetrasubstituted 2,3-allenamides have been prepared from propargyl acetates in good to excellent yields. The reaction featured mild reaction conditions and good functional group tolerance. The applicability of this methodology was further highlighted by the late-stage modification of several natural products and pharmaceuticals.

Atomically dispersed Zn-NxCy sites on N-doped carbon for catalytic transfer hydrogenation of ethyl levulinate into γ-valerolactone

Catalytic transfer hydrogenation (CTH) of biomass-derived carbonyl compounds provides a viable strategy to synthesize high value-added chemicals and biofuels, for which the development of efficient catalysts still remains a formidable challenge. Here, we report a Zn-based single-atom catalyst (Zn/NC-950), prepared by pyrolysis of ZIF-8 at 950 °C, for the CTH of ethyl levulinate to γ-valerolactone (GVL). This catalyst exhibited excellent performance, affording a GVL selectivity of 95.3 % at an ethyl levulinate conversion of 100 %, using isopropanol as the hydrogen source at 200 °C and autogenous pressure. The structural characterization and theoretical calculation demonstrate that such extraordinary efficacy of the Zn/NC-950 catalyst is attributed to the dual Zn-N3C1 and Zn-N2C2 sites of low Zn oxidation states, which work synergistically to generate the active hydrogen species and activate the carbonyl bonds, respectively. This work provides a rationale for the precise design of the non-noble metal single-atom catalysts efficient for the biomass valorization.

Asymmetric Access to Chiral Sulfinyl Compounds as Bioisosteres of Carbonyl Compounds

AbstractThe sulfinyl group, as one of the bioisosteres of carbonyl groups, attracts considerable attention in the field of synthetic chemistry. In particular, the asymmetric construction of chiral sulfinyl compounds and their derivatives remains in the early stages of development. Sulfinyl compounds mainly include sulfoxides, sulfinate esters and sulfinamides, according to the different functional groups connected to the sulfur atom. This Review summarizes the fascinating recent progress made over the past decade on the asymmetric synthesis of enantiopure sulfinyl derivatives.1 Introduction2 Asymmetric Synthesis of Chiral Sulfoxides3 Asymmetric Synthesis of Chiral Sulfinate Esters4 Asymmetric Synthesis of Chiral Sulfinamides5 Conclusion and Outlook

Redox Approaches to Carbene Generation in Catalytic Cyclopropanation Reactions

AbstractTransition metal‐catalyzed carbene transfer reactions have a century‐old history in organic chemistry and are a primary method for the synthesis of cyclopropanes. Much of the work in this field has focused on the use of diazo compounds and related precursors, which can transfer a carbene fragment to a catalyst with concomitant loss of a stable byproduct. Despite the utility of this approach, there are persistent limitations in the scope of viable carbenes, most notably those lacking stabilizing substituents. By coupling carbene transfer chemistry with two‐electron redox cycles, it is possible to expand the available starting materials that can be used as carbene precursors. In this Minireview, we discuss emerging catalytic reductive cyclopropanation reactions using either gem‐dihaloalkanes or carbonyl compounds. This strategy is inspired by classic stoichiometric transformations, such as the Simmons–Smith cyclopropanation and the Clemmensen reduction, but instead entails the formation of a catalytically generated transition metal carbene or carbenoid. We also present recent efforts to generate carbenes directly from methylene (CR2H2) groups via a formal 1,1‐dehydrogenation. These reactions are currently restricted to substrates containing electron‐withdrawing substituents, which serve to facilitate deprotonation and subsequent oxidation of the anion.

Redox Approaches to Carbene Generation in Catalytic Cyclopropanation Reactions.

