Showing papers on "Alkene published in 1981"
1 Jan 1981
TL;DR: In this article, the authors developed a combustion mechanism based on the present kinetic data for the elementary reactions involved, which explains the currently available experimental results for laminar premixed flames of alkanes, alkenes, and acetylene.
Abstract: The detailed knowledge of combustion mechanisms is important for example for the control of (kinetically determined) pollutant formation (e.g., NO, hydrocarbons, soot), or for the extrapolation to technologically important but experimentally inaccessible conditions. By suitable separation and elimination of unimportant reactions, a mechanism is developed with the aid of the present kinetic data for the elementary reactions involved. This mechanism explains, without fitting, the currently available experimental results for laminar premixed flames of alkanes, alkenes, and acetylene (flame velocity and structure of free flames, concentration and temperature profiles in burner-stabilized flames). These experimental results are simulated by the solution of the corresponding conservation equations with suitable models describing diffusion and heat conduction in the multicomponent mixture considered. In lean and moderately rich flames the hydrocarbon is attacked by O, H, and OH, in the first step. These radicals are produced by the chain-branching steps of the oxyhydrogen reaction. The alkyl radicals formed in this way always decompose to smaller alkyl radicals by fast thermal elimination of alkenes. Only the relatively slow thermal decomposition of the smallest alkyl radicals (CH 3 and C 2 H 5 ) competes with recombination and with oxidation reactions by O atoms and O 2 . This part of the mechanism is rate-controlling in the combustion of alkanes and alkenes, and is therefore the reason for the similarity of all alkane and alkene flames.
253 citations
TL;DR: In this article, second-order rate constants for ozone reactions with ethene, propene, but-1-ene, trans-but-2-ene and isobutene were obtained.
Abstract: By measuring the rates of decay of ozone in a large excess of reactant, second-order rate constants have been obtained for the reactions of ozone with ethene, propene, but-1-ene, trans-but-2-ene, isobutene, hex-1-ene, cyclopentene, cyclohexene, isoprene, vinyl fluoride, 1,1-difluoroethene, cis-1,2-difluoroethene, trans-1,2-difluoroethene, trifluoroethene, tetrafluoroethene, and 2,5dihydrofuran. The reactions have been studied in synthetic air at atmospheric pressure and at temperatures of 294 and 260 K. The rate constants and Arrhenius parameters are discussed in relation to existing kinetic data on ozone–alkene reactions.
60 citations
TL;DR: In this article, the results from photocyclopropanation of a variety of alkenes are summarized in Tables 1 and 3-4, and the α-iodocation 2 is suggested as the methylene transfer species.
58 citations
3 Sep 1981
56 citations
TL;DR: In this article, the authors studied the first-order hydrogenation of alkenes by homogeneous rhodium(I) complexes at 1.1 atm hydrogen pressure and 37 − 67 °C.
54 citations
TL;DR: In this article, the enantiomeric purity of a mixture of (+)- and (−)- 8 was determined for the chiral alkenes with and without the presence of the salt and one of the lanthanide complexes.
49 citations
TL;DR: In this paper, an ion-beam apparatus was employed to study the reactions of singly charged cobalt positive ions with 12 alkenes, and two processes were observed for larger olefins.
Abstract: An ion-beam apparatus is employed to study the reactions of singly charged cobalt positive ions with 12 alkenes. While ethene and propene undergo no exothermic reactions, two processes are observed for larger olefins. One reaction yields cobalt ion alkadiene complexes and either methane or H/sub 2/. The second process involves cleavage of the alkene into two smaller olefins, one of which remains bound to Co/sup +/. A mechanism involving oxidative addition of an allylic C-C or C-H bond to the metal as the initial step is proposed to account for all observed products. Subsequent formation of a cobaltacyclobutane species is postulated for several of the cleavage reactions.
46 citations
TL;DR: In this paper, the silyl group was placed to control the carbonium ion rearrangement in a preparatively useful way, and the starting γ-silyl alcohols were prepared by a variety of versatile methods.
Abstract: γ-Silyl tertiary alcohols rearrange in protic acid with 1,2-shift of hydride, phenyl, or alkyl groups, and loss of the silyl group to give alkenes. The placing of the silyl group thus controls the carbonium ion rearrangement in a preparatively useful way. Methoxycarbonyl groups do not migrate; instead, cyclopropanes are formed, except when the conformation suitable for cyclopropane formation is unattainable. When the alkene product is 2,2-disubstituted, it can be reprotonated under the reaction conditions and does not therefore always survive. This can be avoided by carrying out the reaction using a Lewis acid on the silyl ether. The starting γ-silyl alcohols are prepared by a variety of versatile methods.
