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Regioselectivity of the Chan–Lam coupling of ambident nitropyrazoles with trans -styrylboronic acid depends on the base and catalyst nature and can vary the N(1)/N(2)-isomer ratio from ∼2 : 1 to ∼1 : 2. 2-Methyl-4-nitro- and 2,4-dinitroimidazoles are unreactive in this reaction. The structure of N(1)/N(2) isomers was elucidated by NOE measurements and by the comparison of experimental and DFT calculated 13C NMR chemical shifts. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance is a technique that is widely used for elucidating and characterizing organic substances. Organofluorine substances have applications in many areas from drugs to liquid crystals, but their NMR spectra are often challenging due to fluoride coupling with other nuclei. For this reason, NMR spectra of this class of substances are not commonly covered in undergraduate and graduate chemistry courses and related fields. Thus, the aim of this work was the presentation and discussion of 1H, 13C, and 19F NMR spectra of eleven organofluorine substances which, in the case of 1H and 13C nuclei, showed classic patterns of first-order coupling and the effects of the fluorine nucleus in different chemical and magnetic environments. In addition, the observation of long distance coupling constants was possible through the use of apodization functions in the processing of the spectra. It is expected that the examples presented herein can be utilized and discussed in undergraduate and graduate NMR spectroscopy disciplines and thus improve the teaching and future research of organofluorine compounds.

The coupling of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry with 13C nuclear magnetic resonance (NMR) is a suitable method for examining the composition of hydrolysable tannins and has been applied to the investigation of valonia oak (Quercus aegylops) acorn tannin extract. Such methods can determine the extract’s structural aspects and other characteristics. It was determined that valonia oak acorn tannin extract is composed of mainly pentagalloylglucose structures; their rearrangement structures, vescalagin/castalagin (with linkages to flavogallonic acid) and vescalin/castalin; ellagic acid and vescavaloneic/castavaloneic acid; and free gallic acid and glucose. Traces of catechin gallate were also observed in this tannin extract. The tannin from acorns of valonia oak was used to substitute up to 50% of the phenol used in the preparation of phenolic resins as adhesives for wood particleboard. These phenol-tannin-formaldehyde resins showed comparable performance to phenol-formaldehyde resins.

In this work, lignin polyols were prepared from the liquefaction of kraft lignin and from the direct liquefaction of Elaeis guineensis lignocellulosic waste. The liquefaction reaction was performed with polyhydric alcohols using sulfuric acid as catalyst at 160 °C. The physical and chemical characterizations of lignin and lignin polyols were conducted by elemental analysis, Fourier transform-infrared spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, molecular weight distribution, and thermogravimetric analysis (TGA). Quantitative 13C NMR showed that all aliphatic hydroxyl group values of polyols noticeably increased with the use of the two methods compared to kraft lignin. The average molecular weight analysis of the liquefied product showed that it exhibited high molecular weight compared to kraft lignin. Both structural and thermal characteristics suggest that lignin polyols would be a good substitute for kraft lignin in the synthesis of polymeric compounds such as environmentally friendly resins or wood adhesives, as it presents higher amounts of activated free ring positions, higher molecular weight, and high thermal stability.

Mesogens that vary in shape anisometry have been investigated by 13 C solid-state NMR in the liquid crystalline phase to inspect the conformations. The molecules examined comprise of (i) rod-like mesogen with three-phenyl ring core and terminal hexyloxy chains, (ii) three-ring core linked to the fourth phenyl ring via a spacer, and (iii) trimesic acid connected to three side arms core units through a spacer. The order parameter (S zz ) values for the phenyl rings of the rod-like mesogen are 0.65-0.68, while the mesogen with a three-ring core linked to a phenyl ring via spacer showed dissimilarity. Consequently, for the core unit phenyl rings, S zz is ~0.70, and the terminal phenyl ring showed a low value of 0.12. For the trimesic acid based mesogen, the S zz value for the side arm phenyl rings is ~0.53, and for the central phenyl ring, a very low value of 0.11 is witnessed. By considering the ordering of the rod-like mesogen as a yardstick and employing the ratios of S zz values of the phenyl rings, the average conformations of other mesogens are arrived. Accordingly, for the trimesic acid based mesogen, a tripod-like conformation instead of λ shape is proposed in the liquid crystalline phase., (© 2023 Wiley-VCH GmbH.)

Quinones are natural products widely distributed in nature, which are involved in stages of several vital biological processes, with mostly having a variety of pharmacological properties. The main groups comprising most of these compounds are benzoquinones, naphthoquinones, anthraquinones, and phenanthraquinones. Quinone isolation has been a focus of study around the world in recent years; for this reason, this study approaches the junction of natural quinones identified by 13 C Nuclear Magnetic Resonance (NMR) spectroscopic analytical techniques. The methodology used to obtain the data collected articles from various databases on quinones from 2000 to 2022. As a result, 137 compounds were selected, among which 70 were characterized for the first time in the period investigated; moreover, the study also discusses the biosynthetic pathways of quinones and the pharmacological activities of the compounds found, giving an overview of the various applications of these compounds., (© 2023 Wiley-VHCA AG, Zurich, Switzerland.)

