Showing papers on "Double bond published in 1981"
TL;DR: Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air.
Abstract: Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air Like the olefins of carbon chemistry, tetramesityldisilene undergoes addition reactions across the silicon-silicon double bond
756 citations
TL;DR: The first successful synthesis of mesomeric-stabilized phosphorus-carbon compounds with coordination number 2, seventeen years ago, was followed nine years later by the preparation of the imino-phosphanes whose intensive investigation has continued to the present day as discussed by the authors.
Abstract: Just as the octet rule had prevented the discovery of the inert-gas compounds, the systematic search for phosphorus-carbon- and phosphorus-nitrogen-compounds having (p-p)π-multiple bonds was hindered by the double bond rule. The first successful synthesis of mesomeric-stabilized phosphorus-carbon compounds with coordination number 2, seventeen years ago, was followed nine years later by the preparation of the imino-phosphanes whose intensive investigation has continued to the present day. A dramatic development has now begun in the phospha-alkene and -alkyne fields, and a large variety of preparative methods have been found. Several compounds of this type are amazingly stable, however they do not participate in typical ylide reactions such as the Wittig reaction. In contrast, the PC double bond is more comparable to that of olefins, which has been confirmed by the occurrence of E,Z-isomers and pericyclic reactions of phospha-l,5-hexadienes.
257 citations
TL;DR: The experimental results reported here strongly support the concept that both hydroxylation and epoxidation are catalyzed by an identical cytochrome P-450 complex utilizing the same active and binding sites.
152 citations
TL;DR: A convenient method for the separation of molecular species of phosphatidylcholine by reversed-phase high performance liquid chromatography (HPLC) is described, finding the average HCN to be remarkably the same for all the three different naturally occurring sources considering a wide variety of different fatty acid compositions of each type.
131 citations
TL;DR: The methyl esters of some mono-unsaturated fatty acids have been methylthiolated by the iodine-catalysed addition of dimethyl disulfide across the double bond.
129 citations
TL;DR: In this article, the vibronic intensity distribution at room temperature and 77'°K of the 1'1Ag→1'1Bu transition for the series of linear polyenes with two through six conjugated double bonds has been measured and analyzed.
Abstract: The vibronic intensity distribution at room temperature and 77 °K of the 1 1Ag→1 1Bu transition for the series of linear polyenes with two through six conjugated double bonds has been measured and analyzed. These inhomogeneously broadened solution spectra can be described reasonably using only two harmonic normal modes of vibration: single and double bond stretches at ∼1200 and ∼1600 cm−1, respectively. Excited state normal coordinate displacements were determined by a least‐squares fitting procedure. For both the double and single bond modes the estimated change in bond length upon excitation decreases as the length of the polyene chain increases. The bandwidth of these spectra decreases with increasing polyene length. This is well described by assuming that in solution a range of conformations differing by very small torsions about the terminal single bonds has been frozen in. The Franck–Condon analysis indicates that under these conditions all of the polyenes are approximately planar in the 1Bu state, ruling out the argument that the lack of fluorescence in butadiene and hexatriene is due to the polyene framework being significantly twisted in the lowest energy 1Bu state.
118 citations
Abstract: Autoxidation of linoleic acid, 9-hydroperoxy-10, 12-octadecadienoic acid (9-HPOD), 13-hydroperoxy-9, 11-octadecadienoic acid (13-HPOD), 2-octenal and 2,4-decadienal at 38 C were investigated with respect to the formation of volatile carbonyl compounds. The 13-HPOD and all compounds having a double bond in ω-6-position produce hexanal. After initiating by small amounts of alkoxy radicals, both hexanal and 2,4-decadienal autoxideize further. While, individually, hexanal reacts somewhat faster than 2,4-decadienal, forming the corresponding acid, in a mixture of the two aldehydes, hexanal is protected to a certain extent by the unsaturated aldehyde against autoxidation. This explains the predominance of hexanal among the volatile carbonyl compounds resulting from linoleic acid autoxidation. Small amounts of 2-octenal originate from both the 9-HPOD and the 2,4-decadienal as a result of oxidation of the ω-8-double bond of these compounds. Aside from its acid as main autoxidation product, 2-octenal yields heptanal and hexanal as volatile compounds.
