- Ferric(III) Chloride Catalyzed Halogenation Reaction of Alcohols and Carboxylic Acids Using α,α-Dichlorodiphenylmethane
-
A new method for chlorination of alcohols and carboxylic acids, using α,α-dichlorodiphenylmethane as the chlorinating agent and FeCl3 as the catalyst, was developed. The method enables conversions of various alcohols and carboxylic acids to their corresponding alkyl and acyl chlorides in high yields under mild conditions. Particulary interesting is the observation that the respective alkyl bromides and iodides can be generated from alcohols when either LiBr or LiI are present in the reaction mixtures.
- Lee, Chang-Hee,Lee, Soo-Min,Min, Byul-Hana,Kim, Dong-Su,Jun, Chul-Ho
-
supporting information
p. 2468 - 2471
(2018/04/25)
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- Metal-free regioselective hydrochlorination of unactivated alkenes via a combined acid catalytic system
-
A combined acid HCl/DMPU-acetic acid catalytic system was used in the hydrochlorination of a wide range of unactivated alkenes. This hydrochlorination strategy is remarkably greener than previous reported methods in terms of high atom efficiency, no toxic waste generated and metal-free process. The higher efficiency, compared with other commercially available HCl reagents, was augmented by the good regioselectivity and functionality tolerance found. A stepwise mechanism for this hydrochlorination process was proposed based on kinetic studies.
- Liang, Shengzong,Hammond, Gerald B.,Xu, Bo
-
supporting information
p. 680 - 684
(2018/02/14)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
-
α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
-
p. 420 - 430
(2015/12/31)
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- METHOD OF CONVERTING ALCOHOL TO HALIDE
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The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
- -
-
Page/Page column 51; 144
(2017/01/02)
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- Method of manufacturing imidoyl diazidosulfochloride compd. various compd. and manufacturing method of using the same
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PROBLEM TO BE SOLVED: To provide a new production method for synthesizing an imidoyl chloride compound dispensing with chlorination agents having poor handleability, to provide a method for producing various compounds in high yield and purity by using the imidoyl chloride compound, and to provide a method for isolating the imidoyl chloride compound in high efficiency and purity from a mixture of the imidoyl chloride compound and a phthalic anhydride compound.SOLUTION: The method for producing the imidoyl chloride compound comprises reaction of a specific amide compound with a specific phthaloyl chloride compound to produce a specific imidoyl chloride compound.
- -
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Paragraph 0072
(2016/12/16)
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- Aromatic cation activation: Nucleophilic substitution of alcohols and carboxylic acids
-
A new method for the nucleophilic substitution of alcohols and carboxylic acids using aromatic tropylium cation activation has been developed. This article reports the use of chloro tropylium chloride for the rapid generation of alkyl halides and acyl chlorides under very mild reaction conditions. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical transformations.
- Nguyen, Thanh V.,Bekensir, Alp
-
supporting information
p. 1720 - 1723
(2014/04/17)
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- A user-friendly procedure for the preparation of secondary alkyl chlorides
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Secondary alkyl chlorides have been efficiently prepared from secondary alkyl sulfonates under mild and user-friendly conditions. The exchange reaction was generally performed by using benzyltributylammonium chloride in acetone (reflux, 30 min). Yields are excellent from functionalized, base-sensitive and hindered secondary alkyl sulfonates. Georg Thieme Verlag Stuttgart New York.
- Cahiez, Gerard,Lefevre, Nicolas,Poizat, Mael,Moyeux, Alban
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p. 231 - 236
(2013/02/23)
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- Stereoretentive chlorination of cyclic alcohols catalyzed by titanium(IV) tetrachloride: Evidence for a front side attack mechanism
-
A mild chlorination reaction of alcohols was developed using the classical thionyl chloride reagent but with added catalytic titanium(IV) chloride. These reactions proceeded rapidly to afford chlorination products in excellent yields and with preference for retention of configuration. Stereoselectivities were high for a variety of chiral cyclic secondary substrates including sterically hindered systems. Chlorosulfites were first generated in situ and converted to alkyl chlorides by the action of titanium tetrachloride which is thought to chelate the chlorosulfite leaving group and deliver the halogen nucleophile from the front face. To better understand this novel reaction pathway, an ab initio study was undertaken at the DFT level of theory using two different computational approaches. This computational evidence suggests that while the reaction proceeds through a carbocation intermediate, this charged species likely retains pyramidal geometry existing as a conformational isomer stabilized through hyperconjugation (hyperconjomers). These carbocations are then essentially "frozen" in their original configurations at the time of nucleophilic capture.
- Mondal, Deboprosad,Li, Song Ye,Bellucci, Luca,Laino, Teodoro,Tafi, Andrea,Guccione, Salvatore,Lepore, Salvatore D.
