Agrochemical Industries Research Articles

Exploiting Imine Photochemistry for Masked N‐Centered Radical Reactivity

AbstractThis report details the development of a masked N‐centered radical strategy that harvests the energy of light to drive the conversion of cyclopropylimines to 1‐aminonorbornanes. This process employs the N‐centered radical character of a photoexcited imine to facilitate the homolytic fragmentation of the cyclopropane ring and the subsequent radical cyclization sequence that forms two new C−C bonds en route to the norbornane core. Achieving bond‐forming reactivity as a function of the N‐centered radical character of an excited state Schiff base is unique, requiring only violet light in this instance. This methodology operates in continuous flow, enhancing the potential to translate beyond the academic sector. The operational simplicity of this photochemical process and the structural novelty of the (hetero)aryl‐fused 1‐aminonorbornane products are anticipated to provide a valuable addition to discovery efforts in pharmaceutical and agrochemical industries.

Mild C−F Activation in Perfluorinated Arenes through Photosensitized Insertion of Isonitriles at 350 nm

AbstractFluorinated compounds have become important in the fields of agrochemical industry, pharmaceutical chemistry and materials sciences. Accordingly, various methods for their preparation have been developed in the past. Fluorinated compounds can be accessed via conjugation with fluorinated building blocks, via C−H fluorination or via selective activation of perfluorinated compounds to give the partially fluorinated congeners. Especially the direct activation of C−F bonds, one of the strongest σ‐bonds, still remains challenging and new strategies for C−F activation are desirable. Herein a method for the photochemical activation of aromatic C−F bonds is presented. It is shown that isonitriles selectively insert into aromatic C−F bonds while aliphatic C−F bonds remain unaffected. Mechanistic studies reveal the reaction to proceed via the indirect excitation of the isonitrile to its triplet state by photoexcited acetophenone at 350 nm. Due to the relatively mild light used, the process shows high functional group tolerance and various compounds of the class of benzimidoyl fluorides are accessible from aryl isonitriles and commercially available perfluorinated arenes.magnified image

Dual pathway for metabolic engineering of Escherichia coli to produce the highly valuable hydroxytyrosol.

One of the most abundant phenolic compounds traced in olive tissues is hydroxytyrosol (HT), a molecule that has been attributed with a pile of beneficial effects, well documented by many epidemiological studies and thus adding value to products containing it. Strong antioxidant capacity and protection from cancer are only some of its exceptional features making it ideal as a potential supplement or preservative to be employed in the nutraceutical, agrochemical, cosmeceutical, and food industry. The HT biosynthetic pathway in plants (e.g. olive fruit tissues) is not well apprehended yet. In this contribution we employed a metabolic engineering strategy by constructing a dual pathway introduced in Escherichia coli and proofing its significant functionality leading it to produce HT. Our primary target was to investigate whether such a metabolic engineering approach could benefit the metabolic flow of tyrosine introduced to the conceived dual pathway, leading to the maximalization of the HT productivity. Various gene combinations derived from plants or bacteria were used to form a newly inspired, artificial biosynthetic dual pathway managing to redirect the carbon flow towards the production of HT directly from glucose. Various biosynthetic bottlenecks faced due to feaB gene function, resolved through the overexpression of a functional aldehyde reductase. Currently, we have achieved equimolar concentration of HT to tyrosine as precursor when overproduced straight from glucose, reaching the level of 1.76 mM (270.8 mg/L) analyzed by LC-HRMS. This work realizes the existing bottlenecks of the metabolic engineering process that was dependent on the utilized host strain, growth medium as well as to other factors studied in this work.

