- Propane activation by palladium complexes with chelating bis(NHC) ligands and aerobic cooxidation
-
The development of efficient aerobic oxidation methods remains a challenge for the selective functionalization of C-H bonds in alkanes. Herein we report the development of a C-H functionalization procedure for propane by using a palladium catalyst with chelating bis(N-heterocyclic carbene) ligands in trifluoroacetic acid together with a vanadium co-catalyst. Halides play a decisive role in the reaction. The experimental results are presented together with supporting kinetic data and an isotope effect. The reaction can be run with dioxygen as the oxidant if vanadium salts and halides are present in the reaction mixture. Experimental as well as computational results favor a mechanism involving C-H activation by palladium(II), followed by oxidation to palladium(IV) by bromine. Reoxidation by dioxygen: The combination of C-H activation by a homogeneous catalytic palladium complex with a vanadiumoxo co-catalyst allows the selective aerobic oxidation of propane with dioxygen (see scheme). Copyright
- Munz, Dominik,Strassner, Thomas
-
-
Read Online
- On the mechanism of the palladium bis(NHC) complex catalyzed CH functionalization of propane: Experiment and DFT calculations
-
We report a detailed mechanistic study on the CH functionalization of alkanes by palladium complexes with chelating bis(N -heterocyclic carbene) (NHC) complexes. The experimental results are complemented by detailed DFT calculations, which allow us to rationalize the regioselectivity and the catalytic activity. The study includes a library of catalysts with different electronic and steric properties, kinetic data, and isotope effects. The combined experimental and computational results favor a mechanism involving organometallic palladium(IV) intermediates. Furthermore, it is shown that at high halide loadings a different mechanism is operative.
- Munz, Dominik,Strassner, Thomas
-
-
Read Online
- Aerobic Partial Oxidation of Alkanes Using Photodriven Iron Catalysis
-
Photodriven oxidations of alkanes in trifluoroacetic acid using commercial and synthesized Fe(III) sources as catalyst precursors and dioxygen (O2) as the terminal oxidant are reported. The reactions produce alkyl esters and occur at ambient temperature in the presence of air, and catalytic turnover is observed for the oxidation of methane in a pure O2 atmosphere. Under optimized conditions, approximately 17% conversion of methane to methyl trifluoroacetate at more than 50% selectivity is observed. It is demonstrated that methyl trifluoroacetate is stable under catalytic conditions, and thus overoxidized products are not formed through secondary oxidation of methyl trifluoroacetate.
- Cao, Yuan,Coutard, Nathan,Goldberg, Jonathan M.,Groves, John T.,Gunnoe, T. Brent,Jeffrey, Philip D.,Jia, Xiaofan,Valle, Henry U.
-
supporting information
(2022/01/11)
-
- Electrocatalytic Oxyesterification of Hydrocarbons by Tetravalent Lead
-
The selective catalytic oxidative monofunctionalization of gaseous alkanes found in natural gas and commodity chemicals such as benzene and cyclohexane is an important objective in the field of carbon-hydrogen bond activation. Past research has demonstrated the possibility of stoichiometric oxyesterification of such substrates using lead(IV) trifluoroacetate (PbIV(TFA)4) as oxidant, which is driven by the high 2-electron redox potential of lead(IV). However, this redox potential then precludes reoxidation of lead(II) by a convenient oxidant such as O2, nullifying an effective catalytic cycle. In order to utilize renewable energy resources as alternatives to high-temperature thermocatalysis, we demonstrate the room-temperature electrocatalytic oxyesterification of alkanes and benzene with PbIV(TFA)4 as catalysts. At 1.67 V versus SHE, alkanes and benzene yielded the corresponding trifluoroacetate esters at room temperature; typically, good yields and high faradaic efficiencies were observed. High intrinsic turnover frequencies were obtained, for example, of >1000 min-1 for the oxyesterification of ethane at 30 bar. An analysis of the possible mechanistic pathways based on previously investigated stochiometric reactions, cyclic voltammetry measurements, kinetic isotope effects, and model compounds led to the conclusion that catalysis involves lead-mediated proton-coupled electron transfer of alkanes at and to the anode, followed by reductive elimination through an SN2 reaction to yield the alkyl-TFA products. Similarly, lead-mediated electron transfer from benzene at and to the anode leads to phenyl-TFA. Cyclic voltammetry also shows the viability of in situ reoxidation of Pb(II) species. The synthesis results obtained as well as the mechanistic insight are important advances towards the realization of selective alkane and arene oxidation reactions.