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p. 2118 - 2127
(2013/04/10)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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p. 2692 - 2698,7
(2012/12/12)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener. Georg Thieme Verlag KG Stuttgart · New York.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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p. 2692 - 2698
(2013/01/15)
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- Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
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Catalytic phosphorus(V)-mediated chlorination and bromination reactions of alcohols have been developed. The new reactions constitute a catalytic version of the classical Appel halogenation reaction. In these new reactions oxalyl chloride is used as a consumable stoichiometric reagent to generate the halophosphonium salts responsible for halogenation from catalytic phosphine oxides. Thus, phosphine oxides have been transformed from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilic substitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including density functional theory calculations on proposed intermediates of the catalytic cycle, are consistent with a catalytic cycle involving halo- and alkoxyphosphonium salts as intermediates.
- Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
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p. 6749 - 6767
(2011/10/02)
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- Iron(III)-catalyzed halogenations by substitution of sulfonate esters
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A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.
- Ortega, Nuria,Feher-Voelger, Andres,Brovetto, Margarita,Padron, Juan I.,Martin, Victor S.,Martin, Tomas
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experimental part
p. 963 - 972
(2011/06/20)
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- Phosphine oxide-catalysed chlorination reactions of alcohols under Appel conditions
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A phosphine oxide-catalysed chlorination reaction of primary and secondary alcohols has been developed. This process represents the first triphenylphosphine oxide-catalysed alcohol chlorination under Appel conditions. The Royal Society of Chemistry 2010.
- Denton, Ross M.,An, Jie,Adeniran, Beatrice
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supporting information; experimental part
p. 3025 - 3027
(2010/08/04)
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- Copper-catalyzed remote sp3 C-H chlorination of alkyl hydroperoxides
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A copper-catalyzed methodology to functionalize remote sp3 C-H bonds in alkyl hydroperoxides is presented. The atom-transfer chlorination utilizes simple ammonium chloride salts as the chlorine source, and the internal redox process requires no external redox reagents.
- Kundu, Rituparna,Ball, Zachary T.
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supporting information; experimental part
p. 2460 - 2463
(2010/07/05)
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- Rhenium complex as a useful catalyst for acylative cleavage of ethers
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It was found that a rhenium complex such as ReBr(CO)5 acts as an efficient catalyst for the acylative cleavage of the carbon-oxygen bond of ethers with acyl chloride, giving the corresponding esters in moderate to good yields.
- Umeda, Rui,Kaiba, Kenta,Tanaka, Toshimasa,Takahashi, Yuuki,Nishimura, Takashi,Nishiyama, Yutaka
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experimental part
p. 3089 - 3091
(2011/02/25)
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- 2,4,6-Trichloro-1,3,5-triazine/dimethylformamide as an efficient reagent for one-pot conversion of alcohols into N-alkylphthalimides
-
An efficient and mild method for the direct conversion of alcohols into N-alkylphthalimides using 2,4,6-trichloro-1,3,5-triazine and dimethylformamide was described. The reaction was preceded via (alcoxymethylene) dimethylammonium chloride intermediate an
- Mokhtari, Babak,Azadi, Roya,Azhdari, Aseieh
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experimental part
p. 171 - 174
(2010/11/18)
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- C-F bond-cleavage reactions of fluoroalkanes with magnesium reagents and without metal catalysts
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An unexpected C-F bond-cleavage reaction of unactlvated fluoroalkanes with the well-known Grlgnard reagents without using metal catalysts has been discovered. For example, a reaction between 1-fluorooctane and phenyl magnesium chloride gave n-octylbenzene In moderate yield. This coupling reaction via the activation of an unactlvated alkyl carbon-fluorine bond proceeds with phenylmagneslum chloride, whereas methylmagneslum chloride did not give the C-C cross-coupling product but rather a halogen exchange product.
- Matsubara, Kouki,Ishibashi, Tomoka,Koga, Yuji
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supporting information; experimental part
p. 1765 - 1768
(2009/09/06)
-
- Aromatic cation activation of alcohols: Conversion to alkyl chlorides using dichlorodiphenylcyclopropene
-
(Chemical Equation Presented) A novel paradigm for the activation of alcohols toward nucleophilic displacement via formation of cyclopropenium ethers is described. The conversion of a range of alcohol substrates to the corresponding alkyl chlorides occurs rapidly upon treatment with 3,3-dichloro-1,2-diphenylcyclopropene. 1H NMR data support the intermediacy of a cyclopropenium intermediate, and the reaction is demonstrated to proceed primarily via the SN2 mechanism for 1-phenylethanol. A total of 12 examples of substrate scope are provided.
- Kelly, Brendan D.,Lambert, Tristan H.
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supporting information; experimental part
p. 13930 - 13931
(2009/12/25)
-
- Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a gallium trichloride/tartrate system under neutral conditions
-
The reaction of secondary alcohols 1 with chlorodimethylsilane (HSiMe 2Cl) proceeded in the presence of a catalytic amount of GaCl 3/diethyl tartrate to give the corresponding organic chlorides 3. In the catalytic cycle, the reaction of diethyl tartrate 4a with HSiMe 2Cl 2 gives the chlorosilyl ether 5 with generation of H2. Alcohol-exchange between the formed chlorosilyl ether 5 and the substrate alcohol 1 affords alkoxychlorosilane 6, which reacts with catalytic GaCl 3 to give the chlorinated product 3. The moderate Lewis acidity of GaCl3 facilitates chlorination. Strong Lewis acids did not give product due to excessive affinity for the oxy-functionalities. Although tertiary alcohols were chlorinated by this system even in the absence of diethyl tartrate, certain alcohols that are less likely to give carbocationic species were effectively chlorinated using the GaCl3/diethyl tartrate system. The Royal Society of Chemistry.