Abstract Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [ Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state 13C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time. Graphical abstract Unlabelled Image Highlights • Bioenergy by-products can be used to replenish the soil organic C (SOC). • Fermentation by-product (FBP) and pyrolysis by-product (biochar) increased SOC. • Biochar increased soil recalcitrant C whereas FBP increased soil labile C. • FBP amendment can be used to stimulate microbial response in soils. • Biochar could be used to facilitate C sequestration over time. [ABSTRACT FROM AUTHOR]

Abstract Spectroscopic studies-based on 1D (1H NMR, 13C NMR), 2D-NMR (COSY, HMBC, HSQC), UV–visible, FTIR techniques and quantum chemical studies established on the density functional theory (DFT) were carried out for the natural withanolide glycosides, isolated from Withania Coagulans Dunal. The new glycoside withanolide named as (20R,22R)-14α,17,20β,27-trihydroxy-1-oxowitha-5,24-dienolide-27β-(O-β- d -glucopyranoside) (1), and a known withanolide (20R,22R)-14α-20β,27-trihydroxy-1-oxowitha-5,24-dienolide-3β-(O-β- d -glucopyranoside) (2) are reported here from W. coagulans. The molecular mass of these compounds were confirmed through Fast Atom Bombardment Mass Spectrometry (FAB-MS). Geometric and spectroscopic detailed were obtained from DFT calculations. 1H and 13C NMR theoretical values were found a little higher than the experimental values, but the trend in the chemical shift correlates well with the experimental values. The RMSD values of 1H and 13C NMR of 1 and 2 were 0.4 and 0.38, and 4.94 and 5.02 respectively. The calculated band gap was found 4.93 and 5.00 eV for 1 and 2 respectively which indicated the stable nature of these compounds towards redox reactions. Graphical abstract Image 1 Highlights • Isolation of a new and known withanolide glycosides from withania coagulans. • IR, UV–vis. 1D- and 2D- NMR data of the isolated compounds. • Quantum chemical calculation based on DFT studies. • DFT study proposes high resistivity towards redox reaction. • Similar location in both compounds of HOMO and LUMO with high band gap. [ABSTRACT FROM AUTHOR]

Graphical abstract The active site for the methane dehydroaromatization forms at reaction conditions in an initial phase where no desired products are observed yet. To characterize the activated Mo inside the pores of HZSM-5 zeolite, a site-sensitive quasi-insitu strategy was developed. A CO-treatment of the as-synthesized catalyst was employed as an alternative way to create the active site, which was then characterized using CO IR, 13C MAS NMR and DNP. Together with theory, these results point to the (oxy-)carbidic nature of the Mo-site. Highlights • A quasi-in situ strategy to distinguish among different Mo sites. • Direct spectroscopic evidence for two kinds of well-defined species as well as nanoparticles. • Mo nanoparticles contribute to the deactivation of the catalyst. • Mo has an oxidation state between 4+ and 6+. • The Mo-site does not transform further once benzene is formed. Abstract The active sites on the methane dehydroaromatization (MDA) catalyst Mo/HZSM-5 are very hard to characterize, because they are present in various geometries and sizes and only form under reaction conditions with methane at 700 °C. To address these issues an experimental strategy is presented that enables distinguishing different active sites for MDA present on Mo/HZSM-5 and helps determining the Mo charge, nuclearity and chemical composition. This approach combines a CO pretreatment to separate the active Mo site formation from coke formation, quasi-in situ spectroscopic observations using DNP, 13C NMR, CO IR and theory. This allows the discrimination between three different types of active sites. Distinct spectroscopic features were observed corresponding to two types of mono- or dimeric Mo (oxy-)carbide sites as well as a third site assigned to Mo 2 C nanoparticles on the outer surface of the zeolite. Their formal Mo oxidation state was found to be between 4+ and 6+. Dynamic nuclear polarization (DNP) measurements of samples carburized in CO as well as in CH 4 confirm the assignment and also show that accumulated aromatic carbon covers the bigger Mo nanoparticles on the outer surface of the zeolite, causing deactivation. It was previously observed that after an initial period where no desired products are formed yet, benzene starts slowly forming until reaching its maximum productivity. Direct observation of the active site with 13C NMR confirmed that Mo-sites do not transform further once benzene starts forming, meaning that they are fully activated during the period where no desired products are observed yet. Therefore the slow increase of the benzene formation rate cannot be attributed to a further transformation of Mo sites. [ABSTRACT FROM AUTHOR]

Abstract In the last couple of years growing attention is paid to environmental concerns with a special attention to bio- and renewable resources as feedstock for the chemical industry. In this article we synthesized bio-based high molecular weight epoxy resins with hydroxylated soybean oil (SMEG) and a low-molecular-weight epoxy resin (EPR 0162), using the epoxy fusion process. The course of the synthesis was studied by means of Matrix-Assisted Laser Desorption/Ionization time of flight (MALDI-TOF) mass spectrometry and NMR spectroscopy. A two-stage change in the value of the epoxy and the hydroxyl value, as well as the weight average molecular weight were observed during the SMEG_EPR polyaddition reaction. As a result of the reaction between functional groups, the product of the reaction of one molecule of SMEG and one molecule of EPR (1SMEG+1EPR) is formed. Then it reacts with subsequent molecules of EPR or SMEG with the creation of products: 1SMEG+1EPR, 1SMEG+2EPR, 2SMEG+1EPR. It is also shown that the obtained adducts are not the main products of the analyzed reaction, but are the intermediate reagents throughout the formation of products with higher molecular weights. Based on the progress of the SMEG_EPR epoxy fusion process in the registered m/z range, it has been found that products with linear, rather than branched, structure are more likely to be formed. At the same time this discovery states about less likelihood of crosslinking of the system based on modified soybean oil. Graphical abstract Determination of the structure of products obtained during the epoxy fusion process of high-molecular weight epoxy resins using hydroxylated soybean oil and bisphenol A based epoxy resin. Image 1 Highlights • Soybean oil modification and application in the synthesis of novel epoxy materials. • Synthesis of bio-based epoxy resins via the epoxy fusion process using hydroxylated soybean oil and a low-molecular-weight epoxy resin. • Determination of the course of the synthesis by means of MALDI-TOF mass spectrometry and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The role of soil organic C (SOC) quality affecting microbial community composition and function under biochar application is poorly understood. We investigated the relationship between the pool size and chemical composition of SOC; composition of main microbial groups; enzyme activities involved in C, N, and P cycling; and soil respiration in a rice paddy amended with biochar for 20 months in a laboratory experiment at 15, 25, and 35 °C. Soil labile and recalcitrant organic C pools were determined by a two-step sulfuric acid (H2SO4) hydrolysis method. The chemical composition of SOC was determined with 13C-nuclear magnetic resonance spectroscopy. The biochar amendment at 20 and 40 t ha−1 significantly decreased the soil labile C pool I (extracted by 5 N H2SO4), alkyl, and carbonyl C contents and increased the recalcitrant C pool (acid-resistant) and aromatic C contents and the aromatic C to O-alkyl C ratio. The phospholipid-fatty acid concentrations and soil enzyme activities were unchanged by biochar application at 10 and 20 t ha−1, but both were increased at 40 t ha−1. Biochar increased the ratio of gram-positive (G+) to gram-negative (G−) bacteria and decreased that of fungi to bacteria. The recalcitrant C pool and aromatic C contents were positively correlated to the G+ bacteria abundance and were important factors in shaping composition of the main microbial groups and improving enzyme activities. Biochar application at 40 t ha−1 lowered soil respiration rates at 15 and 25 °C by decreasing labile C pool and increasing C recalcitrancy while increased temperature sensitivities of soil respiration at 25/15 °C and 35/25 °C by stimulating microbial abundance and enzyme activities. Together, our results suggest that biochar soil amendment shifted microbial community composition and function through influencing the composition of SOC. [ABSTRACT FROM AUTHOR]