111 citations
TL;DR: In this paper, a single vibronic level fluorescence of the C2H3O radical was reported, and the 0-0 band of the fluorescence lies at 28.798 cm−1 (347.2 nm).
Abstract: Laser‐induced single vibronic level fluorescence of the C2H3O radical is reported. The 0–0 band of the fluorescence lies at 28 798 cm−1 (347.2 nm). The C–O and C–C stretching, and the C–C–O bending vibrational energies are 1560, 1150, and 530 cm−1, respectively, in the ground electronic state, and 872, 1110 and 432 cm−1, respectively, in the excited state. The lifetime of the excited state is 0.8 μsec. The double bond nature of C2H3O is more dominant in the C–O bond than in the C–C bond in the ground state. The C2H3O radical is found in the C2H4+O reaction, as well as in the CH3CHO+F reaction.
110 citations
TL;DR: In this article, the olefinic double bonds of cyclo-octene, α-methyl stylene and diethyl maleate were electrochemically hydrogenated on spe composite electrodes in n-hexane without the need to add supporting electrolyte.
103 citations
TL;DR: In this paper, it is shown that the broadening of the Raman lines may be interpreted as contributions to the scattered light from defect free polyene chains with various length, and the experimentally observed spectra of the modes and corresponding linewidths are explained by increasing the C=C stretch force constant from 7.7 mdyn/A (infinite chain) up to 9.5 mdyn /A (short chain).
Abstract: The Raman spectra of trans‐polyacetylene excited with various laser wavelength (4579, 4880, 5145, 5682, and 6471 A) show the lines at 1100 cm−1, 1500 cm−1 in (CH)x, and 860 cm−1 and 1400 cm−1 in (CD)x broadened. From a valence‐force‐field calculation of the optical modes, force constants in agreement with results from ab initio molecular orbital theories are obtained. It is shown that the broadening of the Raman lines may be interpreted as contributions to the scattered light from defect free polyene chains with various length. The experimentally observed spectra of the modes and the corresponding linewidths are explained by increasing the C=C stretch force constant from 7.7 mdyn/A (infinite chain) up to 9.5 mdyn/A (short chain). From the C=C double bond stretch force constant a bond order between 0.67 to 0.85 was found.
100 citations
Patent•
23 Feb 1981TL;DR: The use of symmetrical triarylphosphites of the general formula I ##STR1## wherein R1 is tert.-butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl, and one of R2 and R3 is hydrogen and the other is hydrogen, methyl, tert.- butyl, one, 1-dimethyltimethylpolytope (THP), cyclo-hexyl and phenyl was proposed in this paper.
Abstract: Use of symmetrical triarylphosphites of the general formula I ##STR1## wherein R1 is tert.-butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl, and one of R2 and R3 is hydrogen and the other is hydrogen, methyl, tert.-butyl, 1,1-dimethylpropyl, cyclohexyl or phenyl, in combination with phenolic antioxidants for stabilizing organic polymers which contain hetero atoms, double bonds or aromatic rings.
TL;DR: It is suggested that long-term consumption of hydrogenated fats by humans does not lead to substantial preferential accumulation of positional isomers in human tissue total lipids.
Patent•
19 Nov 1981
TL;DR: In this paper, a mixture of a maleimide compound with a spiroacetal compound having a double-branched double-bond was used to provide a fluidity and improved crack resistance without injuring its thermal resistance.
Abstract: PURPOSE:To provide a maleimide compound with a fluidity, thereby improving its workability, and an improved crack resistance without injuring its thermal resistance, by blending the maleimide compound with a spiroacetal compound having a double bond CONSTITUTION:The object resin composition is prepared by mixing (A) 100pts maleimide compound of a low mp (eg, formula I), (B) approx 0-70pts N, N'-substd bismaleimide compound (eg, N, N'-diphenylmethanebismaleimide or N, N'-m-phenylenebismaleimide) and (C) approx 0-200pts spiroacetal compound having a double bond (eg, formula I) or its prepolymer (eg, formula III, where R is H or CH3) This composition has a long pot life and can be used not only as solventless varnish but also as solvent-sensitive varnish, and a hardened resin thereof is superior in electric insulation, mechanical characteristics, etc
Journal Article•
TL;DR: Two FFA, 1 saturated and 1 unsaturated, and a FFA carrier protein are essential for in vitro growth of Con A-stimulated lymphocytes and the effectiveness of unsaturated FFA was influenced by the chain length, the number of double bonds, and the configuration at the double bond.
