- Carbodeoxygenation of biomass: The carbonylation of glycerol and higher polyols to monocarboxylic acids
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Glycerol is converted to a mixture of butyric and isobutyric acid by rhodium- or iridium-catalysed carbonylation using HI as the co-catalyst. The initial reaction of glycerol with HI results in several intermediates that lead to isopropyl iodide, which upon carbonylation forms butyric and isobutyric acid. At low HI concentration, the intermediate allyl iodide undergoes carbonylation to give vinyl acetic acid and crotonic acid. Higher polyols CnH n+2(OH)n are carbonylated to the corresponding C n+1 mono-carboxylic acids. Copyright
- Coskun, Timur,Conifer, Christopher M.,Stevenson, Laura C.,Britovsek, George J. P.
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supporting information
p. 6840 - 6844
(2013/07/05)
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- Further insights into the chemistry of niobium and tantalum pentahalides with 1,2-dialkoxyalkanes: Synthesis of bromo- and iodoalkoxides, spectroscopic and computational studies
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The room temperature reactions of a series of 1,2-dialkoxyalkanes ROCH 2CH(R′)OR′′ with MX5 (M = Nb, Ta; X = Br, I) in 1:1 ratio result in single C-O bond cleavage and high-yield formation of the halo-alkoxides MBr4[κ2-OCH 2CH(R′)OR′′] or [NbI4{κ 1-OCH2CH(R′)OR′′}]2, and equimolar amounts of the corresponding alkyl halides RX. The reaction of NbBr5 with 1,2-dimethoxyethane, dme, proceeds with preliminary formation of the ionic species [NbBr4(κ2-dme) (κ1-dme)][NbBr6], 3b, which has been identified by solution NMR at low temperature and conductivity analyses. The gas-phase structure of 3b has been optimized by DFT calculations, confirming that the dme ligands adopt bidentate and monodentate coordination, respectively. Although the formation of NbOBr3(dme), 4b, 1,4-dioxane and MeBr from NbBr 5/dme (ratio 1:2) is an exoergonic process (calculated ΔGr° = -115.96 kcal mol-1), it is inhibited at room temperature. High temperature conditions enhance the production of 1,4-dioxane at the expense of selectivity. The dinuclear species NbOBr3(dme)NbBr5 (Nb-O-Nb), 5b, (X-ray) has been isolated in modest yield as byproduct of the room temperature reaction of NbBr5 with dme. In general, the 1:2 molar reactions of NbX5 (X = Br, I) with ROCH2CH(R′) OR′′ occur with the exclusion of nearly one equivalent of organic reactant.
- Bini, Riccardo,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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experimental part
p. 1412 - 1419
(2011/06/22)
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- Reactions of trimethyliodosilane with mono-, di-, and trioxacycloalkanes
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The reactions of Me3SiI with mono-, di-, and trioxacycloalkanes have been studied first.Preparative methods for the synthesis of some promising synthones, namely α,ω-diiodoalkanes, α,ω-alkanediols, and iodomethyl ω-iodoalkyl ethers, have been developed based on these reactions.The effect of the cycle size and the nature of the substituent on the course of the reactions is demonstrated.Schemes for the mechanism of the reactions are suggested.
- Voronkov, M. G.,Dubinskaya, E. I.
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- Halogenobis(N,N-dialkyldithiocarbamato)iron(III) Complexes as Potential Catalysts for Halogen Addition Reactions to Alkenes
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In the presence of a catalytic amount of iron(III) halogenobisdithiocarbamates, the addition of molecular halogens to alkenes occurs rapidly to afford cis-addition products.
- Tsipis, Constantinos A.,Katsoulos, George A.,Vakoulis, Fotios D.
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p. 1404 - 1405
(2007/10/02)
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- vic-Iodo Thiocyanates and Iodo Isothiocyanates. IX A Synthesis of Penam and Other Polycyclic β-Lactams
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Penam (4-thia-1-azabicycloheptan-7-one) and 2,3-disubstituted penams are prepared conveniently from vic-iodo isothiocyanates beginning with the facile cyclization of the latter with di-t-butyl sodiomalonates.Treatment of the resulting di-t-butyl 2-(thiazolidin-2-ylene)malonates with trifluoroacetic acid gives t-butyl 2-thiazolin-2-ylacetate derivatives which are reduced to the corresponding thiazolidines with aluminium amalgam.Cleavage of these t-butyl esters with hydrogen chloride affords β-amino acid hydrochlorides, which are cyclized to penam and its derivatives with 1--3-ethylcarbodiimide hydrochloride.The structures of the (2α,3aβ,7aβ)-thiazolidine (5) and of the tricyclic β-lactam (41) have been confirmed by X-ray crystallography.
- Cambie, Richard C.,Clark, George R.,Jones, Tony C.,Rutledge, Peter S.,Strange, Gary A.,Woodgate, Paul D.
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p. 745 - 764
(2007/10/02)
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- Synthesis of Ethylene Glycol Acetates Catalyzed by Potassium Iodide and Metal Acetate
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The catalytic activities of various kinds of binary systems consisting of KI and metal acetate were tested in liquid phase oxidation of ethylene in acetic acid at various pressures.KI-Mn(OCOCH3)2 was found to be the most reactive system and new material, CH3COOCH2CH2OCOCH2OCOCH3, was formed as a major by-product.It was also found that the main product at an early stage of the reaction was ethylene glycol monoacetate, from which other products were formed consecutively.It is considered that catalytic reaction does not proceed via ICH2CH2I, but via ICH2CH2OH which is formed by the oxidation of ethylene with HIO.On the basis of the rate equation and the results under various reaction conditions, a mechanism of the KI-Mn(OCOCH3)2-catalyzed reaction has been proposed.
- Shimizu, Kazuo,Imamura, Juichi
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p. 3200 - 3204
(2007/10/02)
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