- Haviv, Eynat,Herman, Adi,Khenkin, Alexander M.,Neumann, Ronny
-
p. 10494 - 10501
(2021/08/31)
-
- SN2 and E2 Branching of Main-Group-Metal Alkyl Intermediates in Alkane CH Oxidation: Mechanistic Investigation Using Isotopically Labeled Main-Group-Metal Alkyls
-
The main-group-metal alkyl compounds trialkyltin and dialkylthallium have been utilized to investigate the mechanism of functionalization of monoalkyl thallium and lead species, proposed to be putative intermediates in alkane (RH) functionalization, formed via CH activation of alkanes (methane, ethane, and propane) using electrophilic Tl(III) and Pb(IV) in trifluoroacetic acid (HTFA). Two different organometallic transalkylation methods were used to generate the putative intermediates in situ. The results herein strongly support a mechanism of CH activation to generate a main-group-metal alkyl intermediate which undergoes reductive functionalization to generate the products, R-TFA, and the reduced metal salt. In the case of ethane there are two products, ethyl trifluoroacetate (EtTFA) and 1,2-bis(trifluoroacetoxy)ethylene glycol (EG(TFA)2), observed in the reaction mixture that are proposed to form in parallel from a common intermediate, EtTl(TFA)2. The alkyl transfer studies herein strongly support the simultaneous formation of both species from this intermediate. Furthermore, studies conducted using regiospecifically isotopically labeled diethylthallium salts strongly support an SN2 functionalization from EtTl(TFA)2 to give EtTFA (and reduced Tl(TFA)) and an E2 elimination (also from EtTl(TFA)2) to generate ethylene, which instantly reacts with an additional 1 equiv of Tl(TFA)3 to generate EG(TFA)2.
- Ess, Daniel H.,Gunsalus, Niles Jensen,Hashiguchi, Brian G.,Konnick, Michael M.,Koppaka, Anjaneyulu,Park, Sae Hume,Periana, Roy A.
-
p. 1907 - 1916
(2020/06/08)
-
- Selective Photo-Oxygenation of Light Alkanes Using Iodine Oxides and Chloride
-
Partial oxidation of light alkanes to generate alkyl esters has been achieved under photochemical conditions using mixtures of iodine oxides and chloride salts in trifluoroacetic acid (HTFA). The reactions are catalytic in chloride and are successful using compact fluorescent light, but higher yields are obtained using a mercury lamp. In this photo-initiated oxyesterification process, the robust alkyl ester products are resistant to over-oxidation, and under optimized conditions yields for alkyl ester production of ~50 % based on methane, ~60 % based on ethane (with a total functionalized yield of EtX (X=TFA or Cl) of 80 %) and ~30 % based on propane have been demonstrated. The reaction also proceeds in aqueous HTFA and dichloroacetic acid with lower yields. Mechanistic studies indicate that the process likely operates by a chlorine hydrogen atom abstraction pathway wherein alkyl radicals are generated, trapped by iodine, and converted to alkyl trifluoroacetates in situ.
