Formation Of Organic Acids Research Articles

Low-molecular-weight organic acids in the Tibetan Plateau: Results from one-year of precipitation samples at the SET station

Background atmospheric organic acids: formic (F), acetic (A), oxalic (O), and methanesulfonic (MSA, abbreviated to M) acids in the southern Tibetan Plateau (TP), were determined in one-year of precipitation measurements at a remote alpine station. These organic acids were dominated by oxalic (volume-weighted mean of 0.51 μmol l−1)/formic acid (0.38 μmol l−1), followed by acetic acid (0.20 μmol l−1) and MSA (0.10 μmol l−1). Their levels were comparable with those from other remote sites, while they were lower than those found in populated areas. The South Asian monsoon is responsible for the seasonal variation of organic acid concentration: a relative abundance of MSA and lower concentrations of other organic acids (by the dilution effect) in the monsoon season, while opposite in the non-monsoon season. Diverse sources were identified by principal component analysis combined with the corresponding tracers. These were anthropogenic disturbances (which explain 41% of the variance), marine emission (24%), and biogenic emission (16%). Moreover, the variances of F/A, M/(F + A), and O/(F + A) in monsoonal versus non-monsoonal samples, were involved with the changes of sources. Furthermore, these chemical indexes suggest that active photochemistry over the TP was significant for the production of organic acids and consequently enhanced the ratios of M/(F + A) and O/(F + A) in monsoonal rainfalls. The elevated organic compounds within the ascending tropical moisture imply potential significances for the secondary formation of organic acids in the high-altitude and the changes of the Asian monsoon.

Inorganic acid-catalyzed tautomerization of vinyl alcohol to acetaldehyde

The vinyl alcohol–acetaldehyde tautomerization reaction has recently received considerable attention as a potential route for the formation of organic acids in the troposphere (Andrews et al., 2012 [7]). We examine the catalytic effect of inorganic acids in the troposphere (e.g. HNO3, H2SO4 and HClO4) on the vinyl alcohol–acetaldehyde tautomerization reaction, by means high-level thermochemical procedures. We show that H2SO4 and HClO4 catalysts lead to near-zero reaction barrier heights for the vinyl alcohol→acetaldehyde reaction, and to low reaction barrier heights in the reverse direction (ΔH298‡=40.6and39.5kJmol-1, respectively).

Approaches for enhancement of N2 fixation efficiency of chickpea (Cicer arietinum L.) under limiting nitrogen conditions

Chickpea (Cicer arietinum) is an important pulse crop in many countries in the world. The symbioses between chickpea and Mesorhizobia, which fix N₂ inside the root nodules, are of particular importance for chickpea's productivity. With the aim of enhancing symbiotic efficiency in chickpea, we compared the symbiotic efficiency of C-15, Ch-191 and CP-36 strains of Mesorhizobium ciceri in association with the local elite chickpea cultivar 'Bivanij' as well as studied the mechanism underlying the improvement of N₂ fixation efficiency. Our data revealed that C-15 strain manifested the most efficient N₂ fixation in comparison with Ch-191 or CP-36. This finding was supported by higher plant productivity and expression levels of the nifHDK genes in C-15 nodules. Nodule specific activity was significantly higher in C-15 combination, partially as a result of higher electron allocation to N₂ versus H⁺. Interestingly, a striking difference in nodule carbon and nitrogen composition was observed. Sucrose cleavage enzymes displayed comparatively lower activity in nodules established by either Ch-191 or CP-36. Organic acid formation, particularly that of malate, was remarkably higher in nodules induced by C-15 strain. As a result, the best symbiotic efficiency observed with C-15-induced nodules was reflected in a higher concentration of the total and several major amino metabolites, namely asparagine, glutamine, glutamate and aspartate. Collectively, our findings demonstrated that the improved efficiency in chickpea symbiotic system, established with C-15, was associated with the enhanced capacity of organic acid formation and the activities of the key enzymes connected to the nodule carbon and nitrogen metabolism.