Improving the Energy Efficiency of Petrochemical Plant Operations: A Measurement and Verification Case Study Using a Balanced Wave Optimizer

The Chinese petrochemical industry is facing pressure to meet strict targets of energy consumption and carbon emission reductions. Water pumps are the primary equipment used in most chemical and agrochemical industries sectors since water is commonly used for cooling and heating purposes, but these pumps also consume a large amount of energy. Other uses of water pumps in these industries include producing steam for heating, preparing reaction media or absorptive reagents, rinsing products, and distilling. As for the electrical components of the water pump systems, current technologies of variable frequency drives and superconducting transmission lines are unable to increase the energy efficiency of these systems with a fixed load. However, the Balanced Wave Technology (BWT) is offered as a solution to overcome these limitations. In this report, a case study using a BWT optimizer is conducted on a closed loop water circulation system. Two BWTs are added to the individual motor-controlled section of each pump that is being used on the switchboard. For the first time, a detailed example was provided on how to implement option B of the International Performance Measurement and Verification Protocol (IPMVP) in China by evaluating the performance of BWT as an energy conservation measure. The evaluated periods included those of the baseline, post-installation, and actual performance of the optimizers. An average saving of energy of about 10.46% is recorded in a 5-week reporting period. On this basis, that annual electricity saved is estimated to be 66,447.18 kWh, which is equivalent to the emission of 68.94 metric tons of CO2e. This case study demonstrates in detail how option B of IPMVP can be implemented for BWTs applied on pumping systems. In addition to petrochemical production plants, other industries like textile and clothing sections, which are heavy users of water and electrical energy with fixed loads in the production processes of raw materials, fiber, yarn, and fabric, as well as textile-dyeing and final treatment, could benefit from applying this new technology.

Mechanisms of Ketone/Imine Hydrogenation Catalyzed by Transition‐Metal Complexes

Alcohols and amines are important in pharmaceutical, perfume, and agrochemical industries. Catalytic asymmetric synthesis is one of the major ways to produce chiral alcohols/amines from prochiral ketones/imines via hydrogenation. Meanwhile, the alcohol/amine dehydrogenation with high hydrogen energy density is paid more and more attention as promising hydrogen‐storage media. In this review, we summarize classifications of mechanisms of ketone/imine hydrogenation and alcohol/amine dehydrogenation catalyzed by transition‐metal (TM) complexes, the H2 activation modes, and the nature of asymmetric ketone/imine hydrogenation (AKH/AIH). This will elaborate our understanding on the nature of the TM‐catalyzed ketone/imine hydrogenation and alcohol/amine dehydrogenation reactions.

Enzyme adds iodine to diverse substrates

Halogenated compounds are widespread in the pharmaceutical and agrochemical industries. But the reagents used to make them can produce hazardous waste and compound mixtures. Enzymes can provide a milder, more specific route to halogenated compounds, but so far the options for adding iodine have been limited. Now, researchers led by Rebecca J. M. Goss of the University of St. Andrews have identified a viral halogenase they call VirX1, which adds iodine to diverse substrates with a preference for aryl species (Nat. Chem. 2019, DOI: 10.1038/s41557-019-0349-z). “Although we once thought that halogens were rare in nature, over the past decade many halogenating enzymes have been reported,” says Sarah O’Connor, an expert on natural product biosynthesis at the Max Planck Institute for Chemical Ecology, who was not involved in the work. “However, iodinating enzymes have remained elusive.” Enzymes such as peroxidases can add iodine to substrates, but they have low selectivity. Goss

Economic Analysis of Rice Production in Central Agricultural Zone of Adamawa State, Nigeria

This paper analysed the economics of rice production in central agricultural zone of Adamawastate, Nigeria. Purposive and simple random sampling techniques were used to collect primary data from 130rice farmers through field survey using well designed pre-tested schedule. Descriptive statistics, costconcept, stochastic frontier cost model, as well as Garrett’s ranking technique were used to analysed the data.The results revealed that rice production was dominated by young literate men who had been in riceproduction for more than 20 years. Rice production was found to be profitable with net income over cost A1which is the direct cost involved in rice production as N146,049.11; while over cost C3 which is the total costof cultivation of rice was N100,083.62. The stochastic cost frontier model shows three parameters seed,family labour and agro-chemicals had positive and significant effect on the revenue of the rice farmers.Inadequate rainfalls, shortage of labour, clashes with pastoralist were the major constrains associated withrice production in the study area. The study suggest that government policies should be geared towardsdeveloping and establishing new fertilizer and agro-chemicals industries to ease the cost of farm inputs, aswell as intensify farmer grazer conflict resolution programmes.