- Liebov, Nichole S.,Goldberg, Jonathan M.,Boaz, Nicholas C.,Coutard, Nathan,Kalman, Steven E.,Zhuang, Thompson,Groves, John T.,Gunnoe, T. Brent
-
p. 5045 - 5054
(2019/10/28)
-
- Ozone oxidation process of preparing a halogenated acetic acid and esters thereof (by machine translation)
-
The invention belongs to the field of chemical synthesis, in particular to a halogenated acetic acid or a halogenated acetic acid ester compound preparation method; halogenated ethane (type I) by ozone oxidation after the reaction, the reaction with water or alcohol to obtain a halogenated acetic acid or halogenated acetate (type II). (by machine translation)
- -
-
Paragraph 0093-0095
(2017/06/29)
-
- A process for the preparation of suitable ester
-
The invention relates to a preparation method of trifluoroacetate. The preparation method is characterized by comprising the following steps: (1) after uniformly mixing potassium fluoride with alcohol, adding trifluoroacetyl fluoride for reaction; (2) filtering a reaction mixture to remove potassium fluoride-potassium bifluoride solids; and (3) rectifying to obtain the trifluoroacetate. The method provided by the invention simplifies the preparation process of the trifluoroacetate, no waste acids and catalysts are generated in the reaction process, and by-products of reaction can be recycled, so that the environmental protection problem in synthesis of the trifluoroacetate is solved.
- -
-
Paragraph 0021-0022
(2020/02/08)
-
- Transfer hydrogenation of ketones, nitriles, and esters catalyzed by a half-sandwich complex of ruthenium
-
Half-sandwich complexes [Cp(PiPr3)Ru(CH3CN)2]PF6 (1; Cp = cyclopentadienyl) and [Cp(phen)Ru(CH3CN)]PF6 (2; Cp = pentamethylcyclopentadienyl, phen = phenanthroline) catalyse the transfer hydrogenation of ketones to alcohols, aldimines to amines, and nitriles to imines under mild conditions. In the latter process, the imine products come from the coupling of the amines formed initially with acetone derived from the reducing solvent (isopropanol). Among functionally substituted nitriles, the aldo and keto groups are reduced concomitantly with the cyano group, whereas ester and amido groups are tolerated. Amides and alkyl esters are not reduced under these conditions even upon heating to 70°C. However, phenylbenzoates and trifluoroacetates are reduced to alcohols. Kinetic studies on the reduction of acetophenone in isopropanol established that the reaction is first order in both the substrate and the alcohol. Stoichiometric mechanistic studies showed the formation of a hydride species. A hydride mechanism was proposed to account for these observations.
- Lee, Sun-Hwa,Nikonov, Georgii I.
-
p. 107 - 113
(2015/01/30)
-
- Partial oxidation of light alkanes by periodate and chloride salts
-
The efficient and selective partial oxidation of light alkanes using potassium periodate and potassium chloride is reported. Yields of methane functionalization in trifluoroacetic acid reach >40% with high selectivity for methyl trifluoroacetate. Periodat
- Kalman, Steven E.,Munz, Dominik,Fortman, George C.,Boaz, Nicholas C.,Groves, John T.,Gunnoe, T. Brent
-
supporting information
p. 5294 - 5298
(2015/03/30)
-
- Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex
-
Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism. Gas up: Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate (TFA) esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic solvent (HTFA). The reaction is highly selective, and for ethane, greater than 0.5 M Et=TFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.
- Konnick, Michael M.,Hashiguchi, Brian G.,Devarajan, Deepa,Boaz, Nicholas C.,Gunnoe, T. Brent,Groves, John T.,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
-
supporting information
p. 10490 - 10494
(2016/02/18)
-
- OXIDATION OF ALKANES TO ALCOHOLS
-
The invention provides processes and materials for the efficient and cost- effective functionalization of alkanes, such as methane from natural gas, to provide esters, alcohols, and other compounds. The method can be used to produce liquid fuels such as methanol from a natural gas methane-containing feedstock. The soft oxidizing electrophile, a compound of a main group, post- transitional element such as Tl, Pb, Bi, and I, that reacts to activate the alkane C- H bond can be regenerated using inexpensive regenerants such as hydrogen peroxide, oxygen, halogens, nitric acid, etc. Main group compounds useful for carrying out this reaction includes haloacetate salts of metals having a pair of available oxidation states, such as Tl, Pb, Bi, and I. The inventors herein believe that a unifying feature of many of the MXn electrophiles useful in carrying out this reaction, such as Tl, Pb, and Bi species, is their isoelectronic configuration in the alkane -reactive oxidation state; the electrons having the configuation [Xe]4f145d10, with an empty 6s orbital. However, the iodine reagents have a different electronic configuration.