34 citations
TL;DR: In this paper, the authors studied the first-order oxidation of p-chlorophenylmethyl sulphide and a series of phenylsubstituted arylmethyl sulphides in the presence of catalytic amounts of three molybdenum derivatives, MoO2(acac)2, Mo(CO)6 and MoO5·HMPT·H2O.
33 citations
TL;DR: The trifluoromethanesulphonate salts of the aminoalkenes CH 2 CH(CH 2 ) 3 -NH 2, its 2-methyl, 2,2-dimethyl and N -iso-propyl-derivatives, and CH 2 √ CH 2 ) 4 NH 2 cyclize in the presence of [PdCl 2 (PhCN) 2 ] and a nitrogen base to produce the corresponding C- or N-substituted 2 -methylpyrrolidines and 2methylpiperidine RE
TL;DR: Phenyl o-styrylphenyl iminyl, generated by oxidation of the corresponding O-carboxymethyloxime with persulphate and by thermolysis of the perester of that acid, cyclises to give a mixture of isoquinoline and 1H-isoindole derivatives as discussed by the authors.
Abstract: Phenyl o-styrylphenyl iminyl, generated by oxidation of the corresponding O-carboxymethyloxime with persulphate and by thermolysis of the perester of that acid, cyclises to give a mixture of isoquinoline and 1H-isoindole derivatives. The intermediate radicals have been investigated by e.s.r.
TL;DR: In this article, the reaction of acid chlorides or thiocarboxylic S-esters with the title reagent in tetrahydrofuran provides ketones in good yield.
Abstract: Reaction of acid chlorides or thiocarboxylic S-esters with the title reagent in tetrahydrofuran provides ketones in good to excellent yields. The coupling reactions with ally lie halides to form alkene derivatives are also disclosed.
TL;DR: The first examples of co-ordination complexes containing a phospha-alkene were described in this article, where the phosphorus lone pair was assumed to be the only co-coordination link.
Abstract: The first examples of co-ordination complexes containing a phospha-alkene are described; n.m.r. studies on cis-M(CO)4L2(M = Cr,Mo,W), trans-RhCl-(PPh3)2L, trans-RhCIL2(CO), Rh(η5-C9H7)L2, cis-PtX2L2(X = Cl,I,Me), and cis- and trans-PtCl2(PEt3)L, [L = P(mesityl)CPh2], suggest that co-ordination to the metal is via the phosphorus lone pair.
Patent•
10 Jul 1981
TL;DR: In this article, a process for the preparation of copolymers consisting of 25-85% by wt. of ethylene, 15-75% of polyethylene and up to 20% of at least one other 1-alkene was described.
Abstract: Process for the preparation of copolymers consisting of 25-85% by wt. of ethylene, 15-75% by wt. of at least one other 1-alkene and optionally up to 20% by wt. of a polyunsaturated compound with application of a catalyst system containing a compound of a metal from sub-groups IV-VI of the periodic system and a compound of a metal from groups I-III of the periodic system, in which at least one hydrocarbon group is bound directly to the metal atom via a carbon atom, the polymerization being carried out in the presence of a halogen-containing compound of one of the following groups: a. compounds of the general formula where A is a phenyl or benzoyl group with one or two substituent nitro groups, X is a chlorine or bromine atom, Y is a chlorine, bromine or hydrogen atom or a hydrocarbon group with 1-8 carbon atoms, and Z is a nitrile group, a carboxyl group, an ester group, a hydrocarbyloxyalkylcarboxyl group, a carboxylhalide group, an amide group, a benzoyl group, a carboxyphenyl group, a carboxyhydrocarbylphenyl group, a phenyl group or a phenyldihalogenmethyl group, b. compounds of the general formula where B is a phenyl group which may contain one or two substituent halogen atoms or alkyl groups, or is a thienyl, furyl, pyrrollyl, N alkyl pyrollyl or pyridyl group, which group is bound to the carbon atom directly or via a carbonyl group, X is a chlorine or bromine atom, Y is a chlorine, bromine or hydrogen atom or a hydrocarbon group with 1-8 carbon atoms, and Q is a phenyl group or a phenyldihalogen methyl group. c. oxalyl chloride or oxalylbromide.
TL;DR: In the presence of bis(maleic anhydride)(norbornene)palladium as a catalyst, two 1-alkene molecules, R-CH2−CH=CH2, were added regioselectively to dimethyl acetylenedicarboxylate in the syn addition mode to give dimethyl 2-(2-alkenyl)-3-alkylmaleates, R
Abstract: In the presence of bis(maleic anhydride)(norbornene)palladium as a catalyst, two 1-alkene molecules, R–CH2–CH=CH2, were added regioselectively to dimethyl acetylenedicarboxylate in the syn addition mode to give dimethyl 2-(2-alkenyl)-3-alkylmaleates, R–CH=CH–CH2–C(COOCH3)=C(COOCH3)–CH2CH2CH2-R under moderate condition (40–45°C) in chloroform.