Highlights • FAME produced from pretreated waste cooking oil using microwave. • Statistical model developed to optimize biodiesel yield. • RSM and ANN were employed for process optimization. • Produced biodiesel characterized by FT-IR, GC–MS, NMR etc. Abstract Fatty acid methyl esters (FAME) were synthesized from the waste cooking oil (WCO) by direct transesterification with methanol. The WCO was pretreated to increase the efficiency of FAME production with 1% of potassium methoxide as a catalyst. The free fatty acid of raw source was reduced using 2% of activated charcoal as adsorbent. The process variables were optimized using Box-Behnken design of Response Surface Methodology (RSM), and developed Artificial Neural Network (ANN) model to predict the FAME yield. The highest percentage of conversion (95%) was achieved at optimum conditions, for the catalyst concentration of 1%, alcohol to oil ratio of 6:1, temperature of 75 °C and time of 60 s. The yield of biodiesel was estimated by higher R2 values of RSM (0.98) and ANN (0.99), respectively. The produced FAME from pretreated WCO at 75 °C by microwave irradiation was examined by proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FT-IR) spectroscopy, and gas chromatography-mass spectrometry (GC–MS). The esters exhibited their two characteristically strong absorption bands arising from carbonyl (C O) at 1741 cm−1 of fresh oil, and C O stretching between 1300 and 1000 cm−1 in the FT-IR spectra. A representative spectrum of 13CNMR for the FAME from WCO was confirmed the presence of methyl esters in the biodiesel of ester carbonyl (COO) and C O at 174.2 ppm and 51.4 ppm, respectively. The characteristic peak of 1H NMR at 1.00 ppm of methoxy protons was observed as a singlet at 3.67 ppm, which proved occurrence of the methyl ester (CH 3 COOR). In addition, a significant weight loss at 139 °C was observed through thermogravimetric (TG) analyses of FAME. [ABSTRACT FROM AUTHOR]

Abstract Cardanol was obtained by vacuum distillation of "cashew nut shell liquid" (CNSL). Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. 1H and 13C NMR signals were assigned using 1D and 2D NMR experiments. The DFT/B3LYP method using the cc-pVTZ basis set was employed for the calculations of the 1H and 13C NMR chemical shifts (δ). The obtained data were used as an auxiliary tool for unequivocal assignment of all 1H and 1³C NMR signals. For these compounds, the adopted theoretical model was sufficient to obtain a good description of the chemical shifts. Graphical abstract Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. Image Highlights • Chemical shift calculations using the DFT/B3LYP method. • Complete NMR assignment for three cardanol derivatives. • Experimental and theoretical approach. [ABSTRACT FROM AUTHOR]

Highlights • Pyrolytic profiles from soil organic matter reveal processes related to C cycle. • New surface density plots from compounds atomic ratios depict humic acid structure. • The proportions of common pyrolytic products are correlated with soils properties. • Up to four different non excluding biogeochemical paths define soil C storage. • An empirical model for soil C storage includes the role of agricultural practices. Abstract Molecular assessment of the origin and transformation processes of soil organic matter (SOM) was carried out based on information obtained from 13C NMR and analytical pyrolysis of humic acids (HAs) in soils from wine-growing regions in Tenerife (Canary Islands, Spain). Principal component analysis, using as variables pyrolysis products, shows different soil groups defined by the molecular assemblages released from the corresponding HAs, characterized by the predominance of: i) plant biomacromolecules (lignin) in soils on pumice substrate, ii) heterocyclic N-compounds and methoxyl-lacking aromatic structures, iii) a substantial domain of alkyl compounds in cultivated soils with active C turnover and finally, iv) polysaccharide and protein-derived compounds in soils developed on amorphous gels. The proportions of the pyrolytic compounds from soil HAs were represented by an upgraded graphical-statistical method (3D Van Krevelen plot) that was used to compare the major SOM structural domains in the different soils. The above results coincide with those suggested by the 13C NMR analysis, and were associated to two groups of local land management practices, in terms of their intensity respectively favoring either the transformation of plant-inherited macromolecular precursors from vascular plants, or the humification of aliphatic precursors in the presence of specific mineralogical substrates controlling microbial degradation and humification processes. [ABSTRACT FROM AUTHOR]

