3,4-Disubstituted derivatives of 1,2,5-thiadiazole 1,1-dioxide. Ethanol addition reactions and electroreduction of 3-methyl-4-phenyl and 3,4-dimethyl derivatives in acetonitrile and ethanol solvents

1996 ◽  
Vol 74 (8) ◽  
pp. 1564-1571 ◽  
Author(s):  
José Alberto Caram ◽  
María Virginia Mirífico ◽  
Silvia Lucía Aimone ◽  
Enrique Julio Vasini
Keyword(s):  
Nmr Spectroscopy ◽  
Addition Reaction ◽  
Uv Spectroscopy ◽  
Equilibrium Constants ◽  
Addition Reactions ◽  
Solvent Mixtures ◽  
Second Order Reaction ◽  
Ethanol Addition ◽  
Derivatives Of ◽  
C Nmr

3-Methyl-4-phenyl-1,2,5-thiadiazole 1,1-dioxide (TMP), as well as 3,4-dimethyl-1,2,5-thiadiazole 1,1-dioxide (TMM), react with ethanol (EtOH), which adds to one of their C = N double bonds. The equilibrium constants for the addition reaction are measured in mixed acetonitrile (ACN) – EtOH solvents by means of UV spectroscopy in the case of TMP, and by 13C NMR spectroscopy in the case of TMM, since TMM presents only terminal UV absorption. Both equilibrium constants are also estimated through cyclic voltammetry (CV) experiments. In the case of TMP, the ethanol molecule adds to the C = N bond located on the methyl-substituted side of the substrate, according to 13C NMR spectroscopy and CV results. The electroreduction characteristics of the substrates and their ethanol addition products are studied using CV techniques in ACN, EtOH, and CAN–EtOH solvent mixtures. The radical anion formed by the first electron transfer to TMM is unstable and decomposes rapidly while that corresponding to TMP undergoes a relatively slow homogeneous second-order reaction with the substrate (k = 3 × 102 M−1 s−1). The equilibrium constant for EtOH addition and the voltammetric properties of the substrates are compared with those of the previously studied 3,4-diphenyl derivative (TPP). Key words: electrochemistry, thiadiazoles, structure–reactivity relations, kinetics.

Synthese von Derivaten des 1-Adamantylbenzols /Synthesis of Derivatives of 1-Adamantylbenzene

1979 ◽  
Vol 34 (9) ◽  
pp. 1286-1288 ◽  
Author(s):  
Jörn-Volker WeiB ◽  
Victor Wray ◽  
Reinhard Schmutzler
Keyword(s):  
Nmr Spectroscopy ◽  
Lewis Acid ◽  
Type Reaction ◽  
Benzene Toluene ◽  
Derivatives Of ◽  
C Nmr

Abstractp-Di(1-adamantyl)benzene (6a), a mixture of the m- and p-isomers of 1-adamantyl-toluene (6b), and p-(l-adamantyl)bromobenzene (6c) were obtained in a Friedel-Crafts type reaction from 1-adamantyl fluoride and benzene, toluene, bromobenzene, respectively, in the presence of the Lewis acid phenyltetrafluorophosphorane. Characterisation of the products -all previously described in the literature -was by analysis and 13C NMR spectroscopy.

Ligand scrambling reactions of cyano(thione)gold(I) complexes and determination of their equilibrium constants

2002 ◽  
Vol 80 (10) ◽  
pp. 1279-1284 ◽  
Author(s):  
Saeed Ahmad ◽  
Anvarhusein A Isab ◽  
Herman P Perzanowski
Keyword(s):  
Ionic Strength ◽  
Nmr Spectroscopy ◽  
Key Words ◽  
Equilibrium Constants ◽  
Solvent Polarity ◽  
Approach To Equilibrium ◽  
Initial Concentration ◽  
C Nmr

Ligand scrambling reactions in cyano(thione)gold(I) complexes ([>C=S-Au-CN]) to form [Au(>C=S)2]+ and [Au(CN)2]– species have been investigated for a series of thiones in DMSO using 13C and 15N NMR spectroscopy. Rapid approach to equilibrium occurred and resulted in distinct signals for the [>C=S-Au-CN] and [Au(CN)2]– complexes, both in 13C and 15N NMR. Equilibrium constants (Keq) were determined for scrambling of all the complexes by integrating the CN resonances in the 13C NMR recorded at 298 K. The influence of various factors (initial concentration, ionic strength, temperature, and solvent polarity) on the Keq value was examined for a representative complex (ImtAuCN (Imt = Imidazolidine-2-thione)).Key words: cyanogold(I) complexes, thiones, ligand scrambling, NMR, Keq.