TL;DR: Polystyrene-bound bis(cyclopentadienyl)titanium dichloride has been shown to react with Grignard reagents to form a reactive alkene isomerization catalyst, which converts 1-alkenes primarily into E 2 -alkenes at room temperature as mentioned in this paper.
Abstract: The reactions of ten C6-alkenes over a Cu2+-montmorillonite catalyst have been examined between room temperature and 100°C. The reaction products depend upon inter alia the branching in the alkene, the position of the double bond, and the temperature. Hex-2-ene, cis and trans-4-methyl-pent-2-ene and 4-methyl-pent-1-ene do not react at all, whereas 2-methyl-pent-1-ene and 2-methyl-pent-2-ene and 3,3-dimethyl-but-1-ene form alcohols below ∼40°C and dimers at higher temperatures. Hex-1-ene forms the di-2,2′-hexyl ether.
TL;DR: In this article, a number of η 3 -allylmetal or mixed η-3 -allium-sulfur clusters of the type [η 3 −C 3 H 5 MS(η3 -C 3H 5 )M′] x, M, M′ = Ni, Pd, Pt, Pt and the pure platinum cluster proved to be a nonselective alkyne and alkene hydrogenation catalyst.
TL;DR: In this paper, the diagnostic vicinal C,H coupling constants of trisubstituted alkenes are reported, and the application of the method confirms the structures of four dimethyl acetylenedicarboxylate adducts.
Abstract: Further examples of the diagnostic vicinal C,H coupling constants of trisubstituted alkenes are reported, and the application of the method confirms the structures of four dimethyl acetylenedicarboxylate adducts.
Patent•
18 Jun 1981
TL;DR: In this article, a semi-permeable membrane is used to separate the concomitantly produced hydrogen peroxide from the first zone through a semipermeability membrane into a second zone wherein an alkene is reacted with said hydrogen peroxy to form oxygenated products of said alkene, said membrane being permeable only to compounds of a molecular weight of less than about 100.
Abstract: Methods of producing glucosone which comprises enzymatically oxidizing glucose with glucose-2-oxidase in a first zone and separating the concomitantly produced hydrogen peroxide from said first zone through a semi-permeable membrane into a second zone wherein an alkene is reacted with said hydrogen peroxide to form oxygenated products of said alkene, said membrane being permeable only to compounds of a molecular weight of less than about 100.
Patent•
8 Jun 1981
TL;DR: The manganese compounds are useful in the separation of a gas such as oxygen, hydrogen, sulfur dioxide, an alkene and the fluid carbon monoxide containing these gases.
Abstract: Manganese compounds according to the formula: MnIILX2 (Q) n (I) where L is a "ligand" monodentate following formula PR1R2R3 (II) or R1, R2 and R3 are identical or different and are alkyl compounds, cycloalkyl, alkenyl , alkynile, aryl or hydrogen or substituted or unsubstituted provided that no more than two aryl groups, substituted or unsubstituted among the three groups R1, R2 and R3 and at least one of the three groups R1, R2 and R3 is alkyl, cycloalkyl, alkenyl, alkynile or substituted or unsubstituted aryl, X is a species capable of existing as an anion, for example Cl or Br, Q is a solvent molecule capable of forming a chemical bond with the manganese and n is composed of 1, 2 or 3 donor atoms of the solvent. The manganese compounds are useful in the separation of a gas such as oxygen, hydrogen, sulfur dioxide, an alkene and the fluid carbon monoxide containing these gases.
TL;DR: In this article, the bridgehead-substituted bicyclo[n.2.2] alkenes (1b-3b) were synthesized based on the oxidative decarboxylation of precarboxylic acids with lead tetraacetate, and the results indicated that the homoallylic participation of the strained bridgehead double bond to the carbonium ion center located at the opposite bridgehead position operates in the solvolysis of 1d and 2d.
