598-53-8Relevant articles and documents
Investigating the α-effect in gas-phase SN2 reactions of microsolvated anions
Thomsen, Ditte L.,Reece, Jennifer N.,Nichols, Charles M.,Hammerum, Steen,Bierbaum, Veronica M.
, p. 15508 - 15514 (2013/11/06)
The α-effect - enhanced reactivity of nucleophiles with a lone-pair adjacent to the attacking center - was recently demonstrated for gas-phase SN2 reactions of HOO-, supporting an intrinsic component of the α-effect. In the present work we explore the gas-phase reactivity of microsolvated nucleophiles in order to investigate in detail how the α-effect is influenced by solvent. We compare the gas-phase reactivity of the microsolvated α-nucleophile HOO-(H2O) to that of microsolvated normal alkoxy nucleophiles, RO-(H2O), in reaction with CH3Cl using a flowing afterglow-selected ion flow tube instrument. The results reveal enhanced reactivity of HOO-(H 2O) and clearly demonstrate the presence of an α-effect for the microsolvated α-nucleophile. The association of the nucleophile with a single water molecule results in a larger Bronsted βnuc value than is the case for the unsolvated nucleophiles. Accordingly, the reactions of the microsolvated nucleophiles proceed through later transition states in which bond formation has progressed further. Calculations show a significant difference in solvent interaction for HOO- relative to the normal nucleophiles at the transition states, indicating that differential solvation may well contribute to the α-effect. The reactions of the microsolvated anions with CH3Cl can lead to formation of either the bare Cl- anion or the Cl-(H2O) cluster. The product distributions show preferential formation of the Cl- anion even though the formation of Cl-(H2O) would be favored thermodynamically. Although the structure of the HOO-(H2O) cluster resembles HO-(HOOH), we demonstrate that HOO- is the active nucleophile when the cluster reacts.
METHOD FOR THE PRODUCTION OF ISOPROPENYL ETHERS
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Page/Page column 14, (2010/02/13)
The invention relates to a method for the production of isopropenyl ethers of formula (A), wherein R represents an aliphatic, cycloaliphatic, aralyphatic, aromatic or heterocyclic radical which can include other substituents which do not react with acetylenes or allens, by reacting a gaseous flow (I), containing MAPD which is obtained from an olefin system and which is used to separate C3-sections, with at least one gaseous flow selected from a gaseous flow (II) containing an acetone ketal of formula (B), wherein R has the above-mentioned meaning, and a gaseous flow (III) containing a monohydroxyalcohol ROH, wherein R has the above-mentioned meaning, in the presence of a heterogeneous catalyst.
Process for removing oxygenates from an olefinic stream
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Page column 38-39, (2008/06/13)
The present invention provides a process for removing oxygenate impurities, e.g., dimethyl ether, from an olefinic product stream by converting the oxygenate impurity to a compound whose boiling point differs by at least about 5° C. from the oxygenate impurity. Typically, the compound is more readily removable from the product stream than the oxygenate impurity.
METHOD FOR THE PRODUCTION OF ETHERS
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Page/Page column 8, (2008/06/13)
The invention relates to a method for the production of ethers of formula (I), where R1 and R2 independently = H, substituted or unsubstituted, branched or linear 1 - 20 C alkyl chains, substituted or unsubstituted 5 - 8 C cycloaliphatic groups with a ring size of from 5 - 8 carbon atoms, whereby the ring can be interrupted by a heteroatom, or R1 and/or R2 = unsubstituted or substituted aromatic groups or together form a chain of 5 - 7 methylene groups and R3 = linear or branched 1 - 20 C alkyl chains, by hydrogenation of acetals of formula (II), where R1, R2 and R3 have the meanings given above, in the presence of hydrogen on a catalyst comprising copper oxide, aluminium oxide and optionally, in addition, manganese oxide.
Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents
Hao, Wei,Fujii, Takayoshi,Dong, Tiaoling,Wakai, Youko,Yoshimura, Toshiaki
, p. 193 - 198 (2007/10/03)
Alkoxy-λ6-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, ptoluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ6-sulfanenitriles showed an opposite trend to the usual SN2 character, i.e. Me (la), Pr (1b), and Bu (1d) ? i-Pr (1c). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ6-sulfanenitrile, was found to undergo an SN2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield.
Trends in alkyl substituent effects on nucleophilic reactions of carbonyl compounds: Gas phase reactions between ammonia and R1R2COCH3+ oxonium ions
Bache-Andreassen, Lihn,Uggerud, Einar
, p. 705 - 713 (2007/10/03)
The reactivity of carbonyl substituted methyl oxonium ions (R1R2COCH3-) towards ammonia has been investigated using an FT-ICR mass spectrometer and ab initio calculations. The monosubstituted ions (R1=H: R2 = H, CH3, C2H5 and i-C3H7) show different reaction patterns with variable degree of: (1) nucleophilic substitution, (2) addition elimination and (3) proton transfer, when reacted with ammonia. In all cases addition-elimination dominates over nucleophilic substitution, and the observed reactions are slow. The trends in reactivity are consistent with the alkyl group's electronic properties, as expressed by a single parameter linear or slightly non-linear model.
