Acid Esters Research Articles

Quantification of agricultural plastic debris loss through soil erosion and associated phthalic acid esters emissions into the aquatic environment

Terrestrial agricultural plastic film (APF) residue migration triggered by soil erosion constitutes a primary disruption in the plastic waste cycle. However, the migration mechanisms of APF residue and phthalate acid esters (PAEs) emissions from APF debris into China’s aquatic environment remain inadequately understood. This study assessed APF residue loss induced by soil erosion and the associated PAEs emissions from 14 crop categories across China for 1998–2020, employing an integrated estimation framework and high-resolution agricultural activity data. Our findings indicate that the APF residue loss ranged in 968.95–2081.76 tons yr-1 during the study period, peaking in 2016. Areas with high APF residue losses were concentrated in southwestern, central, northwestern, northeastern, northern, and eastern China. Moreover, PAEs emitted from APF debris ranged in 29.57–59.42kgyr-1 over the same period, with emission hotspots identified in northwestern, southwestern, and eastern China. The APF application, meteorological factors, and soil properties collectively accounted for 33.82%, 33.33%, and 13.66% of the total variance, respectively. Finally, the potential ecological risk posed by PAEs to the aquatic environment was found to be low. Overall, our findings offer crucial insights into the dynamics of plastic contamination and provide foundational knowledge for safeguarding aquatic environments in China.

High-performance bio-based foam from agricultural waste luffa seed oil polyols

The present study aimed to develop eco-friendly polyurethane viscoelastic foam (PVF) with enhanced tear strength while preserving softness, comfort, and safety by utilizing bio-based polyols derived from luffa seed oil (LSO). Two types of bio-based polyols (PLSO-D and PLSO-M) were synthesized through the epoxidation process using diethylene glycol (DEG) and methanol (MeOH), respectively, for the production of LSO-based polyurethane viscoelastic foams (LSO-PVFs). The analyses revealed that these polyols exhibited high dispersion, appropriate hydroxyl values, and contained by-products such as oligomeric esters of fatty acids that facilitated physical and chemical crosslinking. LSO-PVFs demonstrated a uniform and fine cell structure with abundant open-cells, thick cell walls (55.5–76.6µm), and high apparent density (48.7–50.7kg/m3). Moreover, they exhibited enhanced tensile and tear strength (increasing up to 200% compared to petroleum-based PVFs), lower water absorption, excellent mildew resistance at 10% PLSO substitution. Additionally, these factors endowed LSO-PVFs with low indentation hardness and good bottom support performance, characterized by a compressive deflection coefficient of 2.30–3.54. This approach presents a sustainable alternative for foam production that offers comfort, durability while promoting the value-added utilization of agricultural waste.

Assessment of two benzylation strategies for the analysis of nerve-agent derived ethyl- and pinacolyl methyl phosphonic acids in sandy loam soil by GC–MS

Despite their prohibition by the Chemical Weapons Convention, nerve agents (NAs) remain in use against military and civilian targets. Due to their high reactivity, NAs readily degrade to phosphonic acids, making them important markers in the inspection of areas of presumed NA use. In this work, we assess the use of benzylation to modify ethyl- and pinacolyl methylphosphonic acids, degradation products of VX and Soman respectively, for their efficient detection in a soil matrix at ∼10 and ∼1 μg/g using GC–MS. The soil matrix, Sandy Loam (SL), was chosen for its ubiquitous nature, complex composition with silica particles embedded in clay, and low organic content. In this study, we demonstrate that benzylation via benzyl bromide yields a LOD = 25.6 ng/mL for benzylated-EMPA and LOD = 30.1 ng/mL for benzylated-PMPA. This is superior to the use of p-methoxybenzyl trichloroacetimidate in providing stable phosphonic acid ester derivatives for analysis. A base-modified procedure for p-methoxybenzylation was explored in this study yielding a LOD = 29.1 ng/mL for p-methoxybenzylated-EMPA and LOD = 39.8 ng/mL for p-methoxybenzylated-PMPA. Both benzylation pathways (benzyl bromide and p-methoxybenzyl trichloroacetimidate) can be used to yield phosphonic acid derivatives that provide further confirmation of these Soman and VX degradation products in soil samples in investigative scenarios. The work herein represents the first application of benzylation methods for the analysis of these NA markers in the acidic, silicon-based SL soil.