Abstract Fossil resin (amber) has been recently reported as common, but small, sedimentary components throughout the lower Upper Cretaceous (Cenomanian; 99–94 Ma) strata of the Tupuangi Formation, Chatham Islands, eastern Zealandia. From these deposits, resin has also been identified and obtained from well-preserved, coalified specimens of the conifer fossil Protodammara reimatamoriori Mays and Cantrill, 2018. Here, we employed attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) to both dispersed and in situ amber specimens. These resulted in very similar chemical signatures, indicating that these fossils are likely from the same or closely-related botanical sources. The FTIR data are typical of a conifer source within the 'cupressaceous resins' category of Tappert et al. (2011). Carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) facilitated the probable identification of these ambers as 'Class Ib' (sensu Anderson et al. 1992). Based on these spectral data sets, the likely botanical sources of the amber were either Araucariaceae or Cupressaceae; both of these conifer families were common and widespread in the Southern Hemisphere during the Cretaceous. However, the morphology and anatomy of P. reimatamoriori support an affinity to the latter family, thus indicating that the Cretaceous amber of the Chatham Islands was generally produced by members of the Cupressaceae. Comparing the FTIR data to the published spectra of modern resins, we also identify a band ratio which may aid in distinguishing between the FTIR spectra of Araucariaceae and Cupressaceae, and outline the limitations to this approach. A high concentration of ester bonds in Chatham amber specimens, which exceeds typical Cupressaceae resins, is probably caused by taphonomic alteration via thermal maturation. The source of thermal alteration was likely pre-burial wildfires, conditions for which P. reimatamoriori was adapted to as part of its life cycle. A comparison of ambers of the Chatham Islands with modern resins and amber from various localities in Australasia reveals that, taphonomic influences aside, Chatham amber has a unique signature, suggesting that members of the basal Cupressaceae (e.g., Protodammara) were not major contributors to other documented Australasian amber deposits. The closest analogy to Chatham amber deposits appears to be the Upper Cretaceous Raritan Formation, USA, which is characterised by its rich amber, charcoal and Cupressaceae fossil assemblages. This study further supports the hypotheses that the early Late Cretaceous south polar forests were dominated by Cupressaceae, and regularly disturbed by wildfires. Graphical abstract Unlabelled Image Highlights • Chatham Islands' Late Cretaceous amber chemically analysed with 13C NMR & ATR-FTIR. • Dispersed amber matches signature of Protodammara reimatamoriori (Cupressaceae). • 13C NMR signature distinct from other Australasian ambers. • New FTIR band ratio helps distinguish Cupressaceae and Araucariaceae resins. • FTIR spectrum indicates thermal maturation; supports wildfire pre-burial heating. [ABSTRACT FROM AUTHOR]

Abstract Kerogen was isolated from the source rock of Well L69, Zhanhua depression, Bohai Bay Basin and an artificial pyrolysis experiment was carried out in a closed gold tube system with a heating rate of 2 °C/h. Products were collected at eleven temperature points every ten degrees from 350 °C to 450 °C. The soluble organic matter and residual kerogens from the experiment were quantified by weighing. Furthermore, the residual kerogens were analysed by element analysis, X-ray photoelectron spectroscopy (XPS) and solid 13C nuclear magnetic resonance (13C NMR) spectroscopy to determine the chemical structural of kerogen during oil generation. Combining the data from the analyses, information on the elemental compositions as well as on how functional groups were connected in residues was obtained. Seven molecular models of initial and residual kerogens were established to trace the structure changes in kerogen with maturity. The results suggest that as the temperature increases, aliphatic chains and small clusters of aromatic groups break down from kerogens, generating soluble hydrocarbons at temperatures of less than 390 °C (Easy% Ro1.15). At higher thermal maturity, a few short aliphatic carbons remain in the structure of residues. The number of aromatic groups increases and their size grows with increasing maturity, with condensation occurring at aromatic groups at high temperature, while these residues have little potential for oil generation. Highlights • Pyrolysis, Element analysis and 13C NMR were performed on kerogen. • Seven kerogen molecular structures with maturity were established. • The calculation method of aromatic cluster size was improved. • The variation in kerogen structures was revealed. [ABSTRACT FROM AUTHOR]

In industry, formalin and urea formaldehyde condensates (UFC) are used for the preparation of urea-formaldehyde adhesives. The aim of this study was to evaluate the characteristics of a UF resin prepared with formalin (42% concentration) and two kinds of UFC with various urea content (F/U ∼ 5 and 4.3 malar ratio). The resins were prepared with final molar ratio F/U = 1.1. The UF resin with formalin showed better mechanical properties than those with UFC. The 13C NMR and FT-IR results indicated that methylene, methylene ether and urons groups in a UF resin prepared with formalin were present in higher proportion than observed in industrial UF resins. The DSC (differential scanning calorimetry) results showed that the curing temperature of a UF resin prepared with formalin is lower than that of a UF resin prepared with UFC. The mechanical properties of MDFs prepared with the three types of adhesives showed that MDFs bonded with a UF prepared with formalin yields a better mechanical properties than MDFs prepared with a UF resin based on UFC. Moreover, resin synthesized with UFC (F/U = 5) result in higher IBS (internal bond strength) MOR (modulus of rupture), MOE (modulus of elasticity), TS (thickness swelling) and formaldehyde emission (FE) than resin synthesized with UFC (F/U = 4.3). The MDF bonded with the UF2 resin presented poor results, with the highest TS and the lowest IBS, MOE, MOR and FE. [ABSTRACT FROM AUTHOR]

Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH4, H2O, CO, CO2, etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectrometry, gas chromatography, and 13C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly generate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO2 and CH4 are related to the direct removal of -COO- and -CH3, respectively. [ABSTRACT FROM AUTHOR]

The leaves and stem of Zanthoxylum rubescens Planch. ex Hook. f. growing in Côte d'Ivoire, were submitted to hydrodistillation using a Clevenger type apparatus. Three different localities have been chosen for our investigations, namely Petit Yapo, Anguédédou and Grand-Lahou. The oil obtained was investigated by GC(RI), GC-MS and 13C NMR. Twenty-nine compounds were identified accounting for 81.8-95.2 % in the oil. The leaves oil composition was dominated by (E)-β-caryophyllene (39.3-60.3 %), (E)-nerolidol (32.2 %) accompanied with significant contents of thymol, α-humulene and β-sesquiphellandrene. While (E)-nerolidol (39.4 %) added to caryophyllene oxide (6.9 %) and thymol (6.7 %) were the major components of stem oil. [ABSTRACT FROM AUTHOR]

