[Potential Ecological Risk Assessment and Source Analysis of Heavy Metals in Soil-crop System in Xiong'an New District].

In order to evaluate the distribution characteristics of fluorine geochemistry in the surface soil and human health risk in Xiong'an New District, GIS spatial analysis and correlation analysis were used to analyze the depleted and enriched features and influencing factors of soil fluoride and to carry out the soil fluoride health risk assessment. The uncertainty of the health risk assessment results was studied based on the Monte Carlo stochastic simulation. The results showed that the average content of fluorine was 641 mg·kg-1, which was 1.34 times the background value of the national A-layer soil. The excess fluorine and high-grade samples accounted for more than 85%, and the overall soil fluorine content was relatively high. The average content of fluoride of the irrigation water samples was 0.85 mg·L-1, the spatial distribution characteristics of which were affected by the hydrochemical type and flow direction of shallow groundwater. The vertical spatial variation of soil fluoride, mainly affected by the vertical distribution of soil physicochemical properties such as soil organic carbon and texture, was not obvious. The depletion and enrichment of topsoil fluorine was mainly controlled by the geological background, and its spatial distribution was affected by external inputs, such as human factors (agricultural irrigation water, fertilization, and atmospheric dry and wet deposition). The soil fluoride content was significantly correlated with the iconic indicators of the geomorphological environment, including the content of Al2O3, Fe2O3, MgO, K2O, soil organic carbon (Corg.), cation exchange capacity (CEC), clay, and silt (P<0.01). The results of human health risk assessment showed that oral intake was the main exposure risk route of soil fluoride. The non-carcinogenic health risk index HQ of adults was less than 1, and the harm could be ignored. The probability of non-carcinogenic health risk exceeding the threshold for adults and children was 34.3% and 27.6%, respectively, and daily soil intake was the most sensitive parameter.

Visible-Light-Induced Stoichiometric Coupling of Alkylarenes and Trifluoromethyl Ketones.

A visible-light induced direct C(sp3)-H functionalization of alkylarenes with trifluoromethyl ketones has been reported to access valuable benzyl-substituted trifluoromethyl alcohols in a stoichiometric manner. Readily available petroleum-derived alkylarenes are employed as latent benzylation reagents. With a bromine radical as the hydrogen atom transfer reagent, primary, secondary, and tertiary benzyl C-H bonds are suitable coupling partners. Additionally, the late-stage modification of bioactive molecules highlights the potential application of this approach.

[Characteristics and Origins of Heavy Metals in Soil and Crops in Mountain Area of Southern Sichuan].

Excessive heavy metals in soils and crops will affect the human living environment and health. In order to study the enrichment characteristics and causes of heavy metals in soils and crops in a mountainous area of southern Sichuan, 1699 cultivated soil samples, 30 rice seed samples, 31 corn seed samples, 15 tea samples, and 76 crop root soil samples were collected. The enrichment characteristics and origins of heavy metals in the soil were studied using mathematical statistics, principal component analysis, and correlation analysis. The enrichment characteristics of heavy metals in crops and their correlations with root soil were discussed. The results showed that the content of heavy metals in cultivated soil was higher than the national soil background value, and many sampling points exceeded the risk screening value. Among them, 770 points of Cd, 176 points of Cu, 116 points of Cr, and 106 points of Ni exceeded the standard. Combining the factor analysis results, it was found that Cd, Cr, Cu, Ni, and Zn in cultivated soil mainly originated from the geological background, and Cd was also affected by soil organic matter and pH. Meanwhile, Hg and Pb were mainly related to human activities. The results showed that the contents of heavy metals in the crops were lower than the national standards; the enrichment coefficients of heavy metals in crops were generally small, and were mainly in the following order: tea > rice > corn. The correlation analysis of the heavy metal contents in the root soil and crops showed that there was no significant correlation among them. Thus, the heavy metals in the soil generally had a high content and low activity, which did not affect the quality and safety of the three crops. However, Cu in corn and CaO in root soil, As in corn seed and Fe2O3 in root soil, and Ni in corn seed and Fe2O3 in root soil showed significant correlations, whereas As in rice seed and CaO in root soil and Hg in rice seed and MgO in root soil showed significant correlations, and no significant correlations were found in tea.

[Geochemical Survey Method of Land Quality in Land Parcel Scale City: A Case Study of the Initial Area of the Xiong'an New District].