Transition metal-catalyzed carbene transfer reactions have a century-old history in organic chemistry and are a primary method for the synthesis of cyclopropanes. Much of the work in this field has focused on the use of diazo compounds and related precursors, which can transfer a carbene fragment to a catalyst with concomitant loss of a stable byproduct. Despite the utility of this approach, there are persistent limitations in the scope of viable carbenes, most notably those lacking stabilizing substituents. By coupling carbene transfer chemistry with two-electron redox cycles, it is possible to expand the available starting materials that can be used as carbene precursors. In this Minireview, we discuss emerging catalytic reductive cyclopropanation reactions using either gem-dihaloalkanes or carbonyl compounds. This strategy is inspired by classic stoichiometric transformations, such as the Simmons-Smith cyclopropanation and the Clemmensen reduction, but instead entails the formation of a catalytically generated transition metal carbene or carbenoid. We also present recent efforts to generate carbenes directly from methylene (CR2H2) groups via a formal 1,1-dehydrogenation. These reactions are currently restricted to substrates containing electron-withdrawing substituents, which serve to facilitate deprotonation and subsequent oxidation of the anion.

Multielectron Reduction of Esters by a Diazabenzacenaphthenium Photoredox Catalyst.

A novel diazabenzacenaphthenium photocatalyst, N-BAP, with high photoredox abilities and visible-light absorption was designed and prepared in one step. Under visible-light irradiation, N-BAP promoted the four-electron reduction of esters in the presence of ammonium oxalate as a "traceless reductant" to generate carbinol anion intermediates that underwent protonation with water to give the corresponding alcohols. The resulting carbinol anions also exhibited nucleophilic reactivity under the photocatalytic conditions to undergo a 1,2-addition to a second carbonyl compound, affording unsymmetric 1,2-diols.

Hydrogen production from Fraxinus mandshurica solid wood waste using FeCl3 as a non-precious metal Lewis acid catalyst: A comprehensive utilization approach

The efficient use of wood powder has become increasingly important for protecting the environment and addressing energy shortages. In this study, a proton exchange membrane electrolysis system was utilized to convert biomass into valuable industrial chemicals and hydrogen using ferric ions as redox mediators, reduced reaction costs. GC-MC analysis revealed that the degradation products are mainly consisted of aromatic carbonyl compounds, along with some alcohols, phenols, and alkanes. The degradation efficiency was found to be 55.6 %, and the Faraday’s hydrogen production efficiency exceeds 92.6 %. Moreover, Fe3+/Fe2+ redox mediators was recycled in the electrolysis system, maintaining high reactivity. This research introduces a new approach for the degradation of wood powder, offering potential for sustainable industrial production and a reduction in environmental impact.

Evaporation-Induced Transformations in Volatile Chemical Product-Derived Secondary Organic Aerosols: Browning Effects and Alterations in Oxidative Reactivity.

Volatile chemical products (VCPs) are increasingly recognized as significant sources of volatile organic compounds (VOCs) in urban atmospheres, potentially serving as key precursors for secondary organic aerosol (SOA) formation. This study investigates the formation and physicochemical transformations of VCP-derived SOA, produced through ozonolysis of VOCs evaporated from a representative room deodorant air freshener, focusing on the effects of aerosol evaporation on its molecular composition, light absorption properties, and reactive oxygen species (ROS) generation. Following aerosol evaporation, solutes become concentrated, accelerating reactions within the aerosol matrix that lead to a 42% reduction in peroxide content and noticeable browning of the SOA. This process occurs most effectively at moderate relative humidity (∼40%), reaching a maximum solute concentration before aerosol solidification. Molecular characterization reveals that evaporating VCP-derived SOA produces highly conjugated nitrogen-containing products from interactions between existing or transformed carbonyl compounds and reduced nitrogen species, likely acting as chromophores responsible for the observed brownish coloration. Additionally, the reactivity of VCP-derived SOA was elucidated through heterogeneous oxidation of sulfur dioxide (SO2), which revealed enhanced photosensitized sulfate production upon drying. Direct measurements of ROS, including singlet oxygen (1O2), superoxide (O2•-), and hydroxyl radicals (•OH), showed higher abundances in dried versus undried SOA samples under light exposure. Our findings underscore that drying significantly alters the physicochemical properties of VCP-derived SOA, impacting their roles in atmospheric chemistry and radiative balance.