Humification plays an important role in stabilization of organic matter in soils of the cryolithic zone. In this context, the degree of organic matter stabilization has been assessed, using instrumental methods, for permafrost peat soils of the eastern European Arctic, based on selected plots from within the Komi Republic (Russian Federation). Humic substances (HSs) isolated from the mire permafrost peats of the forest-tundra subzone of the European Arctic have been characterized in terms of molecular composition. This was accomplished using elemental and amino acid fragments (AAFs) composition. Solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopy was utilized to identify the structure of HSs. Changes in the molar x(H) : x(C) ratio, ratio of aromatic to paraffin fragments and ratio of hydroxy AAFs to heterocyclic AAFs along the peat profiles have been revealed. They are due to the activation of cryogenic processes in the upper part of the seasonally thawing layer, the natural selection of condensed humic molecules, the botanical composition and degree of degradation of peat, which reflect the climatic features of the area in the Holocene. Humic acids and fulvic acids of the peat soils showed the prevalence of compounds with a low degree of condensation and a low portion of aromatic fragments. The aromaticity degree showed the trend to increase within the depth. Changes of quantitative and qualitative parameters of specific organic compounds occur at the permafrost boundary of peatlands, which can serve as an indicator of recent climate changes in environments from the high latitudes. The presented data can be useful in the evaluation of soil organic matter stabilization degree in the active layer and below the permafrost table. [ABSTRACT FROM AUTHOR]

Although hemicellulose is found widely in nature, it is currently under-utilized as a raw material for commercial applications. It would be desirable to find new uses for hemicellulose in order to add value to this agro-based material. A common type of hemicellulose is xylan, which is found in a number of wood species and in cotton. In this work we prepared cationic and anionic xylan derivatives and characterized them by 13C NMR, FT-IR, size exclusion chromatography (SEC), thermal analysis, and rheology. In particular, the 13C NMR spectra of carboxymethyl xylan (CMX) and quaternary ammonium-adducted xylan (QAX) were fully assigned with the help of samples with different degrees of substitution. SEC indicated that the beechwood xylan showed a bimodal molecular weight distribution, but with derivatization the distribution tended to become unimodal. Thermal analysis and rheology studies did not uncover any surprises; the solution of xylan and its derivatives exhibited mostly Newtonian behavior. The blends of CMX and QAX produced a precipitate at almost all ratios, indicating the formation of a polyelectrolyte complex. When cationic and anionic xylan samples were added together to paper, the paper dry strength increased. Thus, the combination of cationic/anionic xylan may be of interest in selected applications. [ABSTRACT FROM AUTHOR]

The chemical composition of 35 leaf oil samples from Polyalthia longifolia (Sonnerat) Thwait., growing in five districts in Abidjan and its suburbs, has been investigated by GC(FID) in combination with retention indices, GC-MS and 13C-NMR. In total, 30 individual components have been identified, mostly sesquiterpenes. The contents of the main components varied substantially from sample to sample: (E)-β-caryophyllene (18.9-31.4%), α-zingiberene (6.1-22.1%), allo-aromadendrene (12.4-17.3%) and α-humulene (6.4-11.0%). However, PCA was unable to differentiate groups within the 35 compositions. The chemical composition of Ivorian P. longifolia leaf oils may be summarized as follow: (E)-β-caryophyllene (M = 25.3%; SD = 1.2), allo-aromadendrene (M = 15.2%; SD = 0.5), α-zingiberene (M = 13.6%; SD = 3.6) and α-humulene (M = 8.4%; SD = 0.2). [ABSTRACT FROM AUTHOR]

Background. Litter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance. The interaction between the litter chemical composition and the metabolism of the soil microbial community has been described as the main factor of the decomposition process based on three hypotheses: substrate-matrix interaction (SMI), functional breadth (FB) and home-field advantage (HFA). The objective of the present study was to evaluate the effect of leaf litter quality (as a direct plant effect, SMI hypothesis), the metabolic capacity of the microbial community (as a legacy effect, FB hypothesis), and the coupling between the litter quality and microbial activity (HFA hypothesis) on the litter decomposition of two contiguous deciduous oak species at a local scale. Methods. To accomplish this objective, we performed a litterbag experiment in the field for 270 days to evaluate mass loss, leaf litter quality and microbial activity in a complete factorial design for litter quality and species site. Results. The litter of Quercus deserticola had higher rate of decomposition independently of the site, while the site of Quercus castanea promoted a higher rate of decomposition independently of the litter quality, explained by the specialization of the soil microbial community in the use of recalcitrant organic compounds. The Home- Field Advantage Index was reduced with the decomposition date (22% and 4% for 30 and 270 days, respectively). Discussion. We observed that the importance of the coupling of litter quality and microbial activity depends on decomposition stage. At the early decomposition stage, the home-advantage hypothesis explained the mass loss of litter; however, in the advanced decomposition stage, the litter quality and the metabolic capacity of the microbial community can be the key drivers. [ABSTRACT FROM AUTHOR]

The homologous series of 2,6-bis(4-Subtituetphenyl)-3-methylpiperidin-4-one compounds were synthesized using Mannich condensation. Then Five series have been synthesized by reaction of different reagents of semicarbazide. With 2,6-bis(4-Subtituetphenyl)-3-methylpiperidin-4-one to sythesize target compounds 2a-2f, 2a-2f, 3a-3f, 4a-4f, 5a-5f and 6a-6f. The chemical structures of the molecules were characterised by FT-IR, 1D NMR and CHN elements analysis. [ABSTRACT FROM AUTHOR]