Synthesis, structure, and reactions of triaryl(methyl)bismuthonium salts
Matano, Yoshihiro
, p. 2258 - 2263 (2008/10/08)
Treatment of triarylbismuth difluorides 2 (Ar3BiF2; a, Ar = Ph; b, Ar = 4-MeC6H4; c, Ar = 4-MeOC6H4; d, Ar = 2-MeOC6H4) with methylboronic acid (3) in the presence of BF3·OEt2 in CH2Cl2 afforded the corresponding triaryl(methyl)bismuthonium tetrafluoroborates 4a-d ([Ar3MeBi+][BF4-]) in 42-91% yield. X-ray crystallographic analysis of compound 4d revealed that the bismuth center possesses a distorted tetrahedral geometry with C-Bi-C bond angles of 106.1(3)-113.6(3)° and Bi-C bond lengths of 2.182(7)-2.195(8) angstrom. Compound 4a transferred the methyl group to Ph3E (E = P, As, Sb), tris(4-methylphenyl)bismuthine, ROH (R = Me, Et, i-Pr, PhCH2), water, sodium benzenesulfinate, sodium benzoate, N,N-dimethylformamide (DMF), and thioacetamide to give the corresponding methylated products with a good recovery of triphenylbismuthine. The pseudo-first-order rate constant (kobsd = 2.9 × 10-4 s-1) observed for the reaction between 4a and benzyl alcohol (5d) was about twice as large as that (kobsd = 1.3 × 10-4 s-1) between MeOTf and 5d (in CDCl3 at 23°C; [4a] or [MeOTf] = 0.062 M; [5d] = 0.97 M). The observed reactivity of 4a clearly demonstrates the high nucleofugality of the triphenylbismuthonio group.
Reaction of 2-propanol over alumina in the presence of methyl acetate. Evidence for the nature of adsorption
Jain
, p. 355 - 357 (2007/10/03)
Dehydration of 2-propanol over alumina at 280°has been studied in the presence of methyl acetate as a co-reactant. Even as low as 2 mol% of methyl acetate strongly inhibits the dehydration reaction (alkene and ether formation). Co-adsorption of methyl acetate leads to the formations of 2-propyl acetate (ester exchange) and methyl 2-propyl ether (ether formation) as competing reactions at low concentrations of methyl acetate and the only reactions at more than 50 mol% of methyl acetate.
Triazene Drug Metabolites. Part 10. Metal-ion Catalysed Decomposition of Monoalkyltriazenes in Ethanol Solutions
Iley, Jim,Moreira, Rui,Rosa, Eduarda
, p. 81 - 86 (2007/10/02)
The metal ions Fe(2+), Zn(2+) and Cu(2+) bring about the rapid decomposition of 1-aryl-3-alkyltriazenes to the corresponding anilines.For Fe(2+), a linear dependence of the pseudo-first-order rate constant, k0, on was observed, while for Zn(2+) and Cu(2+) plots of k0 versus were curved and indicative of complex formation.For Fe(2+), second-order rate constants k2Fe(2+) for substituted 1-aryl-3-methyltriazenes follow a Hammett relationship giving rise to a ρ value of -3.0.For Zn(2+) and Cu(2+), the data were analysed in terms of an equilibrium konstant, KM(2+), for the dissociation of a metal-ion-triazene complex and the first-order rate constant, for the collapse of this complex to products, k2M(2+).Hammett ρ values of 1.0 for both KZn(2+) and KCu(2+) are found, and the corresponding ρ values for k2Zn(2+) and k2Cu(2+) are -1.3 and -1.9.There is reasonable correlation between the Taft Eg parameter for the alkyl group and KCu(2+), giving a δ value of -1.6.The dependence of k2Cu(2+) on the alkyl group is not simple: k2Cu(2+) decreases in the order Pr > Et * PhCH2 ca. 4-MeOC6H4CH2 > CD3 ca.Me.The reactions catalysed by Cu(2+) are inhibited by added nucleophiles e.g.Br(1-) and N-methylimidazole. A mechanism is proposed in which the triazene complexes to the metal ion via the N(1) nitrogen atom of the E-cis conformer, then undergoes a fast proton transfer to form a complex involving the unconjugated tautomer which subsequently decomposes via unimolecular scission of the N(2)-N(3) bond to form an alkyldiazonium ion and an aniline-metal complex.The observed products then arise from rapid solvolysis of the metal-aniline complex and the alkyl diazonium ion.
A Gas-Phase E2 Reaction: Methoxide Ion and Bromopropane
Jones, Mark E.,Ellison, G. Barney
, p. 1645 - 1654 (2007/10/02)
We describe a procedure for studying gas-phase ion-molecule chemistry in which the reaction pathway is elucidated by direct detection of the neutral products.Our experiment uses a flowing afterglow device configured with a novel cold finger trap coupled to a GC/MS.Material collected by the trap is separated by capillary gas chromatography and the individual components identified by their retention times and electron impact mass spectra.We have used this device to study the reaction of methoxide ion with 1-bromopropane.CH3O(-) + CH3CH2CH2Br --> Br(-) + CH3OH + CH3CH=CH2 (a) Br(-) + CH3CH2CH2OCH3 (b) We find that the reaction produces only products resulting from elimination a; there is no evidence for the species resulting from displacement b.The E2 product, propylene, is detected while the SN2 product, 1-methoxypropane, is not.Our gas-phase results contrast sharply with solution studies, which show an overwhelming preference for the displacement channel b.
