2,4-Dimethylphenol

Phenolic compounds seasonal occurrence and risk assessment in surface and treated waters in Minas Gerais-Brazil.[Pubmed:33120340]

Environ Pollut. 2020 Oct 6;268(Pt A):115782.

This study provided a monitoring of phenolic compounds occurrence in a river and in its treated water by a conventional water treatment plant (WTP) throughout a year-period, in Minas Gerais - Brazil. Furthermore, the environmental risk (hazard quotient - HQ), the human health risk (margin of exposure - MOE), and the cancer risk were calculated for the compounds. The results indicated that sixteen out of the seventeen investigated phenolic compounds were detected at some point during the sampling campaign. The most frequent compounds in the raw surface water were 2,3,4-trichlorophenol (234TCP), 2,4-Dimethylphenol (24DMP), and 4-nitrophenol (4NP), whereas in treated water were 4NP and bisphenol A (BPA). In addition, the highest total concentration values were corelated to the months in which there was less precipitation, demonstrating that the presence of this micropollutants may be subject to seasonality. From the treated water results, it was not possible to state the efficiency of the conventional WTP in eliminating the phenols, since in some samples the phenolic compounds were totally removed and in others their increase or formation occurred. Regarding to the risk assessments, most of the evaluated compounds were considered highly toxic to some trophic level and posed a significant human health risk. Additionally, the risk reduction of phenolics using conventional WTP was low. The sixteen phenols contamination in surface and drinking waters appears to be subject to seasonality. Besides that, an alarming risk for environment and human health was identified.

Assessment of cross-reactivity in a tailor-made molecularly imprinted polymer for phenolic compounds using four adsorption isotherm models.[Pubmed:32841770]

J Chromatogr A. 2020 Oct 11;1629:461463.

Cross-reactivity is an important feature of molecularly imprinted polymers (MIPs), and is central to successful use of a pseudo-template in molecular imprinting. The adsorption and cross-reactivity of a molecularly imprinted polymer (MIP) designed for recognition of phenols from water was assessed using four different isotherm models (Langmuir (LI), Freundlich (FI), Langmuir-Freundlich (L-FI), and Brunauer, Emmett, and Teller (BET)). The L-FI model succeeded in explaining the cross-reactivity behavior through the total number of binding sites, the affinity constants and heterogeneity indices of the small phenols (phenol (ph), 2-methylphenol (2-MP), 3-methylphenol (3-MP), 2-chlorophenol (2-CP), 2,4-Dimethylphenol (DMP), 2,4-dichlorophenol (DCP), 4-chloro-3-methylphenol (CMP)) with evidence that the phenols compete for binding sites based on their hydrophobicity as well as pi-pi, pi-sigma and dipole-dipole intermolecular forces. The recognition of the large phenols (2,4,6-trichlorophenol (TCP), pentachlorophenol (PCP), 4-teroctylphenol (4-OP), 4-nonylphenol (4-NP), which have much higher binding affinities than the smaller phenolic compounds, was explained with the BET isotherm model that predicts that multiple layers adsorb to the adsorbed monolayer. The adsorption behavior with MIPs is also shown to be superior to corresponding non-imprinted polymers and applicability of MIPs for trace analysis is highlighted.

Bamboo tar as a novel fungicide: its chemical components, laboratory evaluation, and field efficacy against false smut and sheath blight of rice, and powdery mildew and Fusarium wilt of cucumber.[Pubmed:32772833]

Plant Dis. 2020 Aug 9.