Cellobiose Decomposition in Hot-Compressed Water: Importance of Isomerization Reactions

This paper reports an investigation on the fundamental reaction mechanism of cellobiose decomposition in hot-compressed water (HCW) using a continuous reactor system at 225–275 °C. The importance of isomerization reactions to form two cellobiose isomers (i.e., cellobiulose and glucosyl-mannose) as the primary reaction products is clearly demonstrated under the reaction conditions, using a high-performance anion exchange chromatography with pulsed amperometric detection and mass spectrometry (HPAEC-PAD-MS). The results also confirm another two primary reactions take place during cellobiose decomposition in HCW: retro-aldol condensation reaction to produce glucosyl-erythrose (GE) and glycolaldehyde, and hydrolysis reaction to produce glucose. The data show that isomerization and retro-aldol condensation are the dominant primary reactions while hydrolysis of cellobiose is only a minor primary reaction (accounting for ∼10–20% of cellobiose decomposition depending on reaction temperature). The results indicate that the reaction solution becomes acidic at the early stage of cellobiose decomposition, most likely due to the formation of organic acids, resulting in the subsequent reactions exhibiting more characteristics of acid-catalyzed reactions. The results further suggest that the formed acidic condition has little catalytic effects on the primary reactions of cellobiose decomposition, but is effective in catalyzing secondary reactions of various reaction intermediates such as hydrolysis and dehydration reactions to form glucose and 5-HMF, respectively.

Analyses of organic acids and inorganic anions and their relationship in human saliva before and after glucose intake

The goals of this study were to determine the content of organic acids and inorganic anions in human saliva by using an ion chromatography method, to compare the organic acid and inorganic anion concentrations before and after a sugar rinse, and to investigate the relationships between the levels of each compound. Saliva samples were obtained from 37 subjects before and up to 60min after intake of a 10% glucose solution. Concentrations of seven organic acids (lactate, acetate, propionate, formate, butyrate, pyruvate, and valerate) and four inorganic anions (fluoride, chloride, sulphate, and phosphate) were determined via anion-exchange chromatography with an anion-suppressed conductivity detector. The current analytical method showed good precision and accuracy. Organic acid levels increased after the sugar rinse and recovered to control levels within 20min. Acetate was the predominant organic acid detected in the saliva before the sugar rinse, and lactate was the predominant organic acid detected after the sugar rinse. The overall organic acid content generated by the sugar rinse was positively correlated with the chloride, sulphate, and phosphate concentration, but somewhat negatively correlated with the fluoride concentration. Organic acid levels are increased in human saliva by glucose metabolism. Furthermore, the formation of organic acids following glucose intake is influenced by the prevailing anion content.

Bacteria Community Analysis by Quantitative Real-Time PCR of Fermenting Wax Gourd and its Changes of Organic Acids

The bacterial communities and predominating species during the fermentation of wax gourd were investigated by using 16S rDNA clone library technology combined with a quantitative real-time polymerase chain reaction (qRT-PCR) method. At the beginning of wax gourd pickling, Acinetobacter spp. were the predominant bacteria (∼107 cells/mL). During the next 5–20 days of fermentation, the predominating bacteria were Weissella spp. (∼107–108 cells/mL). Lactobacillus spp. were a significant portion (∼106 cells/mL) of the bacterial flora only at day 10 of the fermentation. At days 15 and 20 of fermentation, W. paramesenteroides was the main species (∼107 cells/mL), identified by using qRT-PCR. Lactic, citric and acetic acids levels were low at the beginning of fermentation and increased significantly (P < 0.05). The increase in lactic acid to 0.33 g/L at day 20 was likely to have occurred because of the sudden increase in W. paramesenteroides and Weissella spp. 5 days earlier. Practical Applications The microorganisms play an important role in the processing and preservation of pickled vegetable foods. The predominant species and its organic acids concentration in the fermentation process of pickled wax gourd were investigated using the 16S rDNA clone library technology combined with quantitative real-time polymerase chain reaction. This method can provide quicker information about the bacterial communities involved in traditional wax gourd fermentation and data regarding flavor formation of pickled vegetables. The formation of organic acids and antimicrobial activity by specific types of lactic acid bacteria may facilitate linking the microbial ecosystem of pickled wax gourd to quality control. It can also provide the microbial and theory identification for quality control of pickled wax gourd processing.