Evaluation of phthalate acid esters (PAEs) in kefir samples by using magnetic chitosan coated with polyaniline (Fe3O4@CHI@PANI)/GC–MS method: A health risk assessment study

In this study, by magnetic chitosan coated with polyaniline (Fe3O4@CHI@PANI) −gas chromatography/mass spectrometry (GC/MS) method was applied to analyze six PAE compounds in kefir samples. The results obtained from kefir samples showed that the lowest and highest mean of PAEs were associated to dimethyl phthalate (DMP was not detected or nd) and di-n-octyl phthalate (DNOP, 2.12 µg/kg), respectively. Also according to results the average of DEHP (Bis(2-ethylhexyl)phthalate) and total PAEs in all samples were 1.31 ± 0.72 and 4.58 ± 1.87 µg/kg, respectively. Furthermore, maximum and minimum mean of total PAEs were detected in the packages with a volume of 1000 mL (5.47 ± 2.03 μg/kg) and packages with a volume of 1500 mL (3.69 ± 1.23 μg/kg), respectively, and the maximum and minimum mean total PAE (μg/kg) were related to samples with a date less than the expiration date (5.42 ± 1.46) and samples with a date greater than the production date (3.73 ± 1.91), respectively. The level of these contaminants was lower than the existing standard levels. The assessment of human health risks, comprising risks of non-carcinogenic and carcinogenic were calculated with Monte Carlo simulation (MCS) and sensitivity analysis under certain removal efficiencies from 5 to 95 %. The result of the carcinogenic risk for DEHP showed that adults are not threatened by the consumption of kefir (1.06E-05), while children are exposed to negligible risk the consumption of kefir (1/48E-04). In all samples, the total non-carcinogenic risk of PAE compounds was less than 1 (TTHQ was 2.03E-04 and 4.33E-05 for children and adults, respectively), this values presenting there would be unlikely risks of non-carcinogenic of PAEs in kefir for consumers. In conclusion, it can be stated it doesn’t pose any threat to Iranian consumers (adults and children).

Occurrence, bioaccumulation, and partitioning of phthalate acid esters in the third largest freshwater lake (Lake Taihu) in China

Phthalate acid esters (PAEs) are a category of plasticizers that are ubiquitous in freshwater environments attributable to extensive utilization. We collected water, suspended particulate matter (SPM), surface sediments, phytoplankton, and zooplankton from 23 sampling sites to investigate and complement the occurrence, bioaccumulation, and partitioning of five PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), and di (2-ethylhexyl) phthalate (DEHP) in the third largest freshwater lake (Lake Taihu) of China. PAEs were extracted using Soxhlet extraction and solid phase extraction, and determined by gas chromatography-mass spectrometry. The average concentrations of the five PAEs in the water column, SPM, sediments, phytoplankton, and zooplankton of Lake Taihu were 1.93±1.57μgL-1, 765±766μgg-1, 1.68±1.47μgg-1, 1358±1877μgg-1, and 72.7±134μgg-1, respectively. DBP and DEHP were the dominant PAE congeners in the five environment compartments. The logarithmic concentrations of DBP, BBP, and DEHP in the SPM were negatively correlated with the logarithmic content of the SPM. Biodilution significantly impacted the occurrence of PAEs in the plankton. Bioaccumulation of PAEs was found in the plankton with log BCF (bioconcentration factor) in the phytoplankton ranging from 1.78±0.86 to 4.13±1.23 and log BAF (bioaccumulation factor) in the zooplankton varying from -0.10±0.26 to 3.04±0.64. Biomagnification of the PAEs from phytoplankton to zooplankton was not observed. DMP, DEP, and BBP migrated from sediments to water. DBP was in dynamic equilibrium in the sediment-water system. DEHP transferred from water to sediments. Our results provide crucial complementary knowledge on bioaccumulation and transfer of PAEs in planktonic food web, and their partitioning in different compartments of waters.

