Olefinic Protons Research Articles

Cyanine-based Fluorescent Probe for Cyanide Ion Detection.

Cyanine-based probe-possessing indolium iodide and indole unit were synthesized in two-step with easy available raw material: a potential probe for the cyanide ion detection. The detecting ability of the probe was investigated and confirmed by a visual and instrumental approach. A noticeable color change from orange to colorless obtained only for cyanide ions and other added ions does not impart any changes visually and through UV and Fluorescence technique. To confirm the mechanism of sensing 1H-NMR recorded. From the result, the peak belonging toN-methyl displayed an upfield shift from 4.01 δ ppm to 2.74 δ ppm due to the disappearance of indolium iodide ion and the olefin protons peaks were shifted from 7.19 to 6.17 and 8.70 to 7.20 δ ppm confirms the nucleophilic addition of cyanide ion to the probe. Test kit from filter paper prepared for the real-time monitoring cyanide ion. The prepared strip is effective in detecting cyanide ion with a visual color change.

DFT Calculations of 1H NMR Chemical Shifts of Geometric Isomers of Conjugated Linolenic Acids, Hexadecatrienyl Pheromones, and Model Triene-Containing Compounds: Structures in Solution and Revision of NMR Assignments.

A DFT study of the 1H NMR chemical shifts, δ(1H), of geometric isomers of 18:3 conjugated linolenic acids (CLnAs), hexadecatrienyl pheromones, and model triene-containing compounds is presented, using standard functionals (B3LYP and PBE0) as well as corrections for dispersion interactions (B3LYP-D3, APFD, M06–2X and ωB97XD). The results are compared with literature experimental δ(1H) data in solution. The closely spaced “inside” olefinic protons are significantly more deshielded due to short-range through-space H…H steric interactions and appear close to or even beyond δ-values of aromatic systems. Several regularities of the computational δ(1H) of the olefinic protons of the conjugated double bonds are reproduced very accurately for the lowest-energy DFT-optimized single conformer for all functionals used and are in very good agreement with experimental δ(1H) in solution. Examples are provided of literature studies in which experimental resonance assignments deviate significantly from DFT predictions and, thus, should be revised. We conclude that DFT calculations of 1H chemical shifts of trienyl compounds are powerful tools (i) for the accurate prediction of δ(1H) even with less demanding functionals and basis sets; (ii) for the unequivocal identification of geometric isomerism of conjugated trienyl systems that occur in nature; (iii) for tackling complex problems of experimental resonance assignments due to extensive signal overlap; and (iv) for structure elucidation in solution.

Isolation and Characterization of Secondary Metabolite from the Stem Bark Extract of Allophylus africanus Beauv (Sapindaceae)

Isolation of secondary metabolites from the stem bark of Allophylus africanus Beauv (Sapindaceae) was carried out. The plant has a wide distribution in West Africa, with Nigeria (Mambila Plateau, Calabar) inclusive. It has been used in communities for both its medicinal and economic importance. The stem bark of A. africanus was extracted by percolation using chloroform as solvent and concentrated by evaporation at room temperature. Single spot with an Rf value of 0.87 was obtained at a solvent mixture of hexane: chloroform at ratio 2:8 from finger column chromatography . Characterization using spectra analysis which include FT-IR, 1H-NMR, 13C-NMR, H-H COSY, H-C COSY, 135 DEPT and mass spectroscopy. Spectroscopic studies of A. Africanus stem bark extract led to the elucidation of the structure of the compound. FT-IR spectrum indicates that the compound is an aromatic derivative. Aromatic protons where seen at the 1H-NMR chemical shift values of 7.25 ppm. Olefinic protons at 5.124, 5.146 and 6.162 ppm appeared as doublets of doublets of doublets. The compound 1-((E)- 7(((1E,5E)-6-((2,3-dimethyl-4-(((E)-3,4,5,6-tetramethyldeca-7,9-dien-2-yl)oxy)pentyl)oxy)-3,4- dimethylhexa-1,5-dien-1-yl)oxy)hept-4-en-1-yl)-4-propylbenzene was isolated.

Catalytic Reductive Cross Coupling and Enantioselective Protonation of Olefins to Construct Remote Stereocenters for Azaarenes.

A novel enantioselective protonation protocol that is triggered by reductive cross coupling of olefins is reported. When under cooperative photoredox and chiral hydrogen-bonding catalytic conditions and using a terminal reductant, various α-branched vinylketones with diverse vinylazaarenes could provide important enantioenriched azaarene derivatives containing tertiary stereocenters at their remote δ-position with high yields and enantioselectivities. This reaction system is also suitable for α-branched vinylazaarenes, thus successfully assembling elusive 1,4-stereocenters. The convenient late-stage modifications of products, especially the formation of remote ε-tertiary and ε-heteroquaternary carbon stereocenters, further highlight the important synthetic value of this method. Control experiments and density functional theory (DFT) calculations were conducted to elucidate the plausible reaction mechanism and origins of regioselectivity and stereoselectivity.

