- Stabilization of long-chain intermediates in solution. octyl radicals and cations
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The rearrangements of 1-octyl, 1-decyl and 1-tridecyl intermediates obtained from thermal lead(IV) acetate (LTA) decarboxylation of nonanoic, undecanoic and tetradecanoic acid were investigated experimentally through analysis and distribution of the products. The relationships between 1,5-, 1,6- and possibly existing 1,7-homolytic hydrogen transfer in 1-octyl-radical, as well as successive 1,2-hydride shift in corresponding cation have been computed via Monte-Carlo method. Taking into account that ratios of 1,5-/1,6-homolytic rearrangements in 1-octyl- and 1-tridecyl radical are approximately the same, the simulation shows very low involvement of 1,7-hydrogen rearrangement (1,5-/1,6-/1,7-hydrogen rearrangement = 85:31:1) in 1-octyl radical.
- Teodorovi?, Aleksandar V.,Badjuk, Dalibor M.,Stevanovi?, Nenad,Pavlovi?, Radoslav Z.
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- Iron-catalysed green synthesis of carboxylic esters by the intermolecular addition of carboxylic acids to alkenes
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Iron triflate, in situ-formed from FeCl3 and triflic acid, or FeCl3 and silver triflate efficiently catalyse the intermolecular addition of carboxylic acids to various alkenes to yield carboxylic esters; the reaction is applicable to the synthesis of unstable esters, such as acrylates. The Royal Society of Chemistry.
- Choi, Jun-Chul,Kohno, Kazufumi,Masuda, Daisuke,Yasuda, Hiroyuki,Sakakura, Toshiyasu
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p. 777 - 779
(2008/09/16)
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- Kinetics and Mechanisms of Nucleophilic Displacement with Heterocycles as Leaving Groups. 17. Solvolysis of 14-(Primary alkyl)-5,6,8,9-tetrahydro-7-phenyldibenzoacridiniums: Rates, Identification of Products, Activation Parameters, and a General Discussion of Mechanism
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Solvolysis rate are reported for the Me, Et, n-Pr, n-Pent, n-Oct, i-Bu, neo-Pent, PhCH2CH2, and MeOCH2CH2 title compounds in MeOH, EtPH, PentOH, CH3CO2H, and CF3CO2H.Rate variations with alkyl group structure are far less than the corresponding rate variations for the tosylate solvolysis, and afford no evidence for rate-enhancing participation by β-phenyl or β-methoxy groups in the acridinium solvolyses.The n-propyl, n-pentyl, and n-octyl title compounds solvolyze in CH3OD and CH3CO2D to give mixtures of normal and rearranged products, none of which contain deuterium and which are therefore not formed via olefin intermediates.Methanolysis of the isobutyl title compounds occurs via olefin, but the acetolysis also involves an important nonolefinic pathway yielding isobutyl and sec-butyl acetates.Methanolysis products from the neopentyl derivative are heavily deuterated, but acetolysis yields undeuterated neopentyl acetate as well as deuterated tert-pentyl acetate.Product proportions calculated using GC/MS were used to deduce the fractions of reactions by various mechanistic pathways.Individual rates are calculated for solvolysis to the various unrearranged and rearranged products.They indicate that normal substitution in MeOH occurs by a classical SN2 reaction, but that such substitution in AcOH involves ion-pair intermediates.It is concluded that such ion pairs under go Me and H migration after the rate-determining stage, in competition with substitution.Activation parameters provide further evidence for the mechanistic paths proposed which are discussed in relation to literature data available for the corresponding tosylate.
- Katritzky, Alan R.,Dega-Szafran, Zofia,Lopez-Rodriguez, Maria L.,King, Roy W.
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p. 5577 - 5585
(2007/10/02)
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- SELECTIVE OXIDATION OF n-ALKANES WITH LEAD TETRAACETATE
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Alkanes, when treated with lead tetraacetate under thermal or photochemical conditions, undergo a slow but highly selective oxidation to form secondary acetates.
- Bestre, R. D.,Cole, E. R.,Crank, G.
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p. 3891 - 3892
(2007/10/02)
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- Classical Carbonium Ions. Part 12. The Deamination of 1- and 4-Amino-n-octane
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The deamination products of 1- and 4-amino-octane in acetic acid were examined.The amines were treated with sodium nitrite directly, and also converted into alkylaryltriazenes derived from several arenediazonium cations, which were then acetolysed.N-Nitrosobutyramides were acetolysed, and N-nitrosoacetamides were butyrolysed, to allow the seperate analysis of rearranged and unrearranged products from internal and external nucleophiles.It is concluded that the primary alkylamine is converted by all these different methods in high yield into a primary alkane diazonium ion RN2+, the properties of which are independent of its method of preparation in that the alkyl cation formed by its decomposition does not capture the leaving group which accompanies its formation, but reacts with solvent to give a constant set of products.The secondary alkylamine behaves differently.Its diazo-derivatives, RN2X, usually undergo effectively concerted decomposition to carbonium ions, nitrogen, and leaving group X.The cations show differing degrees of hydride shift, and capture the internal nucleophile X to a considerable but variable extent, after as well as before rearrangement.The acetolysis of 4-diazo-octane proceeds via a much less reactive intermediate, possibly an intimate ion-pair, giving mainly unrearranged 4-acetoxyoctane, plus an olefin mixture in which the substantial proportion of cis-isomers reflects the conformational preference of the starting material.
- Southam, Richard M.,Whiting, Mark C.
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p. 597 - 604
(2007/10/02)
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- Classical Carbonium Ions. Part 14. The Lifetime of Secondary Carbocations in Acetic Acid
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Oct-1-ene and cis- and trans-oct-4-enes were treated with p-nitrobenzenesulphonic acid in acetic acid (0.1 M) at 25 deg C, when addition of the sulphonic acid and of acetic acid and the direct formation of isomeric octenes were all observed.At a greater rate, the covalent ester underwent acetolysis.The kinetically controlled mixture of products from the olefins was deduced from analyses at varying small degrees of reaction, extrapolating to zero conversion, and correcting for the products known to have been formed via covalent arenesulphonate.The results for cis-oct-4-ene proved that the lifetime of the 4-octyl cation in acetic acid is short compared with the time for rotation around a C3H7C+H-CH2C3H7 bond.
- Monitz, Margaret,Whiting, Mark C.
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p. 613 - 616
(2007/10/02)
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- Solvolysis of N-n-Alkylacridiniums in Phenol and Carboxylic Acids. Primary Carbonium Ions as Possible Intermediates
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N-n-Octyl (1a) and N-n-dodecylacridinium (1b) ions solvolyze in phenol to give mixtures of the n-alkyl phenyl ethers and all the isomeric secondary straight-chain o- and p-alkylphenols.Solvolyses of 1a in carboxylic acids give a mixture of 1-, 2-, 3-, and 4-octyl carboxylic esters.Structures are deduced by GC/MS.Mechanisms are discussed.
- Katritzky, Alan R.,El-Mowafy, Azzahra M.
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p. 3511 - 3517
(2007/10/02)
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- Chemical Conversions using Sheet Silicates: Facile Ester Synthesis by Direct Addition of Acids to Alkenes
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Ethene and acetic acid react in the interlamellar regions of certain cation (e.g.Al3+)-exchanged montmorillonites to yield ethyl acetate as the sole product, and a variety of carboxylic acids readily add to C2-C8 alkenes at temperatures above 100 deg C to yield the corresponding esters in high and selective yields.
- Ballantine, James A.,Davies, Mary,Purnell, Howard,Rayanakorn, Mongkon,Thomas, John M.,Williams, Kevin J.
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