Aim: The plant derivative, the gum’s exudates are of great interest among polysaccharides. Nowadays, it is of crucial importance to study the structural peculiarities and the conditioned biological activity of the Gummi Armenicae of native origin as an alternative version of the Gummi Arabicae. Materials and methods: As a material for research served the gum procured from Apricot trees (Armenian Vulgaris Lam.), cultivated in different regions of Armenia annually in spring during juice motion period in 2010-2014 years. The quantity of polysaccharides in gum was determined by the method of gravimetric balance after drying. The quantitative ratio of monosaccharide in the examined polysaccharide complex was detected by the method of MRI. Results: By the methods of spectral analysis (PMR 1H and NMR 13C) the structure of Apricot gums polysaccharide fraction was detected. From the analysis of PMR 1H and NMR 13C spectra it is obvious that polysaccharide complex fraction is composed from the rest of α- L-arabionopyranose, β -L-arabionopyranose, α- D-galactopyranose, β -D-galactopyranose, α -D-glucopyranose, β -D-glucopyranose. Low molecular compounds in nonpolar fraction of apricot gum were determined by GC-MS method. The results show that in Rt1=22.5, Rt2=26.3, Rt3=31.4. Simple phenols were registered - peaks of catechols hydroquinones, pyrogallols, amounts of which are respectively 7.58%, 4.27%, 5.69%. [ABSTRACT FROM AUTHOR]

Abstract: The aggregate formation of trans‐2,3‐dimethylcyclopropyllithium (2) was studied in diethylether (DEE). With the help of the isotopic fingerprint method three clusters, a monomer, a dimer, and a fluxional tetramer in the ratio 1.00:0.53:0.22 were identified at 187 K. In the presence of 1 equivalent of LiBr cyclopropyllithium (1) forms in DEE at 163 K a mixed dimer and a mixed tetramer, while in THF a mixed dimer dominates. Under the same conditions 2 and 2,2,3,3‐tetramethylcyclopropyllithium (3) form in the solvent mixture DEE/THF (1:1) mixed dimers, as does 2 also in THF. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of different maize straw returning modes on humus composition and humic acid (HA) structural, a field experiment was designed to have five treatments, i.e. Treatment CK (no straw returned), Treatment EIS (straw incorporated evenly into the soil using the crashing-ridging technique), Treatment SP (straw plowed into the soil), Treatment SM (straw returned as mulch) and Treatment SG (straw returned as pellets). Our results showed that Treatment EIS significantly increased the content of soil organic carbon (SOC), soil humus substances (HEC), soil humic acid carbon (HAC) and fulvic acid carbon (FAC) by 27.8%, 47.6%, 63.3% and 33.8%, respectively, as compared with CK. Among all the straw returning treatments, Treatment EIS was the most significant in effect of increasing the content of HEC, HAC and FAC. Moreover, Treatment EIS altered the composition of humus more significantly than all the other treatments, by increasing the proportion of alkyl C and the ratio of aliphatic C/aromatic C. These results suggest that straw returning accelerated the accumulation of soil organic C and various components of humus, significantly improved the structure of soil HA, with the practice of EIS in particular. [ABSTRACT FROM AUTHOR]

Abstract: Herein, a novel synthesis of a fully renewable lignin‐based building block equipped with cyclic carbonate functionalities is presented. In an efficient two‐step procedure, organosolv lignin from ethanol–water pulping of beech wood is oxyalkylated with glycerol carbonate to insert adjacent hydroxyl groups. The oxyalkylated lignin is then reacted via transesterification with dimethyl carbonate or ethylene carbonate in dimethyl sulfoxide under alkaline conditions producing cyclic carbonate functionalized lignin. This transesterification is studied as a function of time, catalyst type, and catalyst amount using NMR spectroscopy as well as size exclusion chromatography. Transesterification reactions with K2CO3 as catalyst (0.4 eq.) afford lignin‐based cyclic carbonate with almost complete conversion (96%) within 6 h, as analyzed by 31P and 13C NMR spectroscopy. This green building block represents a reactive prepolymer for the synthesis of nonisocyanate polyurethanes. [ABSTRACT FROM AUTHOR]

Abstract: Ongoing global temperature rise has caused significant thaw and degradation of permafrost soils on the Qinghai‐Tibetan Plateau (QTP). Leaching of organic matter from permafrost soils to aquatic systems is highly complex and difficult to reproduce in a laboratory setting. We collected samples from natural seeps of active and permafrost layers in an alpine swamp meadow on the QTP to shed light on the composition of mobilized dissolved organic matter (DOM) by combining optical measurements, ultrahigh‐resolution Fourier transform ion cyclotron resonance mass spectrometry, radiocarbon (14C), and solid‐state 13C nuclear magnetic resonance spectroscopy. Our results show that even though the active layer soils contain large amounts of proteins and carbohydrates, there is a selective release of aromatic components, whereas in the deep permafrost layer, carbohydrate and protein components are preferentially leached during the thawing process. Given these different chemical characteristics of mobilized DOM, we hypothesize that photomineralization contributes significantly to the loss of DOM that is leached from the seasonally thawed surface layer. However, with continued warming, biodegradation will become more important since biolabile materials such as protein and carbohydrate are preferentially released from deep‐layer permafrost soils. This transition in DOM leachate source and associated chemical composition has ramifications for downstream fluvial networks on the QTP particularly in terms of processing of carbon and associated fluxes. [ABSTRACT FROM AUTHOR]

• Complete waste recycling is achieved by botanical concrete. • Mechanism of using kraft lignin (KL) as a reinforcement material is identified. • Alkaline oxidation of KL aided by concrete promotes the condensation of KL. • Low chemical condensation potential of KL should be utilized. Exploring the bonding mechanism of botanical concrete (BC), which is developed by crushing concrete, wood waste and kraft lignin (KL) and hot pressing the obtained powder, aids in comprehending its formation and enhancing performance. This study continues the attempts on this subject, focusing on the microstructural changes between KL and concrete. Herein, the chemical structural transformations in the mixtures of KL with three sources of powder (concrete, carbonated concrete, and sand) during hot pressing are evaluated by FTIR, XRD, TGA, and 13C NMR methodologies. These results show that BC strength is affected by depolymerization, fragmentation, and crosslinking reactions that alter the chemical bonds within KL. Condensation reactions between concrete and KL fragments, facilitated by air, are the most influential factor in improving BC strength. Waste concrete with alkalinity promotes the oxidation of KL and subsequent crosslinking, offering a new perspective for further development of self-bonding lignin-based materials. [ABSTRACT FROM AUTHOR]