Intramolecular substitutions of secondary and tertiary alcohols with chirality transfer by an iron(III) catalyst

Optically pure alcohols are abundant in nature and attractive as feedstock for organic synthesis but challenging for further transformation using atom efficient and sustainable methodologies, particularly when there is a desire to conserve the chirality. Usually, substitution of the OH group of stereogenic alcohols with conservation of chirality requires derivatization as part of a complex, stoichiometric procedure. We herein demonstrate that a simple, inexpensive, and environmentally benign iron(III) catalyst promotes the direct intramolecular substitution of enantiomerically enriched secondary and tertiary alcohols with O-, N-, and S-centered nucleophiles to generate valuable 5-membered, 6-membered and aryl-fused 6-membered heterocyclic compounds with chirality transfer and water as the only byproduct. The power of the methodology is demonstrated in the total synthesis of (+)-lentiginosine from D-glucose where iron-catalysis is used in a key step. Adoption of this methodology will contribute towards the transition to sustainable and bio-based processes in the pharmaceutical and agrochemical industries.

Exposure to the azo dye Direct blue 15 produces toxic effects on microalgae, cladocerans, and zebrafish embryos.

Aquatic pollution caused by dyes has increased together with the growth of activities using colorants such as the textile, leather, food, and agrochemicals industries. Because most popular azo dyes are synthesized from benzidine, a carcinogenic compound, a threat to aquatic biota could be expected. The use of single species for toxicity assessment provides limited data, so a battery of test organisms, including representatives of different trophic levels such as algae, zooplankters, and fish, could undoubtedly provide more information. Therefore, our study was aimed at evaluating the toxic effect of the azo dye Direct blue 15 (DB15) on a battery of bioassays using a primary producer (Pseudokirchneriella subcapitata), a primary consumer (Ceriodaphnia dubia), and a secondary consumer (Danio rerio). P. subcapitata was more sensitive to DB15 (IC50 = 15.99 mg L-1) than C. dubia (LC50: 450 mg L-1). In the algae exposed to DB15, chlorophyll-a and -b were significantly increased, and carotenoids were reduced. The concentrations of protein, carbohydrates, and lipids per cell in P. subcapitata exposed to all DB15 concentrations were significantly higher than that measured in control. At 25 mg L-1 of DB15, survival, total progeny, and the number of released clutches were significantly decreased, and the start of reproduction was delayed in C. dubia. DB15 did not induce lethal or sublethal effects in D. rerio embryos at any of the tested concentrations from 24 to 72 h post-fertilization (hpf), but from 96 to 144 hpf, the larvae exposed to 100 and 500 mg L-1 developed yolk sac edema, curved tail, and skeletal deformations. After 144 hpf, DB15 produced a significant increase in embryos without a heartbeat, as the concentration of dye raised. The textile-used, azo dye DB15, caused toxic effects of different magnitude on microalgae, cladocerans, and zebrafish embryos; for this reason, the discharge of this colorant into waterbodies should be regulated to prevent environmental impacts.

Conversion of Chitin to Defined Chitosan Oligomers: Current Status and Future Prospects.