Abstract: Two FFA, 1 saturated and 1 unsaturated, and a FFA carrier protein are essential for in vitro growth of Con A-stimulated lymphocytes. Optimal growth was obtained with a combination of palmitic and oleic acid. As carrier proteins, serum albumin and beta-lactoglobulin served equally well. Palmitic and oleic acid could be replaced by other saturated and unsaturated FFA, respectively. The effectiveness of unsaturated FFA was influenced by the chain length, the number of double bonds, and the configuration at the double bond. The position of the double bond appeared to have no effect. 125I-HSA binds to lymphocytes in a specific and nonspecific way. beta-Iac competes with 125I-HSA for the SA-binding sites. The specific binding and the growth supporting ability of SA have a similar dose response.
TL;DR: In this article, a 4-layer atomic cluster with a single surface pair, using the MNDO and MINDO/3 quantum chemistry programs, is found to lead to a symmetric dimer pair for the clean diamond (100) surface and for hydrogenated C and Si surfaces.
TL;DR: In this paper, Batiment sci phys,inst cristallog,ch-1015 lausanne dorigny,switzerland. Reference LGSA-ARTICLE-1981-007
Abstract: Note: Batiment sci phys,inst cristallog,ch-1015 lausanne dorigny,switzerland. Reference LGSA-ARTICLE-1981-007doi:10.1002/hlca.19810640613 Record created on 2005-11-09, modified on 2017-05-12
Patent•
21 Aug 1981TL;DR: In this paper, the general formula for 7-Amino-1-cyclopropyl-4-oxo,1,4-diphydro-naphthyridine-3-carboxylic acids is given.
Abstract: 1. 7-Amino-1-cyclopropyl-4-oxo-1,4-diphydro- naphthyridine-3-carboxylic acids of the general formula I see diagramm : EP0049355,P9,F2 in which A can be nitrogen or CR**3 wherein R**3 can be hydrogen, nitro, halogen, preferably fluorine or chlorine, or a nitrile, carboxamide, carboxyl or ester group, and B represents nitrogen or C-H, and A and B cannot simultaneously be nitrogen, and R**1 and R**2 are identical or different and represent hydrogen or a branched or straight-chain alkyl, alkenyl or alkinyl radical which has 1-12 carbon atoms and can optionally be substituted by hydroxyl groups, alkoxy, alkylmercapto or dialkylamino groups with 1-3 carbon atoms in each alkyl radical, the nitrile group or an alkoxy-carbonyl group with 1-4 carbon atoms in the alcohol part of furthermore denotes cycloalkyl with 3-6 carbon atoms, or, together with the nitrogen atom which they substitute and, if appropriate, a hetero-atom, such as, for example, oxygen or sulphur, or NR**4 , form a 3-membered to 7-membered ring which can be monosubstituted or polysubstituted by alkyl or alkenyl groups with 1-6 carbon atoms, hydroxyl groups, alkoxy or alkylmercapto groups with 1-3 carbon atoms, an alkoxycarbonyl group with 1-4 carbon atoms in the alcohol part, the nitrile group or a phenyl radical and can furthermore possess a double bond, and R**4 represents hydrogen, or a branched or straightchain alkyl, alkenyl or alkinyl group which has 1-6 carbon atoms and can optionally be substituted by hydroxyl, an alkoxy, alkylmercapto or dialkylamino group with 1-3 carbon atoms per alkyl radical or the alkoxycarbonyl group with 1-4 carbon atoms in the alcohol part, or represents a phenylalkyl group which is optionally substituted in the phenyl radical and has up to 4 carbon atoms in the aliphatic part, or an optionally substituted phenyl or naphthyl group or a heterocyclic radical, such as, for example, a pyridine, pyrimidine, thiazole or benzothiazole nurcleus, or denotes an alkoxycarbonyl group which is optionally substituted by a phenyl radical and has 1-4 carbon atoms in the alcohol part, an alkanoyl radical with 1-6 carbon atoms, a benzoyl radical, an optionally substituted C1 -C6 -alkyl or phenylsulphonyl radical or an optionally substituted aminosulphonyl radical, possible substituents of phenyl and naphthyl groups being halogen, alkyl, alkoxy or alkylmercapto groups with 1-3 carbon atoms, phenyloxy, phenylmercapto, trifluoromethyl, nitro, nitrile or carboxylic ester groups with 1-4 carbon atoms in the alcohol part, and pharmaceutically usable salts thereof.
