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Showing papers on "Double bond published in 1978"


Journal ArticleDOI
TL;DR: In this article, all-electron calculations have been performed for the catalyzed reaction, related to the Ziegler-Natta polymerization process TiCl4⋅Al(CH3)3+C2H4 →TiCl4 ⋅al(CH 3)2⋆C3H7.
Abstract: Ab initio SCF–LCAO–MO all‐electron calculations have been performed for the catalyzed reaction, related to the Ziegler–Natta polymerization process TiCl4⋅Al(CH3)3+C2H4 →TiCl4⋅Al(CH3)2⋅C3H7. The energy of the Ti–Al–ethylene complex during the reaction pathway is associated to the following processes: First, the ethylene coordinates to the catalyst complex and subsequently it reacts with the methyl moiety producing an activation energy barrier mainly due to the breaking of the ethylene double bond. The computed barrier height (15 kcal/mole) is in reasonable agreement with experimental activation energies. The identification of the energy barrier is based on the analysis of the electron population, bond energies, and molecular orbitals of the system as they evolve during the reaction. A comparison with the qualitative picture resulting from the classical model of Cossee and with semiempirical calculations is presented. From these calculations a model is derived which leads to a tentative suggestion for the e...

276 citations


Journal ArticleDOI
TL;DR: In this article, the variation of the bond length D with the bond strength s in oxygen and halogen compounds of 3d, 4d, 5d-4f and 6d-5f elements is discussed.
Abstract: The variation of the bond length D with the bond strength s in oxygen and halogen compounds of 3d, 4d, 5d-4f and 6d-5f elements is discussed The functional form D(s) = D(1) (1—Alns) = D(1) —Bins is adopted and the parameters D(1) and A (or B) are given for a great many bonds

268 citations


Journal ArticleDOI
TL;DR: The synthesis of olefins from β-acyloxy-sulphones by reduction with sodium amalgam in methanol-ethyl acetate can be applied to the preparation of a wide variety of conjugated dienes as discussed by the authors.
Abstract: The synthesis of olefins from β-acyloxy-sulphones by reduction with sodium amalgam in methanol–ethyl acetate can be applied to the preparation of a wide variety of conjugated dienes. When used for the synthesis of 1,2-disubstituted olefins in which the new double bond is either isolated or conjugated, the reaction is highly stereoselective, and leads to the trans-isomers.

124 citations


Journal ArticleDOI
TL;DR: In this article, the authors described direct total synthesis of 3-deoxyvitamin D2, vitamin D2 and vitamin D3, and showed that the original Z-allyl geometry of the phosphine oxides was completely preserved in the 5,6-double bond of the products, and the new (7,8-) double bond was formed with exclusive E-geometry.
Abstract: Direct total syntheses are described of 3-deoxyvitamin D2, vitamin D2, and vitamin D3. For the first, the lithio-derivative of (Z)-2-(2-methylenecyclohexylidene)ethyl(diphenyl)phosphine oxide and the Windaus–Grundmann ketone C19H32O were the reacting partners; for the second, the same ketone and the lithio-derivative of a protected form of (S)-(Z)-2-(5-hydroxy-2-methylenecyclohexylidene)ethyl(diphenyl)Phosphine oxide; and for the third, the same lithio-derivative and des-AB-cholestan-8-one. In these reactions, the original Z-allyl geometry of the phosphine oxides was completely preserved in the 5,6-double bond of the products, and the new (7,8-) double bond was formed with exclusive E-geometry.