In order to evaluate the land quality geochemical survey achievement in the service of the accurate management of urban land resources, the initial area of the Xiong'an New District as urbanization pathfinder in China is chosen as the research subject. The sample points were set by differential classification, and the spatial interpolation accuracy of the soil elements at a plot scale and a quantitative assessment of the consistency of the land plot (pattern spot) prediction evaluation were studied under the conditions of different sampling densities. The regional geochemical variation values randomly distributed on the plane can be reflected quantitatively by differential classification sampling, which can meet the basic demand of the quality attribute of a single plot (map spot) by the accurate management of urban land resources. The spatial variability of soil elements is mostly middle to moderate, and Cd, Cu, Pb, Hg, Se, N, P, and other elements of high spatial variability are affected by human industrial and agricultural production activities. Under the same sampling density, the larger the element variation coefficient, the worse the spatial interpolation accuracy. Although the interpolation accuracy of the same element index is affected by the sampling density, the increase in the sampling density could not identify the continuous component on the structure of the soil element content. The soil environment is clean, and the heavy metal content is lower than the GB15618-2018 standard. The interpolation results are basically consistent with the grading results of the measured values, while the contents of N, P, and K of the nutrient indices vary greatly, and the predicted and measured geochemical grades of the plots (map spot) differ substantially under the influence of factors such as human disturbance and spatial variability. The quantitative evaluation of the six different sampling densities indicates that the 16 points·km-2 sampling density adopted in the geochemical survey and evaluation of urban land quality can satisfy the needs of an accurate control of urban land resources in the study area and similar areas. The research can provide key technologies to support and serve the accurate management of urban land resources for geochemical surveys and the evaluation of land quality in land parcel scale cities.

[Potential Ecological Risk Assessment and Source Analysis of Heavy Metals in Soil-crop System in Xiong'an New District].

In order to evaluate the potential ecological risk of heavy metals in the soil-crop system in the Xiong'an New District, the heavy metal contents and forms in wheat seed and root soil samples are analyzed, and the comprehensive pollution index (IPIN), potential ecological risk index (RI), bio-enrichment coefficient (BFC), risk assessment code (RAC), principal component analysis, and correlation analysis are used to assess the potential ecological risk of heavy metals and analyze their sources. The results indicate that the average content of Cd, Cu, Pb, and Zn in the root soil is significantly higher than the soil background value in Hebei province. The IPIN ranges from 0.2 to 5.18, 94.83% of the soil samples are in the safe and pollution-free grade, and the potential ecological risks of heavy metal are slight and moderate, accounting for 64.66% and 30.17%, respectively. Cd has the greatest potential ecological harm, followed by Hg, Cr, Ni, and Zn. All the heavy metal elements besides Cd in the root soil are dominated by the residual form, which accounts for 60%, and the bioactive form (ion-exchange and water-soluble state) of Cd accounts for 33.43%, indicating relatively high bio-availability. The risk assessment code can be ranked as Cd > Ni > Hg > As > Cu > Cr > Zn > Pb, and the risk of Cd is moderate, while other elements are of low or no risk. The leading potential source of heavy metals is human activity combined with the geological background. The migration and enrichment capability of the wheat seeds is in order from strong to weak of Zn > Cu > Cd > Hg > As > Ni > Pb > Cr, and the biological effective components of As, Cd, Pb, and Zn plays an substantial role in promoting the absorption of heavy metals. The content of heavy metals in the wheat seeds has a negative correlation with the soil pH, and the physical and chemical indices, such as OM and CEC, has bi-directional influence on the biological effective state of the heavy metals.

Cu-Catalyzed Oxidative Dual Arylation of Active Alkenes: Preparation of Cyanoarylated Oxindoles through Denitrogenation of 3-Aminoindazoles.

A novel and mild Cu-catalyzed oxidative dual arylation of carbon-carbon double bonds in acrylamides with 3-aminoindazoles is proposed for the synthesis of cyanoarylated oxindoles. Notably, 3-aminoindazoles are employed as efficient arylating agents via the cleavage of two C-N bonds. This oxidative dual arylation of active alkenes involves a radical process and undergoes a sequence of 3-aminoindazole oxidation, two-C-N-bond cleavage, cyanoaryl radical addition, and intramolecular cyclization.

Visible-light photoredox-catalyzed dual C-C bond cleavage: synthesis of 2-cyanoalkylsulfonylated 3,4-dihydronaphthalenes through the insertion of sulfur dioxide.