Derivative mechanisms of organic acids in microwave oxidation of landfill leachate

This study compared formation and degradation behaviors of organic acids in landfill leachate under microwave oxidation process (MOP) and under conventional heating oxidation (CHO) and explored derivative mechanisms of organic acids in MOP. The results showed that formation and degradation behaviors of oxalic acid were very similar under CHO and MOP, in which its concentrations decreased in the temperature-raising period, then increased due to decomposition of TOC from 10 to 70min, decreased due to persulfate oxidation from 70 to 130min, and stayed the same afterwards. The pH values of the leachate solution dropped 0.51 and 0.65 pH units after MOP and CHO treatment, respectively. Oxalic acid was the dominant organic acid formed in MOP. The derivative mechanisms of organic acids were developed using the experimental results. Lactic acid was generated from decomposition of malic acid, and oxalic acid was formed from oxidation of its precursors. Acetic acid was formed and soon decomposed. Lactic acid had its maximum concentration with a persulfate dose of 0.5M, while lower or higher persulfate doses yielded few or no lactic acid in MOP.

The impact of Ca2+ combination with organic acids on green tea infusions

The effect of Ca2+ in brewing water on the organic acid content, turbidity, and formation of tea cream and sediment in green tea infusions was studied. When the Ca2+ concentration of the brewing water was >40mgL−1, the green tea infusion became more turbid. The turbidity of the tea infusion was highly negatively correlated with the contents of oxalic acid (R=−0.89, p<0.01), quinic acid (R=−0.90, p<0.01) and tartaric acid (R=−0.82, p<0.01). Oxalic acid on its own interacted with Ca2+ at low concentrations, whereas polyphenols and protein did not. In conclusion, Ca2+ in brewing water influences the quality of a tea infusion by inducing tea cream and sediment formation from combination of Ca2+ and organic acids, such as oxalic acid, quinic acid and tartaric acid. Ca2+ and oxalate are the main metal ion and anion, respectively, involved in tea cream and sediment formation on tea infusion cooling or concentrating.

Chemically activated formation of organic acids in reactions of the Criegee intermediate with aldehydes and ketones

Reactions of the Criegee intermediate (CI, ˙CH2OO˙) are important in atmospheric ozonolysis models. In this work, we compute the rates for reactions between ˙CH2OO˙ and HCHO, CH3CHO and CH3COCH3 leading to the formation of secondary ozonides (SOZ) and organic acids. Relative to infinitely separated reactants, the SOZ in all three cases is found to be 48-51 kcal mol(-1) lower in energy, formed via 1,3-cycloaddition of ˙CH2OO˙ across the C=O bond. The lowest energy pathway found for SOZ decomposition is intramolecular disproportionation of the singlet biradical intermediate formed from cleavage of the O-O bond to form hydroxyalkyl esters. These hydroxyalkyl esters undergo concerted decomposition providing a low energy pathway from SOZ to acids. Geometries and frequencies of all stationary points were obtained using the B3LYP/MG3S DFT model chemistry, and energies were refined using RCCSD(T)-F12a/cc-pVTZ-F12 single-point calculations. RRKM calculations were used to obtain microcanonical rate coefficients (k(E)) and the reservoir state method was used to obtain temperature and pressure dependent rate coefficients (k(T, P)) and product branching ratios. At atmospheric pressure, the yield of collisionally stabilized SOZ was found to increase in the order HCHO < CH3CHO < CH3COCH3 (the highest yield being 10(-4) times lower than the initial ˙CH2OO˙ concentration). At low pressures, chemically activated formation of organic acids (formic acid in the case of HCHO and CH3COCH3, formic and acetic acid in the case of CH3CHO) was found to be the major product channel in agreement with recent direct measurements. Collisional energy transfer parameters and the barrier heights for SOZ reactions were found to be the most sensitive parameters determining SOZ and organic acid yield.