84 citations


Journal ArticleDOI
TL;DR: The palladium catalyzed vinylic substitution reaction with organic halides is a new and useful method for producing carbon-carbon bonds as discussed by the authors, and the best phosphine to employ for a specific synthesis can now be predicted based upon knowledge of how the phosphines influence vinyl substitution rates and side reactions forming phosphonium salts and palladium metal.
Abstract: The palladium catalyzed vinylic substitution reaction with organic halides is a new and useful method for producing carbon-carbon bonds. The reaction is useful with aryl, heterocyclic, benzylic, and vinylic bromides and iodides. The most useful reactions are with bromides in which cases a triarylphosphine is required with the palladium catalyst. The best phosphine to employ for a specific synthesis can now be predicted based upon knowledge of how the phosphines influence vinylic substitution rates and side reactions forming phosphonium salts and palladium metal. Essentially all common functional groups can be tolerated by the reaction under the same conditions with the exception of α,β-unsaturated ketones and aldehydes. These react normally in the form of their acetals or ketals, however. Reactions proceed well with conjugated or isolated double bonds with mono-, di- and often tri-substituted olefins, generally in a stereospecific manner. A syn addition of the organopalladium compound to the olefin followed by a syn elimination of the palladium hydride is observed. The direction of addition of the organopalladium complex to the olefin depends upon the substituents present. Both steric and electronic influences have been observed. The direction of addition is dominated by steric effects; the organic group always adds, at least mainly, to the least substituted carbon of the double bond. Electron withdrawing substituents on the double bond generally cause exclusive addition of the organic group to the olefinic carbon not having the substituent. With electron donating groups, some addition to the carbon carrying the substituent is usually observed.

82 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the cis disposition of the Li and O atoms about the double bond, requisite of the intramol. solvation mechanism, is preferred even to halogen-metal exchange.
Abstract: (Z)-EtOCH:CHLi (I) reacts with carbonyl compds. as an acetaldehyde anion equiv. The exceptional stability of I is attributed mainly to an intramol. solvation mechanism. That the cis disposition of the Li and O atoms about the double bond, requisite of the intramol. solvation mechanism, is preferred even to halogen-metal exchange is illustrated in the formation of (E)-EtOCH:CBrLi from (E)-EtOCH:CHBr. [on SciFinder (R)]

79 citations


Journal ArticleDOI
TL;DR: In this paper, the position of double bonds and cyclopropane rings in long-chain fatty acid esters is analyzed using a combination of gas chromatography-mass spectrometry.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the steric protection of the carbonyl groups in diastereomeric amides has been used to prevent ready hydrolysis to amines and alcohols.
Abstract: CH-Acidity in α-position to the N-Atom ofN, N-Dialkylamides withSterically ProtectedCarbonyl Groups Contribution to the Nucleophilic Amino Alkylation Sterically protected amides 1 such as the 2,4,6-triisopropyl-benzoic acid derivatives 3, 8b and 10 undergo readily H/Li-exchange with s-butyllithium at the CH3N- or CH2N-groups. The resulting organolithium compounds (cf. 9, 11) are alkylated and hydroxyalkylated with primary haloalkanes, aldehydes, and ketones under chain elongation in the amine position of the amides. The (E/Z)-rotamers of the dialkylamides 7 and 8are separated by chromatography; the amides 4–6, 12, and 13 formally derived from β-hydroxyamines are obtained in the (Z)-form only. The configurational (E/Z)-assignments follow from NMR. and IR. data. The erythro and threo configuration of the two diastereomeric amides 12a and 12b are tentatively concluded from Eu(fod)3-1H-NMR.-shift experiments. The results strongly suggest that the H/Li-exchange takes place regioselectively at the CHN group which is in cis-position to the CO double bond (14). The methyl 2,4,6-tri(t-butyl)benzoate (18) can also be deprotonated to the lithium acyloxymethanide 19 which is trapped by alkylation with 1-iodooctane (20). – The steric protection of the carbonyl groups in the products 4–8, 10, 12, 13, and 20 prevents their ready hydrolysis to amines and alcohols, respectively. Therefore, triphenylacetic acid derivatives 21 rather than 2,4,6-triisopropylbenzoic acid derivatives for use in the electrophilic substitution of equation (1) are recommended. The trityl group in 21 may be considered a C-leaving-group (CC protective group, cf. 22, 23). The acetamide 25 reacts readily (26) and then with electrophiles to give products 27a–c. As shown in the Table, the amides 27 are cleaved under a variety of conditions with formation of triphenylmethane. LiAlH4 produces a tertiary amine, CH3Li a secondary amine, and dissolving alkali metals/naphthalene under aprotic conditions mixtures of secondary amine and its formamide (hydrolysed by acid treatment). Thus the overall process (2) is feasible.

