Poly(vinylidene chloride-co-vinyl acetate): comprehensive microstructure analysis by NMR spectroscopy

The microstructure analysis of poly(vinylidene chloride-co-vinyl acetate) was done using chemical shift modeling and 2D NMR spectroscopy. Chemical shift modeling was applied to analyze the compositional sensitive resonances of quaternary carbon of vinylidene chloride unit. Reactivity ratios determination was done from the diad and triad fractions. To resolve the complex ¹H and ¹³C{¹H} NMR spectra of copolymers, 2D ¹H/¹³C hetero-nuclear single quantum coherence (HSQC), ¹H/¹H total correlation spectroscopy (TOCSY) and hetero-nuclear multiple bond correlation (HMBC) experiments were conducted. The combination of 2D NMR experiments supported by chemical shift modeling enabled to assign the complex and overlapping proton and carbon-13 resonances unambiguously.     

Investigation of grafting sites of acrylic monomers onto alkyd resins via gHMQC two-dimensional NMR: Part 1

Acrylic monomers were grafted onto alkyds via free radical chemistry. The alkyd was a medium oil soya-based alkyd with glycerol, phthalic anhydride, and tetrahydrophthalic anhydride (THPA) as the other components. To identify the specific graft locations, 1D and 2D NMR spectroscopy techniques were utilized. Gradient heteronuclear multiple quantum coherence (gHMQC) 2D NMR was required to assign the chemical shifts of the 1D carbon and proton NMR spectra. Three acrylic monomers, methyl methacrylate (MMA), butyl acrylate (BA), and methacrylic acid (MAA) were grafted to the alkyd, resulting in either MMA, BA, or MAA modified alkyds. Two-dimensional gHMQC spectra for each system confirm grafting at doubly allylic hydrogens located on the fatty acid chains and the polyol segment of the alkyd backbone. The gHMQC spectra show no evidence of grafting across double bonds on either pendant fatty acid groups or THPA unsaturation sites for any of the monomer choices.     

Characterization of poly(1‐methyl‐1,4‐butanediol‐1,4‐diyl/2,3,4‐trihydro‐5‐methylfuran‐2,5‐diyl) prepared from natural rubber through 2D NMR spectroscopy

Poly(1‐methyl‐1,4‐butanediol‐1,4‐diyl/2,3,4‐trihydro‐5‐methylfuran‐2,5‐diyl) was prepared by epoxidation of deproteinized natural rubber with m‐chloroperbenzoic acid followed by hydrolysis with sulfuric acid. Characterization of the resulting product was performed through FT‐IR, ¹H NMR, and ¹³C NMR spectroscopies. All signals appearing in the ¹H and ¹³C NMR spectra were assigned by distortionless enhancement by polarization transfer (DEPT), quaternary carbon observation (QUAT), correlation spectroscopy (COSY), and heteronuclear multiple quantum correlation (HMQC) measurements. After proving the primary structure of the product, one pot synthesis of poly(1‐methyl‐1,4‐butanediol‐1,4‐diyl/2,3,4‐trihydro‐5‐methylfuran‐2,5‐diyl) from deproteinized natural rubber latex was carried out with peracetic acid and 2‐propanol. The resulting product was characterized by ¹H NMR spectroscopy on the basis of the assignments established in this study, and its gas permeability was measured for a practical application as a film. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

固体酸催化合成3,5-二乙酰氧基苯乙烯

以3,5二-羟基苯乙酮(4)为原料,经三步反应制得3,5二-乙酰氧基苯乙烯(1)。在硫酸催化下化合物(4)与乙酸酐反应,得到3,5二-乙酰氧基苯乙酮(3),收率92%,对于化合物(3)进行了1H NMR表征;化合物(3)经催化加氢,得到1-(1羟-基乙基)-3,5二-乙酰氧基苯(2),收率98%,对于化合物(2)进行了1H NMR表征;化合物(2)在固体酸催化下反应得到3,5二-乙酰氧基苯乙烯(1),制备化合物(1)的反应条件为:m[化合物(2)]∶m(固体酸)=5∶1,110℃回流5 h,收率95%,纯度98%,对化合物(1)进行了IR,1H NMR,MS表征,并对化合物(1)的1HNMR,MS表征结果进行了进一步分析。     

Novel ceramides and a new glucoceramide from the roots of <Emphasis Type="Italic">Incarvillea arguta</Emphasis>