The application of agricultural and forest residues can benefit the environment and the economy; however, they also generate a large amount of by-products. In this study, bamboo tar (BT), a waste product of bamboo charcoal production, was dissolved in natural ethanol and the surfactant alkyl glucoside to manufacture a 50% (wt/wt) BT emulsifiable concentrate (BTEC) biopesticide. BTEC was screened for fungicidal activity against pathogens. The greatest activity was seen against Ustilaginoidea virens with an EC50 (half-maximal effective concentration) value of 6 mg/L. Four phytopathogenic fungi, Podosphaera xanthii, Rhizoctonia solani, Fusarium oxysporum, and Botrytis cinerea, showed EC50 values of < 60 mg/L. Greenhouse tests in vivo showed 2,000 mg/L BTEC had a 78.4% protective effect against U. virens, and replicated treatments had an 80.6% protective effect. In addition, replicated two-year field trials were conducted in two geographical locations with four plant diseases; namely, false smut (U. virens), rice sheath blight (Thanatephorus cucumeris (Frank) Donk), cucumber powdery mildew (P. xanthii) , and cucumber Fusarium wilt (F. oxysporum). Results showed that 1,000-2,000 mg/L BTEC significantly inhibited these diseases. GC-MS analysis showed that the total phenolic mass fraction of two BT samples were 45.39% and 48.26%. Eleven components were detected and their percentage content was the following order (from high to low): 2,6-dimethoxyphenol > 2- or 4-ethylphenol > 2- or 4-methylphenol > phenol > 4-ethylguaiacol > dimethoxyphenol > 4-methylguaiacol > 4-propenyl-2,6-dimethoxyphenol > 2,4-Dimethylphenol. Some of the phenolic compounds identified from the tar might be fungicidally active components. BT is a biochar waste, which has potential as a biofungicide and has promise in organic agriculture. The value of this tar may not be due to any fundamental physical differences from other synthetic fungicides, but rather due to reduced production expenses and more efficient utilization of waste products.

Structure-activity studies on analogues of 4-methylguaiacol, a cattle anal odour constituent repellent to the brown ear tick (Rhipicephalus appendiculatus).[Pubmed:30922799]

Acta Trop. 2019 Jun;194:78-81.

Previously, 4-methylguaiacol, a major constituent of cattle anal odour, was found to have a high repellency on Rhipicephalus appendiculatus. In the present study, 10 structural analogues of the phenol were tested for repellency against R. appendiculatus in order to assess the effects of (i) absence or presence of the 4-alkyl group of varying length, (ii) inclusion of a double bond in the 4-alkyl chain, (iii) linking the two phenolic oxygen in a methylenedioxy bridge, (iv) replacement of the OCH3 with CH3 and inclusion of another CH3 at position 6, and (v) presence of an additional OCH3 group at position 6. The analogues comprised of 2-methoxyphenol (guaiacol), 4-ethyl-2-methoxyphenol, 4-propyl-2-methoxyphenol, 4-allyl-2-methoxyphenol (eugenol), 3,4-methylenedioxytoluene, 2,4-Dimethylphenol, 4-ethyl-2-methylphenol, 2,4,6-trimethylphenol, 4-propyl-2,6-dimethoxy-phenol and 4-allyl-2,6-dimethoxyphenol, which were compared at different concentrations in a two-choice climbing assay set up. Each analogue showed either increased or reduced repellency compared with 4- methylguaiacol. The structural feature that was associated with the highest repellency was 4-propyl moiety in the guaiacol unit (RD75 = 0.031 for 4-propyl-2-methoxyphenol; that of 4-methylguaiacol = 0.564). Effects of blending selected analogues with high repellency were also compared. However, none of the blends showed incremental increases in repellency compared with that of 4-propyl-2-methoxyphenol. We are currently evaluating the effects of controlled release of this compound at different sites on cattle on the behavior and success of R. appendiculatus to locate their predilection for feeding sites.

Water-Tolerant Trifloaluminate Ionic Liquids: New and Unique Lewis Acidic Catalysts for the Synthesis of Chromane.[Pubmed:30483493]

Front Chem. 2018 Nov 12;6:535.