Abstract: The bridgehead-substituted bicyclo[n.2.2] bridgehead alkenes (1b–3b) (1, n=4; 2, n=5; 3, n=6; b, R=OAc) were synthesized based on the oxidative decarboxylation of [n.2.2]propellanecarboxylic acids with lead tetraacetate. The parent alkene (1a–3a) (a, R=H) and other bridgehead-substituted derivatives (1c–3c and 1d–3d) (c, R=OH; d, R=Cl) were prepared from 1b–3b. The examination of the 13C NMR chemical shifts of 1a–c, 2a–c, and 3a–c indicates the presence of electronic interaction between the bridgehead double bond (Cγ) and the opposite bridgehead carbon (Cα), being the homoallylic position of the double bond. From the product study and the kinetic results of the solvolysis of the bridgehead chlorides 1d–3d, it is indicated that the homoallylic participation of the strained bridgehead double bond to the carbonium ion center located at the opposite bridgehead position operates in the solvolysis of 1d and 2d. It may be, therefore, concluded that highly strained bridgehead alkenes, especially, bicyclo[4.2.2]de...
TL;DR: In this paper, it was shown that styrene reacts with complexes [IrH2S2L2]BF4 to give [Ir(η6-PhEt)L 2 ]BF4(S = H2O or Me2CO; L = PPh3): this accounts for the failure of styrene to act as a hydrogen acceptor in related alkane activation system, and may account for the anomalously low hydrogenation rates observed for styrene using PF6 as catalyst precursor.
Abstract: Styrene reacts with complexes [IrH2S2L2]BF4 to give [Ir(η6-PhEt)L2]BF4(S = H2O or Me2CO; L = PPh3): this accounts for the failure of styrene to act as a hydrogen acceptor in our related alkane activation system, and may account for the anomalously low hydrogenation rates observed for styrene using [Ir(cod)-(PMePh2)2]PF6 as catalyst precursor.
TL;DR: In this article, the available data on the reaction of sym-tetrazines with various unsaturated compounds from 1958 to 1980 are systematized, including unsaturated carbocycles and heterocycles.
Abstract: The available data on the reaction of sym-tetrazines with various unsaturated compounds from 1958 to 1980 are systematized. The reaction of sym-tetrazines with alkenes, alkadienes, alkynes, and unsaturated carbocycles and heterocycles are presented.
TL;DR: The acid-catalysed reactions of two phenylethylcyclohexanols, precursors to tricyclic diterpenoids, are reported in this paper.
Abstract: The acid-catalysed reactions of two phenylethylcyclohexanols, precursors to tricyclic diterpenoids, are reported. The reaction produced both a bicyclic alkene and a tricyclic molecule; the former was converted into the latter in protic media. Conditions for the formation of the naturally occurring trans A–B ring stereochemistry were defined and the mechanism was explored by the use of a deuterium label. Polyphosphoric acid-catalysed cyclisation produced a more complex mixture.
TL;DR: In this paper, the reaction of 1 with 1-pyrrolidino-1-cyclopentene leads to insertion of the alkene into the metal carbene bond with formation of 6.
Abstract: Reaction of Complex Ligands, XXI1) Competing Olefin Scission and Cyclopropanation of Enamines in the Reaction with Carbene Complexes
Pentacarbonyl(methoxyphenylcarbene)chromium (1) reacts with 1-phenyl-1-piperidinoethene (2) to give both 1-methoxy-1,2-diphenyl-2-piperidinocyclopropane (3) and pentacarbonyl(phenyl-piperidinocarbene)chromium (4. The reaction of 1 with 1-pyrrolidino-1-cyclopentene (5) leads to insertion of the alkene into the metal carbene bond with formation of 6.
TL;DR: The β-silylsulphoxides ( 2 and 4 ) undergo a fast syn-elimination to give the alkene ( 3 ) and the alkyne ( 6 ), respectively; however, when there is a hydrogen α to the silyl group, only hydrogen is lost, and the products are β-Silylenones as discussed by the authors.
TL;DR: In this article, the Ir 4 -carbonyl compounds have been characterized by i.r. spectroscopy and electron microscopy and shown to be thermally stable below 330 K, but undergo slow, irrversible, structural changes at higher temperatures.
TL;DR: In this paper, a double-bonded 1-(Alkylthio)cyclopropyl azide was shown to interact not only with the three-membered ring but also with the double bond, leading to spirocyclic products.
Abstract: 1-(Alkylthio)cyclopropyl azides - readily accessible from the corresponding chlorides and bromides - are smoothly decomposed at 70°C with nitrogen evolution. The main process is a ring enlargement to 2-(alkylthio)azetines 2, accompanied by cleavage to thiocyanate and alkene. Reaction parameters for the thioazetine formation suggest a two-step mechanism involving an intermediate cyclopropylnitrene. Ring enlargement can be averted if the alkylthio group contains a double bond. Thus, the allylthiocyclopropyl azide 8 gives a nitrene that can interact not only with the three-membered ring but also with the double bond, leading to spirocyclic products (15 and 16 in Scheme 1). The photolysis (300 nm) of these azides gives exclusively the fragmentation products thiocyanate and olefin.