- Consecutive addition esterification and hydrolysis of cyclic olefins catalyzed by multi-SO3H functionalized multi heteropolyanion-based ionic hybrids undersolvent-free conditions
-
An efficient protocol for the synthesis of cycloalkyl carboxylates and alcohols from cyclic olefins is described. The cyclic olefins were converted to corresponding target molecules under solvent-free conditions catalyzed by two novel multi-SO3H functionalized multi heteropolyanion-based ionic hybrids through one-pot consecutive addition esterification and hydrolysis reactions. This approach has several advantages, including high yield, simple workup and simple purification.
- Zheng, Guocai,Li, Xinzhong
-
p. 933 - 941
(2019/03/17)
-
- Fractional distribution of graphene oxide and its potential as an efficient and reusable solid catalyst for esterification reactions
-
Graphene oxide (GrO) prepared by the Hummers method was separated into three different fractions (GrO5000, GrO2000, and GrOres) on the basis of their dispersion stability in the water. Infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analyses revealed that GrO5000 possesses a high degree of oxygen functionalities including phenolic, carboxylic, and -OSO2H groups, compared with the other fractions. The GrO5000 was found to be a highly efficient and reusable solid catalyst for the esterification of various carboxylic acids with a variety of alcohols to furnish corresponding esters in high to excellent yields. The catalytic activity of the GrO5000 was attributed to the ability of highly polar GrO5000 scaffold to adsorb/attract reactants, where the acid functionalities of GrO5000 facilitated the esterification process efficiently. The chemical and structural features of GrO5000 were discussed to understand the improved catalytic activity compared with GrO2000 and conventional solid acid catalysts.
- Mungse, Harshal P.,Bhakuni, Niharika,Tripathi, Deependra,Sharma, Om P.,Sain, Bir,Khatri, Om P.
-
p. 944 - 951
(2015/02/02)
-
- Stabilization of long-chain intermediates in solution. octyl radicals and cations
-
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.
-
-
- Iron-catalysed green synthesis of carboxylic esters by the intermolecular addition of carboxylic acids to alkenes
-
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
-
p. 777 - 779
(2008/09/16)
-
- An algorithm for the deconvolution of mass spectrosopic patterns in isotope labeling studies. Evaluation for the hydrogen-deuterium exchange reaction in ketones
-
(Graph Presented) An easy to use computerized algorithm for the determination of the amount of each labeled species differing in the number of incorporated isotope labels based on mass spectroscopic data is described and evaluated. Employing this algorithm, the microwave-assisted synthesis of various α-labeled deuterium ketones via hydrogen-deuterium exchange with deuterium oxide was optimized with respect to time, temperature, and degree of labeling. For thermally stable ketones the exchange of α-protons was achieved at 180°C within 40-200 min. Compared to reflux conditions, the microwave-assisted protocol led to a reduction of the required reaction time from 75-94 h to 40-200 min. The α-labeled deuterium ketones were reduced by biocatalytic hydrogen transfer to the corresponding enantiopure chiral alcohols and the deconvolution algorithm validated by regression analysis of a mixture of labeled and unlabeled ketones/alcohols.
- Gruber, Christian C.,Oberdorfer, Gustav,Voss, Constance V.,Kremsner, Jennifer M.,Kappe, C. Oliver,Kroutil, Wolfgang
-
p. 5778 - 5783
(2008/02/10)
-
- Lipase/aluminum-catalyzed dynamic kinetic resolution of secondary alcohols
-
(Chemical Equation Presented) Racemization wanted: The dynamic kinetic resolution of secondary alcohols can be achieved by a simple and readily available catalyst system. Substrate racemization is effected at room temperature by a combination of (racemic) 1,1′-bi-2-naphthol (binol) or 2,2′-biphenol with AIMe3, and a lipase performs enantiospecific acylation (see scheme).
- Berkessel, Albrecht,Sebastian-Ibarz, M. Luisa,Mueller, Thomas N.
-
p. 6567 - 6570
(2007/10/03)
-
- Catalysts for asymmetric addition of organozinc reagents to aldehydes and method for preparation
-
Novel chiral aminoalcohol catalysts and methods for their preparation are provided. The first catalyst is prepared via selective hydrogenation of one of two benzene rings in a precursor. The aminoalcohol promotes the asymmetric addition of organozinc reagents to aldehydes to afford optically active alcohols or their esters. The second catalyst is prepared by selective dialkylation of 3-exo-aminoisoborneol with a 2-haloethyl ether. The aminoalcohol promotes the addition of organozinc reagents to aliphatic aldehydes containing a β-branch with greatly enhanced enantioselectivity relative to DAIB.