- -
-
Page/Page column 12; 13; 14
(2014/09/03)
-
- Selective monooxidation of light alkanes using chloride and iodate
-
We describe an efficient system for the direct partial oxidation of methane, ethane, and propane using iodate salts with catalytic amounts of chloride in protic solvents. In HTFA (TFA = trifluoroacetate), >20% methane conversion with >85% selectivity for MeTFA have been achieved. The addition of substoichiometric amounts of chloride is essential, and for methane the conversion increases from 20%. The reaction also proceeds in aqueous HTFA as well as acetic acid to afford methyl acetate. 13C labeling experiments showed that less than 2% of methane is overoxidized to 13CO2 at 15% conversion of 13CH4. The system is selective for higher alkanes: 30% ethane conversion with 98% selectivity for EtTFA and 19% propane conversion that is selective for mixtures of the mono- and difunctionalized TFA esters. Studies of methane conversion using a series of iodine-based reagents [I2, ICl, ICl3, I(TFA)3, I2O4, I 2O5, (IO2)2S2O 7, (IO)2SO4] indicated that the chloride enhancement is not limited to iodate.
- Fortman, George C.,Boaz, Nicholas C.,Munz, Dominik,Konnick, Michael M.,Periana, Roy A.,Groves, John T.,Brent Gunnoe
-
p. 8393 - 8401
(2014/06/24)
-
- Main-group compounds selectively oxidize mixtures of methane, ethane, and propane to alcohol esters
-
Much of the recent research on homogeneous alkane oxidation has focused on the use of transition metal catalysts. Here, we report that the electrophilic main-group cations thallium(III) and lead(IV) stoichiometrically oxidize methane, ethane, and propane, separately or as a one-pot mixture, to corresponding alcohol esters in trifluoroacetic acid solvent. Esters of methanol, ethanol, ethylene glycol, isopropanol, and propylene glycol are obtained with greater than 95% selectivity in concentrations up to 1.48 molar within 3 hours at 180°C. Experiment and theory support a mechanism involving electrophilic carbon-hydrogen bond activation to generate metal alkyl intermediates. We posit that the comparatively high reactivity of these d 10 main-group cations relative to transition metals stems from facile alkane coordination at vacant sites, enabled by the overall lability of the ligand sphere and the absence of ligand field stabilization energies in systems with filled d-orbitals.
- Hashiguchi, Brian G.,Konnick, Michael M.,Bischof, Steven M.,Gustafson, Samantha J.,Devarajan, Deepa,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
-
p. 1232 - 1237
(2014/04/03)
-
- Ortho-Phenylene bridged palladium bis-N-heterocyclic carbene complexes: Synthesis, structure and catalysis
-
A series of ortho-phenylene bridged palladium bis-NHC complexes has been synthesized. Complexes with imidazolium and benzimidazolium derived NHCs and methyl-/benzyl-wingtips are reported. Bis(benz)imidazoles with a doubly brominated ortho-phenylene bridge could be obtained by an electrophilic substitution reaction. The structure of the complexes could be confirmed by three solid-state structures. All catalysts have been tested in the catalytic functionalisation of propane. The catalytic activity is highly dependent on the ligand, whereas ligand effects on the regioselectivity (n/iso) are much smaller.
- Munz, Dominik,Poethig, Alexander,Tronnier, Alexander,Strassner, Thomas
-
p. 7297 - 7304
(2013/07/11)
-
- Catalytic oxidation of hydrocarbons of natural and oil gas
-
Alkane oxidation by O2 and CO in the presence of Rh-, Pd-, and Pt-containing catalytic systems leads to the product of C-H bond oxidation and the products of C-C bond oxidative destruction. A deuterated methyl group in acetic acid is observed in the oxidation of n-propane in a deuterium-donor medium. The possible mechanisms of alkane C2-C4 conversion are proposed.
- Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman
-
experimental part
p. 332 - 337
(2011/04/26)
-
- Homogeneous catalytic oxidation of light alkanes: C-C bond cleavage under mild conditions
-
The combined oxidation of CO and C2-C4 alkanes (associated petroleum gas and natural gas components) under the action of oxygen in trifluoroacetic acid solutions in the presence of rhodium and copper chlorides was accompanied by the oxidative degradation of C-C bonds in a hydrocarbon chain with the formation of carbonyl compounds, alcohols, and esters. For butane and isobutane, the reaction path with C-C bond cleavage was predominant. The buildup curves of isobutane oxidation products (both with the retention and with the degradation of the chain) were S-shaped and characterized by the same induction period; they did not pass through a maximum. A reaction scheme was proposed to reflect the main special features of the mechanism of transformations occurring in the O2/Rh/Cu/Cl- oxidation system.
- Chepaikin,Bezruchenko,Menchikova,Moiseeva,Gekhman
-
experimental part
p. 666 - 671
(2011/02/16)
-
- Biomimetic trifunctional organocatalyst showing a great acceleration for the transesterification between vinyl ester and alcohol
-
Trifunctional organocatalysts 1a and 1b mimicking the active site of serine hydrolases showed high catalytic activity with up to a 3 700 000-fold acceleration for the acyl-transfer reactions from vinyl trifluoroacetate to alcohol. The Royal Society of Chemistry.
- Ema, Tadashi,Tanida, Daisuke,Matsukawa, Tatsuya,Sakai, Takashi
-
p. 957 - 959
(2008/09/21)
-
- Highly efficient direct carboxylation of propane into butyric acids catalyzed by vanadium complexes
-
A direct and highly efficient carboxylation of propane by carbon monoxide into butyric acids (mainly isobutyric and, in a smaller amount, n-butyric), in the presence of potassium peroxodisulphate (K2S2O 8) and in trifluoroacetic acid solution, has been achieved by using a vanadium catalytic system based on Ca[V{ON(CH(CH3)COO) 2}2] (synthetic amavadine), its model compounds Ca[V{ON-(CH2COO)2}2] or [VO(N(CH 2CH2O)3}] - other simpler vanadium compounds, such as [VO(acac)2] or VOSO4, are less active. Overall yields (based on pro- ane) of carboxylic acids up to 70% and TON values up to 18.4 × 103 have been reached. The effects of various factors such as the propane and carbon monoxide pressures, temperature, time, catalyst amount and radical traps have been investigated, the reactions are shown to proceed via both C- and O-centred radicals, with K2S 2O8 playing the role of an oxidant via a free radical mechanism.
- Kirillova, Marina V.,Da Silva, Jose A. L.,Da Silva, Joao J. R. Frausto,Palavra, Antonio F.,Pombeiro, Armando J. L.
-
p. 1765 - 1774
(2008/02/11)
-
- Heterolytic decarboxylation involving acyltrifluoroacetyl peroxide intermediates
-
Selective carboxylic acid decarboxylation was elaborated. Generation of acyltrifluoroacetyl peroxides from carboxylic peracids and trifluoroacetyl anhydride (Method A), as well as from trifluoroperacetic acid and acyltrifluoroacetyl anhydride (Method B), leads to simultaneous peroxide decomposition into the corresponding alkyltrifluoroacetates. DFT computations, as well as experimental data, support an acid-catalyzed heterolytic mechanism for acyltrifluoroacetyl peroxide decomposition.
- Krasutsky, Pavel A.,Kolomitsyn, Igor V.,Botov, Evgenij M.,Carlson, Robert M.,Semenova, Irina G.,Fokin, Andrey A.