A refined picture of the native amine dehydrogenase family revealed by extensive biodiversity screening

Native amine dehydrogenases offer sustainable access to chiral amines, so the search for scaffolds capable of converting more diverse carbonyl compounds is required to reach the full potential of this alternative to conventional synthetic reductive aminations. Here we report a multidisciplinary strategy combining bioinformatics, chemoinformatics and biocatalysis to extensively screen billions of sequences in silico and to efficiently find native amine dehydrogenases features using computational approaches. In this way, we achieve a comprehensive overview of the initial native amine dehydrogenase family, extending it from 2,011 to 17,959 sequences, and identify native amine dehydrogenases with non-reported substrate spectra, including hindered carbonyls and ethyl ketones, and accepting methylamine and cyclopropylamine as amine donor. We also present preliminary model-based structural information to inform the design of potential (R)-selective amine dehydrogenases, as native amine dehydrogenases are mostly (S)-selective. This integrated strategy paves the way for expanding the resource of other enzyme families and in highlighting enzymes with original features.

Synthesis and utility of N-boryl and N-silyl enamines derived from the hydroboration and hydrosilylation of N-heteroarenes and N-conjugated compounds.

Catalytic hydroboration and hydrosilylation have emerged as promising strategies for the reduction of unsaturated hydrocarbons and carbonyl compounds, as well as for the dearomatization of N-heteroarenes. Various catalysts have been employed in these processes to achieve the formation of reduced products via distinct reaction pathways and intermediates. Among these intermediates, N-silyl enamines and N-boryl enamines, which are derived from hydrosilylation and hydroboration, are commonly underestimated in this reduction process. Because these versatile intermediates have recently been utilized in situ as nucleophilic reagents or dipolarophiles for the synthesis of diverse molecules, an expeditious review of the synthesis and utilization of N-silyl and N-boryl enamines is crucial. In this review, we comprehensively discuss a wide range of hydrosilylation and hydroboration catalysts used for the synthesis of N-silyl and N-boryl enamines. These catalysts include main-group metals (e.g., Mg and Zn), transition metals (e.g., Rh, Ru, and Ir), earth-abundant metals (e.g., Fe, Co, and Ni), and non-metal catalysts (including P, B, and organocatalysts). Furthermore, we highlight recent research efforts that have leveraged these versatile intermediates for the synthesis of intriguing molecules, offering insights into future directions for these invaluable building blocks.

The combination of tetramethylpyrazine and vitamin A acid in the treatment of skin photoaging by activating the HIF-1α pathway.

Skin photoaging is a skin degenerative disease that causes patients to develop malignant tumors. The existing clinical treatment of photoaging has limitations. This greatly reduces the recovery rate of photoaging patients. Studies have confirmed that Ligusticum wallichii Franch (LWF) monomer tetramethylpyrazine (TMP) alleviates various skin diseases. The combination of traditional Chinese medicine and Western medicine helps with this process. Our research aimed to explore the specific treatment mode and molecular mechanism of TMP in treating skin photoaging. CCK-8 assays were used to evaluate the activity and toxicity of HaCaT cells. β-galactosidase aging, Carbonyl compound and nitrosylated tyrosine assays were used to analyze the aging of HaCaT cells. ROS assays and ELISA were used to analyze the enrichment of ROS. The molecular docking experiment analyzed the binding of TMP and HIF-1α. qRT-PCR and Western blot were used to detect the activation of skin aging-related pathways. HE staining was used to analyze the thickness of the stratum corneum skin on the back skin of mice. 200μg/L LWF alleviates cellular photoaging and mouse skin photoaging by reducing ROS enrichment. Its monomer TMP plays an important role in this process. The combination of TMP and HIF-1α accelerates the degradation of ROS by activating the Nrf2/ARE signaling pathway. This process reduces the apoptosis of cells damaged by light. In addition, we also found that the combination of TMP and retinoic acid (RA) is more beneficial for the treatment of skin damage caused by light in mice. The combination therapy of TMP and RA alleviates skin oxidative stress response through overexpression of HIF-1α. This plan is beneficial for the treatment of skin photoaging.

Effect of the addition of black garlic on the quality parameters of jerked beef meat with pork.

