Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Chemical Industry and Chemical Engineering Quarterly , 2010,
Abstract: The electron-ionization induced mass spectra of twenty six N-monosubstituted cyanoacetamides were recorded and their fragmentation patterns were stu died. The effect of N-alkyl and N-aryl substituents to the fragmentation of the investigated compounds was discussed. Mechanistic generalization lead to a conclusion that fission of the carbon-carbon bonds next to carbonyl function or nitrogen were processes common for N-alkyl and N-(4-substituted phenyl) cya noacetamides. In some amides, the elimination of the acyl group by a ketene fragment gave rise to the more stable ion. Cycloalkyl amides could not frag ment by single carbon-carbon bond fission, but subsequent rearrangement resulted in formation of stable even electron ion. N-(4-substituted phenyl) cyanoacetamides were more stable showing also characteristic fragmentation depending on substituent present at phenyl ring.
Substituent effect on IR, 1H and 13C NMR spectral data in n-(substituted phenyl)-2-cyanoacetamides: A correlation study  [PDF]
Marinkovi? Aleksandar D.,Brki? Dominik,Martinovi? Jelena S.,Mijin Du?an ?.
Chemical Industry and Chemical Engineering Quarterly , 2013, DOI: 10.2298/ciceq120109044m
Abstract: Linear free energy relationships (LFER) were applied to the IR, 1H and 13C NMR spectral data of N-(substituted phenyl)-2-cyanoacetamides. A variety of substituents were employed for phenyl substitution and fairly good correlations were obtained using the simple Hammett and the Hammett-Taft dual substituent parameter equations. The correlation results of the substituent induced 13C NMR chemical shifts (SCS) of the C1, C=O and N-H atom indicated different sensitivity with respect to electronic substituent effects. A better correlation of the SCSC=O with a combination of electrophilic and nucleophilic substituent constants indicated a significant contribution of extended resonance interaction (π-delocalization) within the π1-unit. The conformations of the investigated compounds were studied using the DFT B3LYP/6-311G method and, together with the results of 13C NMR and IR spectroscopic studies, a better insight into the influence of such a structure on the transmission of electronic substituent effects was obtained.
Comparative analysis of oxidative synthesis of N-alkyl, N,N-dialkyl and N-cykloalkyl-O-isobutyl thioncarbamate
Sovrli? Milica ?.,Milosavljevi? Milutin M.,Marinkovi? Aleksandar D.,?ukanovi? Jasmina S.
Hemijska Industrija , 2011, DOI: 10.2298/hemind110504038s
Abstract: A optimized synthesis of N-alkyl, N,N-dialkyl- and N-cycloalkyl-O-isobutyl thioncarbamates by aminolysis of sodium isobutylxanthogenic acid (NaiBXAc) and primary, secondary and cycloalkyl amines was developed at laboratory scale and applied at semi-industrial level. Studies on dependence of N-n-propyl-O-isopropylthiocarbamate yield and purity with respect to reaction parameters: reaction time and molar ratio of n-propylamine and NaiBXAc, were performed. In such way, optimal reaction conditions for synthesis of N-alkyl, N,N-dialkyl- and N-cycloalkyl-O-isobutyl thioncarbamates, by aminolysis of NaiBXAc, were established. Also, comparative results of thioncarbamates synthesis starting from potassium isobutyl xanthate (KiBX) and corresponding amines in presence of different oxidants: hydrogen peroxide, sodium hypochlorite and new oxidative agent potassium peroxodisulfate were evaluated. Synthesized compounds have been fully characterized by FTIR, 1H and 13C NMR and MS data, elemental analysis and purity have been determined by gas chromatographic method (GC). According to our knowledge, ten synthesized thioncarbamates are for the first time characterized. Synthesized compounds could be used as selective reagents for flotation of copper and zinc ores. The presented methods offer several benefits, namely, high product yields and purity, simple operation, mild reaction conditions without use of hazardous organic solvents, while some of them could be implemented on industrial scale production.
NMR study of 1,4-dihydropyridine derivatives endowed with long alkyl and functionalized chains
Suárez, Margarita;Molero, Dolores;Salfrán, Esperanza;Rodríguez, Hortensia;Coro, Julieta;Sáez, Elena;Martínez-álvarez, Roberto;Martín, Nazario;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000100022
Abstract: the 1h , 13c and 15n nmr spectroscopic data for 1,4-dihydropyridine endowed with long alkyl and functionalized chain on c-3 and c-5, have been fully assigned by combination of one- and two dimensional experiments (dept, hmbc, hmqc, cosy, noe).
Structural identification of the sulfonamides by the methods of IR and NMR spectroscopy
Veremeychik Ya. V.,Shurpik D. N.,Kupriyanova G. S.,Plemenkov V. V.
Vestnik Immanuel Kant Baltic Federal University , 2013,
Abstract: Structures of new type of sulfonamide preparations were determined complex using methods of IR spectroscopy and 1H NMR spectroscopy. This methodology proposed as a general approach for structural identification of the pharmaceutical substances.
A new phenylethyl alkyl amide from the Ambrostoma quadriimpressum Motschulsky  [cached]
Guolei Zhao,Chao Yang,Bing Li,Wujiong Xia
Beilstein Journal of Organic Chemistry , 2011, DOI: 10.3762/bjoc.7.158
Abstract: A new phenylethyl alkyl amide, (10R)-10-hydroxy-N-phenethyloctadecanamide (1), was isolated from the beetle Ambrostoma quadriimpressum Motschulsky. The structure of the amide was determined by NMR and MS. The absolute configuration of compound 1 was confirmed by an asymmetric total synthesis, which was started from L-glutamic acid. The construction of the aliphatic chain was accomplished by the selective protection of the hydroxy groups and two-time implementation of the Wittig olefination reaction.