-
p. 8687 - 8691
(2007/10/03)
-
- CaCl2-catalyzed functionalization of saturated hydrocarbons with CO to carboxylic acids and esters
-
The functionalization of saturated hydrocarbons, e.g., ethane, cyclopentane, propane, cyclohexane, cycloheptane, and cyclooctane, with CO by CaCl2 catalyst in the presence of CF3COOH and K2S2O8 was studied. Carboxylic acids and alkyl trifluoroacetates were formed as dominant products and by-products, respectively. In the reaction of propane, isobutyric acid was the main product, and isopropyl trifluoroacetate and n-butyric acid were the by-products in 95% total yield based on propane when 1 bar of propane reacted with 30 bar of CO in the presence of CaCl2, K2S2O8, and CF3COOH at 80°C for 24 hr. Ethane gave ~ 88% total yield, but 23% acetic acid was formed by the oxidation of ethane. Cyclopentane, cycloheptane, and cyclohexane underwent reaction, giving ~ 44, 12, and 33% yields, respectively. However, cyclooctane did not undergo this reaction.
- Asadullah, Mohammad,Kitamura, Tsugio,Fujiwara, Yuzo
-
p. 180 - 186
(2007/10/03)
-
- Synthesis of carboxylic acids through the formation of C-C bond between saturated hydrocarbons and CO in the presence of Mg/K2S2O8/TFA system
-
Magnesium powder (Mg) promoted the carboxylation reaction of saturated hydrocarbons with carbon monoxide (CO) in the presence of potassium peroxodisulfate (K2S2O8) in trifluoroacetic acid (TFA) to yield the corresponding carboxylic acids and alkyl trifluoroacetates. About 80% conversion of cyclohexane was achieved when 5 mmol of magnesium, 5 mmol of potassium peroxodisulfate, 3 mL of TFA, 1 mmol of cyclohexane, 50 atm of CO were used at 80 °C for 30 h.
- Asadullah, Mohammad,Kitamura, Tsugio,Fujiwara, Yuzo
-
p. 449 - 450
(2007/10/03)
-
- Cobalt catalyzed carboxylation reaction of saturated hydrocarbons with CO in the presence of K2S2O8 and TFA under mild conditions
-
Cobalt(II) acetate (Co(OAc)2) has been found to be an efficient catalyst for the carboxylation reaction of saturated hydrocarbons with CO to yield the corresponding carboxylic acids in high yields in the presence of K2S2O8 and CF3COOH. About 89.5% conversion of propane is obtained in this reaction. The activation parameters of the reaction of propane have been determined by Arrhenius and Eyring plots.
- Asadullah, Mohammad,Taniguchi, Yuki,Kitamura, Tsugio,Fujiwara, Yuzo
-
p. 8867 - 8871
(2007/10/03)
-
- High-yield, radical-initiated oxidative functionalization of ethane by perfluorocarboxylic acid anhydrides. Role of metal ions in catalytic alkane oxidations in the presence of perfluorocarboxylic acid anhydrides
-
Hydrogen peroxide and a trace of either ethene or propene initiated the conversion of ethane to propionic acid and its mixed anhydride (CH3CH2CO2H + CH3CH2COOCOCF3) and trifluoromethyl ethyl ketone, CH3CH2COCF3, by trifluoroacetic anhydride at 80 °C. For a fixed amount of H2O2, the amount of products formed increased with increasing amount of trifluoroacetic anhydride employed and was always higher than the amount of H2O2 added. These products were also obtained when H2O2 was replaced by other radical initiators: m-chloroperbenzoic acid, azobisisobutyronitrile, and PbEt4. With PbEt4, ethene or propene was not required for product formation and close to 500 equiv of products was formed for every equivalent of PbEt4 employed! Longer chain perfluorocarboxylic acid anhydrides reacted analogously; however, as the R(f) group increased in length, a corresponding increase in mixed anhydride to ketone selectivity was observed. Methane gave very little product under the reaction conditions whereas propane underwent simple stoichiometric oxidation to 2-propanol and acetone by H2O2. The addition of (CF3CO2)2Pd to the ethane reaction resulted in simple oxidation to ethanol and acetaldehyde in amounts lower than that corresponding to the H2O2 present. In complete contrast to the ethane reaction, the yield of products from methane increased significantly (although less than the H2O2 added) upon the addition of (CF3CO2)2Pd, with methanol being the principal product.