Isolasi dan Uji Aktivitas Antioksidan Ekstrak Metanol Dari Buah Senduduk Bulu (Clidemia hirta (L.) D. Don)

A study on isolation and antioxidant activity of secondary metabolit of methanol extract of fruit of Senduduk Bulu (Clidemia hirta (L.) D. Don) has been carried out. Senduduk bulu is used for folk medicine to many diseases. Flavonoid and phenolic has been reported to its activity as antioxidant. The aim of this research was to find antioxidant compound and antioxidant activity of this fruit. Isolation works were conducted using Vacuum Liquid Chromatography and Column Chromatography method. Antioxidant activity was determined using DPPH free radical scavenging methods. The isolation works afforded 10 mg of pure compound CHP1 which was obtained as white crystal, with its melting point of 165–167ºC, soluble in chloroform and slightly soluble in methanol. This compound gave positive reaction with Liebermann-Burchard (LB) reagent and concluded as terpenoid. Based on it UV spectrum, this compound showed a λ max of 316 nm. Its FT-IR spectrum showed appearence of some functional groups of OH, C-H aliphatic, C=O ester,C=C alkene, CH bending and C-O. The 1H-NMR spectrum showed the alkene protons and methyl protons which is a characteristic of terpenoid compounds. The pure compound (CHP1) provided a weak antioxidant activity with the IC50 of 327,01µg/mL.

Synthesis of Hydroxylated Polyisoprene-graft-Polylactide Copolymer

Polyisoprene (PI) has been widely used in many industries for decades. Many researches have reported that most significant weaknesses of polyisoprene are caused by unsaturated double bond C=C. The aim of this research was to synthesis and characterize a new copolymer utilizing the unsaturated double bond C=C of polyisoprene. PI is first modified to form hydroxylated polyisoprene (PIOH). The absence of alkene proton peak in NMR spectrum of PIOH is a strong evidence that the unsaturation of PI has been reduced. After that, PIOH is subjected as an initiator for the ringopening polymerization of D,L-lactide in bulk condition to form hydroxylated polyisoprene-graft-polylactide copolymer (PI-g-PLA). The NMR spectrum of the new copolymer structure showed an unique peak at 4.09 ppm corresponding to methine proton of polyisoprene backbone adjacent to the PLA chains, indicating the grafting of D,L-lactide is successful to form PIOH-g-PLA. The average molecular weight, Mw of PIOH-g-PLA was significantly increased compared to PIOH, from 38260 to 56870 according to GPC. The surface of PIOH-g-PLA displayed significantly higher wettability and hidrophilicity than polyisoprene with water contact angle of below 30°. This owes to the terminal hydroxyl groups of PLA chains that lead to the formation of hydrogen bonds. Thermal stability studies by TGA and DTG of PIOH-g-PLA indicated two thermal degradations at Tmax 260 and 392 ℃ corresponding to PLA side chains and PIOH backbone, respectively, with PIOH exhibiting highest thermal stability compared to PI and the graft copolymer.

Quantitative 1 H nuclear magnetic resonance (qHNMR) methods for accurate purity determination of glucosinolates isolated from Isatis indigotica roots.

Glucosinolates (1-5) are important secondary metabolites found in Isatis indigotica roots. Due to their high hydrophilic and ionic nature, purified glucosinolates often contain salt impurities and moisture. Accurate assessment of their purities is important for glucosinolates being utilised as chemical markers. To develop and validate quantitative proton (1 H) nuclear magnetic resonance (qHNMR) methods for purity assessments of aliphatic and indole glucosinolates (1-5). Several NMR parameters such as pulse program, relaxation time, and delay time were optimised. Three qHNMR methods were developed using gluconapin (3), neoglucobrassicin (4), and sinigrin (5) for method validation and with maleic acid as internal standard. The quantification was based on the integrated area ratios of an olefinic proton (H-4 for 1-3; H-6 for 4; and H-3 for 5) of the side chain from glucosinolates relative to the olefinic proton from the internal standard using deuterated water (D2 O) as the solvent. The qHNMR methods were successfully applied for purity assessments of four aliphatic glucosinolates (1-3 and 5: progoitrin, epiprogoitrin, gluconapin, and sinigrin), and an indole glucosinolate (4: neoglucobrassicin). The purity of glucosinolates isolated from I. indigotica and commercial sinigrin was accurately assessed using the developed qHNMR method. The qHNMR provides a reliable and superior means to determine the purity of glucosinolates.