Influence of Ca/Mg ratio and Cd2+ and Pb2+ elements on low molecular weight organic acid secretion by Salix viminalis L. roots into the rhizosphere

A modified hydroponic experiment was focused on the influence of mutual changes in the Ca/Mg ratio and trace elements (Cd and Pb) concentration in solution on the efficiency of low molecular weight organic acid (LMWOA) formation in the Salix viminalis rhizosphere. The study showed that changes in the LMWOA contents were caused by the Ca/Mg ratio as well as the kind and concentration of trace element (Cd or Pb) in hydroponic solution. Under 0.5 mM solution of Cd, the total concentration of LMWOAs—depending on the Ca/Mg ratio—decreased according to the formula: 20:1 > 4:1 > 1:10 > 1:¼, while under 0.5 mM of Pb, it was as follows: 20:1 ≈ 4:1 > 1:¼ > 1:10. When comparing all the experimental systems, it is important to underline that regardless of the Ca/Mg ratio, the concentration of LMWOAs in the rhizosphere was higher under 0.5 mM Cd than Pb, with the exception of 1:1/4 Ca/Mg ratio, where the opposite observation was made and both of these values were lower than in the control. In addition, accumulation of Cd and Pb in Salix roots and young shoots was dependent on Ca/Mg ratio only and decreased according to the formula 1:10 > 4:1 > 20:1 > 1:1/4, regardless of Cd or Pb supplementation.

ChemInform Abstract: Laboratory Studies of Organic Peroxy Radical Chemistry: An Overview with Emphasis on Recent Issues of Atmospheric Significance

AbstractReview: 224 refs.

Production of organic acids from alginate in high temperature water

Hydrothermal treatment was conducted on alginate in the interest of obtaining organic acids. Formic acid, acetic acid, lactic acid, glycolic acid, 2-hydroxybutyric acid, succinic acid, malic acid, mannuronic acid and guluronic acid were obtained by the hydrothermal treatment of alginate. The total yield of the organic acids were 46% at maximum yield 350°C, 40MPa and 0.7s reaction time. The formation of organic acids, suggest that the carboxyl group structure of the alginate was preserved during the hydrothermal decomposition of the alginate. The formation of dicarboxylic acids is evidence that oxidation reactions occur during the hydrothermal treatment, introducing carboxyl groups into the decomposition products. The product distribution indicates that both acid and base catalyzed reactions occurred during the hydrothermal treatment of alginate. Hydrothermal treatment of an uronic acid, glucuronic acid, gave the same organic acids as those obtained from hydrothermal treatment of alginate. The reaction from alginate to organic acids probably proceeds via the formation of hexuronic acid (mannuronic acid and guluronic acid) under hydrothermal conditions.