An efficient novel visible-light photoredox-catalyzed dual carbon-carbon bond cleavage of methylenecyclopropanes and cycloketone oximes for the synthesis of 2-cyanoalkylsulfonated 3,4-dihydronaphthalenes through the insertion of sulfur dioxide is established. This dual cleavage of carbon-carbon bonds involves a radical pathway and goes through a sequence of iminyl radical formation, carbon-carbon bond cleavage, sulfur dioxide insertion, sulfonyl radical addition, another carbon-carbon bond cleavage, and intramolecular cyclization.

Visible Light-Catalyzed Cascade Radical Cyclization of N-Propargylindoles with Acyl Chlorides for the Synthesis of 2-Acyl-9H-pyrrolo[1,2-a]indoles.

A novel and convenient visible light-catalyzed tandem radical cyclization of N-propargylindoles with acyl chlorides for accessing 2-acyl-9H-pyrrolo[1,2-a]indoles is established. This transformation involves sequential addition of the acyl radical to the carbon-carbon triple bond, intramolecular cyclization with the 2-position of indole, and isomerization of the carbon-carbon double bond. The experimental results show that this reaction contains a radical pathway and a radical chain process is not the major pathway for the formation of products.

Visible-light-induced cascade sulfonylation/cyclization of N-propargylindoles with aryldiazonium tetrafluoroborates via the insertion of sulfur dioxide.

A simple and efficient visible-light-catalyzed cascade sulfonylation/cyclization of N-propargylindoles with K2S2O5 and aryldiazonium tetrafluoroborates for the construction of 2-sulfonyl-substituted 9H-pyrrolo[1,2-a]indoles is developed. In this transformation, K2S2O5 as a simple and inexpensive sulfur dioxide source provides sulfur dioxide for accessing sulfonyl radicals. This method features excellent functional group tolerance and offers a convenient route for assembling a new C-C bond and two new C-S bonds in one step.

Visible-light promoted one-pot synthesis of sulfonated spiro[4,5]trienones from propiolamides, anilines and sulfur dioxide under transition metal-free conditions.

A novel visible-light promoted sulfonylation/ipso-cyclization of N-arylpropiolamides with arylamines and DABCO·(SO2)2 to synthesize various sulfonated spiro[4,5]trienones is reported. This sulfonylation/ipso-cyclization reaction proceeds via a radical process and undergoes arylsulfonyl radical formation, sulfonylation, and ipso-cyclization. The experimental results indicate that H2O provides an oxygen atom for the construction of the carbonyl group.

Visible-light-mediated difunctionalization of vinylcyclopropanes for the synthesis of 1-sulfonylmethyl-3,4-dihydronaphthalenes.

An efficient method for visible-light-mediated sulfonylation/arylation of the C-C σ-bond in vinylcyclopropanes with sulfonyl chlorides to synthesize 1-sulfonylmethyl-substituted 3,4-dihydronaphalenes has been developed. A radical-type pathway has been proved in this transformation. This difunctionalization procedure shows a series of advantages, such as the use of commercially and easily available sulfonyl chlorides, mild conditions, and eco-friendly energy.

Synthesis of 2-Acyl-3,4-dihydronaphthalenes by Silver-Promoted Oxidative C-C σ-Bond Acylation/Arylation of Alkylidenecyclopropanes with α-Ketoacids.

A novel and efficient AgNO3-facilitated oxidative C-C σ-bond difunctionalization of alkylidenecyclopropanes with α-ketoacids for preparing 2-acyl-substituted 3,4-dihydronaphthalenes is developed. This radical acylation/arylation transformation proceeds via decarboxylation of the α-ketoacid, acylation of the carbon-carbon double bond, cleavage of the carbon-carbon σ-bond, and cyclization with a connected aromatic ring and offers a mild and facile strategy for acylation/arylation of carbon-carbon σ-bonds with an acyl radical and an aromatic ring to build two new carbon-carbon bonds. This method uses an inexpensive oxidant, features a wide substrate scope, and is operationally simple.

Oxone-Mediated Radical C-C Bond Acetmethylation/Arylation of Methylenecyclopropanes and Vinylcyclopropanes with α-Alkyl Ketones: Facile Access to Oxoalkyl-Substituted 3,4-Dihydronaphthalenes.

