Showing papers on "Double bond published in 1974"

Linear Polyene Electronic Structure and Spectroscopy

Abstract: A linear polyene is a chain of conjugated carbon-carbon double bonds with an unbranched n-electron system. The conventional representation of alternating double and single bonds corresponds to the resonance structure of major impor­ tance in the ground state. Polyenes are distinguished from symmetrical cyanines and aromatic compounds by the fact that these other compounds have at least two resonance structures which contribute significantly to their ground state. A more quantitative distinction between linear polyenes and other classes of compounds concerns the presence of bond length

Pyrrolidides for mass spectrometric determination of the position of the double bond in monounsaturated fatty acids.

Abstract: Mass spectra of pyrrolidides of monounsaturated straight chain fatty acids are presented and discussed. The spectra of pyrrolidides contain mainly ions from the polar part of the molecule. This gives simple spectra from which double bond positions can be deduced directly. If an interval of 12 atomic mass units is observed between the most intense peaks of clusters of fragments containing n and n−1 carbon atoms of the acid moiety, the double bond occurs between carbons n and n+1 in the molecule This rule is valid for double bonds occurring at positions Δ5-Δ15 in an 18-carbon chain and has been applied to acids having 10–24 carbon atoms.

Plasma Polymerization of Saturated and Unsaturated Hydrocarbons

Abstract: : A series of nine saturated and unsaturated hydrocarbons were polymerized by subjecting them to a radio frequency glow discharge at reduced pressures. It was found that acetylene polymerizes most rapidly, followed by ethylene and butadiene, then by propylene, cis-2-butene and isobutylene. The saturated alkanes: methane, ethane, and propane polymerize most slowly. Infrared spectra of the polymers made of ethane ethylene, and acetylene showed that with increasing monomer unsaturation the polymer contained more double bonds, fewer methylene groups, and a greater tendency to be oxidized after preparation. An examination of the mechanism of ethylene polymerization led to the conclusion that a significant amount of oligomerization occurs in the gas phase. In addition it is hypothesized that an important initial step is the partial conversion of ethylene to acetylene.

Prostaglandin F2α Receptor in Ovine corpora lutea

Abstract: Evidence is presented for the existence of a prostaglandin-F2α receptor in ovine corpora lutea. Prostaglandin F2α was specifically bound to a particulate fraction of this tissue with a dissociation constant of 0.1μM. Prostaglandins F1α, E1 and E2 had considerably less affinity for the receptor whereas prostaglandins A2 and B2 had little or no affinity. From a comparison of the binding constants of various prostaglandins and related compounds it could be concluded that the carboxyl group, the three hydroxyl groups and the 5,6-cis double bond (but not the 13,14-transdouble bond) of prostaglandin F2α were all important for binding to the receptor.

Process for the production of polymeric hydrocarbons having reactive silyl end groups

Abstract: Polymeric hydrocarbons having reactive silyl end groups are produced by conducting a catalyzed ring opening polymerization of a cyclic olefin in the presence of, or reacting with a polymeric hydrocarbon having an unsubstituted non-conjugated ethylenic double bond in a polymer unit thereof, an organic silicon compound having at least one nonconjugated unsubstituted double bond or a polymeric hydrocarbon having a non-conjugated unsubstituted terminal double bond, with an organic silicon compound having at least one organic group, bound to the silicon atom by a carbon-silicon bond, which contains at least one unsubstituted, non-conjugated acyclic double bond and having at least one silicon atom bearing, via a carbon-silicon bond, at least one substituent which is readily removable by hydrolysis.

[49] Monolayers-description of use and interaction

Abstract: Publisher Summary Biological membranes contain a great variety of phospholipids with different fatty acid constituents. The monolayer technique can demonstrate the effect of changes in chain length and of unsaturation of the fatty acid constituents on the molecular architecture of these molecules. Reduction of the chain length of 18 or 16 carbon atoms to 14, 12, or 10 carbon atoms renders the monomolecular layers more expanded and the area occupied by these molecules is increased. The introduction of double bonds in the fatty acid chains is of particular interest. In phospholipids, unsaturated fatty acids as, oleic acid (monoenoic), linoleic acid (dienoic), linolenic acid (trienoic), or arachidonic acid (tetraenoic) are preferentially located at the 2-position of the glycerol moiety. Unsaturation, and particularly the first double bond, increases the area per molecule in monomolecular layers. Phospholipids with two polyunsaturated fatty acid constituents occur only in small quantities in mammalian membranes.