Chitin is an abundant polysaccharide primarily produced as an industrial waste stream during the processing of crustaceans. Despite the limited applications of chitin, there is interest from the medical, agrochemical, food and cosmetic industries because it can be converted into chitosan and partially acetylated chitosan oligomers (COS). These molecules have various useful properties, including antimicrobial and anti-inflammatory activities. The chemical production of COS is environmentally hazardous and it is difficult to control the degree of polymerization and acetylation. These issues can be addressed by using specific enzymes, particularly chitinases, chitosanases and chitin deacetylases, which yield better-defined chitosan and COS mixtures. In this review, we summarize recent chemical and enzymatic approaches for the production of chitosan and COS. We also discuss a design-of-experiments approach for process optimization that could help to enhance enzymatic processes in terms of product yield and product characteristics. This may allow the production of novel COS structures with unique functional properties to further expand the applications of these diverse bioactive molecules.

Selective C-F Functionalization of Unactivated Trifluoromethylarenes.

Fluorinated organic molecules are pervasive within the pharmaceutical and agrochemical industries due to the range of structural and physicochemical properties that fluorine imparts. Currently, the most abundant methods for the synthesis of the aryl-CF2 functionality have relied on the deoxyfluorination of ketones and aldehydes using expensive and poorly atom economical reagents. Here, we report a general method for the synthesis of aryl-CF2R and aryl-CF2H compounds through activation of the corresponding trifluoromethyl arene precursors. This strategy is enabled by an endergonic electron transfer event that provides access to arene radical anions that lie outside of the catalyst reduction potential. Fragmentation of these reactive intermediates delivers difluorobenzylic radicals that can be intercepted by abundant alkene feedstocks or a hydrogen atom to provide a diverse array of difluoalkylaromatics.

Activation of Saturated Fluorocarbons to Synthesize Spirobiindanes, Monofluoroalkenes, and Indane Derivatives.

SummaryFluorinated organic compounds are produced in abundance by the pharmaceutical and agrochemical industry, making such compounds attractive as building blocks for further functionalization. Unfortunately, activation of C(sp3)-F bond in saturated fluorocarbons, especially for aliphatic gem-difluoroalkanes, remains challenging. Here we describe the selective activation of inert C(sp3)-F bonds catalyzed by B(C6F5)3. In hexafluoro-2-propanol (HFIP), chemically robust aliphatic gem-difluorides are converted in high yields to the corresponding substituted 2,2′,3,3′-tetrahydro-1,1′-spirobiindenes via a B(C6F5)3-catalyzed intramolecular cascade Friedel-Crafts cyclization, not requiring a silicon-based trapping reagent. However, in the absence of a hydrogen-bonding donor solvent such as HFIP, the aliphatic gem-difluorides preferentially engage in a defluorination/elimination process that provides monofluorinated alkenes in good yields. Furthermore, a series of substituted 1-alkyl-2,3-dihydro-1H-indenes was obtained in high yield from the B(C6F5)3-catalyzed defluorinative cyclization of aliphatic secondary monofluorides in HFIP. The protocol could inspire development of a new class of main-group Lewis acid-catalyzed C(sp3)-F bond activation in general unactivated fluorocarbons.

Lewis base-catalyzed intermolecular triazene alkyne cycloaddition for late-stage functionalization and scaffold diversification

3-Trifluoromethylpyrazole and its derivatives are of major interest to both the agrochemical and pharmaceutical industry for their diverse biological activities. Reported routes for the synthesis of 3-trifluoromethylpyrazoles are hindered by poor regioselectivity and limited scope of application. Here we report a directed Lewis base catalyzed intermolecular triazene-alkyne cycloaddition. It is featured that the combination of 1,8-diazabicyclo[5.4.0]undec-7-ene and 2,2,2-trifluorodiazoethane produces reactive triazene intermediates, which readily participate in cycloaddition reactions with terminal/internal alkynes, thus assembling densely substituted 3-trifluoromethylpyrazole scaffolds with environmental friendliness and operational simplicity. Synthetic utility of the protocol is highlighted by late-stage functionalization and scaffolds diversification. The practical value is also emphasized in potential platelet aggregation inhibitor synthesis.