Copolymerizations of long side chain di n-alkyl itaconates and methyl n-alkyl itaconates with styrene: Determination of monomers reactivity ratios by NMR Copolimerización de diitaconatos y metil itaconatos de n-alquilo de cadenas laterales largas con estireno: Determinación de de las relaciones de reactividad de los monómeros por RMN
Elizabeth Rangel-Rangel,Carlos Torres,Luís Rincón,Sonia Koteich-Khatib
Revista Latinoamericana de Metalurgia y Materiales , 2012,
Abstract: Low yields copolymerization of styrene (S) with di-n-alkylitaconates (DI-n) and methyl n-alkylitaconates (MeI-n) with alkyl side chain of 12, 14, 16, 18 and 22 carbon atoms were carried out in bulk via radical at 60oC with AIBN as initiator. The copolymers chemical structure was characterized by FTIR and 1H and 13C-NMR, and the composition was determined by 1H-NMR. The NMR studies indicate that the copolymers are random, but with some tendency to alternation. The monomers reactivity ratios between the styrene and itaconates in the copolymerization (ri) were calculated by the Fineman-Ross (FR), Kelen Tüd s (KT) methods and a modification of the last one. The obtained values of r1(DI) and r2(S) in the copolymerization among DI-n with n = 12, 14 and 16 with S were in the range of 0.22 to 0.28 for DI-n and 0.19 to 0.39 for S. Whereas for DI-n with n = 18 and 22 the values are in the order of 0.42-0.50 and 0.37-0.47 respectively. For the copolymer series derivatives of MeI-n the values were between 0.01-0.41 for the itaconate and 0.44-0.97 for S. La copolimerización a bajos grados de conversión de estireno (S) con di-n-alquilitaconatos (DI-n) y de metil-n-alquil itaconatos (MeI-n) con cadenas laterales de 12, 14, 16, 18 y 22 átomos de carbono se llevó a cabo por vía radical, en masa a 60oC y empleando AIBN como iniciador. La estructura química de los copolímeros se caracterizó por FTIR y RMN-1H y 13C y la composición se determinó por RMN-1H. Los estudios de RMN indican que los copolímeros son estadísticos pero con cierta tendencia a la alternancia. Las relaciones de reactividad (ri) entre el estireno e itaconatos se calcularon mediante los métodos de Fineman-Ross (FR), Kelen Tüd s (KT) y una modificación esta última. Los valores obtenidos de r1(DI) y r2(S) en la copolimerización entre los DI-n con n = 12, 14 y 16 con S estuvieron en el rango de 0.22 a 0.28 para DI-n y 0.19 a 0.39 para S, mientras que los valores encontrados para los DI-n con n = 18 y 22 son del orden de 0.42-0.50 y 0.37-0.47 para el itaconato y estireno respectivamente. Para la serie de MeI-n, los valores oscilaron entre 0.01 hasta 0.41 para los itaconatos y 0.44 a 0.97 para el S.
Syntheses and Spin Trapping-ESR Studies of Novel Saturated Alkyl Spin-traps

ZHAO Ji-shou,CHU Yu-jie,DU Li-Bo,HAN Lu,YAO Tong-wei,HE Chao,WANG Wei-jun,TIAN Qiu,JIA Hong-ying,LIU Yang,

波谱学杂志 , 2009,
Abstract: Two new saturated alkyl linear nitrone spin-traps N-(Ethylidene)-t- butylamine N-oxide] (EBN) and (N-(Ethylidene)-1-diethoxyphosphoryl-1- methylethylamine -Oxide) (EPN) were synthesized. Characterization of the structures of these spin traps were carried out using NMR, MS, IR, UV and other means. The two compounds were shown to be able to trap hydroxyl radicals produced in the Fenton reaction and carbon-, oxygen- or sulfur- entered radicals.
Synthesis, characterization of amine-bridged bis(phenolate) yttrium alkyl complex and its catalytic behavior for the Tishchenko reaction
MingLun Pang,YingMing Yao,Yong Zhang,Qi Shen
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0257-x
Abstract: Reaction of homoleptic yttrium tris-alkyl complex YR3(R=CH2C6H4NMe2-o) with 1 equivalent of amine bis(phenol)s LH2 (L=Me2NCH2CH2N(CH2-(2-O-C6H2-Bu2 2-3,5))2) afforded the solvent-free yttrium alkyl complex LYR (1), which has been characterized with elemental analysis, 1H NMR and IR spectra, and structural determination. The coordination geometry around the center metal atom can be best described as a distorted octahedron. It was found that complex 1 can be used as an efficient catalyst for the Tishchenko reaction.
Koenigs-Knorr Synthesis of Cycloalkyl Glycosides  [PDF]
Zdenek Wimmer,Lucie Pechova,David Saman
Molecules , 2004, DOI: 10.3390/91100902
Abstract: Cadmium carbonate was found to be a useful promoter in the Koenigs-Knorrsynthesis of 2-(4-methoxybenzyl)cyclohexyl-β-D-glycopyranosides. Using this promotermodel glucoside and galactoside derivatives of cyclic (i.e., secondary) alcohols weresynthesized in 50–60 % overall yields. Diastereoisomeric mixtures of products wereobtained in these syntheses, which started from racemic isomers of 2-(4-methoxy-benzyl)cyclohexanol. The prepared compounds have been purified and characterized bytheir 1H- and 13C-NMR spectra, as well as by their IR and MS spectra, in order to usethem as reference compounds in planned subsequent research.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.