- -
-
-
- Bromide ions and methyltrioxorhenium as cocatalysts for hydrogen peroxide oxidations and brominations
-
Oxidation of alcohols by hydrogen peroxide is negligible; even when catalyzed by methyltrioxorhenium (MTO), the process requires a long reaction time. The addition of a catalytic quantity of bromide ions, as HBr or NaBr, greatly enhances the rate. Some of the reactions were carried out on a larger scale in glacial acetic acid, and others at kinetic concentrations. The data establish that Br2 is the active oxidizing agent in the system, because the catalytic rates under suitable circumstances match those for the independently measured Br2 reaction with alcohol (benzyl alcohol, in particular). At much lower levels of MTO, however, Br2 formation plays a role in the kinetics. Certain other reluctant transformations are conveniently carried out with the MTO/H2O2/Br- combination: aldehydes to methyl esters; 1,3-dioxolanes to glycol monoesters; and ethers (with cleavage) to ketones (mostly), but in fair yield only. When Br- was used in stoichiometric quantity, certain bromination reactions occur. Thus, phenyl acetylenes (PhC2R, R = H, Me, Ph) are converted to dibromoalkenes that are entirely or largely formed as the trans isomer, and phenols are brominated. The latter reaction shows the preference para > ortho > meta. Kinetic studies of benzyl alcohol oxidation with MTO/H2O2Br- were carried out in aqueous solution. With sufficient (normal) levels of MTO, the rate constant for the formation of benzaldehyde agreed with the independently determined value for Br2 + PhCH2OH, k = 4.3 x 10-3 L mol-1 s-1 at 25.0 °C; for sec- phenethyl alcohol, k = (9.8 ± 0.4) x 10-3 L mol-1 s-1. Bromine is formed from the known oxidation of Br- with H2O2, catalyzed by MTO. This reaction results in BrO-/HBOr, which is then rapidly converted to Br2. However, with substantially lower concentrations of MTO, the buildup of benzaldehyde is ca. 4-fold slower, reflecting the diminished rate of Br- oxidation.
- Espenson,Zhu,Zauche
-
p. 1191 - 1196
(2007/10/03)
-
- Alkane reaction with a mixture of nitric acid and acetic anhydride
-
Alkanes C6-C10 at 15-20°C react with a mixture of concentrated HNO3 and acetic anhydride to afford nitrates of secondary alcohols in the yield up to 70%. Acetates of secondary alcohols, acetates and nitrates of β-nitroalcohols form in small quantity. Isooctane reacts under milder conditions to give a nitrate of β-nitroalcohol.
- Svetlakov
-
p. 1081 - 1084
(2007/10/03)
-
- The chemistry of acylals. Part I. The reactivity of acylals towards Grignard and organolithium reagents
-
Aldehyde acylals have been prepared and reacted with Grignard and alkyllithium reagents. Acylals from formaldehyde furnished complex reaction mixtures when reacted with both reagents. Acylals of other aldehydes gave reaction mixtures that consisted mainly of an ester, generated by replacing one of the carboxy groups with the organic part of the organometallic reagent, and regenerated aldehyde. The esters were formed in the highest yields. Yields above 90% were experienced when the acylals were reacted with Grignard reagents under Barbier conditions.
- Sydnes, Leiv K.,Sandberg, Marcel
-
p. 12679 - 12690
(2007/10/03)
-
- 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
-
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.
-
p. 5577 - 5585
(2007/10/02)
-
- SELECTIVE OXIDATION OF n-ALKANES WITH LEAD TETRAACETATE
-
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.
-
p. 3891 - 3892
(2007/10/02)
-
- Classical Carbonium Ions. Part 12. The Deamination of 1- and 4-Amino-n-octane
-
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.
-
p. 597 - 604
(2007/10/02)
-
- Solvolysis of N-n-Alkylacridiniums in Phenol and Carboxylic Acids. Primary Carbonium Ions as Possible Intermediates
-
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.
-
p. 3511 - 3517
(2007/10/02)
-
- Chemical Conversions using Sheet Silicates: Facile Ester Synthesis by Direct Addition of Acids to Alkenes
-
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.
-
-