The first example of triflometallate ionic liquids, named in analogy to chlorometallate ionic liquids, is reported. Trifloaluminate ionic liquids, synthesized from 1-alkyl-3-methylimidazolium triflates and aluminum triflate, were characterized by multinuclear NMR spectroscopy and FT-IR spectroscopy, revealing the existence of oligonuclear, multiply-charged trifloaluminate anions, with multiple bridging triflate modes. Acceptor numbers were determined to quantify their Lewis acidity, rendering trifloaluminate ionic liquids as medium-strength Lewis acids (AN = ca. 65). Used as acidic catalysts in the cycloaddition of 2,4-Dimethylphenol and isoprene (molar ratio 2:1) to prepare chromane, trifloaluminate systems outperformed literature systems, showing high activity (conversions 94-99%, selectivities 80-89%) and at low loadings (0.2 mol%) at 35 degrees C. Using these new systems as supported ionic liquid phase (SILP) on multi-walled carbon nanotubes (ionic liquid loading 16 wt%) delivered a recyclable catalytic system, with activity enhanced with respect to the homogenous regime.

On the applicability of a hybrid bioreactor operated with polymeric tubing for the biological treatment of saline wastewater.[Pubmed:28511350]

Sci Total Environ. 2017 Dec 1;599-600:1056-1063.

Effective biological treatment of high salt content wastewater requires consideration of both salt and organic toxicity. This study treated a synthetic saline wastewater containing NaCl (100gL(-1)) and 2,4-Dimethylphenol (1.2gL(-1)) with a hybrid system consisting of a biological reactor containing spiral-coiled polymeric tubing through which the mixed feed was pumped. The tubing wall was permeable to the organic contaminant, but not to the salt, which allowed transfer of the organic into the cell-containing bioreactor contents for degradation, while not exposing the cells to high salt concentrations. Different grades of DuPont Hytrel polymer were examined on the basis of organic affinity predictions and experimental partition and mass transfer tests. Hytrel G3548 tubing showed the highest permeability for 2,4-Dimethylphenol while exerting an effective salt barrier, and was used to verify the feasibility of the proposed system. Very high organic removal (99% after just 5h of treatment) and effective biodegradation of the organic fraction of the wastewater (>90% at the end of the test) were observed. Complete salt separation from the microbial culture was also achieved.

Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.[Pubmed:26961915]

J Chromatogr A. 2016 Apr 8;1441:8-15.

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-Dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 mug/L. The linear range was 0.25-500 mug/L for 2-nitrophenol, 0.5-500 mug/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-Dimethylphenol, and 1-500 mug/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 mug/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 mug/L, respectively.

Preconcentration of polar phenolic compounds from water samples and soil extract by liquid-phase microextraction and determination via liquid chromatography with ultraviolet detection.[Pubmed:26653452]

Talanta. 2016;148:292-300.

This work proposes a liquid-phase microextraction (LPME) method to extract the highly polar compounds phenol (Ph), o-cresol (o-Cr), m-cresol (m-Cr), p-cresol (p-Cr), and 2,4-Dimethylphenol (2,4-DMP) from aqueous matrices. The first extraction step of the LPME method employed a common volumetric flask and n-octanol, and the second extraction step used NaOH as the acceptor phase. The optimized extraction conditions were 900 muL of n-octanol as the extraction solvent, NaOH at 0.60 mol L(-1) as the acceptor phase, an extraction time of 5.0 min, HCl at 0.01 mol L(-1) and NaCl at 20.0% as the donor phase, and an extraction temperature of 20.0 degrees C. The analysis of 50.0 mL of aqueous sample, pretreated under the optimized LPME conditions, afforded a limit of detection (LOD) between 0.3 and 3.5 mug L(-1), a limit of quantification (LOQ) between 1.2 and 11.6 mug L(-1), and a linear range from 2.50 to 50.0 mug L(-1) for Ph, o-Cr, m-Cr and p-Cr and from 12.5 to 250 mug L(-1) for 2,4-DMP. The proposed LPME method was a successful sample preparation strategy, and allowed for precise and accurate quantification of polar phenolic compounds in aqueous matrices such as tap water, river water, groundwater, and seawater, and also in a soil extract. The recovery values ranged from 72.5% to 126.0%, and the relative standard deviation was between 0.3 and 11.5%.