Horticultural oils: possible alternatives to chemical pesticides and insecticides.

The farmers and agrochemical industries lack science-based knowledge about sustainable utilization of pesticides and insecticides. The investigation on rising use of chemical pesticides and insecticides has remarkable issue related to environment pollution, soil fertility, and human health; as such, nowadays, many people prefer natural alternatives over synthetic chemicals. Natural products, like horticultural oils, play a significant role for sustainable and safe integrated pest management, providing natural alternatives to chemical pesticides and insecticides. For several decades, both plant- and petroleum-based spray oils have been always used to control various pests, mites, and insects. Currently, these horticultural oils are used as a part of the integrated pest management, which utilizes secure and non-chemical pesticides rather than conventional pesticides. Horticultural oil refers to a complex mixture of hydro-carbons with traces of sulfur- and nitrogen-based compounds, extracted from plants. The key components of horticultural oils include paraffin and olefin. The horticultural oils are considered suitable since they are non-toxic to both plants and animals, are applied easily, have low risk properties, cost-effective, and play significant role in pest control, but show little effects on the beneficial insects. As a result, these attributes make horticultural oils to be considered as secure and effective alternative for chemical insecticides and pesticides for both commercial and domestic agriculture.

Surface Engineered ZnO-Humic/Citrate Interfaces: Photoinduced Charge Carrier Dynamics and Potential Application for Smart and Sustained Delivery of Zn Micronutrient

Nanoscale science and nanotechnology are expected to bring about revolutionary advances in the agrochemical industry. Smart delivery of micronutrients enabling sustained release is one such innovative approach to combat the poor nutrient uptake efficiency of conventional micronutrient sources. Herein, we report a bottom-up surface fabrication strategy to modify nanosized zinc oxide (ZnO NPs) surfaces at an atomic scale for sustained release of Zn micronutrients. A large sized environmentally relevant macromolecule humic acid (HA) and a comparatively smaller biologically pertinent citrate ligand were used to functionalize ZnO NPs (30 nm), and the resultant nanohybrids were characterized using electron microscopy, diffraction, and spectroscopic techniques. Functionalization with citrate ligand turns the NP smaller than its original size. The resultant modification in the dissolution characteristics of ZnO NPs leads to sustained release of Zn over a broad pH range. Functionalization with HA causes minimum alteration of NP sizes. But dissolution patterns of NPs examined separately in the presence of HA depicts stabilization of colloidal suspensions. Additionally, picosecond-resolved lifetime measurements reveal efficient photoinduced charge transfer at the nanoheterojunction interfaces. To evaluate the impact of newly developed Zn delivery system on Zn bioavailability, their impacts on the growth of wheat plants (Triticum aestivum) was tested. Results reveal considerable growth enhancements of plants treated with functionalized NPs. The micronutrient nanoformulation requires no auxiliaries and is applicable to plant systems in aqueous dispersions. Our study reinstates the importance of “convergence thinking” or coming together of technologies as a key to creating a fundamental framework toward environmental sustainability.

Evaluation of genetic damage in pesticides applicators from the province of Córdoba, Argentina.

The impact evaluation of pesticide exposure is conducted using combined data from biomonitoring and environmental monitoring. Damage to the human genome is, probably, the leading cause of chronic-degenerative disorders, reproductive toxicology, and developmental problems. Although the general population is exposed to pesticides, workers in the agrochemical industry and farmers represent a high-risk group due to the occupational and environmental exposure. The aim of this study is to determine whether occupational exposure to agrochemicals in Córdoba (Argentina) constitute a factor of genotoxic damage. The study was conducted in 30 pesticide applicators from the province of Córdoba. Chromosomal aberrations (CAs), micronuclei (MN), and comet assays (CO) were performed. The current study shows that occupational exposure to pesticides increases values of CAs, MN, and DNA fragmentation biomarkers, all indicators of damage to the genetic material. Evidence suggests that chronic exposure to pesticides is a potential risk to workers health.

