Showing papers on "Double bond published in 1975"

Properties of Sulfur‐Sulfur Bonds

Abstract: SS bonds are extraordinarily flexible and have properties that are observed only on isolated occasions for other homonuclear bonds: the bond lengths very between 1.8 and 3.0A, the bond angles between 90 and 180° and the dihedral angles between 0 and 180°; the bond energies amount to up to 430 kJ/mol. The SS stretching frequencies can appear over the range 177–820 cm−1 and force constants of 1.4 to 6.3 mdyne/A have been calculated. This variability is illustrated with examples containing isolated and cumulated SS bonds.

Identification of 3, 6, 9, 12, 15-octadecapentaenoic acid in laboratory-cultured photosynthetic dinoflagellates.

Abstract: Polar and nonpolar chromatograms of fatty acid methyl esters derived from 11 species of photosynthetic, marine dinoflagellates cultured in modified Erd-Schrieber medium contained a component (4–23%) not identifiable by conventional graphic or arithmetic methods. Hydrogenation followed by gas liquid chromatography of the product showed the unknown component to be a straight chained 18 carbon fatty acid methyl ester. Chemical (CH4) ionization mass spectrometry of the isolated ester gave a spectrum characteristic of methyl esters and a mol wt of 288, indicating an 18 carbon molecule with 5 double bonds, or equivalent unsaturation. The IR spectrum showed that the double bonds are nonconjugated, and all arecis in geometry. Electron impact mass spectrometry of the pyrrolidide derivative provided evidence that double bonds are located in the 3, 9, 15 positions and probably also in the 6 and 12 positions of the molecule. These double bond positions were confirmed by NMR spectrometry. Data obtained by quantitation of the algal methyl esters suggest the possibility that these dinoflagellates synthesize 18∶5ω3 (shorthand) notation for chain length: number of double bonds and position of final double bond counted from the terminal methyl group) by a 2 carbon chain shortening of 20∶5ω3, rather than by the insertion of a †3 bond into 18∶4ω3.

Reactions of Vinyl Azides

Abstract: This review is designed to demonstrate the versatility of vinyl azides in organic reactions. The reactive azide function is susceptible to thermolysis, photolysis, cycloadditions, and attack by nucleophiles and electrophiles. The neighboring double bond accentuates the reactivity of the azide function and provides additional intramolecular pathways for reaction. Last but not least, the presence of an appreciable electron density at the β-vinyl carbon makes this class of compounds comparable with enamines in their reactions with electrophiles and 1,3-dipoles.

Chemical Studies of Enzyme Active Sites

Abstract: ion from the IJ(-carbon (266). Although the dienic acids have high intrinsic reactivity, the enzyme is most potently inhibited by dienic acids of ten carbons. This correspondence to the enzyme specificity, also observed for inhibition by acetylenic derivatives, indicates that inhibition by the dienic acids proceeds via reversible binding followed by covalent bond formation (267). Comparison of the various Cl O dienic acid deriva­ tives shows that the effectiveness of inhibition decreases in the series thioester, oxygen ester, free acid, and amide. This pattern of reactivity would be expected if a Michael-type addition reaction (equation 28) was responsible for covalent bond H H 1 1 R C = C = C C X I I I N HN� R o H H I I R C = C C C X I � � N \) R 28. formation, since electrophilicity would be greatest for those derivatives where the resonance form, O-C = X, is least important. Although the precise structure of the histidine adduct has not been determined, model studies have demonstrated that the derivative with the /3-y double bond (28-1) is more likely than the 1J(-/3 isomer (267). It is not yet known which nitrogen in the imidazole nucleus of histidine serves as the nucleophile. However, these chemical modification experiments un­ ambiguously demonstrate the essential role of a histidine residue as a general base catalyst at the active site of fl-hydroxydecanoyl thioester dehydrase.

Methods for the Preparation of Bridgehead Olefins

Abstract: During the past eight years, bridgehead olefins have attracted rapidly increasing attention. In view of their significance with regard to the stereochemistry of alkenes, the study of certain reaction mechanisms, and the nature of the double bond, detailed research into this structural type appears highly desirable. Bridgehead olefins represent connective linkages between olefins in the ground state and species which can arise in the deactivation of photochemically excited alkenes and cycloalkenes and also contribute to our understanding of the structural conditions prevailing during cis-trans isomerization of alkenes.

Structure-response relationships in noctuid sex pheromone reception. An introductory report.