Synthesen der Nonactinsäure

Abstract: Two stereoselective syntheses of nonactic acid I, the building block of the macrotetrolide antibiotic nonactin are described. The characteristic cis-configuration of the 2,5-substituents on the tetrahydrofuran ring of I is obtained in the first synthesis by catalytic hydrogenation of the furan derivative X. This key intermediate possesses the carbon skeleton and correct distribution of oxygen functions for conversin into nonactic acid. It is synthesized by an electrophilic substitution of 2-acetonylfuran (VI) with the N-cyclohexyl-N-propenyl nitrosonium ion (V) generated from the corresponding α-chloronitrone (VII) and silver fluoroborate, followed by hydrolysis and oxidation of the aldehyde group. The second synthesis starts with a diol already having the correct configuration of the side chain that contains the hydroxyl group. For this purpose threo-1-octen-5,7-diol (XV) is synthesized from acetylacetone in two steps. Oxidative cleavage of the terminal double bond of this threo-diol yields an aldehyde which is converted by a Wittig reaction, with the carbanion, obtained from diethyl α-methoxycarbonylethyl phosphonate, into the open chain intermediate, 2-methyl-6,8-dihydroxy-2-nonenoic acid methylester (XVIII). Base-catalyzed cyclisation of this α,β-unsaturated dihydroxy ester yields the methyl ester of nonactic acid (I) as the main product.

Selektive Synthesen mit Organometallen I. Konfigurativ einheitliche Folgeprodukte aus Alkenylkalium‐Zwischenstufen

Abstract: Me groups adjacent to an olefinic double bond were metalated by KOCMe3 and BuLi without cis-trans isomerization. Thus, (E)-MeCH:-CHMe was metalated to give (E)-MeCH:CHCH2K (I) which reacted with ethylene oxide to give 41% (E)-MeCH:CH(CH2)3OH. If I was allowed to equilibrate, the Z-isomer predominated (>99:1). Longer-chain olefins were metalated more slowly, with side reactions taking place. Thus, metalation of BuCH:CMe2 with EtCHMeBu and KOCMe3, followed by reaction with MeI gave 45% (Z)-BuCH:CMeEt, 9% BuCHMeCMe:CH2, and 19% Me(CH2)4CEt:CH2. [on SciFinder (R)]

Polymer-analogous reactions of polyenes in poly(vinylchloride)

Abstract: The primary process in the thermal degradation of PVC in an inert atmosphere and at relatively low temperatures, is the elimination of hydrogen chloride molecules and the formation of polyene sequences of different lengths. The polyenes formed are highly reactive and participate in different secondary reactions. It has been shown for PVC samples degraded both in dilute solution and in the solid state that the amount of polyenes does not correspond to the degree of dehydrochlorination: proportionality may be observed only at the initial stage of degradation and, later on, the number of double bonds in the system is much lower than the amount of hydrogen chloride molecules split off. With the increase of conversion the increase in the amount of polyenes containing three or more double bonds gradually slows down and, later on, practically ceases. This phenomenon is also quantitatively well interpretable by intramolecular cyclization (backbiting) of polyenes. The reaction leads to cyclohexadiene structures. On completing the kinetic treatment of the process, we determined the relative rate constant of cyclization. Reactive dienophilic reagents readily react with the polyenes formed in degraded PVC. Based on the changes observed in the u.v. and visible spectra, a kinetic study was made on the Diels–Alder reaction with chloromaleic anhydride. The kinetic treatment, performed on the basis of a presumed mechanism, allowed the determination of the rate constants and their temperature dependence. Depending on the experimental conditions, the polyenes formed in the course of degradation may participate in other reactions as well. Some of the possible reaction routes are: the change in molecular weight, the formation of low molecular weight aromatic compounds (e.g. benzene) and the considerable proton exchange observed in the reaction of polyenes with hydrochloric acid.