Novel ceramides, rel-(3S,4S,5S)-3-[(2R)-2-hydroxycosanoyl-hexacosanoylamino]-4-hydroxy-5-[(4Z)-tetradecane-4-ene]-2,3,4,5-tetrahydrofuran (1a-g), and a new glucoceramide, 1-O-β-d-glucopyranosyl-(2S,3S,4R,8E)-2-[(2R)-2-hydroxytetracosanoylamino]-1,3,4-octodecanetriol-8-ene (2) were isolated from the aqueous ethanolic extract of the roots of Incarvillea arguta, together with eight known compounds: β-sitosterol (3), oleanolic acid (4), ursolic acid (5), piperin (6), maslinic acid (7), β-sitosterol 6′-O-acyl-β-d-glucopyranoside (8), 8-epideoxyloganic acid (9), and plantarenaloside (10). Their structures were elucidated on the basis of spectral data including IR, MS, NMR [¹H NMR, ¹³C NMR (distortionless enhancement by polarization transfer), ¹H−¹H COSY, heteronuclear multiplequantum coherence, and heteronuclear multiple-bond coherence correlations]. The relative configurations were established by nuclear Overhauser effect spectroscopy experiments and by comparison of the NMR spectral data and coupling constants with those already reported in the literature.     

NMR Spectra of Nitrobenzanthrones Obtained by Using Double-Pulsed Field-Gradient Spin Echo

We have synthesized several nitrobenzanthrones (NBAs) and investigated their structures in solution using NMR spectroscopy. In our study, however, low solubility of NBAs in organic solvents always became a serious problem and led to NMR spectra with low signal-to-noise ratios. To solve this problem, we adopted a new method of conventional coherence transfer pathway selection using pulsed field-gradients. The double-pulsed field-gradient spin echo (DPFGSE) sequence was used for selecting natural-abundance carbon-13 isotopomers by using a bilinear rotation decoupling (BIRD) sequence and a so-called gradient-BIRD pulse for the excitation sculpting technique. We performed NMR measurements on 3,9-dinitro-7 H -benz[ d,e ]anthracene-7-one (compound 1), 3,9,11-trinitro-7 H -benz[ d,e ]anthracene-7-one (compound 2), and 2-nitro-7 H -benz[ d,e ]anthracene-7-one (compound 3) by this method and obtained spectra of high quality. Combining the results from phase-sensitive 2D NOESY, HOHAHA, and DPFGSE-HMQC, DPFGSE-HMQC TOCSY, and phase-sensitive FG-HMBC permitted us to complete NMR assignments. It was confirmed that the present method enables us to improve the sensitivity and to assign the NMR signal readily, even for compounds with low solubility.     

NMR analysis of butyl acrylate/methylmethacrylate/α‐methyl styrene terpolymers

Composition analysis for butyl acrylate (BA)/ methyl methacrylate (MMA)/α‐methyl styrene terpolymers was carried out by NMR spectroscopy methods. ¹H‐NMR was used primarily for this analysis, but because the method did not provide independent measurements for the BA and MMA fractions, the terpolymer composition analysis was open to higher than normal levels of uncertainty. Supplementary analyses were made with quantitative ¹³C‐NMR methods to confirm the results from ¹H‐NMR (quantitative ¹³C‐NMR was used to provide corroboration of selected composition analyses). To confirm spectral assignments in the ¹H‐ and ¹³C‐NMR spectra, heteronuclear multiple quantum coherence and J Modulated Spin Echo (JMOD) pulse sequences were used. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2093–2098, 2007     

芒果苷元的人工全合成研究

以2-溴-4,5-二甲氧基苯甲酸(6)和均苯三酚三甲醚(5)为起始原料,经Friedel-Crafts酰基化、选择性脱甲基、Ullmann成醚环合、全部脱甲基四步反应,合成了芒果苷元(1),总收率51%。目标产物经高效液相检测,纯度达99.5%,其结构经IR、MS、1H NMR和13C NMR表征。     

新疆白麻药用成分的提取与表征

以新疆白麻Poacynum pictum(Schrenk)Baill叶为原料,采用溶剂萃取及色谱技术从新疆白麻叶中共分离并鉴定了11个化合物的结构,并通过理化常数、MS、1H NMR和13C NMR等现代波谱技术鉴定其化学结构,分别为羽扇醇棕榈酸酯(1)、异莨菪亭(2)、正十六烷酸(3)、正二十六烷酸(4)、β-谷甾醇(5)、槲皮素(6)、槲皮素-3-O-β-D-吡喃葡萄糖苷(7)、金丝桃苷(8)、Δ′-异戊烯-3-O-β-D-吡喃葡萄糖苷(9)、丁香树脂醇-β-D-吡喃葡萄糖苷(10)和蔗糖(11)。其中化合物2为首次从属中分离得到。     