A Triterpene and A Phytosterol from Rhynchosia Minima

The Chemical examination of the n-hexane extract of Rhynchosia minima results the separation of two compounds. To separate these compounds, the dried powder of Rhynchosia minima was succumbed to hot extraction with n-hexane and submitted to chromatography.
 Mass spectra for the separated compounds appeared their molecular formula which was C30H50O for compound 1 and C29H48O for compound 2. In the 1H-NMR range of compound 1, H-3 proton revealed as a triplet of a double doublet (tdd) at δ 3.13, H-29 protons give two multiplets at δ 4.50 and δ 4.62 and seven methyl protons showed up at δ 27.46, 15.34, 16.09, 15.99, 14.55, 18 and 19.31. In the 1H-NMR range of compound 2, H-3 proton revealed as a triplet of a double doublet (tdd) at δ 3.45, olefinic proton H-6 revealed as a multiplet at δ 5.28 and six methyl protons showed up at δ 12.18, 19.3, 18.97, 21.02, 21.09 and 12.04. From the physical, chemical and spectral characteristics, compound 1 and 2 were distinguished as Lupeol and Stigmasterol.

Alkylation of lignin-derived aromatic oxygenates with cyclic alcohols on acidic zeolites

Moderately strong BAS and spacious microporous environments (i.e., large-pore acidic zeolites HBEA and HY) are important criteria for efficient alkylation of phenols with cyclic alcohols and alkenes, while very strong BAS appear to be responsible for catalyst deactivation. BAS confined in HBEA and HY pores show substantially higher turnover frequencies compared to solids without molecularly sized pore constraints. HBEA favors the formation of mono-alkylates, while enhanced formation of di-alkylates is observed on HY. Dehydration of alcohols always dominates over the alkylation at the onset of the reaction. Carbenium ions, the direct electrophile for aromatic oxygenates, are produced mainly from the adsorption and protonation of olefins. The present study shows that for the alkylation of phenols and cyclic alcohols in apolar liquids, the alcohol concentration should be kept low to avoid the formation of unreactive surface dimers and mitigate their inhibitory effects on olefin adsorption and protonation.

DFT Calculations of 1H- and 13C-NMR Chemical Shifts of Geometric Isomers of Conjugated Linoleic Acid (18:2 ω-7) and Model Compounds in Solution.

A density functional theory (DFT) study of the 1H- and 13C-NMR chemical shifts of the geometric isomers of 18:2 ω-7 conjugated linoleic acid (CLA) and nine model compounds is presented, using five functionals and two basis sets. The results are compared with available experimental data from solution high resolution nuclear magnetic resonance (NMR). The experimental 1H chemical shifts exhibit highly diagnostic resonances due to the olefinic protons of the conjugated double bonds. The “inside” olefinic protons of the conjugated double bonds are deshielded than those of the “outside” protons. Furthermore, in the cis/trans isomers, the signals of the cis bonds are more deshielded than those of the trans bonds. These regularities of the experimental 1H chemical shifts of the olefinic protons of the conjugated double bonds are reproduced very accurately for the lowest energy DFT optimized single conformer, for all functionals and basis sets used. The other low energy conformers have negligible effects on the computational 1H-NMR chemical shifts. We conclude that proton NMR chemical shifts are more discriminating than carbon, and DFT calculations can provide a valuable tool for (i) the accurate prediction of 1H-NMR chemical shifts even with less demanding functionals and basis sets; (ii) the unequivocal identification of geometric isomerism of CLAs that occur in nature, and (iii) to derive high resolution structures in solution.

Thermal-oxidation study of biodiesel by proton nuclear magnetic Resonance (1H NMR)

Biodiesel is a renewable biofuel suitable for diesel replacement. Biodiesel has in its composition unsaturated fatty esters making it easily degraded. The objective of the present work was to investigate biodiesel thermal-oxidation by 1H NMR spectroscopy. Using the NMR was possible to analyze the signal intensities of the olefinic, bis-allylic and allylic protons of the chemical bonds, obtain the oleic, linoleic, linolenic and saturated acyl groups proportions, observe and classify some oxidation products. Two sets of biodiesel were analyzed, the first was oxidize in the Rancimat equipment at 110 °C during 8 h, and the second was oxidized in an oven at 50 °C during 17 days. The biodiesel oxidized at 110 °C had a more expressive degradation when compared to the samples oxidized at 50 °C. The samples presented an increase in the saturated proportion. It was possible to observe the formation of oxidation products as hydroperoxides and aldehydes as propanal and 2-propenal.

Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy

Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic, bis-allylic and allylic protons signals of the chemical bonds, and by the induction period of the Rancimat. Biodiesel samples with metallic ions (Fe and Cu) and with rosemary natural extract were analyzed. The metal compounds showed a catalytic effect in the samples and the rosemary natural extract showed to be efficient by retarding the degradation process. The extract was ineffective in the presence of iron. Through the 1H NMR spectra was possible to observe changes in the signal intensities of the olefinic, bis-allylic and allylic protons as well as the formation of oxidation products in the biodiesel in the degradation process.

(R)-N-trans- feruloyloctopamine from the root timber of Melochia umbellata (Houtt.) Stapf var. Visenia (Paliasa)

A phenolic amide namely (R)-N-trans-feruloyloctopamine has been isolated from chloroform fraction of the root timber Melochia umbellata (Houtt) Stapf var. Visenia (Paliasa). Isolation compound has been done by maceration, fractionation, and purification. The molecular structure was determined by IR spectroscopy, NMR 1D and 2D (1H-NMR, 13C-NMR, HSQC and HMBC). Isolate formed yellow paste (83.4 mg) with melting point of 156 – 158 °C. The λmaks data on the UV-Vis spectrum of 333.80 nm (3.795) indicate compound has a long conjugated double bond. Data IR vmax cm−1 for groups as follows : 3327 (-OH), 2933 (C-H aliphatic), 1653 (C=O amide), 1593 (olefin). The data of NMR 1,2D show that this compound contains 18 carbon atoms, consisting of: 1 methyl, 1 methylene, 11 metin and 5 carbon quartener. Metin carbon consists of 2 alkene protons (olefins), 7 aromatic protons, and 1 alkyl alcohol (δC 72.58 ppm). NMR data also shows that one quartener carbon as C = O amide group (δC 166.92 ppm) and one methoxy (δC 55.35 ppm). The (R)-N-trans-feruloyloctopamine is the first compound found in the genus Melochia.

Lewis Acid Catalyzed Transfer Hydromethallylation for the Construction of Quaternary Carbon Centers.

The design and gram‐scale synthesis of a cyclohexa‐1,4‐diene‐based surrogate of isobutene gas is reported. Using the highly electron‐deficient Lewis acid B(C6F5)3, application of this surrogate in the hydromethallylation of electron‐rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp3)−C(sp3) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate.

Isolation and characterization of lupeol from the whole plant of <i>Phaulopsis bateri</i>

This work was aimed at isolating and characterizing the bioactive constituents from the crude methanol extract of the whole plant of Phaulopsis barteri . The crude extract which was subjected to a silica gel column chromatography separation using petroleum ether/ethyl acetate blend, eluted a white crystalline substance with a melting point of 215-216 0 C. PBA shows recognizable peak at 79.02ppm which is characteristic of a carbon carrying an oxygen and the 1 HNMR spectrum which shows an olefinic proton at δ 4.71 and 4.56 respectively was identified as lupeol which is a C 30 H 50 O moiety. Identification of the compound was purely by spectral analysis. Keywords: Phaulopsis barteri , Lupeol, C 30 H 50 O, Chromatography

Effect of triglyceride glycerol CH signal on olefinic resonance quantification with proton magnetic resonance spectroscopy at 3 T

The in-vivo Magnetic Resonance Spectroscopy (MRS) techniques STimulated Echo Acquisition Mode (STEAM) and Point RESolved Spectroscopy (PRESS) are used to assess fat unsaturation levels in human adipose tissue by measuring the olefinic proton resonance at ≈5.4 ppm. At clinical field strengths, the resonance is overlapped by that of the triglyceride glycerol CH proton at ≈5.2 ppm. In the presented work, olefinic resonance contamination by that of the glycerol CH proton for STEAM and PRESS as a function of echo time (TE) is assessed at 3 T. MRS spectra were acquired from the triglyceride tricaprylin (contains glycerol but no olefinic protons), and from free oleic acid (contains olefinic but no glycerol protons) using STEAM (TE of 20 to 300 ms, mixing time of 20 ms) and PRESS (TE of 40 to 300 ms), with TE increments of 10 ms. Estimated olefinic signal contamination by the glycerol CH resonance was evaluated for short-TE (STEAM with TE of 20 ms and PRESS with TE of 40 ms) for human adipose tissue based on a literature composition and using the spectra acquired for tricaprylin and oleic acid. Contaminations of ≈20% for STEAM with a TE = 20 ms and ≈13% for PRESS with a TE = 40 ms were obtained. Glycerol CH contributions to the olefinic resonance was also estimated for eight oils in a similar manner. High-resolution in-vitro 16.5 T Nuclear Magnetic Resonance (NMR) spectra of the oils suggest that in the absence of significant T2 relaxation and J-coupling effects, 9 to 17% (depending on unsaturated fatty acid content) of the olefinic signal is attributable to the glycerol CH proton. The signal yield responses of the glycerol CH and the olefinic protons as a function of TE indicate that a TE of 90 ms for STEAM and a TE of 200 ms for PRESS are suitable for quantification of the olefinic resonance with minimal impact from the glycerol CH resonance. Signal area yields relative to those obtained with short-TE were 30% and 29% for the olefinic resonance and 4% and 5% for the glycerol resonance for STEAM with a TE of 90 ms and PRESS with a TE of 200 ms, respectively. The efficacy of the timings was verified in vivo on tibial bone marrow.