Hydrogel capsules with alfalfa as micronutrients carrier

The aim of this work was to study the properties of biocomposite based on sodium alginate and carboxymethyl cellulose with immobilized alfalfa as a material with controlled release of Cu2+ ions. Physicochemical (swelling, pHZPC) and sorption (kinetics, equilibrium) properties of the produced structures were investigated. Kinetic data were best described using a general rate law model, and the value of kinetic rate constant was 5.34 × 10−6. The sorption kinetics are also described using the Weber–Morris model, and the analysis revealed a three-step sorption. The maximum sorption capacity was determined using the Sips model and amounted to 9 mg g−1. Desorption of Cu2+ ions in soil solution (NaNO3 1 wt%) was carried out, and biocomposites released micronutrients in a slow way. The results showed that biocomposites with immobilized alfalfa are a very good material for potential applications in the agrochemical industry as a controlled released fertilizer.

Food security in 2044: How do we control the fungal threat?

Plant fungal pathogens place considerable strain on agricultural productivity and threaten global food security. In recent decades, advances in crop breeding, farming practice and the agrochemical industry have allowed crop yields to keep pace with food demand. In this opinion article, we speculate on which recent technological advances will allow us to maintain this situation into the future. We take inspiration that it is 25 y since the first plant disease resistance genes were cloned, and imagine if and how agricultural control of pathogens will be achieved by the year 2044. We examine which technologies are best poised to make the jump from lab bench to field application, and propose that future control measures will likely depend on effective integrated disease management.

Stereoselective carbonyl reductases and their roles in asymmetric synthesis of bulky chiral hydroxyl compounds

Chiral hydroxyl compounds have been widely used in pharmaceutical, agrochemical, fine chemicals, and functional materials industries, due to their unique physical and chemical properties. Stereoselective carbonyl reductases can be efficiently applied to catalyze asymmetric synthesis of chiral hydroxyl compounds with high optical purity from directed reduction of prochiral carbonyl group of the corresponding keto substrates. Based on the diversity of substrates, single enantiomers of various chiral hydroxyl compounds, including chiral alcohols, hydroxyl esters, and hydroxyl amino acids, can be prepared through carbonyl reductase-catalyzed asymmetric reduction in a high efficiency. However, most of the available carbonyl reductases only exhibit low activity towards the substrates involving bulky groups. This review summarizes the basic traits and principles of biocatalytic asymmetric oxidoreductions, and the key characteristics and structure-function relationship of stereoselective carbonyl reductases. In addition, the carbonyl reductases and their systems for asymmetric synthesis of bulky chiral hydroxyl compounds are also addressed, and the potential strategies targeting the critical issue are further discussed.

Nickel-catalyzed Suzuki\u2013Miyaura cross-couplings of aldehydes

Transition-metal-catalyzed cross-couplings have been extensively used in the pharmaceutical and agrochemical industries for the construction of diverse C–C bonds. Conventional cross-coupling reactions require reactive electrophilic coupling partners, such as organohalides or sulfonates, which are not environmentally friendly and not naturally abundant. Another disadvantage associated with these transformations is the need for an exogenous base to facilitate the key transmetalation step, and this reagent inevitably induces side reactions and limits the substrate scope. Here, we report an unconventional Suzuki-type approach to the synthesis of biaryls, through nickel-catalyzed deformylative cross coupling of aldehydes with organoboron reagents under base-free conditions. The transformation tolerates structurally diverse (hetero)aryl substituents on both coupling partners and shows high reactivity and excellent functional group tolerance. Furthermore, the protocol was carried out on gram scale and successfully applied to the functionalization of complex biologically active molecules. Mechanistic investigations support a catalytic cycle involving the oxidative addition of the nickel into the aldehyde C(acyl)–H bond with subsequent hydride transfer, transmetalation, decarbonylation and reductive elimination processes.