Separation and Purification of Quinolone Alkaloids from the Chinese Herbal Medicine Evodia rutaecarpa (Juss.) Benth by High Performance Counter-Current Chromatography

Preparative separation of quinolone alkaloids in Evodia rutaecarpa (Juss.) Benth was conducted by high performance counter-current chromatography (HPCCC) with a pair of two solvent systems consisting of n-hexane-methanol-water-acetic acid (2:1:1:0.2, v/v) and (5:4:2:0.1, v/v). Consequently, 31.78 mg 1-methyl-2-nonyl-4 (1H)-quinolone (I), 59.25 mg 1-methyl-2-(6-undecenyl)-4 (1H)-quinolone (II), 333.27 mg evocarpine (III), 101.13 mg 1-methyl-2-(6,9-pentadecadienyl)-4(1H)-quinolone (IV), 132.17 mg dihydroevocarpine (V), and 86.99 mg 1-methyl-2-(10-pentadecenyl)-4(1H)-quinolone (VI) were obtained from 1.3 g of the crude extract. The structures of these compounds were identified by mass spectrometer (MS), nuclear magnetic resonance (¹H NMR and ¹³C NMR).     

清香木姜子的化学成分Ⅱ

利用硅胶柱层析分离及与标准品对照等方法从清香木姜子枝叶中分离得到4个化合物,1H NMR、13C NMR等技术及理化性质鉴定为:黄堇碱(1)、二十二酸(2)、二十六酸(3)、三十酸(4)。以上化合物均系首次从该植物中分离得到。     

Application of high-resolution, two-dimensional 1H and 13C nuclear magnetic resonance techniques to the characterization of lipid oxidation products in autoxidized linoleoyl/linolenoylglycerols

Subjection of polyunsaturated fatty acid (PUFA)-rich culinary oils to standard frying episodes generates a range of lipid oxidation products (LOP), including saturated and α,β-unsaturated aldehydes which arise from the thermally induced fragmentation of conjugated hydroperoxydiene precursors. Since such LOP are damaging to human health, we have employed high-resolution, two-dimensional ¹H-¹H relayed coherence transfer, ¹H-¹H total correlation, ¹H-¹³C heteronuclear multiple quantum correlation, and ¹H-¹H J-resolved nuclear magnetic resonance (NMR) spectroscopic techniques to further elucidate the molecular structures of these components present in (i) a model linoleoylglycerol compound (1,3-dilinolein) allowed to autoxidize at ambient temperature and (ii) PUFA-rich culinary oils subjected to repeated frying episodes. The above techniques readily facilitate the resolution of selected vinylic and aldehydic resonances of LOP which appear as complex overlapping patterns in conventional one-dimensional spectra, particularly when employed in combination with solvent-induced spectral shift modifications. Hence, much useful multi-component information regarding the identity and/or classification of glycerol-bound conjugated hydroperoxydiene and hydroxydiene adducts, and saturated and α,β-unsaturated aldehydes, present in autoxidized PUFA matrices is provided by these NMR methods. Such molecular information is of much value to researchers investigating the deleterious health effects of LOP available in the diet.     

Comprehensive analysis of stereoregularity and sequence distribution in 2-N-carbazolylethyl acrylate and methyl methacrylate copolymers by 2D NMR spectroscopy and their thermal studies

A series of 2-N-carbazolylethyl acrylate (C) and methyl methacrylate (M) copolymers with varying compositions were prepared in toluene at 60 °C using AIBN as an initiator. The molar outfeed ratio (F_C) for various compositions was determined from ¹H NMR spectra. Reactivity ratios calculated using Kelen-Tudos (KT) and non-linear error in variable (RREVM) methods were found to be r_C=0.43±0.8 and r_M=2.78±0.52. Molecular weight distribution was determined by gel permeation chromatography (GPC). The methine carbon of C unit showed splitting up to the pentad level in ¹³C{¹H} NMR spectra and was found to be sensitive to the variation in C/M copolymer compositions. The backbone methylene and carbonyl carbons of both M and C unit along with α-methyl carbon of the M unit showed both compositional and configurational sensitivity. Distortionless enhancement by polarization transfer (DEPT) helped in differentiating the methylene carbon signals from the methine and methyl carbon resonances. 2D heteronuclear single quantum coherence (HSQC) and 2D total correlation spectroscopy (TOCSY) were used in tandem to deduce all spectral assignments. 2D heteronuclear multiple bond coherence (HMBC) played an important role in studying the stereoregularity of the carbonyl carbon. The trend in variation of glass transition temperature (T_g) of various C/M copolymer compositions was also studied.     

