Pd-Catalyzed Autotandem Reactions withN-Tosylhydrazones. Synthesis of Condensed Carbo- and Heterocycles by Formation of a C–C Single Bond and a C═C Double Bond on the Same Carbon Atom

2017 ◽  
Vol 19 (8) ◽  
pp. 2034-2037 ◽  
Author(s):  
Miguel Paraja ◽  
Carlos Valdés
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Single Bond

The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process

1943 ◽  
Vol 16 (4) ◽  
pp. 841-847
Author(s):  
A. Gantmacher ◽  
S. Medvedev
Keyword(s):  
Raman Spectrum ◽  
Double Bond ◽  
Raman Spectra ◽  
Polymer Molecule ◽  
Polymerization Process ◽  
High Polymer ◽  
Single Bond ◽  
Double Bonds ◽  
Continuous Background ◽  
Single Bonds

Abstract 1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.

scholarly journals Crystal structure ofN′′-benzyl-N′′-[3-(benzyldimethylazaniumyl)propyl]-N,N,N′,N′-tetramethylguanidinium bis(tetraphenylborate)

2015 ◽  
Vol 71 (12) ◽  
pp. o1086-o1087
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Positive Charge ◽  
Planar Geometry ◽  
Methyl Groups ◽  
Two Dimensional ◽  
Single Bond ◽  
Double Bond Character ◽  
Bond Lengths ◽  
Bond Character

In the crystal structure of the title salt, C24H38N42+·2C24H20B−, the C—N bond lengths in the central CN3unit of the guanidinium ion are 1.3364 (13), 1.3407 (13) and 1.3539 (13) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3plane. The bonds between the N atoms and the terminal methyl groups of the guanidinium moiety and the four C—N bonds to the central N atom of the (benzyldimethylazaniumyl)propyl group have single-bond character. In the crystal, C—H...π interactions between the guanidinium H atoms and the phenyl C atoms of the tetraphenylborate ions are present, leading to the formation of a two-dimensional supramolecular pattern parallel to theacplane.

Remarkably Slow Rotation about a Single Bond between an sp3-Hybridised Carbon Atom and an Aromatic Ring withoutorthoSubstituents

2009 ◽  
Vol 15 (9) ◽  
pp. 2185-2189 ◽  
Author(s):  
Sarah Murrison ◽  
David Glowacki ◽  
Christian Einzinger ◽  
James Titchmarsh ◽  
Stephen Bartlett ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Aromatic Ring ◽  
Slow Rotation ◽  
Single Bond

Époxydes α-éthyléniques et phénate de sodium: accès à des éthers phénoliques et phénols ortho-allyliques

1985 ◽  
Vol 63 (9) ◽  
pp. 2449-2454 ◽  
Author(s):  
Michèle David ◽  
Jean Sauleau ◽  
Armelle Sauleau
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Steric Hindrance ◽  
Transition States ◽  
Ring Cleavage ◽  
Reaction Conditions ◽  
Carbon Compounds ◽  
Judicious Choice ◽  
Ethylenic Carbon ◽  
Cleavage Reactions

The ring cleavage reactions of α-ethylenic epoxides by sodium phenoxide afforded a mixture of products. Problems of competitive attack by this nucleophile, at the less substituted carbon (compounds A) or at the β-ethylenic carbon atom (compounds B and C), were encountered and could be resolved by judicious choice of reaction conditions (solvents, stereochemistry of the oxiranes). The regioselectivity of the attack was dependent on the transition states, implying weak steric hindrance and a conjugation oxirane – double bond.

Photoreactions of Nitroso Compounds in Solution. XIX Stereochemistry of Nitrosamine Photoaddition to Olefin

1971 ◽  
Vol 49 (18) ◽  
pp. 3069-3071 ◽  
Author(s):  
Y. L. Chow ◽  
S. C. Chen ◽  
D. W. L. Chang
Keyword(s):  
Free Radical ◽  
Double Bond ◽  
Intermediate Stage ◽  
Nitroso Compounds ◽  
Radical Mechanism ◽  
Single Bond ◽  
Carbon Double Bond ◽  
Free Radical Mechanism ◽  
Cis And Trans

The stereochemical course of the photoaddition of nitrosamines to a carbon–carbon double bond was shown to follow a free radical mechanism initiated by aminium radicals. The photoaddition to cyclohexene was highly stereoselective in which the addendum approached in anti-diaxial mode. Similar photoadditions to cis- and trans-2-butenes were less stereoselective, giving mixtures of the erythro- and threo-adducts, owing to the rotation of the carbon-carbon single bond in the intermediate stage.

Hétérobicycles oxygénés. Synthèse d'alkyl-3,6,8-trioxabicyclo[3.2.1]octanes et d'alkyl-3,7,9 et -4,7,9-trioxabicyclo[4.2.1]nonanes

1978 ◽  
Vol 56 (17) ◽  
pp. 2292-2300 ◽  
Author(s):  
Pierre Calinaud ◽  
Jacques Gelas
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Coupling Constants ◽  
Basic Medium ◽  
Main Interest ◽  
Proton Coupling ◽  
Geminal Proton

The cyclization in a basic medium of 2 (or 4)-chloroalkyl-4 (or 2) -hydroxyalkyl-1,3-dioxolanes leads to bicyclic acetals, the 3,6,8-trioxabicyclo[3.2.1]octanes, which are useful intermediates for synthesis, yielding notably functionalized 1,4-dioxanes. The nmr spectra of these heterobicyclics were studied. The geminal proton coupling constants permit oneto distinguish between five- and six-membered rings and the determination of couplings over several bonds (4J and 5J) yields information concerning the conformation of the model bicyclics.Two isomeric series of alkylated bicyclic acetals (3,7,9- and 4,7,9-trioxabicyclo[4.2.1]nonanes) are accessible by the following routes: (a) the intramolecular addition of a 4-hydroxy-alkyl group to the ethylenic double bond on the carbon atom a to C-2 in the 1,3-dioxolanes; (b) the dechlorohydration of 2-chloromethyl-4-hydroxyalkyl-1,3-dioxolanes; (c) the dehydration of dioxolane-diols. The main interest in these heterobicyclics is to prepare a seven-membered ring and to be able to prepare functionalized 1,4-dioxepanes. [Journal translation]

RELATIVE RATES OF REACTION OF OZONE WITH OLEFINS IN THE VAPOR PHASE

1960 ◽  
Vol 38 (7) ◽  
pp. 1053-1062 ◽  
Author(s):  
T. Vrbaski ◽  
R. J. Cvetanović
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Vapor Phase ◽  
Reaction Products ◽  
Initial Formation ◽  
Inhibiting Effect ◽  
Π Complex ◽  
Olefinic Double Bond

Relative rates of reaction of ozone with a number of olefins in the vapor phase have been determined by the use of the competitive method and GLC analysis of the reaction products. The results indicate a basic electrophilic trend onto which is superimposed a trend due to a partially inhibiting effect of the substituent groups, in particular of those on the more substituted carbon atom of the olefinic double bond. The results are discussed particularly in terms of a two-step addition process, involving an initial formation of an ozone–olefin π-complex and a slower rearrangement of the π-complex into the cyclic "initial ozonide".

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