• A combination of laboratory experiments and numerical simulations is employed. • The coal macromolecule model before and after NMP treatment was constructed. • NMP can effectively promote the diffusion ability of CH 4 in coal. • The distribution of methane around functional groups was discussed. Chemical stimulation of the coal reservoir is a potential method for enhancing coalbed methane production. N-Methylpyrrolidone (NMP) solvent extraction is a promising chemical stimulation method. To evaluate the effects of NMP treatment on the adsorption and diffusion characteristics of CH 4 in coal, the coal molecular model was established based on elemental analysis analysis, solid-state 13C nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). Then, the adsorption and diffusion characteristics of methane were simulated using Materials Studio software and the distribution of methane molecules around functional groups was studied. The simulation results show that: under the action of NMP solvent, the saturated adsorption capacity of methane molecules was reduced by 41.6%, and the diffusion capacity was increased by 1.72 times. Additionally, methane molecules were mainly enriched around hydroxyl groups and thiophenes, and adding NMP reduced the methane enrichment around functional groups. These show that NMP treatment can promote the diffusion of methane from coal matrix. Hydroxyl and thiophenes affect the diffusion of methane molecules. This study helps to understand the effect of NMP solvent on the adsorption and diffusion mechanism of coal methane from a molecular perspective. [ABSTRACT FROM AUTHOR]

• Field incubation clarified drainage effect on SOM quality in 3 peat forest soils. • C loss after 5 years at depths of 0–20 cm and 60–80 cm was 12–37 % versus 2–31 %. • Decomposition rates of alkyl, O -alkyl, and aromatic C were similar in each soil. • Lignin is also decomposed if groundwater level before drainage is high. • % alkyl C and degree of humification are indicators of the peat SOM decomposability. Tropical peatlands serve as huge carbon (C) pools in the global C balance, and degradation due to agricultural use is a major concern. The objective of the present study was to examine the relationship between the C loss rate in agriculturally drained tropical peat soils in relation to groundwater level (GWL) and the chemical structure of the resulting soil organic matter (SOM). Soil mesocosms containing three peat soils collected from three forest types in Malaysia, Mixed peat swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests, which are classified based on dominant plant species, species diversity, and forest structure, were buried in an oil palm plantation for a period of five years. Soil samples packed in the top layer (0–20 cm depth) and the bottom (60–80 cm depth) layer were then analyzed and the results were compared with the initial values for these soils. Weight loss, total C and N contents, ash content, and pyrophosphate solubility index (PSI; an index of the degree of humification) were measured. Changes in the chemical structure of the SOC were investigated using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with phase-adjusted spinning side bands and thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry (THM-GC/MS). The C loss in the MPS forest soil, 2–12%, was smaller than that in the ABt and ABg forest soils, 20–37%, especially in the bottom layer. The higher C loss in the ABt and ABg soils, without significant difference between the top and bottom layers, can be attributed to the greater accumulation of less decomposed plant components as evidenced by the larger yields of lignin-derived phenols and polysaccharide-related compounds in THM-GC/MS analysis. The C composition as estimated by 13C NMR did not vary during incubation of the ABt and ABg soils while the yields of lignin-derived and other phenols as well as polysaccharide-related compounds in THM-GC/MS were decreased, especially in the top layer. These findings suggest that plant components with a low degree of decomposition are susceptible to drainage regardless of their structure. The progression of the oxidative degradation of lignin in the top layer of all soils was also suggested by the increases in PSI and the vanillic acid/vanillin ratio. The % O -alkyl C and % alkyl C may control the rate of C loss positively and negatively, respectively. PSI also appears to be useful for roughly estimating the decomposability of tropical peat SOM in various GWLs. [ABSTRACT FROM AUTHOR]

[Display omitted] • SS 13C NMR is introduced into the research for all coal extraction products. • Carbon skeleton characteristics are quantitatively analyzed for all extraction products. • Influence of particle size on the evolution of coal microstructure during the extraction is focused on. • The work promotes the thorough elucidation on the carbon skeleton structure for all extraction products at a molecular level. To better understand the molecular structure of superfine pulverized coal and promote its practical utilization, the NMR (nuclear magnetic resonance) technology is adopted to study the structural information of all the products from the solvent extraction process, including raw coal, residue, and extract. The whole set of NMR spectra is resolved into different individual curves with specific linewidths, shapes, and intensities. According to the chemical shift, the carbon skeleton characteristics like the aromaticity, cluster size, and other structural lattice parameters are analyzed in detail. More importantly, the influences of coal maturity, coal size, and solvent on the carbon structural evolution during the extraction process are focused on. The results show that the aromatic ring stacking and aromatic ring exposure and fragmentation occur competitively during the superfine comminution, promoting the structural evolution of the coal. In addition, aliphatic carbon transfers more from raw coal into the extract than aromatic carbon in the whole extraction process, which is accompanied by the disappearance of carbonyl groups. Furthermore, the reduction of particle size can promote the extraction effect of the extractant on the coal powder, and reduce the proportion of aliphatic carbon in the residue. The work introduces the correlations among the raw coal, residue and extract from a carbon skeleton point of view, providing a reference for elucidating the solvent extraction mechanisms. The results shed light on better understanding the coal structure and its further molecular modeling. [ABSTRACT FROM AUTHOR]

