Tetracyclosqualene and Its Bearing on the Structure of Cyclized Rubber

1964 ◽  
Vol 37 (2) ◽  
pp. 486-490 ◽  
Author(s):  
Morton A. Golub ◽  
Jorge Heller
Keyword(s):  
Double Bond ◽  
Ir Spectra ◽  
Nmr Spectra ◽  
Bicyclic Structure ◽  
Fused Ring ◽  
Ring Structures ◽  
Methylene Groups ◽  
Cis And Trans ◽  
Rule Out

Abstract Recently we reported that cyclized rubber consists of six-membered rings fused into predominantly bicyclic structures which are connected by methylene groups and/or uncyclized isoprene units. Each of the fused ring structures is presumed to contain a single tetra-, tri- or di-substituted double bond, the relative amounts of which are in the order, tetra- > tri- > di-substituted. The predominantly bicyclic structure was not rigorously established, but it was considered reasonable on the basis of a comparison of the nmr spectra of cyclized cis-polyisoprene and cyclized cis-poly (2-methyl-d3-1,3-butadiene-1,1-d2). However, although a predominantly monocyclic structure was clearly excluded, it was not possible to rule out a structure in which the average number of rings per fused segment (“cyclicity”) exceeds two and may even be as high as three. In an effort to determine this cyclicity more accurately, we now compare the nmr and ir spectra of cyclized cis- and trans-polyisoprenes with the corresponding spectra of tetracyclosqualene (TCS). The latter is known to have a structure consisting of two bicyclic segments connected by two methylene groups.

THE REACTION OF POLYISOPRENE WITH TITANIUM TETRACHLORIDE

1963 ◽  
Vol 41 (4) ◽  
pp. 937-953 ◽  
Author(s):  
Morton A. Golub ◽  
Jorge Heller
Keyword(s):  
Double Bond ◽  
Titanium Tetrachloride ◽  
First Order ◽  
First Order Kinetics ◽  
Carbonium Ion ◽  
Fused Ring ◽  
Ring Structures ◽  
Methylene Groups ◽  
Pseudo First Order ◽  
Total Disappearance

The reaction of titanium tetrachloride with hevea, balata, and synthetic cis-polyisoprene in benzene at 80 °C has been studied. The most prominent change in the infrared spectra of these polymers is the nearly total disappearance of the 12 μ band after prolonged reaction with TiCl4. The diminution of this band, associated with the loss of the original —C(CH3)=CH— units, whether cis or trans, followed pseudo-first-order kinetics, the rate varying with [TiCl4]n, where n is 1.0 in the case of the cis polymers and 1.5 in the case of the trans polymer. Contrary to previous reports, practically no cis–trans isomerization of polyisoprene occurs in the course of this reaction, the data being explained entirely by cyclization. With the help of cis-1,4 polymers of isoprene-3-d and 2-methyl-d3-1,3-butadiene-1,1-d2, it was concluded that cyclization, involving a TiCl4-induced carbonium ion mechanism, leads to the formation of six-membered rings fused into predominantly bicyclic structures, connected by methylene groups and/or uncyclized monomer units. Each of the fused ring structures contains a single tetra-, tri-, or di-substituted double bond, the relative amounts of which are in the order tetra- > tri- > di-substituted.

Dinuclear Derivatives of Mn2(CO)10 with the Ligand Tri(1-Cyclohepta- 2,4,6-Trienyl)Phosphane, P(C7H7)3, and their Oxidative Cleavage

2003 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Max Herberhold ◽  
Wolfgang Milius ◽  
Andreas Pfeifer
Keyword(s):  
Double Bond ◽  
Ir Spectra ◽  
Single Crystal ◽  
Nmr Spectra ◽  
Oxidative Cleavage ◽  
Carbonyl Ligand ◽  
X Ray ◽  
Derivatives Of ◽  
Induced Reaction ◽  
Π Complexation

