A stereospecific synthesis of trisubstituted double bonds

1970 ◽  
Vol 23 (4) ◽  
pp. 813 ◽  
Author(s):  
AJ Birch ◽  
B McKague
Keyword(s):  
Double Bond ◽  
Stereospecific Synthesis ◽  
Considerable Proportion ◽  
Double Bonds ◽  
Steric Configuration

An aspect of the synthesis of sterically defined trisubstituted double bonds is discussed. Metal-ammonia reductions of hydropyridinium salts such as (1 ; R, R' = H or Me) result in allylic fissions, with a considerable proportion of double bond retention in its original situation and complete retention of the original steric configuration in that position.

MNDO CI study of the photoisomerization of pentadieniminium

1990 ◽  
Vol 55 (12) ◽  
pp. 2874-2879 ◽  
Author(s):  
Peter Ertl
Keyword(s):  
Schiff Base ◽  
Double Bond ◽  
Configuration Interaction ◽  
Mndo Method ◽  
Double Bonds

Photoisomerization mechanism in model retinal-like protonated Schiff base pentadieniminium was investigated by using MNDO method with configuration interaction. Isomerizations around various double bonds were studied and twisted biradical geometries in S0 and S1 states were optimized. Photoisomerization proceeds exclusively around the central double bond where the twisted S1 state is strongly stabilized and the S0-S1 gap is minimal.

Chlorination of Natural Rubber in Solution with Gaseous Chlorine

1953 ◽  
Vol 26 (4) ◽  
pp. 902-911 ◽  
Author(s):  
C. S. Ramakrishnan ◽  
D. Raghunath ◽  
J. B. Pande
Keyword(s):  
Double Bond ◽  
Natural Rubber ◽  
Cyclization Reaction ◽  
Double Bonds ◽  
Chlorine Atoms ◽  
Reaction Stage ◽  
Stage 1 ◽  
Additive Reaction

Abstract The chlorination of rubber solutions by gaseous chlorine was followed by isolating the partially chlorinated products and preparing their ozonides. The ozonides were hydrolyzed, and the acids and aldehydes formed on hydrolysis were determined. By a comparison with the amounts of acids and aldehydes obtained from ozonides of unreacted rubber, the amount of residual isoprenic double bonds present was found. The loss of double bonds attending the introduction of chlorine atoms into the molecule of rubber indicates four definite stages in chlorination : (1) initial substitutive attack by chlorine, with concomitant cyclization, resulting in a loss of one double bond between two isoprenic units, (2) substitution, (3) additive reaction, and (4) essentially substitution. Chlorination of aged rubber solutions differs from the above in that the cyclization reaction (stage 1) seems to be absent.

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.

Mechanisms of Nucleophilic Attack at Carbon Nitrogen Double-Bonds: The Reaction of Benzohydrazonoyl Halides With Amines

1987 ◽  
Vol 40 (10) ◽  
pp. 1777 ◽  
Author(s):  
AF Hegarty ◽  
P Rigopoulos ◽  
JE Rowe
Keyword(s):  
Double Bond ◽  
Nucleophilic Attack ◽  
Rate Data ◽  
Double Bonds ◽  
Nitrogen Double Bond

Rate data for the reaction of a series of benzohydrazonoyl halides with pyrrolidine and butan- 1-amine at 303 K are presented. Linear Hammett plots were obtained with each amine. The mechanism of the reactions and the stereochemical outcome of these displacements at the carbon-nitrogen double bond are discussed.

scholarly journals Phenolation of vegetable oils

2011 ◽  
Vol 76 (4) ◽  
pp. 591-606 ◽  
Author(s):  
Mihail Ionescu ◽  
Zoran Petrovic
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Double Bond ◽  
Vegetable Oils ◽  
Raw Materials ◽  
Complex Mixture ◽  
Double Bonds ◽  
Triflic Acid ◽  
Model Compounds ◽  
Phenol Alkylation

Novel bio-based compounds containing phenols suitable for the synthesis of polyurethanes were prepared. The direct alkylation of phenols with different vegetable oils in the presence of superacids (HBF4, triflic acid) as catalysts was studied. The reaction kinetics was followed by monitoring the decrease of the double bond content (iodine value) with time. In order to understand the mechanism of the reaction, phenol was alkylated with model compounds. The model compounds containing one internal double bond were 9-octadecene and methyl oleate and those with three double bonds were triolein and high oleic safflower oil (82% oleic acid). It was shown that the best structures for phenol alkylation are fatty acids with only one double bond (oleic acid). Fatty acids with two double bonds (linoleic acid) and three double bonds (linolenic acid) lead to polymerized oils by a Diels Alder reaction, and to a lesser extent to phenol alkylated products. The reaction product of direct alkylation of phenol with vegetable oils is a complex mixture of phenol alkylated with polymerized oil (30-60%), phenyl esters formed by transesterification of phenol with triglyceride ester bonds (<10 %) and unreacted oil (30%). The phenolated vegetable oils are new aromatic-aliphatic bio-based raw materials suitable for the preparation of polyols (by propoxylation, ethoxylation, Mannich reactions) for the preparation of polyurethanes, as intermediates for phenolic resins or as bio-based antioxidants.