당 첨가 민들레(Taraxacum officinale) 발효 추출물의 발효과정 중 이화학적 및 미생물학적 변화

본 연구는 민들레에 당을 첨가 후 젖산발효를 시켜 발효과정 중의 이화학적, 미생물학적 변화를 탐구하였고 최종 발효물의 성분분석을 통해 기능성 음료로서의 가치를 평가하기 위해 연구를 진행했다. 30% 당을 첨가하여 발효시킨 민들레 발효물 (FD30)과 50% 당을 첨가하여 발효시킨 민들레 발효물 (FD50)은 발효가 진행됨에 따라 FD30의 초기 pH 및 산도가 각각 pH 6.4, 0.18%에서 숙성 30일에 pH 3.85 및 0.72%로 변화되었고, FD50 보다 저하 속도가 다소 빠른 경향을 보였으며 숙성 120일 이후에는 안정된 값을 나타내었다. 발효과정에 따른 총 균수 변화는 Soluble solid와 상관없이 초기에는 비슷한 총 균수를 나타냈고, 점차로 증가하여 최대균수에 도달한 후 다시 서서히 감소하는 발효양상을 나타냈다. 유산균수 결과도 총 균수의 결과와 비슷한 양상을 보였고 유산균수가 초기에 크게 증가하였다가 최대 유산균수를 보인 후 서서히 감소했다. 발효 및 숙성이 완료된 민들레 발효물의 유리당 함량은 각 농도별의 처리구 간에서 fructose, sucrose의 함량은 FD30, FD50 간에 큰 변화를 보이지 않았으나 glucose의 경우에는 FD50이 <TEX>$46.86{\pm}1.93%$</TEX>로 FD30에 비하여 2배 이상 증가하였다. 유기산 함량 분석결과 FD30이 FD50보다 유기산의 종류가 다양하고 함량이 높은 것으로 나타났고 유리아미노산 함량은 유기산의 경우와 같은 양상을 보였으며 발효물 모두 민들레물 추출물 (DWE)보다 많은 유기산과 유리아미노산을 함유했다. 이는 민들레에 함유된 각종 효소들과 미생물이 당 발효에 의해 유용한 작용을 거쳐 주요성분이 분해되고, 또한 재합성이 이루어져 각종 유리당, 유기산 및 유리아미노산 등을 생성한다고 판단된다. 따라서 발효를 통한 민들레의 기능성 식품으로의 활용가치를 기대할 수 있고 발효시 첨가물과 시기에 따른 성분변화에 대한 보다 구체적인 연구가 추가로 진행되어야 할 것으로 사료된다. This study was carried out to investigate the physiochemical and microbiological changes of dandelion during fermentation. Thirty and fifty percentage raw sugar groups (SFE30 and SFE50) were introduced into dandelions and fermented for 120 days at <TEX>$15-20^{\circ}C$</TEX>. This study was conducted to investigate the utilization of sucrose on lactic acid bacteria from dandelions and their effect on the pH, titratable acidity, microorganism and formation of organic acids in dandelions during fermentation. The number of lactic acid bacteria increased remarkably up to 15 days of fermentation and then decreased rapidly thereafter. The maximum number of lactic acid bacteria, 7.9 log CFU/mL was reached at pH 4.17 and the pH of dandelion showed a slight decrease during fermentation and decreased steadily up to 90 days to reach an optimum pH of 4.0. The titratable acidity of dandelions fermented increased during fermentation. The concentration of organic acid, amino acid and free sugar in SFE30 was higher than both SFE50 and DWE. The results of dandelions fermented were remarkably retarded in the 50% raw sugar group compared to the 30% raw sugar group.

Degradation of Phenolic Compounds in Creosote Treated Wood Waste by A Mixed Microbial Culture Augmented with Cellulolytic- Thermophilic Actinomaycets &amp;lt;i&amp;gt;Thermobifida fusca&amp;lt;/i&amp;gt;

Creosote is used for preservation of railway ties and timbers, electric utility poles, marine and foundation piling, fences and garden furniture. Creosote-treated wood waste may cause potential contamination of soil and water if they are not disposed properly. Creosote contains over 300 organic compounds including polycyclic aromatic hydrocarbons, phenolic compounds and heterocyclic organic compounds, many of which are toxic to human and can cause damage to kidney, liver, eyes and skin. The feasibility of using a composting technique inoculated with the cellulose degrading actinomycetesThermobifidafusca as a mesophilic/thermophilic bioremediation option to degrade phenolic compounds in creosote treated wood waste was evaluated. The temperature profile of bioremediation process clearly identified mesophilic and thermophilic phases in both experiments. Different degradation rates were observed in the mesophilic and thermophilic phases. Fluctuations of pH was observed in both experiment as the result of the breakdown of organic nitrogen to ammonium in the first week and the formation of organic acids and the loss of ammonium with the exhaust gases in the latter stage. The moisture content decreased in both trials because of the net loss of water with the exhaust gas. Both experiments achieved similar reductions in total carbon and TKN, volatile solids and phenolic compounds, cellulose and lignin indicating similar levels of microbial activities during the composting process. The stability and maturity of the final products were also similar. The inoculation of the cellulolytic-thermophilicactinomycetesThermobifidafusca did not manifest observable differences in degrading cellulose, lignin and phenolic compounds compared with the control.