Inherent organic compounds in biochar--Their content, composition and potential toxic effects.[Pubmed:25845996]

J Environ Manage. 2015 Jun 1;156:150-7.

Pyrolysis liquids consist of thermal degradation products of biomass in various stages of its decomposition. Therefore, if biochar gets affected by re-condensed pyrolysis liquids it is likely to contain a huge variety of organic compounds. In this study the chemical composition of such compounds associated with two contaminated, high-volatile organic compound (VOC) biochars were investigated and compared with those for a low-VOC biochar. The water-soluble organic compounds with the highest concentrations in the two high-VOC biochars were acetic, formic, butyric and propionic acids; methanol, phenol, o-, m- and p-cresol, and 2,4-Dimethylphenol, all with concentrations over 100 mug g(-1). The concentrations of 16 US EPA PAHs determined by 36 h toluene extractions were 6.09 mug g(-1) for the low-VOC biochar. For high-VOC biochar the total concentrations were 53.42 mug g(-1) and 27.89 mug g(-1), while concentrations of water-soluble PAHs ranged from 1.5 to 2 mug g(-1). Despite the concentrations of PAHs exceeding biochar guideline values, it was concluded that, for these particular biochars, the biggest concern for application to soil would be the co-occurrence of VOCs such as low molecular weight (LMW) organic acids and phenols, as these can be highly mobile and have a high potential to cause phytotoxic effects. Therefore, based on results of this study we strongly suggest for VOCs to be included among criteria for assessment of biochar quality.

Production of recalcitrant organic matter under the influence of elevated carbon dioxide and temperature.[Pubmed:25327018]

Water Environ Res. 2014 Sep;86(9):779-87.

The effects of elevated CO2 and temperature on the quantity and quality of dissolved organic carbon (DOC) of wetland sediments were investigated by measuring organic matter decomposition rates and phenolic compounds as target recalcitrant organic matter. Mean rates of anaerobic microbial metabolism were consistently higher both in vegetated sediments and in elevated CO2 and temperature, although the differences were not statistically significant (P < 0.05). Concentrations of phenolic compounds in sediments with vegetation are significantly different (P < 0.05) from those in sediments without vegetation. Regarding the biodegradability of the phenolic compounds, vegetated sediments showed higher concentrations of 2-chlorophenol and 2,4-Dimethylphenol under elevated CO2 and temperature conditions, which means that more refractory material can be produced through enhanced organic matter degradation by elevated CO2 and temperature. The produced phenolic compounds can be transported to the freshwater ecosystem and influence the recalcitrance of DOC.

Possible intermediates of Cu(phen)-catalyzed C-O cross-coupling of phenol with an aryl bromide by in situ ESI-MS and EPR studies.[Pubmed:24935814]

Dalton Trans. 2014 Aug 7;43(29):11410-7.

The C-O coupling reaction between 2,4-Dimethylphenol and 4-bromotoluene catalyzed by the CuI/K2CO3/phen system can be inhibited by the radical scavenger cumene. Complexes [Cu(i)(phen)(1-(2,4-dimethylphenoxy)-4-methylbenzene)](+) (denoted as A), {H[Cu(i)(phen)(2,4-dimethylphenoxy)]}(+) and [Cu(i)(2,4-dimethylphenoxy)2](-) (denoted as B) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the copper(i)-catalyzed C-O coupling reaction under the catalytic reaction conditions indicating that they could be intermediates in the reaction. The in situ EPR study of the reaction solution detected the Cu(ii) species with a fitted g value of 2.188. A catalytic cycle with a single electron transfer (SET) step was proposed based on these observations.