Skin lipids of the Florida indigo snake

Abstract: Cast skins of the Florida indigo snake (Drymarchon corais) yielded up to 8% chloroform: methanol-extractable lipid, which was found to contain methyl ketones (20%), free secondary alcohols (15%), free primary alcohols (30%), free cholesterol (15%), free fatty acids (5%), and hydrocarbons (5%). The hydrocarbons appeared to be contaminants, because gas chromatography revealed a distribution characteristic of petroleum hydrocarbons. The methyl ketones were predominantly monounsaturated, with double bonds almost exclusively in the ω7 position. The structures of the secondary alcohols corresponded with the methyl ketones in regard to chain length distribution, location of the oxygen function in the 2 position, and the proportion and position of unsaturation. The primary alcohols were also predominantly straight, odd-carbon, unsaturated compounds, with ω7 double bonds, but with chain lengths principally of 29 and 31 carbon atoms. The free fatty acids were mainly even-carbon monounsaturated compounds of 16–20 carbon atoms with double bonds mainly in the Δ9-position. Inspection of the lipid structures obtained from the Indigo snake suggest a biogenetic relationship whereby palmitic and palmitoleic acids are extended in chain length mainly to 32 and 34 carbonatom fatty acids. Retention or introduction of an oxygen function in the 3 position, followed by decarboxylation, could then yield structures corresponding with the methyl ketones and the related secondary alcohols. Insertion of an oxygen atom between carbons 2 and 3 of the methyl ketones, followed by loss of the two carbon atoms thereby isolated from the chain, would produce the series of odd-carbon primary alcohols that were observed.

Location of double bonds in long chain esters by methoxymercuration-demercuration followed by mass spectroscopy

Abstract: Methyl esters of simple mono-, di-, and triunsaturated long chain fatty acids quantitatively react with mercuric acetate in methanol to produce methoxyacetoxymercuri derivatives. Demercuration of these derivatives with sodium borohydride yields methoxylated fatty acid esters, readily isolable by thin layer chromatography. Mass spectra of the methoxylated esters are characterized by intense peaks due to cleavage adjacent to methoxy-functions which allow the position of the original double bond in the chain to be ascertained. The methoxylated derivatives are conveniently analyzed by gas liquid chrovmatography and also by combined gas chromatographymass spectrometry. In comparison with other methods for double bond location, the procedure described in simple, reliable, and rapid.

9,12,15-octadecatrien-6-ynoic acid, new acetylenic acid from mosses

Abstract: Lipids of the moss,Ceratodon purpureus, yield up to 25% of an acetylenic acid which was identified as allcis-9,12,15-octadecatrien-6-ynoic acid. The methyl ester of this acid was isolated in 95% purity by gas liquid chromatography. Mass spectroscopy provided the mol wt and confirmed methyl stearate as product of hydrogenation. Ozonization indicated a triple bond in position 6 and a double bond in position 15. UV and IR spectra showedcis-double bonds, no conjugation, and notrans-double bonds. The Raman spectrum provided direct evidence for the triple bond and confirmed the presence of double bonds and the absence of conjugation. The ratio of intensities indicated 1 triple bond/3 double bonds. 9,12,15-Octadecatrien-6-ynoic acid has not previously been isolated from biological materials. It was found only in the triglycerides ofCeratodon purpureus and several other mosses. In contrast to arachidonic and eicosapentaenoic acids, the acetylenic acid seems to be restricted to few moss genera.

Finely-divided polymeric solids having improved physical properties

Abstract: Finely-divided dispersed solids are prepared by polymerizing in the presence of a free radical catalyst and an organic solvent a major amount of an ethylenically unsaturated monomer or mixture of monomers and a minor amount of a hydroxy-terminated organic compound having from one to eight hydroxyl groups, an equivalent weight of from 500 to 10,000 and containing a polymerizable carbon-to-carbon double bond. The resulting polymeric solids are particularly useful in the preparation of reinforced polymer compositions.