Abstract The photo-induced reaction of Mn2(CO)10 with the olefinic phosphane P(C7H7)3 (1; [P] if coordinated to a metal) leads stepwise to the axially substituted derivatives ax-{Mn2(CO)9[P]} (2) and ax,ax-{Mn2(CO)8[P]2} (3). Oxidative cleavage of 3 by halogens gives cis-{Mn(X)(CO)4[P]} (X = Cl (4a), Br (4b), I (4c)), whereas oxidation of 3 with NOBF4 provides a route to the salt {Mn(CO)4[P]}BF4 (5) which is also accessible by halide abstraction from 4b by AgBF4. The reactivity of the bromo complex 4b has been studied, and analogues such as cis-{Mn(R)(CO)4[P]} (R = Me (4d), Fc (4e) and N(iPr)2 (4f)) have been prepared. The displacement of a carbonyl ligand from 4b by iodide leads to mer-{Mn(I)(CO)3[P]} (6c) and by 1 to mer,trans-{Mn(Br)(CO)3[P]2} (7b). The complexes mer-{Mn(X)(CO)3[P]} (6a-c) are obtained by splitting the dimers, Mn2(CO)6(CH3CN)2- (μ −X)2 (X = Cl, Br, I), with P(C7H7)3 (1). The cation in 5 and the halogeno compounds 6a-c contain [P] (1) as a chelating four-electron ligand which uses one cyclohepta-2,4,6-trienyl substituent for π-complexation. The coordinated double bond in 6c can be displaced by phosphites P(OR)3 (R = Me, Et) to give fac-{Mn(I)(CO)3[P(C7H7)3][P(OR)3]} (8c). The structures of the new complexes 2-8 have been assigned on the basis of their carbonyl stretching absorption patterns in the IR spectra and by their NMR spectra (1H, 13C, 31P). Single-crystal X-ray structure analyses have been carried out for 3 and 6c.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

15N, 13C, and 1H NMR Spectra of Azo and Hydrazo Compounds Derived from 1,3,3-Trimethyl-2-methylidene-2,3-dihydroindole (Fischer Base)

1998 ◽  
Vol 63 (7) ◽  
pp. 1012-1020 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Alois Koloničný
Keyword(s):  
Double Bond ◽  
Hydrochloric Acid ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Azo Compounds ◽  
Passive Component ◽  
Geometric Isomers ◽  
H Nmr ◽  
Fischer Base ◽  
Hydrazone Form

The 15N, 13C, and 1H NMR spectra were measured for azo and hydrazo compounds derived from 1,3,3-trimethyl-2-methylidene-2,3-dihydroindole (Fischer base), which is a passive component with a terminal methylidene group. Products prepared by coupling in hydrochloric acid exist in the corresponding hydrazone form as the E-isomers. Neutralization gives a mixture of two isomeric azo compounds which differ in the arrangement at the C(2)=C(10) double bond. This mixture was alkylated with methyl iodide to obtain the =N-N(CH3)- hydrazone derivatives. The geometric isomers were resolved based on the NOESY approach and the stereospecific behaviour of the 2J(15N,13C) coupling constants was studied for the 15N-labelled compounds.

scholarly journals New Perfluorophtalate Complexes of Platinum(II) With Chemotherapeutic Potential

1996 ◽  
Vol 3 (3) ◽  
pp. 117-122
Author(s):  
M. B. de Oliveira ◽  
J. Miller ◽  
R. E. Banks ◽  
L. R. Kelland ◽  
C. A. McAuliffe ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Ovarian Carcinoma ◽  
Elemental Analysis ◽  
Nmr Spectra ◽  
Carcinoma Cell ◽  
Acquired Resistance ◽  
Cross Resistance ◽  
Carcinoma Cell Lines ◽  
Human Ovarian Carcinoma ◽  
Anti Hiv

Two new platinum(II) complexes have been synthesized and their anti-tumour and anti-HIV activities have been evaluated.The new complexes are: (i) cis-tetrafluorophthalate-ammine-morpholine-platinum(II) or MMF3 and (ii) cis-tetrafluorophthalate- ammine-piperidine-platinum(II) or MPF4. They were characterized by elemental analysis, IR spectra and H1 and C13 NMR spectra.They were tested against five human ovarian carcinoma cell lines, viz., CH1, CH1cisR, A2780, A2780cisR and SKOV-3. They were less active than cis-platin and showed cross-resistance with cis-platin in the CH1cisR and A2780cisR acquired resistance lines.They were also tested for possible anti-HIV activity using the HIV-I IIIB virus and C8166 cells, but they were inactive compared with AZT.