Humic substances are the major components of soil organic matter. Among the three humic substance components (humic acid, fulvic acid, and humin), humin is the most insoluble in aqueous solution at any pH value and, in turn, the least understood. Humin has poor solubility mainly because it is tightly bonded to inorganic soil colloids. By breaking the linkage between humin and inorganic soil colloids using inorganic or organic solvents, bulk humin can be partially soluble in alkali, enabling a better understanding of the structure and properties of humin. However, the structural relationship between bulk humin and its alkaline-soluble (AS) and alkaline-insoluble (AIS) fractions is still unknown. In this study, we isolated bulk humin from two soils of Northeast China by exhaustive extraction (25 to 28 times) with 0.1 mol L-1 NaOH + 0.1 mol L-1 Na4P2O7, followed by the traditional treatment with 10 % HF-HCl. The isolated bulk humin was then fractionated into AS-humin and AIS-humin by exhaustive extraction (12 to 15 times) with 0.1 mol L-1 NaOH. Elemental analysis and solid-state 13C cross-polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy were used to characterize and compare the chemical structures of bulk humin and its corresponding fractions. The results showed that, regardless of soil types, bulk humin was the most aliphatic and most hydrophobic, AS-humin was the least aliphatic, and AIS-humin was the least alkylated among the three humic components. The results showed that bulk humin and its corresponding AS-humin and AIS-humin fractions are structurally differed from one another, implying that the functions of these humic components in the soil environment differed.

The adsorption of Cu(II) from aqueous solution onto humic acid (HA) which was isolated from cattle manure (CHA), peat (PHA), and leaf litter (LHA) as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy (XAS) was used to examine the coordination environment of the Cu(II) adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy (NMR). The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu(II) on CHA, PHA, and LHA were 229.4, 210.4, and 197.7 mg g−1, respectively. The adsorption of Cu(II) on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH>7. The adsorption of Cu(II) was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L−1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L−1 NaNO3. The Cu(II) adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu(II) concentrations of 15 to 40 mg L−1. For all the Cu(II) adsorption samples, each Cu atom was surrounded by 4 O/N atoms at a bond distance of 1.95 Å in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu(II) was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu(II) was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu(II). These results are important to achieve better understanding of the behavior of Cu(II) in soil and water bodies in the presence of organic materials.

Ergometrine and methylergometrine are two alkaloids that are used as maleate salts for the prevention and control of postpartum hemorrhage. Although the two molecules have been known for a long time, few and discordant crystallographic and NMR spectroscopic data are available in the literature. With the aim of providing more conclusive data, we performed a careful NMR study for the complete assignment of the 1H, 13C, and 15N NMR signals of ergometrine, methylergometrine, and their maleate salts. This information allowed for a better definition of their conformational equilibria. In addition, the stereochemistry and the intermolecular interactions in the solid state of the two maleate salts were deeply investigated by means of single-crystal X-ray diffraction, showing the capability of these derivatives to act as both hydrogen-bond donors and acceptors, and evidencing a correlation between the number of intermolecular interactions and their different solubility.

The conversion of lignin into value-added products is traditionally hampered by its stochastic structure and its complex reactivity. The allylation reaction and the aromatic Claisen rearrangement of the allyl group on lignin as chemical modifications are reported for the first time in this work. This approach is aimed at the development of new lignin-based materials and the improvement of its compatibility and ease of processing. In particular, the Claisen rearrangement of lignin is foreseen as a valuable approach to release phenolic groups in an already chemically modified lignin, giving additional reactive sites for further transformation. These reactions were carried out on a purely guaiacylic lignin (TMP), taken as reference material due to its simplicity, and on a more structurally complex herbaceous lignin (P1000®). The Claisen rearrangement of the allylic chain was successfully achieved by treatment in dimethylformamide at reflux temperature for 15 hours. Finally, a screening of the antioxidant activity of reference, allylated, and Claisen rearranged lignins was carried out. Rearranged lignins exhibited satisfactory antioxidant activities if compared to the reference ones.

Biochar has been shown as a potential mean to enhance carbon sequestration in the soil. In Brazil, approximately 15% of the produced charcoal is discarded as charcoal fines, which are chemically similar to biochar. Therefore, we aimed to test charcoal fines as a strategy to increase soil carbon sequestration. Charcoal fines of hardwood Mimosa scabrella were incorporated into a Cambisol down to 10 cm (T1 = 0 and T4 = 40 Mg ha−1) in Southern Brazil. Soil samples were collected (0−30 cm) 20 months after charcoal amendment. Soil organic matter (SOM) acid extract, humic acid, fulvic acid, and humin fractions were separated. Solid-state 13C nuclear magnetic resonance (NMR) spectra from charcoal and SOM in T1 and T4 were obtained before and after 165 days of incubation under controlled conditions. Charcoal increased soil carbon as fulvic (10−20 cm) and humic acids (10−30 cm) and, especially, as humin (0−5 cm), which probably occurred due to the hydrophobic character of the charcoal. The 13C NMR spectra and mean residence times (MRT) measured from incubation essays indicated that the charred material decomposed relatively fast and MRT of T1 and T4 samples were similar. It follows that the charcoal fines underwent similar decomposition as SOM, despite the high charcoal dose applied to the soil and the high aryl C contribution (78%) to the total 13C intensity of the charcoal NMR spectra.

ABSTRACT To further extend temperature range of application and low temperature performance of the ethylene-styrene copolymers, a series of poly(ethylene-styrene-propylene) samples with varying monomer compositions and relatively low glass-transition temperatures ( Tg = −28 - 22 °C) were synthesized by Me2Si(Me4Cp)(N-t-Bu)TiCl2/MMAO system. Since the 13C NMR spectra of the terpolymers were complex and some new resonances were present, 2D-1H/13C heteronuclear single quantum coherence and heteronuclear multiple bond correlation experiments were conducted. A complete 13C NMR characterization of these terpolymers was performed qualitatively and quantitatively, including chemical shifts, triad sequence distributions, and monomer average sequence lengths. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 340-350 [ABSTRACT FROM AUTHOR]