Modelling of Biogas Production from Glycerol by Anaerobic Process in a Baffled Multi-Stage Digestor

ABSTRACTThe anaerobic conversion of glycerol by the bacterium Klebsiella sp. is a well-known process. According to its metabolism glycerol is converted into different products, e.g. 2,3-butanediol, 1,3-propanediol, acetic acid, formic acid, lactic acid and biogas. The latter is produced by two competitive ways: decarboxylation of acetic acid or self-reduction of carbon dioxide by hydrogen, acetic acid, carbon dioxide and hydrogen being intermediate products of one of the competitive metabolic routes. Which of these compounds is a desired final product depends on the purpose of the fermentation.In the present work a non-structured mathematical model is developed to describe these competitive processes. The model consists of nine ordinary non-linear differential equations for the kinetics of some selected more important reactions from the metabolic pathway. The model takes into account the microbial growth, the pH drop caused by the organic acid formation and the resulting inhibition of the methanogenic microbial activity. The pH-optima of the enzymes are approximated by Gaussian distribution. The enzyme sensitivity toward pH-variations is presented by the half-width of the Gaussian curve.A large set of experimental data for glycerol anaerobic digestion by Klebsiella sp. in a baffled multistage reactor was used for verification of the model. The comparison of the experimental data with the model results revealed the number of reactor stages, sufficient for complete methanization and to determine the optimum conditions for 2,3-butanediol or methane production.

Laboratory studies of organic peroxy radical chemistry: an overview with emphasis on recent issues of atmospheric significance

Organic peroxy radicals (often abbreviated RO(2)) play a central role in the chemistry of the Earth's lower atmosphere. Formed in the atmospheric oxidation of essentially every organic species emitted, their chemistry is part of the radical cycles that control the oxidative capacity of the atmosphere and lead to the formation of ozone, organic nitrates, organic acids, particulate matter and other so-called secondary pollutants. In this review, laboratory studies of this peroxy radical chemistry are detailed, as they pertain to the chemistry of the atmosphere. First, a brief discussion of methods used to detect the peroxy radicals in the laboratory is presented. Then, the basic reaction pathways - involving RO(2) unimolecular reactions and bimolecular reactions with atmospheric constituents such as NO, NO(2), NO(3), O(3), halogen oxides, HO(2), and other RO(2) species - are discussed. For each of these reaction pathways, basic reaction rates are presented, along with trends in reactivity with radical structure. Focus is placed on recent advances in detection methods and on recent advances in our understanding of radical cycling processes, particularly pertaining to the complex chemistry associated with the atmospheric oxidation of biogenic hydrocarbons.

Augmenting Composting Microbial Community with Thermophilic Cellulolytic Organisms for Enhanced Degradation of Phenolic Compounds in Creosote Treated Wood Waste

Creosote is widely used as a wood preservative in railway sleepers, utility poles, bridges, building foundations, fences, stakes for vegetables and fruits, garden furniture and outdoor recreational facilities. Contamination of soil and water and threat to human and animals health are the major constraints to disposal of creosote-treated wood waste. Composting provides a treatment option for creosote-treated wood waste and production of a value- added product. The aim of this study was to test the effectiveness of inoculating the composting process with three thermophilic-cellulolytic microorganisms ( T. curvata , T. aurantiacus and T. fusca ) in degrading phenols in creosote treated wood waste. Used cooking oil was added into the composting system as a bio-available carbon source. The temperature, pH, moisture content, solids, total carbon, nitrogen, phenols, cellulose and lignin were monitored. The temperature profiles showed that the thermophilic phase (>45 ?C) was achieved and successfully maintained due to the addition of used cooking oil. The moisture content decreased because the water produced by microbial respiration did not compensate for the water vapour lost with the exhaust gases. The breakdown of organic nitrogen to ammonium caused an initial increase in the pH which was then decreased due to the formation of organic acids from the decomposition of fats and the loss of ammonia with the exhaust gases. The inoculated experiments achieved higher reductions in volatile solids, total carbon, TKN, phenols, cellulose and lignin compared to the control. Different degradation rates were observed in the psychrophilic, mesophilic and thermophilic stages of composting. The product from the inoculated experiment had improved stability and phytotoxicity compared to that of the control (uninocualted). The inoculation of thermophilic-cellulolytic microorganisms ( T. curvata , T. aurantiacus and T. fusca ) accelerated the composting process and resulted in higher degradation of phenolic compounds, lignocellulose and lignin.