Solution carbocation stabilities measured by internal competition for a hydride ion

1982 ◽  
Vol 60 (17) ◽  
pp. 2180-2193 ◽  
Author(s):  
Nancy E. Okazawa ◽  
Ted S. Sorensen
Keyword(s):  
Nmr Spectroscopy ◽  
Equilibrium Constants ◽  
Analytical Tool ◽  
Steric Interactions ◽  
Hydride Ion ◽  
Methylene Chain ◽  
Internal Competition ◽  
Equilibration Process ◽  
Better Than ◽  
C Nmr

Although many techniques are known which allow one to compare the stabilities of solution carbocations, that involving the intermolecular competition for a hydride ion is conceptually (but not experimentally) the simplest procedure. This paper describes a variant of this which is experimentally more reliable and which uses intramolecular equilibria where the two competing systems are held together by a —(CH2)n— chain, e.g.[Formula: see text]By systematically varying "n" in this example (n = 0, 1,2, or 3), it has been found that a methylene chain of two or more carbons is necessary in order to minimize steric interactions between the end "systems". It has also been found that all cycloalkyl rings studied (except cyclohexyl) stabilize a cation centre much better than an aliphatic equivalent, i.e. [Formula: see text], in agreement with solvolysis rate studies. The same situation was found when comparing this aliphatic "system" against the 2-norbornyl cation (bicyclic) or against the tricyclic 2-adamantyl cation. In fact, in these cases the equilibria are too lop-sided to obtain numerical values for the equilibrium constants concerned. Finally, three carbocations were looked at where the 2-norbornyl cation structure was pitted against the structurally very related cyclopentyl, bicyclo[2.1.1]hexyl, and bicyclo[3.2.1]octyl cations. In all cases, the 2-norbornyl cation is the more stable. 13C nmr spectroscopy was used as the analytical tool to measure (or attempt to measure) the equilibrium constants. Depending on the rate of the equilibration process, three different techniques are involved and the relative merits of these are discussed in the latter part of the paper.

9-Silyl(-Germyl,-Stannyl) Substituted Derivatives of 1-(9-Fluorenyl)- germatranes. Synthesis, Characterisation, and Crystal Structures

1998 ◽  
Vol 53 (11) ◽  
pp. 1247-1254 ◽  
Author(s):  
Galina S. Zaitseva ◽  
Sergey S. Karlov ◽  
Bettina A. Siggelkow ◽  
Evgeni V. Avtomonov ◽  
Andrei V. Churakov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Elemental Analyses ◽  
Derivatives Of ◽  
C Nmr

9-Trimethylsilyl- and 9-trimethylgermyl substituted derivatives of 1-(9-fluorenyl)germatranes C13H8(R)Ge(OCH2CH2)3N (1 - 3) (1: R = H; 2: R = Me3Si; 3: R = Me3Ge) were prepared by the reaction of 9-tribromogermyl derivatives of fluorene C13H8(R)GeBr3 (4 - 6) with N(CH2CH2OSnAlk3)3 (7: Alk = Et; 8: Alk = Bu). 1-(9-Trimethylstannyl- 9-fluorenyl)germatrane (14) was synthesised by the reaction o f the germatrane (1) with Me3SnNMe2 . Formulas and structures were established by elemental analyses, (1H, 13C) NMR spectroscopy and mass spectrometry; crystal structures of 2 and 14 are reported.

Synthesis, spectroscopic characterization, and structural studies of organogermanium tri- and monothiocarbonates. Crystal structures of Me2Ge[S2CSEt]2, Ph3Ge[SCO2Me], Ph3Ge[SCO2(i-Pr)], and Ph2Ge[SCO2Me]2

1998 ◽  
Vol 76 (3) ◽  
pp. 319-334 ◽  
Author(s):  
John E Drake ◽  
Jincai Yang
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Sodium Salt ◽  
Variable Temperature ◽  
Spectroscopic Characterization ◽  
Structural Studies ◽  
Cell Parameters ◽  
Derivatives Of ◽  
C Nmr