Biochar amendment affects the fate of phthalic acid esters in the soil-vegetable system.

Phthalates, e.g., esters of phthalic acid (PAEs), when used as plasticizers due to weak physical bonding with polymer matrix favoring leaching, are widely noted in the environment. Their confirmed toxicity to plants and animals implies that their fate should be monitored in the environment, especially when considering the interaction between soil and vegetables. Removal of PAEs from the environment or limiting their bioavailability is a key point in reducing their harmful effects. In the present paper, the fate of six PAEs in the biochar-amended soil during the cultivation of two popular vegetables, lettuce, and radish, was estimated. High bioaccumulation in the soil was noted with the biochar obtained from residues from biogas production being up to 15% higher than in the case of the other biochar and up to 10 times higher than in plants due to increased basic character of biochar. This biochar reduced the bioavailability of DEP (diethyl phthalate), DBP (dibutyl phthalate), BBP (butyl benzyl phthalate), and DNOP (di-n-octyl phthalate) in radish roots and DBP in lettuce leaves. However, PAEs significantly increased the fresh mass of radish and slightly increased the mass of lettuce. All six tested PAEs in both plants reached higher concentrations in the leaves (up to two orders of magnitude) than in the roots. Additionally, PAEs were present in two times higher concentrations in the lettuce than in the radish. The biochar aromaticity, porosity, and the presence of organic carbon and inorganics (ash) affect the fate of tested pollutants depending on the tested plant and compound.

Catalytic properties of selenium and phosphorus ionic liquids heterogenized on algae-based biochar

Catalytic performance of pyridinium hydrogen selenate (PHSe) and pyridinium dihydrogen phosphate (PH2P) ionic liquids immobilized on algae-based biochar (AC) was studied for the first time. For that purpose, acetic acid esterification with butanol was used as a test reaction. To investigate the surface effects, textural properties and thermal behavior for PHSe/AC and PH2P/AC, physicochemical methods such as X-ray powder diffraction (XRD), nitrogen adsorption–desorption isotherms (SBET) scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied. In addition, influence of the catalyst content (5–12 wt%) and reaction temperature (60–80 °C) on the butyl acetate yield and rate constant of esterification were evaluated. SBET and SEM measurements revealed that all of the samples (AC, PHSe/AC and PH2P/AC) obtained are mixed microporous-mesoporous materials. XRD and XPS data showed more highly dispersed PH2P particles than PHSe on the carrier surface due to stronger surface ionic liquid-support interaction for PH2P/AC in comparison with PHSe/AC. The latter was responsible for higher thermal stability of PH2P/AC with respect to PHSe/AC. In addition, more obvious PH2P sites (than PHSe) on the biochar surface favored the ester production in the presence of PH2P/AC (77.4 % and 53.26 × 10−4 l/mol × min) more evidently than PHSe/AC (58.1 % and 28.82 × 10−4 l/mol × min).

Metal-Exchanged Phosphomolybdic Acid Salts-Catalyzed Esterification of Levulinic Acid

We examined the effectiveness of metal-exchanged phosphomolybdic acid salts in converting levulinic acid, derived from biomass, into valuable products (alkyl levulinate). We prepared salts of phosphomolybdic acid using different metals (Fe3+, Al3+, Zn2+, Cu2+, Mn2+, Ni2+, and Co2+). The influence of metal cations on the conversion and selectivity of the reactions was assessed. We found that the salts prepared with iron and aluminum phosphomolybdate were the most effective catalysts for the esterification of levulinic acid with methanol, with the conversion and selectivity tending towards 100% after 6 h of reaction at a temperature of 323 K. The effect of catalyst loading and its recovery and reuse was evaluated; the results from the reaction using aluminum phosphomolybdate remained similar for four cycles of use. The influence of temperature on conversion and selectivity was investigated between 298 and 353 K. The reactivity of different alcohols with a carbon chain size of C1-C4 was assessed and conversions above 65% were obtained for all alcohols tested under the conditions evaluated, except for tert-butyl alcohol. These catalysts are a promising alternative to the traditional soluble and corrosive Brønsted acid catalysts. The superior performance of these catalysts was ascribed to the higher pH decline triggered by the hydrolysis of these metal cations.