Isolation and characterization of Β-sitosterol from methanol extracts of the stem bark of large- leaved rock fig (<i>Ficus abutilifolia</i> Miq)

This work was aimed at isolating and characterizing some bioactive constituent(s) from the stem bark of Ficus abutilifolia . The phytochemical analysis of the crude methanol extract indicates the presence of flavonoids, alkaloids, cardiac glycosides, saponnins, tannin, steroids and triterpenes. The extract was subjected to column chromatography which resulted in the isolation and purification of a white needle-like crystalline substance with a melting point of 134 – 136 0 C, the 13 CNMR shows recognizable peak at 71.98 ppm assignable to the beta hydroxyl group and the 1 HNMR spectrum which shows an olefinic proton at δ 5.37 was identified as β-sitosterol. Identification of the compound was purely by spectral evidence. Keywords: Ficus abutilifolia , methanol extracts, phytochemical analysis, β-sitosterol

Comparative Analysis of Surface and Thermal Properties of Oil—Polymer Resins

Data on the surface-energy, acid–base, and thermal characteristics of a wide range of oil–polymer resins have been obtained using wetting methods and differential-thermal analysis. The composition of resins is determined by nuclear magnetic resonance on protons. The dependence of acid–base properties (acidity parameter) of the resin surface on the content of olefinic protons has been found. Samples with best thermal stability are noted.

Lipogenesis inhibition and adipogenesis regulation via PPARγ pathway in 3T3-L1 cells by Zingiber cassumunar Roxb. rhizome extracts

Zingiber cassumunar (ZC) is used by tribal people in northern Thailand in traditional remedies for anti-obesity and in food recipes. Extracts from this plant have been studied for several pharmacological effects including anti-obesity, but with no clear evidence on cellular mechanism of activity. This study aim to investigate the lipolytic and anti-adipogenic activity of crude extracts from ZC on in vitro cultures of the mouse adipocyte cell-model, 3T3-L1. Dry rhizome powder was extracted with absolute ethanol and boiled-water. On the exposed pre-adipocytes to the extracts, cytotoxicity was not detected by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Lipid content and glycerol release were assessed using Oil Red-O and a commercial Adipolysis Assay kits respectively. The extracts exhibited no significant lipolytic activity on the exposed mature-adipocytes, in serial dilutions ranging from 1 to 800 µg/ml. However, anti-lipogenic activity was presented. All extracts significantly reduced the lipid content of exposed differentiating-adipocytes. This anti-lipogenic activity was confirmed by the expression of selected genes, determined by using real-time PCR techniques, in four groups namely: adipocyte differentiation genes, glucose uptake genes, lipid metabolism genes and fatty acid oxidation genes. 1H NMR spectrum of the extracts exhibited the prominent olefinic protons of phenylbutanoids, the group of compounds previously proved with several bioactivities. This study provided evidences of mechanisms that apparently verify the traditional use of ZC to prevent obesity.

Free Radical Scavenging Capacity, Carotenoid Content, and NMR Characterization of Blighia sapida Aril Oil.

Blighia sapida aril oil is rich in monounsaturated fatty acids but is however currently not utilized industrially. The oil was characterized utilizing nuclear magnetic resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). A spectrophotometric assay was conducted to determine the free radical scavenging properties and carotenoid content of the oil. Chemical shifts resonating between δ 5.30 and 5.32 in the 1H NMR are indicative of olefinic protons present in ackee aril oil which are due to the presence of oleic acid. A peak at 3006 cm−1 in the FTIR spectra confirms the high levels of monounsaturation. The oil has a free radical scavenging activity of 48% ± 2.8% and carotenoid content of 21 ± 0.2 ppm.