Two series of S-alkyl trithiocarbonate derivatives of imethylgermane, Me2Ge[S2CSR]2, and halodiphenylgermane, Ph2GeX[S2CSR], where R = Me, i-Pr, n-Pr, n-Bu and X = Cl, Br, and three series of O-alkyl monothiocarbonate derivatives of triphenylgermane, Ph3Ge[SCO2R], diphenylgermane, Ph2Ge[SCO2R], and trimethylgermane, me3Ge[SCO2R], where R = Me, i-Pr, and n-Pr, have been prepared in 73-92% yields by the reaction of the potassium or sodium salt of the appropriate tri- or monothiocarbonic acid with dichlorodimethyl-, chlorotriphenyl-, dichlorodiphenyl-, and chlorotrimethylgermane. The compounds were principally characterized by infrared, Raman, and 1H and 13C NMR spectroscopy, including some variable temperature studies, as well as by mass spectrometry. Me2Ge[S2CSEt]2, 1: P21/m (No. 11) with cell parameters a = 6.647(4) Å, b = 7.423(2) Å, c = 16.290(4) Å, β = 91.07(3)°, V = 803.6(4) Å3, Z = 2, R = 0.0484,Rw = 0.0485. Ph3Ge[SCO2Me],13: P1bar (No. 2) with cell parameters a = 9.970(4) Å, b = 10.660(3) Å, c = 9.853(2) Å, α = 101.78(2)°, β = 109.98(2)°, γ = 89.76(3)°, V = 961.0(5) Å3, Z = 2, R = 0.0534, Rw = 0.0451. Ph3Ge[SCO2(i-Pr)], 14: P 1bar (No. 2) with cell parameters a = 14.386(7) Å, b = 18.598(6) Å, c = 9.223(3) Å, α = 102.85(3)°, β = 94.58(3)°, γ = 108.13(3)°, V = 2256(1) Å3, Z = 2, R = 0.0545, Rw = 0.0552. Ph2Ge[SCO2Me]2, 16: Cc, (No. 9) with cell parameters a = 11.790(4) Å, b = 13.696(5) Å, c = 23.232(6) Å, β = 92.26(3)°, V = 3748(2) Å3, Z = 8, R = 0.0563, Rw = 0.0512. The immediate environment about Ge is that of tetrahedral but the orientations of the thiocarbonate groups display interesting features.Key words: structure, germanium, phenyl, methyl, thiocarbonates.

scholarly journals Tannins of Tamarind Seed Husk: Preparation, Structural Characterization, and Antioxidant Activities

2011 ◽  
Vol 6 (6) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Puksiri Sinchaiyakit ◽  
Yohji Ezure ◽  
Sarin Sriprang ◽  
Supakorn Pongbangpho ◽  
Nasapon Povichit ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Antioxidant Activities ◽  
Uv Spectroscopy ◽  
Degree Of Polymerization ◽  
Dpph Assay ◽  
One Pot ◽  
Acetone Water ◽  
Seed Husk ◽  
C Nmr ◽  
Ir And Uv Spectroscopy

The high content (about 39%) of polymeric tannins in tamarind ( Tamarindus indica L.) seed husk (TSH) was demonstrated, and an extract (crude TSE) with a high content (about 94%) of polymeric tannins was prepared from TSH with a one pot extraction using ethanol/water (3:2, v/v). The crude TSE was further purified with Sephadex LH20 to give one fraction (metTSE) eluted with methanol/water (3:2, v/v) and another (acTSE) eluted with acetone/water (3:2, v/v). The tannins of acTSE were established as polymeric proanthocyanidins (PA) by 13C NMR spectroscopy; this was further confirmed by IR and UV spectroscopy, n-BuOH/HCl and vanillin assays, and from HPLC pattern. The ratio of procyanidins to prodelphinidins was 2:3, and the average degree of polymerization of acTSE was 7. Galloylated flavan-3-ols were not detected in acTSE. The main ingredients of metTSE were confirmed to be polymeric PA by 13C NMR spectroscopy. The antioxidant activities using DPPH and ABTS assays were investigated. The IC50 values of acTSE were 4.2±0.2 (DPPH assay) and 6.2±0.3 μg/mL (ABTS assay).

Enantioselective fluorescent sensors for chiral carboxylates based on BINOL — Synthesis and chiral recognition

2010 ◽  
Vol 88 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Kuo-xi Xu ◽  
Yu-xia Wang ◽  
Shu-yan Jiao ◽  
Jin Zhao ◽  
Chao-jie Wang
Keyword(s):  
Nmr Spectroscopy ◽  
Chiral Recognition ◽  
Fluorescent Sensors ◽  
Enantioselective Recognition ◽  
H Nmr ◽  
Recognition Ability ◽  
Chiral Materials ◽  
Fluorescent Recognition ◽  
Derivatives Of ◽  
C Nmr

The four novel derivatives of 1,1′-bi-2-naphthol (BINOL) have been prepared, and the structures of these compounds have been characterized by IR, MS, 1H and 13C NMR spectroscopy, and elemental analysis. The enantioselective recognition of these receptors has been studied by fluorescence titration and 1H NMR spectroscopy. The receptors exhibited different chiral-recognition abilities towards some enantiomers of chiral materials and formed 1:1 complexes between host and guest. The receptors exhibit excellent enantioselective fluorescent-recognition ability towards the amino acid derivatives.