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

In this study, novel fluorinated carboxylic acid esters of the generic structure TfO–CH2–(CF2)n–COOCH3 (n = 2,4,6, Tf = triflate) were synthesized. The triflates were reacted with 2-hydroxy-3,4,5-trimethoxybenzaldehyde via Williamson ether syntheses. The resulting electron-rich compounds were used as aldehydes in the Rothemund reaction with pyrrole to form ester-substituted porphyrins. After metalation with Ni(acac)2 and hydrolysis electron-rich porphyrins were obtained, that are equipped with covalently attached long chain acid substituents. The target compounds have potential applications in catalysis, sensing, and materials science. The fluorinated aliphatic carboxylic acids (TfO–CH2–(CF2)n–COOCH3) with triflate as leaving group in terminal position are easily accessible and versatile building blocks for attaching long chain acids (pKa 0–1) to substrates in Williamson ether-type reactions.

One-Step Esterification of Phosphoric, Phosphonic and Phosphinic Acids with Organosilicates: Phosphorus Chemical Recycling of Sewage Waste.

Global concerns regarding the depletion and strategic importance of phosphorus resources have increased demand for the recovery and recycling. However, waste-derived phosphorus compounds, primarily as chemically inert phosphoric acid or its salts, present a challenge to their direct conversion into high-value chemicals. We aimed to develop an innovative technology that utilizes the large quantities of sewage waste, bypasses the use of white phosphorus, and enables esterification of phosphoric acid to produce widely applicable phosphate triesters. Tetraalkyl orthosilicates emerged as highly effective reagents for the direct triple esterification of 85% phosphoric acid, as well as the esterification of organophosphinic and phosphonic acids. Furthermore, we achieved esterification of recovered phosphoric acid with tetraalkyl orthosilicate, thus pioneering a recycling pathway from sewage waste to valuable phosphorus chemicals. Experimental and theoretical investigations revealed a novel mechanism, wherein tetraalkyl orthosilicates facilitate multimolecular aggregation to achieve alkyl transfer from tetraalkylorthosilicate to phosphoric acid via multiple proton shuttling.

Impact of Citrate on Mitigating Iron Mediated Polysorbate 80 Degradation in Biotherapeutic Formulation Placebos.

Polysorbate 80 (PS80), a widely used polymeric surfactant in biotherapeutic formulation, possesses a unique structural composition that effectively prevents protein aggregation in highly concentrated protein drug formulations. However, PS80 is susceptible to hydrolysis, due to the presence of fatty acid esters that can be enzymatically hydrolyzed, The unsaturated bonds in the fatty acids are prone to oxidative degradation when exposed to air, especially in the presence of transition metals such as iron and copper, which may be introduced during production and purification processes or from contamination in raw materials used in drug formulation. The degradation of PS80, particularly through metal-mediated oxidative degradation, poses a significant challenge for the industry. Among the identified trace metals, iron plays a crucial role as the redox reaction between ferrous ion (Fe(II)) and ferric ion (Fe(III)) generates radicals that initiate the degradation process. In order to investigate the impact of iron on PS80 degradation and understand the mechanism of iron-catalyzed oxidation, we utilized charge-reduction mass spectrometry and two-dimensional ion density mapping technologies to characterize the degradation of PS80. This method has proven to be a convenient and effective tool for the quick and detailed profiling of PS80, allowing for visual monitoring and examination of the changes that reflect the difficult-to-identify and easy-to-miss oxidized species of PS80. Additionally, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry method was developed for the separation and measurement of Fe(II) and Fe(III). Through this investigation, we determined that the involvement of Fe(II)/Fe(III) in PS80 degradation is a temperature dependent process. Furthermore, we found citrate not only promotes the conversion of Fe(II) to Fe(III), but it also chelates Fe(III) and prevents its reduction to Fe(II), thus inhibiting the initiation of the PS80 degradation. Therefore, the addition of citrate can be a crucial ingredient for controlling the degradation of PS80 in biologic drug substances and products. Overall, this investigation has provided valuable insights to enhance product stability, optimize processes, and ensure the quality of formulations containing PS80.