65 citations


Journal ArticleDOI
TL;DR: In this article, the double-bond positions and geometry of monoenoic fatty acids were determined from four sections of a core sampled in diatomaceous ooze off the shore of Walvis Bay (S.W. Africa).

63 citations




Journal ArticleDOI
TL;DR: In this article, the α-enones 1a-g with acetonitrile anion 5, in THF at −80° gives, irreversibly, alcohols 7 or 11, resulting from carbonyl carbon attack, whatever the associated cation is (K + or Li + ).

Journal ArticleDOI
TL;DR: Oxygen plasma treatment of ABS polymer surfaces has the effect of increasing the adhesion of evaporated metal films on those surfaces as mentioned in this paper, and it is suspected that these additional carbon-oxygen chemical bonds affect the surface adhesion between polymers and metals.
Abstract: Oxygen plasma treatment of ABS polymer surfaces has the effect of increasing the adhesion of evaporated metal films on those surfaces. To help understand this, surfaces of commercial ABS and polypropylene were examined with ESCA both before and after oxygen plasma treatment. The plasma treatment was found to change the basic chemical nature of the polymer surface by increasing the number of single and double bonds between carbon and oxygen atoms. It is suspected that these additional carbon–oxygen chemical bonds affect the adhesion between polymers and metals. In addition to the carbon–oxygen bond formation, the plasma treatment removed residual impurities of silicon and increased the residual amounts of other metallic impurities originating in the bulk. The binding energies of these metallic impurities are all indicative of oxides.


Journal ArticleDOI
TL;DR: In this paper, the selectivity of the catalytic oxidation of hydrocarbons is discussed in terms of the type of intermediate complex formed, and two different intermediate complexes initiate two different routes of the reaction.
Abstract: Selectivity of the catalytic oxidation of hydrocarbons is discussed in terms of the type of intermediate complex formed. Two different intermediate complexes initiate two different routes of the reaction. Activation of oxygen leads to total oxidation through electrophilic attack on the double bond and formation of the complex of the peroxide or epoxide type, whereas partial oxidation requires activation of the hydrocarbon molecule resulting in the formation of the allyl species bonded as ligand in the intermediate complex. It proceeds then in a series of consecutive oxidative elementary steps, each of them requiring different active centers to be present at the catalyst surface. The type of product obtained and its selectivity depend thus on the type and mutual proportions of these centers. Oxidation is performed by the cationic active centers, whereas oxygen is inserted by a nucleophilic attack which may also be considered as an acid-base process. Mechanisms of these elementary steps is are discussed on the basis of the quantum chemical description of intermediate complexes.

Journal ArticleDOI
01 Sep 1978-Lipids
TL;DR: The positions of double bond in the monounsaturated C15−C32 fatty acids of Mycobacterium tuberculosis H37Ra were established by gas chromatography/mass spectrometry of the ozonized esters and their pyrrolidide derivatives.
Abstract: The positions of double bond in the monounsaturated C15−C32 fatty acids ofMycobacterium tuberculosis H37Ra were established by gas chromatography/mass spectrometry of the ozonized esters and their pyrrolidide derivatives. The monounsaturated C15−C21 fatty acids had the double bond primarily at the Δ9 position while the monounsaturated longer chain fatty acids (C22−C32) had the double bond in several positions. Many of the latter acids, especially the odd-numbered series, were very complex isomeric mixtures. Quantitation showed the most abundant even-numbered long chain fatty acid isomers to be as follow: C22, Δ4; C24, Δ5; C26, Δ7 and Δ9; C28, Δ9; C30, Δ11 and Δ13; C32, Δ13 and Δ15.

Journal ArticleDOI
TL;DR: In this paper, a mechanism involving synchronous bond formation was proposed for the cyclisation of ethoxylactam in trifluoroacetic acid-dichloromethane with a high degree of stereoselectivity.