An efficient oxone-mediated radical carbon-carbon σ-bond acetmethylation/arylation of methylenecyclopropanes with α-C(sp3)-H bonds of ketones is described for the preparation of 2-(2-oxopropyl)-3,4-dihydronaphthalenes. This acetmethylation/arylation undergoes a series of α-C(sp3)-H bond activation, carbon-carbon double bond acetmethylation, carbon-carbon σ-bond cleavage, and cyclization with intramolecular aromatic ring. The experimental result indicates that the carbon-carbon σ-bond acetmethylation/arylation transformation contains a radical process. The difunctionalization method can also be applied to carbon-carbon σ-bond acetmethylation/arylation of vinylcyclopropanes with ketones. This strategy offers an efficient and convenient method for acetmethylation/arylation of a carbon-carbon σ-bond with a α-carbonyl radical and an aromatic carbon in one pot, building two new carbon-carbon bonds.

Oxidative radical ring-opening/cyclization of cyclopropane derivatives.

The ring-opening/cyclization of cyclopropane derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be of sufficient interest for the scientific community to further advance the application of oxidative radical strategies in the ring-opening/cyclization of cyclopropane derivatives.

Visible-Light-Catalyzed C-C Bond Difunctionalization of Methylenecyclopropanes with Sulfonyl Chlorides for the Synthesis of 3-Sulfonyl-1,2-dihydronaphthalenes.

A novel visible-light-catalyzed sulfonylation/arylation of carbon-carbon σ-bond with sulfonyl chlorides for the synthesis of 3-sulfonylated 1,2-dihydronaphthalenes is developed. This difunctionalization proceeds via a sequence of C═C bond sulfonylation, C-C σ-bond cleavage, and intramolecular cyclization, and the experiment result shows that the C-C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for difunctionalization of C-C bonds with an aromatic carbon and a sulfonyl radical by one-pot construction of a C-S bond and a new C-C bond.

Silver-mediated oxidative C-C bond sulfonylation/arylation of methylenecyclopropanes with sodium sulfinates: facile access to 3-sulfonyl-1,2-dihydronaphthalenes.

The novel AgNO3-mediated oxidative sulfonylation/arylation of a C-C σ-bond in methylenecyclopropanes with sodium sulfinates to synthesize various 3-sulfonylated 1,2-dihydronaphthalenes is reported. This sulfonylation/arylation transformation proceeds via a sequence of sulfonylation, C-C σ-bond cleavage and intramolecular cyclization, and the experimental results show that the C-C σ-bond difunctionalization reaction includes a radical process. This strategy provides a simple and convenient route for the difunctionalization of C-C bonds with a phenyl ring and a sulfonyl radical via the one-pot construction of a C-S bond and a new C-C bond.

Oxidative C-C Bond Functionalization of Methylenecyclopropanes with Aldehydes for the Formation of 2-Acyl-3,4-dihydronaphthalenes.

A new FeCl2- and DTBP (di- tert-butyl peroxide)-promoted oxidative ring-opening and cyclization of methylenecyclopropanes with aldehydes for the synthesis of 2-acyl-3,4-dihydronaphthalenes is presented. This oxidative cyclization reaction proceeds via a radical addition, ring-opening, and cyclization sequence facilitated by a Lewis acid, and it offers a practical and straightforward route for the oxidative cyclization of methylenecyclopropanes with an aromatic carbon and a C(sp2)-H bond by simultaneously forming two new carbon-carbon bonds.

Visible-Light-Mediated Ipso-Carboacylation of Alkynes: Synthesis of 3-Acylspiro[4,5]trienones from N-(p-Methoxyaryl)propiolamides and Acyl Chlorides.

A novel visible-light-mediated ipso-carboacylation of N-(p-methoxyaryl)propiolamides with acyl chloride has been established for the synthesis of diverse 3-acylspiro[4,5]trienones with high selectivity and efficiency. This method represents a new difunctionalization of alkynes through cross coupling of the acyl chloride C-Cl bonds with an ipso-aromatic carbon by simultaneously forming two new carbon-carbon bonds and one carbon-oxygen double bond.

Metal-Free Oxidative C-C Bond Functionalization of Methylenecyclopropanes with Ethers Leading to 2-Substituted 3,4-Dihydronaphthalenes.

A novel metal-free oxidative ring-opening/cyclization of methylenecyclopropanes with ethers was established for the synthesis of diverse 2-substituted 3,4-dihydronaphthalenes with high selectivity and efficiency. This oxidative cyclization is achieved by C(sp3)-H functionalization, ring-opening, and cyclization, and this method represents a new example of methylenecyclopropane oxidative cyclization with an aromatic carbon and a C(sp3)-H bond by simultaneously forming two new carbon-carbon bonds.