Photochemical Deracemization of N‐Carboxyanhydrides En Route to Chiral α‐Amino Acid Derivatives

AbstractReadily accessible, racemic N‐carboxyanhydrides (NCAs) of α‐amino acids underwent a deracemization reaction upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst. The enantioenriched NCAs (up to 98 % ee) serve as activated α‐amino acid surrogates and, due to their instability, they were directly converted into consecutive products. N‐Protected α‐amino acid esters were obtained after reaction with MeOH and N‐benzoylation (14 examples, 70 %‐quant., 82–96 % ee). Other consecutive reactions included amide (ten examples, 65 %‐quant., 90–98 % ee) and peptide (three examples, 75–89 %, d. r.=97/3 to 94/6) bond formation. Limitations of the method relate for some NCAs to issues with solubility, photooxidation, and high configurational lability.

Asymmetric Synthesis of 3,3′-Pyrrolidonyl Spirooxindole-5′-Carboxylic Ester from l-Tryptophan

AbstractA highly efficient, multi-gram scale asymmetric synthesis of 3,3′-pyrrolidonyl spirooxindole-5′-carboxylic ester, which could be a potential precursor for the synthesis of cyanogramide, is accomplished from commercially available l-1-methyltryptophan in two pots. Fluoride-promoted desilylative spiro-cyclization of (semi) in situ generated isocyanate derived from l-1-methyltryptophan is the key reaction. Further, a variety of arene-substituted 3,3′-pyrrolidonyl spirooxindole-5′-carboxylxic acid esters were synthesized by late stage functionalization of easily accessible 3,3′-pyrrolidonyl spirooxindole-5′-carboxylic ester.

Photochemical Deracemization of N-Carboxyanhydrides En Route to Chiral α-Amino Acid Derivatives.

Readily accessible, racemic N-carboxyanhydrides (NCAs) of α-amino acids underwent a deracemization reaction upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst. The enantioenriched NCAs (up to 98 % ee) serve as activated α-amino acid surrogates and, due to their instability, they were directly converted into consecutive products. N-Protected α-amino acid esters were obtained after reaction with MeOH and N-benzoylation (14 examples, 70 %-quant., 82-96 % ee). Other consecutive reactions included amide (ten examples, 65 %-quant., 90-98 % ee) and peptide (three examples, 75-89 %, d. r.=97/3 to 94/6) bond formation. Limitations of the method relate for some NCAs to issues with solubility, photooxidation, and high configurational lability.

Asymmetric Organocatalysed Synthesis of (R)-Mandelic Acid Esters and α-Alkoxy Derivatives from Commercial Sources.

Optically active mandelic acid esters represent a highly valuable class of building blocks in organic synthesis and recurrent motifs embedded in bioactive compounds and drugs. Herein, we provide an enantioselective one-pot synthesis based on Knoevenagel condensation/asymmetric epoxidation/domino ring-opening hydrolysis (DROH) sequence to the crude mandelic acids, which underwent a final esterification step to (R)-methyl mandelates. These products have been obtained in good to high overall yield and enantioselectivity, using commercially and widely available reagents and catalyst including aldehydes, phenylsulfonyl acetonitrile, cumyl hydroperoxide, water and an epi-quinine-derived urea as the organocatalyst. Moreover, the versatility of the process has been demonstrated to prepare the corresponding α-alkoxy esters in highly enantioselective manner, when using primary alcohols in a domino ring-opening esterification (DROE) step. This system is a first example of non-enzymatic catalytic one-pot protocol which allows a straightforward asymmetric synthesis of highly valuable mandelic acid derivatives from aldehyde feedstocks.