C-Stannane derivatives of carbohydrates

1979 ◽  
Vol 57 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Laurance D. Hall ◽  
Paul R. Steiner ◽  
Diane C. Miller
Keyword(s):  
Nmr Spectroscopy ◽  
Stable Carbon ◽  
Derivatives Of ◽  
C Nmr

Triphenyltin lithium (1) was reacted separately with 1,2:3,5-di-O-methylene-6-O-tosyl-α-D-glucofuranose (2), with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (4), and with methyl 2,3-anhydro-4,6-O-benzylidene-α-D-mannopyranoside (6), to form in each case a sugar-stannane derivative having a stable carbon-tin bond. These products have been studied by 1H and 13C nmr spectroscopy.

scholarly journals Selektive Metallierung von BicycIo[3.2.1]octa-2,6-dien, II Distannylierte Derivate und stannylierte tricyclische Sekundärprodukte / Selective Metalation of Bicyclo[3.2.1]octa-2,6-diene, II Distannylated Derivatives and Stannylated Tricyclic Secondary Products

1988 ◽  
Vol 43 (11) ◽  
pp. 1405-1415 ◽  
Author(s):  
N. Hertkorn ◽  
F. H. Köhler
Keyword(s):  
Nmr Spectroscopy ◽  
Low Temperature ◽  
Nmr Spectra ◽  
Considerable Change ◽  
Coupling Constants ◽  
Secondary Products ◽  
Starting Compound ◽  
Derivatives Of ◽  
C Nmr ◽  
Dibromo Derivative

Abstract Distannylated bicyclo[3.2.1]octa-2,6-diene (1) with (CH3)3 Sn groups in positions exo-4 and 7 (7a), endo-4 and 7 (7b), exo-4 and 6 (7c), and probably exo-4 and endo-4 (7d) are obtained when 1 is treated first with an excess of n-BuLi/t-BuOK in alkane and then with (CH3)3 SnCl. Byproducts are monostannylated derivatives of 1 and l,4-bis(trimethylstannyl)but-2-ene (3). The formation of 7a/b/c is best understood when the two possible bicyclo[3.2.1]octa-2,6-dienyl dianions are generated as intermediates. 3,exo-4-Bis(trimethylstannyl)bicyclo[3.2.1]octa-2,6-diene (7e) is ob-tained from the corresponding dibromo derivative of 1 and (CH3)3SnLi with 3-bromo-exo-4-trimethylstannylbicyclo[3.2.1]octa-2,6-diene (9) as an intermediate. The bicyclic stannyl com-pounds are susceptible to a 1,5-homopentadienyl shift of a (CH3)3Sn group at relatively low temperature when the starting compound has the stannyl group in position 4 of 1 and when positions 6 or 7 are unsubstituted. Tricyclo[3.2.1.02.7]oct-3-enes with (CH3)3Sn groups in positions exo-6 (5a), endo-6 (5b), 3 and exo-6 (10a), and 3 and endo-6 (10b) are thus obtained. On further heating, 10b gives l-trimethylstannyl-3-vinylbenzene (11). All compounds have been studied systematically by NMR spectroscopy including δ(119Sn), δ(13C), δ(1H), 4/5J(119/117Sn-119Sn), nJ(119/117Sn-13C) , nJ(119/117Sn-1H), 1J(13C-1H ) , and nJ(1H-1H ). Among all nuclei, 119Sn gives the most simple spectra. From the 13C NMR spectra a series of useful increments of (CH3)3Sn groups emerges. The most interesting coupling constants are 5J(119/117Sn-119Sn), for which a considerable change with the dihedral angle is established, and nJ(119/117Sn-13C). For n = 3 and 4 the latter are especially useful because their angular dependence leads to unambiguous signal assignments.

17-(O-(2-Carboxyethyl)oxime) Derivatives of Androstanes of 3-Hydroxy-5α-, -5β-, -5-ene and 3-Oxo-4-ene Series

1995 ◽  
Vol 60 (1) ◽  
pp. 137-149 ◽  
Author(s):  
Vladimír Pouzar ◽  
Ivan Černý
Keyword(s):  
Nmr Spectroscopy ◽  
Hydroxy Group ◽  
Alkyl Acrylate ◽  
Subsequent Hydrolysis ◽  
Jones Reagent ◽  
Oxime Derivatives ◽  
Derivatives Of ◽  
C Nmr

Androstane 17-(O-(2-carboxyethyl)oxime) derivatives were prepared either by the reaction of 17-keto derivatives with corresponding substituted hydroxylamine or by the addition of 17-oximino derivatives to the alkyl acrylate and subsequent hydrolysis. Oxidation of the hydroxy group in position 3 in derivatives of this type was performed either by the Oppenauer reaction, transforming 5-ene derivatives into 3-oxo-4-enes, or with Jones reagent in the case of saturated 5α- or 5β-derivatives. Configuration 17E in the whole series of oximes was confirmed by the 1H and 13C NMR spectroscopy.

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