Abstract: Electroantennogram (EAG) data reflecting response spectra of male pheromone receptors have been analyzed for 16 species of Noctuidae (Lepidoptera). The test compounds included 100 pheromone analogues, altered in chain length, in position and configuration of double bond(s), and in the functional end groups. On comparison of amounts of substance required to elicit an equivalent EAG response, a single compound was determined to be most effective on a given species: these structures, either known or proposed as the natural sex pheromones of the species, were cis-7-dodecen-1-y1 acetate, cis-7-tetradecen-1-y1 acetate, cis-9-tetradecen-1-yu acetate, trans-9-tetradecen-1-y1 acetate, cis-11-hexadecen-1-y1 acetate, cis-9, trans-12-tetradecadien-1-y1 acetate, cis-9-tetradecen-1-y1 formate, and cis-9-tetradecen-1-ol, respectively. Elongation (shortening) of the chain by 1 or 2 methylene groups, the movement of a double bond 1 carbon from the optimum, a change to the opposite geometrical isomer, or the introduction of a second double bond invariably reduced EAG responses to 1.8 to 56 times below that observed with the most stimulating compound, in all 16 species. Further alterations in chain length or in double bond position caused even greater reduction in activity, as did certain in end group (Tables I and II). A set of distinct rules could be derived from these structure-response relationships; one of these rules concerns the optimum position of the double bond(s) in relation to chain length, and another one the ratios in activity values produced by end group variations, irrespective of chain length. The same rules described here for 16 noctuid species held also for the structure-response relationships observed within various additional groups of Lepidoptera. From EAG values determined in this study, an attempt has been made to calculate physicochemical propteries of underlying acceptor structures.

Mechanism of diene polymerization

Abstract: An industrial catalyst comprised of nickel carboxylate, boron fluoride, tnalkylaluminium and butadiene was developed in Japan. Kinetic study suggested that catalyst structure to be it-allylic nickel borate. In order to elucidate the mechanism for cis-polymenization, the structure of ic-crotyl nickel halides were analysed by nuclear magnetic resonance. All kinds of halides were found to possess a syn-ic-allylic structure irrespective of their different modes of polymerization, chloride, bromide and iodide yielding cis-, cis-trans-, and trans-polymer, respectively. For the cis-polymenization a mechanism involving a ir-allylic polymer terminal with an intramolecular coordination of the double bond of the penultimate unit (called 'back-biting coordination') is proposed in which a cis-double bond is formed not only from anti-x-allylic but also from the syn-2tallylic polymer terminal, because the resulting cis-double bond has little hindrance whereas the trans-one has large hindrance. Effects of additives to the catalyst were discussed. An electron donor may coordinate to the catalyst to hinder the back-biting coordination and has a tendency to give trans-polymer. On the contrary, an electron acceptor releases ligand anion to remove its steric hindrance. As a result cis—trans (1:1) polybutadiene is formed. Various phenomena such as the incorporation of a trans-unit in polymerization at a low concentration of butadiene and in the copolymerization with styrene are accounted for. 1,2-Polymerization is explained as an attack on the 'y-position of the rc-allylic terminal. The selection of and 'y-positions is controlled by the nature of the anion ligand. The polymerization of substituted dienes is also discussed, in which a large steric hindrance is considered only for 13,y-disubstituted monomer.

18 OR 19 Hydroxy prostaglandins

Abstract: Novel 18 -, 19 - and 20 -hydroxy-prostaglandin derivatives of the formula I ##STR1## wherein the dotted line in the position 8-12 indicates the optional presence of a double bond, the waved lines in position 15 indicate that the hydroxyl group and the group R 4 are either in α- or β-position and Z represents a -- CH 2 CH 2 -- or a cis -- CH=CH -- group, and wherein R represents one of the groups: ##STR2## (wherein the waved lines indicate that the hydroxyl groups are either in α- or β-position and R 1 represents a hydrogen atom, a methyl or ethyl group), R 2 represents either an oxygen atom or a hydrogen atom and an α- or β-hydroxyl group, R 3 represents a hydrogen atom or a hydroxyl group and R 4 represents a hydrogen atom or a methyl group, with the proviso that when simultaneously, R 1 , R 3 and R 4 each represents a hydrogen atom, R 2 represents an oxygen atom, a double bond is in 8-12 position and the 15-hydroxyl group is in position α, R does not represent the group (b), but that when in addition to these conditions, Z represents a cis -- CH=CH -- group and the 8-12 position is saturated, R either represents the groups (b) or (c); and the pharmaceutically acceptable salts and esters thereof, novel process for their preparation by selective microbiological hydroxylation of compounds of formula II ##STR3## wherein the dotted line in the position 10-11 indicates the optional presence of a double bond in case the 8-12 position is saturated and the other symbols are as defined hereinabove, by means of microorganisms of the Division of Eumycota or, as far as the introduction of a hydroxyl group in the 18- or 19-position is concerned, of the Family of Streptomycetaceae, and, if desired, conversion of the 18 -, 19 - and 20 -hydroxy-prostaglandin derivatives thus obtained into pharmaceutically acceptable salts and esters thereof, and pharmaceutical compositions containing at least one of the novel hydroxy-prostaglandin derivatives of formula I.