Crystal and molecular structure of four 1:1 adducts from 2-methylquinoline and different acidic components

Abstract Four 2-methylquinoline derived supramolecular complexes [2-methylquinoline: (2,4,6-trinitrophenol) [(HL)+ · (pic−), pic− = picrate, L = 2-methylquinoline] (1), 2-methylquinoline: (5-nitrosalicylic acid) [(HL)+ · (5-nsa−), 5-nsa− = 5-nitrosalicylate] (2), 2-methylquinoline: (5-sulfosalicylic acid): H2O [(HL)+ · (5-ssa−). H2O, 5-ssa− = 5-sulfosalicylate] (3), and 2-methylquinoline: (trimesic acid) [(L)⋯(Tma), Tma = trimesic acid] (4) were synthesized and structurally characterized by X-ray crystallography. All supramolecular architectures of 1–4 involve extensive classical hydrogen bonds as well as other noncovalent interactions. The results presented herein indicate that the strength and directionality of the N H⋯O, O H⋯N, and O H⋯O hydrogen bonds (ionic or neutral) between acidic components and 2-methylquinoline are sufficient to bring about the formation of binary organic acid–base adducts. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, the complexes 1–4 displayed 2D–3D framework structure.

Salt and co-crystal formation from 2-(imidazol-1-yl)-1-phenylethanone and different acidic components

Abstract Four crystalline adducts derived from 2-(imidazol-1-yl)-1-phenylethanone and the acidic compounds (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, and 5-nitrosalicylic acid) were prepared and characterized by X-ray diffraction analysis, infrared spectrum, melting point, and elemental analysis. All supramolecular architectures of 1 – 4 involve extensive classical hydrogen bonds as well as other noncovalent interactions. The results presented herein indicate that the strength and directionality of the N H⋯O, O H⋯N, and O H⋯O hydrogen bonds (ionic or neutral) between acidic components and 2-(imidazol-1-yl)-1-phenylethanone are sufficient to bring about the formation of binary organic acid–base adducts.

Quality characteristics of virgin coconut oil: Comparisons with refined coconut oil

Virgin coconut oil (VCO) is a vegetable oil that is extracted from fresh coconut meat and is processed using only physical and other natural means. VCO was compared to refined, bleached, and deodorized coconut oil (RCO) using standard quality parameters, 31P nuclear magnetic resonance (NMR) spectroscopy, and headspace solid-phase micro-extraction/gas chromatography mass spectrometry (SPME/GCMS). VCO tends to have higher free fatty acids (FFAs), moisture, and volatile matter and lower peroxide value than RCO. However, the range of values overlap and no single standard parameter alone can be used to differentiate VCO from RCO. Using 31P NMR, VCO and RCO can be distinguished in terms of the total amount of diglycerides: VCO showed an average content (w/w %) of 1.55, whereas RCO gave an average of 4.10. There was no overlap in the values found for individual VCO and RCO samples. There are four common methods of producing VCO: expeller (EXP), centrifuge (CEN), and fermentation with and without heat. VCO products prepared using these four methods could not be differentiated using standard quality parameters. Sensory analysis showed that VCO produced by fermentation (with and without heat) could be distinguished from those produced using the EXP and CEN methods; this sensory differentiation correlated with the higher levels of acetic acid and octanoic acid in the VCO produced by fermentation. Studies on physicochemical deterioration of VCO showed that VCO is stable to chemical and photochemical oxidation and hydrolysis. VCO is most susceptible to microbial attack, which leads to the formation of various organic acids, in particular, lactic acid. However, at moisture levels below 0.06 %, microbial action is significantly lessened.