A 19F nuclear magnetic resonance study of the conjugate Brönsted-Lewis superacid HSO3F-SbF5. Part 1

1999 ◽  
Vol 77 (11) ◽  
pp. 1869-1886 ◽  
Author(s):  
Dingliang Zhang ◽  
Markus Heubes ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Formation Reaction ◽  
H Nmr ◽  
Acid Conjugate ◽  
Nmr Methods ◽  
Cis And Trans

The Brönsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated by modern 19F NMR methods over a wide concentration range. The system is found to be considerably more complex than had been assumed previously. A total of 13 different anions are identified of which only five have previously been identified in magic acid. With increasing SbF5 contents the concentration of monomeric anions like [SbF6]-, [SbF5(SO3F)]-, cis- and trans-[SbF4(SO3F)2]-, and mer-[SbF3(SO3F)3]- gradually decreases. Except for [Sb2F11]-, which is present in very small concentrations only, the formation of oligomers involves exclusively μ-fluorosulfato bridges. In addition to donor (SO3F)- and acceptor (SbF5) complex formation to give [SbF5(SO3F)]- and possibly ligand redistribution, the solvolysis of SbF5 or SbF4(SO3F) in HSO3F appears to be the principal formation reaction for polyfluorosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis product HF is converted to the oxonium ion [H3O]+, which has previously been identified by 1H NMR and structurally characterized as [H3O][Sb2F11] by us.Key words: magic acid, conjugate superacid, fluorosulfuric acid, 19F NMR spectra.

β-Amino ketoximes: a study of basicity, hydrogen bonding and isomerism

1977 ◽  
Vol 30 (7) ◽  
pp. 1467 ◽  
Author(s):  
HK Powell ◽  
JM Russell
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Calorimetric Data ◽  
Amino Groups ◽  
Or Groups ◽  
Inductive Effects ◽  
Methylene Groups ◽  
Secondary Amino ◽  
Intramolecular Hydrogen ◽  
Cis And Trans

The protonation reactions of the diamine dioxime 4,4,9,9-tetramethyl- 5,8-diazadodecane-2,11-dione dioxime and its O-methyl and bis-O-methyl ethers have been studied at 25�, I 0.10 M NaCl. The (substituted) oxime groups cause a marked reduction in the basicity of the secondary amino groups. log K (potentiometric) and ΔH (calorimetric) data are interpreted in terms of inductive effects of the oxime group and possible intramolecular hydrogen bonding, N+-H...N(OR)=, pKa for methoxy-amine, NH2OMe, has been determined (4.62�0.01, I 0.10 M NaCl, 25�). ������ P.m.r. spectra are assigned for β-amino ketoximes having α- methyl and α-methylene groups cis and trans to =N-OR groups. Infrared spectra are reported.

Preparation of New Oxidized 18-α-Oleanane Derivatives

2005 ◽  
Vol 70 (9) ◽  
pp. 1447-1464 ◽  
Author(s):  
Miroslav Kvasnica ◽  
Iva Tišlerová ◽  
Jan Šarek ◽  
Jan Sejbal ◽  
Ivana Císařová
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Biological Activities ◽  
Oxidative Cleavage ◽  
Allylic Oxidation ◽  
Unsaturated Ketone ◽  
Ruthenium Tetroxide ◽  
Unsaturated Compounds ◽  
Starting Compound ◽  
C Nmr

19β,28-Epoxy-4,5-seco-3,5-cyclo-18α-olean-3(5)-ene (2) is an appropriate compound for oxidations, which lead to new oxidized compounds with potential biological activities. Several oxidations were used such as epoxidation, allylic oxidation, oxidative cleavage of double bond and other ones. From the starting compound epoxides 3a, 3b and unsaturated ketone 4 were prepared. This ketone was further oxidized to diketone 6 and anhydride 7. The double bonds of all unsaturated compounds were cleaved with ruthenium tetroxide to afford new A-seco oleananes. The structure and stereochemistry of the compounds were derived from IR, MS, 1H and 13C NMR spectra (1D and 2D COSY, TOCSY, NOESY, HSQC, HMBC).

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