Chemical and Sensory Profile of Grape Distillates Aged in Quercus alba Casks Previously Used for Sherry Wine or Brandy

This work investigates the influence of oak-cask ageing on the chemical composition and sensory profile of a variety of grape distillates. Wine spirit, wine distillate, neutral alcohol, and grape marc distillate were investigated. It is known that the characteristics of the ageing casks may have a considerable impact on the ageing process, so casks that had previously contained some type of sherry wine, sherry cask®, and casks that had previously contained brandy were studied. The results showed that ageing in either type of cask resulted in significant changes regarding volatile compound composition and a noticeable increase in phenolic and furfural compound content. Furthermore, sherry casks® contributed with sherry wine characteristic compounds that enriched the aromatic profile of the distillates, such as a greater increase in ethyl esters of organic acids. A less noticeable evolution was exhibited by the distillates with higher levels of congeners (wine spirit and grape marc distillate) when compared to wine distillate or neutral alcohol, where changes due to ageing were more evident. The sensory analysis confirmed that ageing significantly modified the organoleptic characteristics of all the distillates, with an increasing perception of certain notes such as oak, vanilla, spicy, and vinous when aged in sherry cask®.

Isolation of Novel Compounds from Lepidium sativum Seeds and Evaluation of Their Potential Anti-Tumor Activity.

Four undescribed compounds including a pair of enantiomers of a dihydroarylnaphthalene lignan [(±)-1], an arylnaphthalene lignan (2), and an indoleacetic acid ester (3), together with four known compounds (4-7), were isolated from the seeds of Lepidium sativum. Their structures were identified by HRMS and NMR spectroscopic data, and the absolute configuration of these compounds were assigned by ECD data in combination with quantum chemical calculations. Compound (-)-1 had weak inhibitory activity against HeLa cell line with an IC50 value of 60.23±3.51 μM, and compound (+)-1 presented moderate inhibitory effect against HeLa cell line with an IC50 value of 19.99±1.00 μM (IC50 value of the positive control was 0.40±0.02 μM).

In vitro skin permeation of flavonoid esters enzymatically derived from natural oils: release mechanism from gel emulsion, stability, and dermatological compatibility

Due to their broad spectrum of biological activities and attractive pharmacological properties, flavonoids are very promising molecules for application in skin care products. In this study, phloridzin and naringin medium- and long-chain fatty acid esters were enzymatically synthesized in reaction with natural oils (coconut and linseed oil) and in vitro transdermal delivery of synthesized esters through artificial Strat-M® membrane was investigated. Experimental results were succesfully fitted using Peppas and Sahlin model which includes the lag phase. Release kinetics of all examined flavonoid esters from gel emulsions through the membrane depended on both diffusion and polymer relaxation effect (0.5<n < 1). The estimated effective diffusion coefficients ranged from 0.168·10-8 to 6.149·10-8 cm2 s-1 for phloridzin esters and from 0.116·10-8 to 4.210·10-8 cm2 s-1 for naringin esters. The effective diffusion coefficients decreased with the increase in ester molecular weight indicating the size-dependent diffusion. All formulation showed good stability, excellent hydration effect, and excellent dermatological compatibility without irritating effect. It can be concluded that gel emulsions with a mixture of flavonoid esters enzymatically synthesized in reaction with vegetable oils can be effectively topically applied as a skin care products.

Tungstic Acid-Functionalized Natural Zeolite as a Solid Acid Catalyst for Levulinic Acid Esterification

Tungstic Acid-Functionalized Natural Zeolite as a Solid Acid Catalyst for Levulinic Acid Esterification

Synthesis of the C1-C15 Fragment of Incednine

We report on our progress towards the synthesis of the exotic, delicate and tense polyketidic macrolactam of incednine. This work constitutes a significant advancement towards the total synthesis of a family of molecules of biological and medicinal interest. Some of the key features of this synthesis required evolutions from the initially designed strategy, leading to the use of a HWE to build the C2-C9 tetraene. For this purpose, a polyfunctionalized phosphonate was used and obtained through an unprecedented Pd-catalyzed cross-coupling involving the zinc anion of diethyl methylphosphonate. The resulting desired C1-C15 fragment displays a carboxylic acid ester at C1 and a vinyl iodide at C15, both functions being ready for subsequent amide coupling with the C16-C23 fragment and final Suzuki cyclization respectively.