The objective of this work was to evaluate the effects of the replacement of nitrite by natural antioxidants from black garlic (BG) on the quality parameters of jerked beef meat with pork for 60 days. Four formulations were prepared: control, 0.02% of sodium nitrite in brine curing, w/v (CON); 1.5% BG in brine curing, w/v (ASU); 1.5% BG in dry curing, w/w (ASS); and 1.5% of BG in the brine curing, w/v and 1.5% of BG in dry curing, w/w (ASUS). Nutritional composition, pH, water activity, shear force, fatty acid profile, color, and oxidative stability of the formulations were analyzed. The addition of BG did not affect the nutritional composition, pH, water activity, shear force, and fatty acid profile. On the other hand, it resulted in lower weight loss after centrifugation and lower values of L* and a*. TBARS values from the 30th day of storage were lower in the ASUS formulation, while carbonyl compounds at all times were lower than in the CON formulation. Results suggest that BG was an efficient alternative to nitrite in controlling protein oxidation during storage. Thus, the use of pork for the manufacture of jerked beef can be an alternative, and black garlic can be applied as a natural additive to the replacement of nitrite. In addition, black garlic was efficient in improving the oxidative stability of the jerked beef meat with pork.

Decarboxylative Aldol Reaction of α,α-Difluoro-β-keto Esters: Easy Access to Difluoroenolate.

Yb(OTf)3 promoted the Krapcho decarboxylation of 2,2-difluoro-3-oxopropanoate, and a subsequent aldol reaction was achieved. This process is the first example of generating difluoroenolates through a decarboxylation-type process, and a large number of carbonyl compounds are applicable to the aldol reaction. The protocol is a complete one-pot reaction that uses the bench-stable and nonhygroscopic 2,2-difluoro-3-oxopropanoate to generate the difluoroenolate. This strategy has been applied for the synthesis of CF2-containing bioactive GABAB agonists, contributing to drug design.

Effects of hydroxyl radical oxidation on the stability and biochemical functions of rex rabbit meat

Reactive oxygen species (ROS)-generating system in muscle food is an important factor as it greatly influences shelf life and quality of meat. In this study, whole muscle homogenate was used as the research object, and the Fenton reaction system as an inducer was established for analyzing the effect of oxidation on Chuanbai Rex and Hyla rabbits meat. The homogenates were exposed to varying concentrations of hydrogen peroxide (H2O2, 0, 2, 4, 6, 8, and 10 mmol/L), the level of lipid oxidation of both breeds increased with the increased H2O2 concentration, while Hyla rabbits was higher. Oxidation and molecular aggregation of myofibrillar protein (MP) was observed in both breeds, including formation of carbonyl compounds, depleted sulphydryl, and increased hydrophobicity while fluorescence decreased. After oxidation, the loss of amino acids was higher in Hyla (16%) than in Rex rabbits (11%). Cys content was identified as the most discriminant parameter capable of elucidating the variations between the two breeds under this oxidation system.

Ultrastable Organic Anode Enabled by Electrochemically Active MXene Binder toward Advanced Potassium Ion Storage.

Conjugated carbonyl compounds are regarded as promising organic anode materials for potassium ion batteries (PIBs) due to their rich redox sites, excellent reversibility, and structural tunability, but their low electrical conductivity and severe solubility in organic electrolytes have substantially restricted their practical application. Herein, 2D MXene is utilized as an electrochemically active binder to fabricate perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) electrodes for high-performance PIBs. MXene, coupled with Super-P particles, served as a binder and conductive matrix to facilitate rapid ion and electron transport, restrain the solubility of PTCDA, promote potassium adsorption, and alleviate the volume expansion of PTCDA during potassiation. Consequently, the PTCDA electrode bonded by the MXene/Super-P system delivers excellent potassium storage performance in terms of a high capacity of 462 mAh g-1 at 50 mA g-1, superior rate capability of 116.3 mAh g-1 at 2000 mA g-1, and stable cycle performance over 3000 cycles with a low capacity decay rate of ∼0.0033% per cycle. When configured with the PTCDA@450 cathode, an all-PTCDA potassium ion full cell delivers a maximum energy density of 179.5 Wh kg-1, indicating the superiority of MXene as an electrochemically active binder to promote the practical application of organic anodes for PIBs.