Asymmetric reduction of carbon–nitrogen, carbon–oxygen, and carbon–carbon double bonds by homogeneous catalytic hydrogenation

Abstract: Asymmetric homogeneous hydrogenations of carbon-nitrogen, carbon-oxygen, and carbon-carbon double bonds have been achieved with the same RhI-chiral diphosphine [(–)-diop] catalyst; all the products have the R configuration and a small increase in optical yields is obtained by changing the solvent from methanol to propan-2-ol.

Process for preparing cyclohexane derivatives

Abstract: PURPOSE: Cyclohexane derivatives of formula I (where R 1 , R 2 , R 3 and R 4 are H, halogens, CF 3 , lower alkyls, lower alkoxys, OH or methylenedioxys; dotted line in ring A means a single or double bond; S and T are H, halogens, CF 3 or lower alkyls; Z is a reactive activated ester), for instance 1,1-bis(4-fluoro-enyl)-4-[4-(2-oxobenzimidazoline-1-yl)-1,2,5,6-tetrahydropyridyl] cyclo-2phenyl)-4-[4-(2-oxobenzimidazoline-1-yl)-1,2,5,6-tetrahydropyridyl] cyclo-2hexene of formula II. COPYRIGHT: (C)1977,JPO&Japio

Free radical addition to olefins. Part 14.—Addition to trifluoromethyl radicals to fluoroethylenes

Abstract: A competitive method has been used to determine the relative Arrhenius parameters for the addition of trifluoromethyl radicals to specific sites in fluoroethylenes taking the addition to one end of ethylene as standard.[graphic omitted]The relative activation energies correlate well with those for the addition of other halogenoalkyl radicals to the same olefins. The A-factors have been calculated from absolute rate theory using two models of the transition state, one resembling the products and the other resembling the reactants. Comparison of the calculated and experimental A-factors suggests that formation of the bond between the trifluoro-methyl radical and the alkene has proceeded sufficiently far, in the transition state, to cause significant breaking of the alkene double bond.

Polymorphism in single-acid triglycerides of positional and geometric isomers of octadecenoic acid

Abstract: The polymorphism of 25 glycerol trioctadecenoates with double bonds ranging from Δ4-Δ17 was investigated by differential scanning calorimetry. Triglycerides withcis bonds in odd positions Δ7-Δ13 exhibited three intermediate melting (β′-) forms, but those withcis bonds in even positions, exceptcis Δ4, lacked β′-forms. Among thetrans compounds, only Δ11, 13, and 14 showed β′-forms. Thecis andtrans Δ5 triglycerides were unusual, because they readily assumed low melting (α-) forms that were not easily converted to high melting (β-) forms. β-Form mp of compounds in each series (cis ortrans) alternated depending upon double bond position; an even position correlated with high mp. Heats of fusion (ΔHf) for β-forms, likewise, fluctuated with double bond position but nonuniformly;trans Δ6 had the highest ΔHf (43 cal/g),cis Δ12 the lowest (21 cal/g).

Novel copolymer and process for producing same

Abstract: A novel copolymer is obtained by reacting [A] at least one norbornene derivative having at least one polar group or polar-group-containing substituent with [B] at least one unsaturated polymer having carbon-to-carbon double bonds in the presence of a metathesis catalyst. This copolymer is excellent in chemical and mechanical properties. Particularly, when 50% by weight or more of the component [A] is contained, the resin is distinguished for its high impact strength.

Support for photosensitive resin

Abstract: A support for a photosensitive resin for use in making a printing plate using a liquid photosensitive resin, said support comprising a flexible self-supporting base plate and an adhesive layer formed thereon for applying a layer of the photosensitive resin, wherein said adhesive layer is a three-dimensional cured product containing 1 × 10-4 to 1 × 10-2 mol/gr. of the effectively photopolymerizable unsaturated carbon-to-carbon double bond, which has been formed from a composition consisting of (A) a compound containing at least two 1,2-epoxy groups in the molecule; (B) a compound selected from one of the group comprising (i) a compound containing an effectively photopolymerizable unsaturated carbon-to-carbon double bond and a 1,2-epoxy group in the molecule and having a boiling point of at least 120° C., or (ii) a compound containing an effectively photopolymerizable unsaturated carbon-to-carbon double bond and an amino group in the molecule and having a boiling point of at least 120° C.; and (C) an organic curing agent.