TL;DR: The authors showed that deprotonation and reprotonation of ethyl (Z)-2-pentenoate (2) gives the (3 E)-isomer 6 exclusively.
Abstract: Deprotonation of ethyl (E)-2-alkenoates 1, 3 and 4 yields after protonation the double bond migrated (3 Z)-isomers 5, 7 and 9 as major products. In contrast, deprotonation and reprotonation of ethyl (Z)-2-pentenoate (2) gives the (3 E)-isomer 6 exclusively. These findings are explained by reaction paths starting from different ester conformations.
TL;DR: The trimethylsilyl ethers of the epimeric pairs of sterols with saturated side chains and a pair with two double bonds in the side chain were completely separated from each other by GLC.
Abstract: Paris of C-24 epimeric sterols have been very difficult to separate by physical emthods. We report here the partial or complete separation of the trimethylsilyl ethers of nine pairs of C-24 epimeric sterols by gas liquid chromatography on a glass capillary column coated with SP-2340. The trimethylsilyl ethers of the epimeric pairs of sterols with saturated side chains and a pair with two double bonds in the side chain were completely separated from each other by GLC. The epimeric pairs with a double bond at C-22 showed partial separation. The 24β-epimer with a saturated side chain eluted before the corresponding 24α-epimer. This order was reversed for pairs of C-24 epimeric sterol trimethylsilyl ethers containing a double bond in the side chain at C-22.
TL;DR: The properties of monolayers spread at the air-water interface were measured for saturated, unsaturated, and hydroxy fatty acids, differing in the type and degree of unsaturation, geometric isomerism, and position of unsaturated and Hydroxy groups as mentioned in this paper.
TL;DR: In this paper, a syn-anti photoisomerization of the carbon-nitrogen double bond was shown to be responsible for photochromic properties observed with 2-arylhydrazones of 2-substituted 1,2-diketones.
TL;DR: In this article, a new synthetic method for γ-acetoxy-α,β-unsaturated esters by the acetoxylation of β,γ-uns saturated esters catalyzed by PdCl2 in the presence of KOAc and pentyl nitrite in acetic acid is presented.
TL;DR: Potassium permanganate adsorbed on solid supports can be used to oxidize unsaturated secondary alcohols to the corresponding ketones without degradation of the carbon-carbon double bonds as discussed by the authors.
TL;DR: In this paper, the authors summarized the spectroscopic properties and reactivity of benzvalene and its derivatives as building blocks in organic synthesis and concluded with a summary of substituted benzvalenes.
Abstract: Today, thanks to the versatile synthesis developed by Katz et al, benzvalene is not only the most extensively studied valence isomer of benezene but also one of the most easily synthesized bicyclo[110]butane derivatives The double bond in this highly strained hydrocarbon is particulary reactive owing to interactions between the σ system and the double bond Benzvalene is one of the most reactive olefins toward electron deficient substrates Furthermore, the compound is bifunctional, since after addition to the π system the ring strain of the σ system provides the driving force for rearrangement or further addition reactions This paper summarizes the spectroscopic properties and the reactivity of benzvalene In order to demonstrate the importance of benzvalene and its derivatives as building blocks in organic synthesis the chemistry of compounds arising from benzvalene is also discussed The article concludes with a summary of substituted benzvalenes
TL;DR: In this paper, the total synthesis of (±)-modhephene (2 ) and (µ)-epimodhephemide (3 ) were reported.