Perfluoroalkylation Reactions by Electron Donor‐Acceptor Complexes: Recent Advances

AbstractThis Perspective analyses the perfluoroalkylation reactions by electron donor‐acceptor (EDA) complexes since 2018, while summarizes, in Tables , the vast majority of representative perfluoroalkylation reactions of various classes of organic compounds by EDA complexes and halogen‐bonding interactions. Numerous intriguing reaction methodologies and valuable synthetic instances have emerged. We aim to delve into these new examples comprehensively, while also contemplating the future directions in the field. Subsequent sections will elaborate on the perfluoroalkylation of (hetero)aromatic compounds, carbon‐carbon multiple bonds, perfluoroalkylation of carbonyl compounds, and perfluoroalkylation of isocyanides, covering their synthetic scope and mechanistic insights. Perfluoroalkylation reactions of (hetero)aromatic compounds by EDA complexes. Entry Substrate Complex Reaction conditions Product Ref. 1 [13] 2 [46] 3 RFI (3 equiv.) KOH (1.5 equiv.) Blue LEDs H2O, Ar, 20 h [47] 4 TEEDA (3 equiv.) CFL (25 W) THF, r.t. RF−I (3 equiv.) [48] 5 ICF2CO2Et (1.3 equiv.) Na2CO3 (1.5 equiv.) DMSO (3 mL) Ar, rt. 427 nm LED, 16 h [49] 6 TMG (2.5 equiv.) RF−I (2.5 equiv.) 23 W CFL, MeCN/Hexf (5 : 1) [42,50] 7 TMG (2.5 equiv.) RF−I (2.5 equiv.) 23 W CFL, MeCN [51] 8 Umemoto's reagent (2 equiv.) N‐methylmorpholine (2.5 equiv.) DMF, r.t. [52] 9 Cs2CO3 (2 equiv.) RF−I (3 equiv.) white light H2O (3 equiv.) DMF, r.t., 2 h [53] 10 4.5 W 450 nm laser CaCl2, MeNO2, 0 °C [3] 11 RF−I (1.5 equiv.) t‐BuONa (2 equiv.) DMF Green LEDs [54] 12 or EDA complex I−Rf (2.1 equiv.) TMEDA (2 equiv.) or DBU (2 equiv.) Blue LEDs 24 W [55,56] 13 TFE/water (1 : 1) (0.2 M) CF3SO2Na Blue LEDs r.t., 12 h [84] Perfluoroalkylation reactions of carbon‐carbon multiple bonds and constrained cyclic compounds by EDA complexes. Entry Substrate Complex Reaction conditions Product Ref. 1 Bu4NCl, Hg lamp (6 W) RF−I (1.2 equiv.) CH3OH, 1.5 h r.t, Ar [39] 2 RFI (3 equiv.) KOH (1.5 equiv.) Blue LEDs H2O, Ar, 20 h [47] 3 [57] 4 DIPEA or TMEDA or DBU or TEEDA ……..CF3I CF3−I (3 equiv.) Base (2 equiv.) MeCN or DMF or THF CFL, 25 W with DIPEA, TMEDA or TEEDA; with DBU [48,58,59] 5 Bn2NH MeCN RF−I Blue LED, r.t. [60] 6 Base, Blue LEDs DMF or THF [61] 7 I−RF H2O/toluene=9 : 1 Blue LEDs, 65 °C, 12 h [41] 8 K3PO4 (3 equiv.) RF−I (3 equiv.) CuCl (10 mol%) TMSNCS (3 equiv.) CH3CN (2 mL) Violet LEDs (24 W) Ar, 4 h [37] 9 RF−I (3 equiv.) Diphenylacetaldehyde (10 mol%) Pyrrolidine (40 mol%) DIPEA (2 equiv.) DCE (2.5 mL); O2 (0.8 eq.); Ar White LEDs (2.5 W); 24 h [44,62] 10 DIPEA,DMA Ar (trace air) Blue LEDs, rt. 36–72 h [63] 11 TMEDA Blue LEDs n‐C4F9I DMSO air, 24 h RT [64] 12 K3PO4 (2 equiv.) DABCO (1.2 equiv.) hυ (400 Watt) 50 °C CnF2n+1I (1.8 equiv.) [65–67] 13 Blue LEDs DCE, r.t. [27] 14 2,4,6‐trimethylpyridine MeCN, 60 °C Togni's reagent [68] 15 PMDETA (2 equiv.) DMSO (2 mL) N2, Blue LEDs [69] 16 Blue LEDs [70,71] 17 MeCN (0.2 M) with less than 1 % water CF3SO2Na (1 mmol) Blue LEDs [84] Perfluoroalkylation of carbonyl compounds, isocyanides and hydrazones. Entry Substrate Complex Reaction conditions Product Ref. 1 [72,73] 2 RF−I (0.2 mmol) cis‐catalyst M (20 mol%) 2,6‐lutidine (1.2 equiv.) Blue LEDs, Et2O (0.7 M) ‐10 °C, 20 h [74] 3 white light RF−I [75] 4 phase transfer catalyst Cs2CO3, C6H5Cl/8F18 (2 : 1), 25 °C, RF−I [32] 5 ambient light C4F9−I NaOH (4.1 equiv.) MeCN, R.T. [76] 6 RFI (3 equiv.) KOH (1.5 equiv.) Blue LEDs THF, Ar, 36 h [47] 7 RF−I (2 equiv.) TMEDA (2 equiv.) THF (2 mL) Blue LEDs (25 W) 30 °C, N2 [77] 8 TEEDA (1.5 equiv.) CFL (25 W) THF I−C4F9 [48] 9 Bn2NH Blue LEDs MeCN, RT RF−I [78] 10 TMG (1.5 equiv.) ambient light MeCN, RT I−RF [79] 11 Imidazole (3 equiv.) MeCN, RF−I (2 equiv.) r.t. [80]