Reactions of allylboranes with unsaturated compounds

Abstract: Allylboranes may react with compounds containing an activated double bond as well as with cyclopropenic hydrocarbons. The reactions of allylboranes with acetylenes yield the substituted diallyl(pentadiene-l ,4-yl-1)borane, boracyclohexene, 3-borabicyclo(3,3,l)nonene and 7-methylene-3-borabicyclo(3,3,l)nonane. The allenic compounds and allylboranes produce substituted 6-methyleneor 7-methylene-3-borabicyclo(3,3,1)nonane. Hydroboration of 7(6)-methylene3-borabicyclo(3,3, 1 )nonanes gives 1 -boraadamantane and 1 -boraprotoadamantane systems respectively which may afford adamantane and protoadamantane compounds. In recent years studies in organoboron chemistry have disclosed many new possibilities for organic syntheses. The syntheses involving organoboranes expand essentially the field of application of organometallic reagents in preparative chemistry and supplement successfully the syntheses involving organomagnesium, zinc and alkaline metal compounds. The allylboron compounds are especially promising as synthetic reagents, being highly reactive and behaving specifically towards a variety of organic compounds. One of the features of triallylborane and some of its analogues is the state of permanent allyl rearrangement whose rate depends on the nature of the compound and temperature'. Allylboranes are highly active in reactions with water, alcohols, and amines even at room temperature, unlike trialkylboranes requiring high temperatures. Allylboranes react with aldehydes, ketones, quinones and nitriles as organometallic compounds but they are more advantageous in many syntheses over magnesium and other metallic compounds1. High reactivity is exhibited by allylboranes in their reactions with various unsaturated compounds. REACTIONS WITH COMPOUNDS CONTAINING AN ACTIVATED DOUBLE BOND Ailylboranes take part in reactions with compounds containing an

Localized molecular orbital studies in momentum space. I. compton profiles of 1s core electrons and hydrocarbons

Abstract: The calculations of momentum space properties for the polyatomic molecules CH 4 , C 2 H 4 and C 2 H 6 using localized molecular orbitals of double zeta quality basis sets are presented. The LMO analysis shows that localized and canonical core electrons have different momentum space properties, and that in agreement with the experimental data of Eisenberger and Marra one can distinguish the momentum properties of the CC single and double bonds. The effect of environment on a bond is seen by comparing the CH bond in these three molecules. The concept of electron pair size is introduced as a quantitative guide for interpreting momentun space properties.

Studies on the Partial Degradation of Polyunsaturated Fatty Acids in Rat‐Liver Mitochondria

Abstract: In rat liver some highly unsaturated fatty acids are partially degraded. In contrast to “normal”β-oxidation some intermediates accumulate in this catabolic pathway. When a docosapolyenoic acid with the first double bond in position 4 is metabolized, two degradation products are to be found. The sequence of reactions has been elucidated. As a first step the docosapolyenoic acid loses its double bond in position 4 while the carbon chain remains unchanged. The enzyme involved has tentatively been called 4-enoyl-CoA reductase. Subsequently chain shortening occurs. Using polyenoic acids with different chain lengths and different double bond positions, it has been possible to demonstrate that the double bond positions rather than the chain length determine whether or not an unsaturated fatty acid is partially degraded. The four double bonds in the positions 4, 7, 10 and 13 seem to be the minimal structural requirement for docosapolyenoic acids in order to function as substrates for the 4-enoyl-CoA reductase. 4, 7, 10-docosatrienoic, 4, 7-docosadienoic, and 4-docosenoic acid, which have not been detected in nature so far, are not metabolized when incubated with rat liver mitochondria.

Lubricating compositions containing hydrogenated block copolymers as viscosity index improvers

Abstract: Lubricating compositions having improved operating life comprise lubricants containing hydrogenated polymers of conjugated dienes wherein at least 98% of the olefinic double bonds present in the non-hydrogenated precursors are reduced and at least 20% of the polymeric molecules contain no olefinic double bonds in the polymer backbone.