Synthesis,characterization and polychelatogenic properties of poly[(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid)‐co‐(methacrylic acid)]

Poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid), poly(methacrylic acid), and five copolymers of poly[(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐co‐(methacrylic acid)] were synthesized by radical polymerization and obtained in yields >97%. The polymers were characterized by FT‐IR, [¹H]NMR, and [¹³C]NMR and studied by means of the Liquid‐phase Polymer‐based Retention (LPR) technique. The metal ion retention ability of the copolymers for Cu(II), Cd(II), Co(II), Hg(II), Ni(II), Zn(II), Cr(III) and Ag(I) was investigated at different pH values because of their environmental and analytical interest. The retention profiles of the copolymers were compared with those of the corresponding homopolymers and retention of metal ions was found to increase with increasing pH. © 2001 Society of Chemical Industry     

1-碘-3,13-二乙酰基-9-烯-16-酮-19,2-内酯-7-赤霉酸甲酯的合成

报道 1 碘 3 ,13 二乙酰基 9 烯 16 酮 19,2 内酯赤霉酸甲酯的合成。碘内酯化中间体 (3 )、臭氧化产物 (4 )的结构均由1 HNMR ,1 3CNMR波谱证实 ;目标产物 (5 )的结构由1 HNMR ,1 3CNMR ,质谱 (MS)及高分辨质谱 (HRMS)证实。     

Two‐dimensional NMR studies of styrene/n‐butyl acrylate copolymers synthesized by atom transfer radical polymerization

Copolymers of styrene and n‐butyl acrylate were prepared by atom transfer radical polymerization (ATRP) using CuBr/N,N,N′,N′,N″‐pentamethyl‐diethylenetriamine as catalyst and Methyl 2‐bromopropionate as initiator. The polydispersity of the copolymers is quite low (1.1–1.3). ¹³C {¹H} NMR spectra of these copolymers show that the methylene and methine signals of the main chain are compositional sensitive and highly overlapped. Even the distortionless enhancement by polarization transfer (DEPT) was not able to assign the complex and overlapping signals. Assignments of the various resonance signals were done with the help of heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple bond correlation (HMBC) experiments. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.     

Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.     

Stereochemical elucidation of complex α‐methyl and β‐methylene carbon resonances in poly(2‐hydroxy ethyl methacrylate‐co‐methacrylonitrile) by 2D NMR

Copolymers of 2‐hydroxy ethyl methacrylate and methacrylonitrile (H/M) of different composition were synthesized by free radical bulk polymerization using azobisisobutyronitrile (AIBN) as an initiator under nitrogen atmosphere. The copolymers composition were calculated from ¹H and quantitative ¹³C{¹H}NMR spectra. The complete spectral assignment of complex and overlapped α‐methyl and β‐methylene carbon regions in ¹³C{¹H} NMR spectrum in term of compositional and configurational sequences of H/M copolymers were done with the help of two‐dimensional heteronuclear single quantum coherence (HSQC) and total correlation spectroscopy (TOCSY). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

pH-Controllable cyclic threading/dethreading of polypseudorotaxane obtained from cyclodextrins and poly(amino ester)

Cyclic threading/dethreading of novel polypseudorotaxane obtained from β-cyclodextrins and poly(amino ester), poly(BDA-DEEDA), obtained from the Michael addition polymerization of 1,4-butanediol diacrylate (BDA) and N, N′-diethyl ethylenediamine (DEEDA), was realized by adjusting pH of the aqueous solutions between ca. 9.0 and 3.2 alternatively. ¹H NMR, XRD profiles, and ¹³C CP/MAS NMR verified the formation of polypseudorotaxane, and acid titration induced dethreaded structures were characterized using 2D ROESY NMR, ¹H NMR and XRD. The appearance/disappearance of precipitates, the kinetics, and the cyclic performance of pH controllable threading/dethreading processes were monitored by the changes in absorbance or transmittance of the solutions as reflected by UV experiments. Further pH-induced protonated and deprotonated states of poly(BDA-DEEDA) were demonstrated by ¹H NMR, which indicated the mechanism of the threading/dethreading processes.