Counterintuitive chemoselectivity in the reduction of carbonyl compounds.

The reactivity of carbonyl functional groups largely depends on the substituents on the carbon atom. Reversal of the commonly accepted order of reactivity of different carbonyl compounds requires novel synthetic approaches. Achieving selective reduction will enable the transformation of carbon resources such as plastic waste, carbon dioxide and biomass into valuable chemicals. In this Review, we explore the reduction of less reactive carbonyl groups in the presence of those typically considered more reactive. We discuss reductions, including the controlled reduction of ureas, amides and esters to aldehydes, as well as chemoselective reductions of carbonyl groups, including the reduction of ureas over carbamates, amides and esters; the reduction of amides over esters, ketones and aldehydes; and the reduction of ketones over aldehydes.

Atmospheric chemistry of the coastal area is influenced by the convergence between the inland and marine air: Insight into carbonyl compounds

Marine biological activity has long been recognized to impact the atmospheric chemistry of coastal areas. In this work, we monitored the seasonal variation of carbonyl compounds in the coastal city of Qingdao, located in the north of China's coastline and the south of Jiaodong Peninsula, with the vast hinterland in the west. The mean total concentration of the 15 carbonyls varied significantly between seasons, with the highest observed in autumn (10.2 ± 6.2 ppbv), followed by spring (9.0 ± 3.0 ppbv), winter (6.4 ± 4.0 ppbv) and summer (3.4 ± 1.4 ppbv). Using bivariate analysis, the agricultural emissions from inland areas were responsible for the high levels of carbonyls in the autumn. In summer, clean and humid sea winds helped reduce the concentration of carbonyls, but they also brought air masses from vegetation, and marine organisms, which contributed to high levels of carbonyls in the spring of coastal areas. The observation-based chemistry box model found that the formation of formaldehyde and acetaldehyde was primarily controlled by the RO + O2 reaction, and alkenes oxidation was the main contributing factor. Based on the OH radical loss rate (LOH) and ozone formation potential (OFP) calculation, we found that autumn and spring seasons have significantly higher values of LOH and OFP than winter and summer due to the presence of high concentrations of carbonyl compounds. Therefore, it is believed that these carbonyl compounds primarily originate from agricultural activities, and marine air influences the atmospheric chemistry of the coastal areas.