Structural Homogeneity in Unsaturated Fatty Acids of Marine Lipids. A Review

1964 ◽  
Vol 21 (2) ◽  
pp. 247-254 ◽  
Author(s):  
R. G. Ackman
Keyword(s):  
Fatty Acids ◽  
Double Bond ◽  
Polyunsaturated Fatty Acids ◽  
Chain Length ◽  
Unsaturated Fatty Acids ◽  
Analytical Data ◽  
Double Bonds ◽  
Marine Origin ◽  
Methyl Group ◽  
Marine Lipids

Consideration of recent analytical data supports the conclusion that the longer-chain polyunsaturated fatty acids of marine origin are all structurally homogeneous in that the double bonds are cis, the double bonds methylene interrupted, and that, with the exception of the C16 chain length, the ultimate double bond will normally be three, six or nine carbon atoms removed from the terminal methyl group.

scholarly journals Reduction of Activated Carbon-Carbon Double Bonds using Highly Active and Enantioselective Double Bond Reductases

2016 ◽  
Vol 60 (4) ◽  
pp. 243-249 ◽  
Author(s):  
By Beatriz Dom�nguez ◽  
Ursula Schell ◽  
Serena Bisagni ◽  
Thomas Kalthoff
Keyword(s):  
Activated Carbon ◽  
Double Bond ◽  
Double Bonds ◽  
Highly Active

Chrom(0)-und Molybdän(0)-Komplexe von 11-Isopropyliden-bicyclo[4.4.1]undeca-2,4,8-trienen / Chromium(0) and Molybdenum(0) Complexes of 11-Isopropylidene-bicyclo[4.4. 1]undeca-2,4,8-trienes

1986 ◽  
Vol 41 (6) ◽  
pp. 722-730 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Eduard Michels ◽  
Jürgen Kaub
Keyword(s):  
Molecular Structure ◽  
Double Bond ◽  
Nmr Spectroscopy ◽  
Transition Metals ◽  
Crystal And Molecular Structure ◽  
Double Bonds ◽  
Conjugated Diene ◽  
X Ray ◽  
Ir And Nmr Spectroscopy ◽  
Elemental Analyses

11-Isopropylidene-bicyclo[4.4.1]undeca-2,4,8-triene (IBU, 1A) and five alkyl substituted de­rivatives (1B-1F) contain a conjugated diene unit and two isolated CC-double bonds, one exocyclic and one incorporated into the bicvclus, each suited for complexation to transition metals. With [Cr(CO)3(CH3CN)3] (2) 1A-1F form [Cr(CO)3(η6-IBU)] complexes (3A−3F). in which the IBU ligands are coordinated to the chromium via the diene unit and the exocyclic CC-double bond. The corresponding [Mo(CO)3(η6-IBU)] complexes (5A−5F) are obtained from the reactions of [Mo(CO)3(diglyme)] (4) with 1A−1F. In addition, the isomeric [Mo(CO)3(η6-IBU)] complexes (6A−6D) are formed, in which the IBU ligands are bound to molybdenum via the three cyclic CC-double bonds. The complexes 3A−3F, 5A−5F and 6A−6D were studied by IR and NMR spectroscopy (1H. 13C) and characterized by C, H elemental analyses. The crystal and molecular structure of 1A was determined by X-ray structure analysis.

Structure and Content of Dicyclopentadiene in Ethylene Propylene Dicyclopentadiene Terpolymers

1967 ◽  
Vol 40 (2) ◽  
pp. 563-568
Author(s):  
R. J. de Kock ◽  
A. Veermans
Keyword(s):  
Double Bond ◽  
Polymer Chain ◽  
Spectroscopic Methods ◽  
Double Bonds ◽  
Model Compounds ◽  
Ethylene Propylene ◽  
Infrared Spectroscopic ◽  
Polymerization Mixture ◽  
Derivatives Of

Abstract With the aid of model compounds—derivatives of endo- and exo-dicyclopentadiene—it has been established that a) the 9, 10-double bond (the double bond in the norbornane ring) is involved in the polymerization of dicyclopentadiene with ethylene and propylene, b) dicyclopentadiene, present in the polymerization mixture in the endo-configuration, occurs in the exo-configuration in the polymer chain. The same model compounds enable the dicyclopentadiene content of ethylene propylene dicyclopentadiene terpolymers to be determined by infrared spectroscopic methods. Use is made of the 3045 cm−1 band, which is characteristic of endo-cyclic double bonds in five-membered rings.

THE SIGNIFICANCE OF AN ABSORPTION BAND AT 968 CM.−1 IN THE INFRARED SPECTRUM OF METHYL ISOLINOLEATE

1949 ◽  
Vol 27b (7) ◽  
pp. 610-615 ◽  
Author(s):  
H. W. Lemon ◽  
C. K. Cross
Keyword(s):  
Fatty Acids ◽  
Absorption Spectrum ◽  
Double Bond ◽  
Absorption Band ◽  
Linseed Oil ◽  
Infrared Absorption Spectrum ◽  
Methyl Esters ◽  
Trans Configuration ◽  
Double Bonds ◽  
Identical Band

The infrared absorption spectrum of methyl isolinoleate, separated from the methyl esters of hydrogenated linseed oil fatty acids, has a well defined absorption band with maximum absorption at about 968 cm.−1 As an identical band was found in the spectra of fatty acids or esters after isomerization with selenium, it is attributed to the presence of double bonds with a trans-configuration. It was found that the same band was present in the spectra of samples taken during hydrogenation of oils, and that its intensity increased to a maximum, then decreased as hydrogenation proceeded. It is concluded that hydrogenation is accompanied by a cis-to-trans change in some of the double bonds of the fatty acids, and that methyl isolinoleate has at least one double bond with a trans-configuration.

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