Journal ArticleDOI
TL;DR: Cubitene was isolated from the hexane extract of C umbratus soldier heads by chromatography over Florisil followed by preparative GLC High resolution mass spectroscopy indicated the formula of cubitene to be C/sub 20/H/sub 32/ as mentioned in this paper.
Abstract: Cubitene was isolated from the hexane extract of C umbratus soldier heads by chromatography over Florisil followed by preparative GLC High resolution mass spectroscopy indicated the formula of cubitene to be C/sub 20/H/sub 32/ Mass spectra of catalytically hydrogenated cubitene products showed peaks at m/rho 279, consistent with their formulation as substituted cycloalkanes of the composition C/sub 20/H/sub 40/ Cubitene is therefore a monocyclic hydrocarbon with four centers of unsaturation the /sup 1/H NMR spectral data revealed the presence of two 1,1-disubstituted double bonds, and two additional olefinic protons Four methyl groups attached to double bonds are also observed The /sup 13/C NMR spectrum indicated the presence of two tribsubstituted double bonds Fortunately, cubitene could be obtained in crystalline form (mp 345-35/sup 0/C) from cold methanol, allowing a single-crystal x-ray diffraction analysis It crystallized in the monoclinic crystal class Lattice parameters were: a = 15963 (5), b = 6799 (2), c = 17038 (5) A; theta = 9699 (2)/sup 0/ Evidence shows cubitene to be 1,5-dimethyl-8,10-bis(isopropenyl)cyclododeca-1,5-diene, a structure in which one isoprene unit is irregularly joined to three others It appears to be the first example of a diterpene hydrocarbon based on a twelve-membered carbocyclic ring Its biosynthesis poses interestingmore » problems Two possible biosynthetic routes are suggested An even more basic question remainswhether termite soldiers synthesize cubitene at all, or whether they simply sequester it (or a closely related precursor) from their food« less

Journal ArticleDOI
TL;DR: Nearly equimolar mixtures of sterols and unsaturated PC condensed maximally, but 16 : 0--20 : 0 PC condensed most in mixtures containing 20--30 mol% of either sterol.

Journal ArticleDOI
TL;DR: The 13C n.m.r. spectra of a series of isoflavones and related compounds have been determined as mentioned in this paper, showing that chemical shifts of the ring A carbon atoms are relatively insensitive to changes of substitution in the rest of the molecule but are markedly influenced by the presence of a double bond between C-2 and C-3.
Abstract: The 13C n.m.r. spectra of a series of isoflavones and related compounds have been determined. Chemical shifts of the ring A carbon atoms are relatively insensitive to changes of substitution in the rest of the molecule but are markedly influenced by the presence of a double bond between C-2 and C-3.

Journal ArticleDOI
R. Meij1, Derk J. Stufkens1, Kees Vrieze1, E. Roosendaal, H. Schenk 
TL;DR: In this article, a crystal and molecular structure determination of [Pt(PPh 3 ) 2 (2,4,6-mesitylNSO)] shows a side-on coordination via the N-S unit to Pt 0, while the mesityl group is in the cis configuration with respect to S O.

Patent
06 Jun 1978
TL;DR: In this article, the specification describes anti-inflammatory steroids having the following formula wherein X represents a hydrogen or fluorine atom, R' represents a methyl, ethyl, n-propyl or isopropyl group, R'' represents a single or double bond.
Abstract: The specification describes anti-inflammatory steroids having the following formula wherein X represents a hydrogen or fluorine atom, R' represents a methyl, ethyl, n-propyl or iso-propyl group, R'' represents a methyl, chloromethyl, fluoromethyl, bromomethyl or 2-fluoroethyl group and represents a single or double bond. The specification describes processes for preparing such compounds as well as pharmaceutical compositions containing the compounds.