- Hogan, Terrence,Sen, Ayusman
-
p. 2642 - 2646
(2007/10/03)
-
- A novel aminomethylation reaction of gaseous alkanes with tert-methylamine N-oxides via C-H bond activation by copper(II) salts
-
The Cu(OAc)2/CF3COOH (TFA) system catalyzes the aminomethylation of gaseous alkanes such as propane and ethane with trimethylamine N-oxide to give N,N-dimethylisobutylamine (1) and N,N-dimethylpropylamine (7), respectively.The corresponding trifluoroacetates are also formed as by-products from the reactions of methane and propane. Keywords: Copper acetate; Aminomethylation; Amine N-oxide; C-H bond activation; C-C bond formation; Alkane
- Taniguchi, Yuki,Horie, Shiro,Takaki, Ken,Fujiwara, Yuzo
-
p. 137 - 142
(2007/10/03)
-
- The Chemistry of Pentavalent Organobismuth Reagents. Part 8. Phenylation and Oxidation of Alcohols by Tetraphenylbismuth Esters
-
Tetraphenylbismuth trifluoroacetate under neutral or slightly acidic conditions O-phenylates primary alcohols in reasonable (65-75percent) yield, but gives only moderate yields with secondary alcohols and no O-phenylation with tertiary alcohols.An SN2 type mechanism is proposed with attack of oxygen on aryl carbon.In contrast, the reaction of Bi(V) reagents with alcohols under basic conditions gives, exclusively, oxidation, often with benzene as a leaving group.The presence of a Bi(V) intermediate with a bismuth-oxygen bond has been proved in several different ways using n.m.r. spectroscopy.Thus the reactions of alcohols with Bi(V) reagents parallel the corresponding reactions with phenols.
- Barton, Derek H. R.,Finet, Jean-Pierre,Motherwell, William B.,Pichon, Clotilde
-
p. 251 - 260
(2007/10/02)
-
- Oxidative Displacement of Halogen from Alkyl Halides by Phenyliodine(III) Dicarboxylates
-
The reaction of alkyl iodides with aryliodine(III) dicarboxylates affords as the main product the ester derived through substitution of iodine by an acyloxy group; in some cases α-iodoalkyl esters are also formed along with other minor products.Certain reactive bromides and chlorides react along similar lines.The mechanism of these reactions is briefly discussed.
- Gallos, John,Varvoglis, Anastasios
-
p. 1999 - 2002
(2007/10/02)
-
- Thiono-Thiolo Rearrangement and Solvolysis of the Secondary Alkyl Phosphorothionates. 3
-
The protic acid catalyzed thiono-thiolo (O->S) migration of secondary alkyl groups in trialkyl phosphorothionates 1 occurs in a complex fashion.Analysis of product distribution, stereochemistry, and deuterium incorporation experiments supports an ion-pair-type intermediate, 7, as being responsible for the entire process.Nucleophilic attack by 1 on 7 initiates the chain reaction leading to 2.In trifluoroacetic acid medium inversion of configuration (96percent) at the carbon atom of the migration sec-butyl group was observed.A high concentration of 1 promotes this mode of rearrangement.However, the overall stereospecificity of sec-butyl migration is much lower due to an elimination process leading to the dialkyl hydrogen phosphorothioate 3 and an intermediate olefin which after protonation in acidic medium returns to the ion pair 7.The latter process is responsible for the nonstereospecific formation of part of the rearrangement product 2 and contributes to the lower stereospecificity of the trifluoroacetolysis process.The role of reaction-medium acidity is discussed.
- Bruzik, K.,Stec, W. J.
-
p. 1618 - 1624
(2007/10/02)
-