Journal ArticleDOI
TL;DR: In this paper, the photoreaction of 5,6-dimethylene-7-oxabicyclo [2.2.1] hept-2-ene with Fe(CO)5 yields initially the dihapto-tetracarbonyl iron complex (3), which reacts further to give a diHaptotetricarbonyl tricarbionyl complex (C8H8O)Fe2(CO),7 (4), and the molecular structure of 4 has been determined by X-ray crystall

Journal ArticleDOI
TL;DR: In this article, the PPP-SCF-LCAO-MO-Cl model was refined using the solution structure of a bilatriene-abc derivative, and it was shown that the configuration at a particular double bond induces a certain torsional angle at the adjacent single bond which leads to dramatic spectral changes on isomerization of this double bond.
Abstract: Using the recently established solution structure of a bilatriene-abc derivative the parameter set of thePPP-SCF-LCAO-MO-Cl model was refined. The general trend, that molecular configuration itself does not so much determine the absorption spectra as was deduced by investigation of partial bile pigment structures, was confirmed for the bilatrienes-abc. Instead, the configuration at a particular double bond induces a certain torsional angle at the adjacent single bond which leads to dramatic spectral changes on isomerization of this double bond. Isomerization without this torsional effect brings about different relative intensities of the two main spectral bands. Comparing measured spectra of several bilatrienes-abc and calculated spectra a helicalsyn, syn, syn-conformation with three torsional angles at the methine fragments of appr. 20° was deduced for systems with (Z, Z, Z)-configuration. For a recently prepared (E, Z, Z)-derivative a nearly helicalsyn, syn, syn-conformation with torsional angles of 40°, 20° and 20° at the methine single bonds is the most probable.

Journal ArticleDOI
TL;DR: In this article, the synthesis and direct observation of a 1, 1-dialkyldiazene, N-(2,2,6,6-tetramethylpiperidyl)nitrene, was reported.
Abstract: We report here the synthesis and direct observation of a 1, 1-dialkyldiazene, N-(2,2,6,6-tetramethylpiperidyl)nitrene (3). The visible spectrum provides the first experimental information concerning the electronic structure of a 1, 1-dialkyldiazene. Moreover, the infrared spectrum provides evidence that there is considerable double bond character in the N=N bond, similar to a 1,2-diazene (2).

Patent
Friedrich Karrer1
13 Jul 1978
TL;DR: Homopolymeric acrylates and methacryls which carry N-heterocyclic rings in a side position and their copolymers with compounds containing at least one polymerizable double bond are suitable as additives for plastics.
Abstract: Homopolymeric acrylates and methacrylates which carry N-heterocyclic rings in a side position and their copolymers with compounds containing at least one polymerizable double bond are suitable as additives for plastics.



Journal ArticleDOI
TL;DR: The positions of the double bonds in fatty acids with conjugated double bonds may be determined by mass spectrometry of the methyl esters of their trimethylsilyl ether derivatives obtained by hydroxylation of thedouble bonds followed by silylation of the resulting polyols.
Abstract: The positions of the double bonds in fatty acids with conjugated double bonds may be determined by mass spectrometry of the methyl esters of their trimethylsilyl ether derivatives obtained by hydroxylation of the double bonds followed by silylation of the resulting polyols. The method has been applied to trans-9,trans-11- and trans-10, trans-12-octadecadienoic acid.

Journal ArticleDOI
TL;DR: In this article, the alicyclic double bond of eburnamenine and apovincamine has been used to obtain the corresponding analogues of vincanol (5b-h), epivincanol(7b-d), vincamine (10b-e) and Epivincamine(11b-g) with varying stereoselctivity.
Abstract: Addition reactions on the alicyclic double bond of eburnamenine and apovincamine The addition of alcohols, amines or thiols on the 14, 15-double bond of (−)-eburnamenine (3a) or (+)-apovincamine (9a) yielded the corresponding analogues of vincanol (5b-h), epivincanol (7b-d), vincamine (10b-e) and epivincamine (11b-g) with varying stereoselctivity. The reaction was achieved by addition of hydrogenbromide at −78° followed by nucleophilic attack, or in the (−)-eburnamenine series also by direct addition of alcohols and thiols under acidic conditions. Without exception the analogues of epivincamine (11a-g) exhibited two carbonyl absorption bands in thier IR. spectra. (−)-Eburnamenine (3a) was obtained from (+)-apovincamine (9a) in a simple one pot reaction.