- Yasuda, Makoto,Shimizu, Kenji,Yamasaki, Satoshi,Baba, Akio
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supporting information; experimental part
p. 2790 - 2795
(2009/02/03)
-
- Copper-catalyzed cross-coupling reaction of Grignard reagents with primary-alkyl halides: Remarkable effect of 1-phenylpropyne
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(Chemical Equation Presented) A general get-together: The Cu-catalyzed cross-coupling reaction of primary-alkyl halides with primary-, secondary-, and tertiary-alkyl and phenyl Grignard reagents proceeds efficiently in THF under reflux in the presence of 1-phenylpropyne (see scheme). The reaction is also applicable to alkyl mesylates (OMs) and tosylates (OTs). The reactivities of alkyl-X with a Grignard reagent increase in the order X = Cl F OMs OTs Br.
- Terao, Jun,Todo, Hirohisa,Begum, Shameem Ara,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 2086 - 2089
(2008/02/14)
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- 4-Aminophenyldiphenylphosphinite (APDPP), a new heterogeneous and acid scavenger phosphinite - Conversion of alcohols, trimethylsilyl, and tetrahydropyranyl ethers to alkyl halides with halogens or N-halosuccinimides
-
A new heterogeneous phosphinite, 4-aminophenyldiphenylphosphinite (APDPP), is prepared and used for the efficient conversion of alcohols, trimethylsilyl ethers, and tetrahydropyranyl ethers to their corresponding bromides, iodides, and chlorides in the presence of molecular halogens or N-halosuccinimides. The amino group in this phosphinite acts as an acid scavenger and removes the produced acid. A simple filtration easily removes the phosphinate by-product.
- Iranpoor, Nasser,Firouzabadi, Habib,Gholinejad, Mohammad
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p. 1006 - 1012
(2007/10/03)
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- An efficient method for chlorination of alcohols using PPh3/Cl3CCONH2
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A new and convenient method for the chlorination of alcohols utilizing PPh3/Cl3CCONH2 is addressed. Various alcohols could smoothly be converted into their corresponding alkyl chlorides in high yield under mild conditions with short reaction times. A mechanism is disclosed with the evidence of inversion of configuration of the analogous alkyl chloride derived from R-(-)-2-octanol.
- Pluempanupat, Wanchai,Chavasiri, Warinthorn
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p. 6821 - 6823
(2007/10/03)
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- The first example of tungsten-based carbene generation from WCl6 and atomic carbon and its use in olefin metathesis
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We describe a new route for the synthesis of tungsten-based carbenes generated by the reaction of WCl6 with atomic carbon in a carbon arc reactor. The active species formed under these conditions, [W] = CCl2, was found to catalyze olefin metathesis reactions of 1-octene, 2-octene and 1-heptene. We also evaluated the mechanism of formation of [W] = CCl2 within the WCl6/C system at the DFT level.
- Düz, Bülent,Yüksel, Dilek,Ece, Abdulilah,Sevin, Fatma
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p. 5167 - 5170
(2007/10/03)
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- Migratory aptitudes of simple alkyl groups in the anionotropic rearrangement of quaternary chloromethyl borate species: A combined experimental and theoretical investigation
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A combined experimental and theoretical investigation at the DFT and MP2 levels on the boronto-carbon 1,2-shift in "ate species", coming from the quaternization of boranes (A) and boronate (B), is reported. To discuss the different migratory aptitudes of various alkyl groups, we have examined the migration of primary (R = Me, Et), secondary (R = i-Pr), and tertiary (R = t-Bu) alkyl groups. The effect of the counterion Li+ and of the solvent (polarized continuous model (PCM) method) has been considered. The following results are relevant: (a) in all cases, the reaction proceeds via a concerted-type mechanism which explains the retention of configuration at the migrating group and the inversion at the migration terminus experimentally observed. (b) The trend of the migration barriers along the direction primary → secondary → tertiary alkyl group observed in "ate" species A is reversed in boronate species B, in agreement with the experimental evidences. (c) A simple theoretical model is proposed where the barrier trend is the result of a delicate interplay between two opposite factors: (1) a "steric effect", which favors the most sterically demanding migrating groups, and (2) a "charge effect" associated with the partial carbanionic nature of the migrating carbon atom and which favors the less substituted migrating carbons.
- Bottoni, Andrea,Lombardo, Marco,Neri, Andrea,Trombini, Claudio
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p. 3397 - 3405
(2007/10/03)
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- On the mechanism of arene-catalyzed lithiation: The role of arene dianions - Naphthalene radical anion versus naphthalene dianion
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The use of lithium and a catalytic amount of an arene is a well-established methodology for the preparation of organolithium reagents that manifest greater reactivity than the classical lithium-arene solutions. In order to rationalize this conduct, the participation of a highly reduced species, the dianion, is proposed and its reactivity explored. Studies of kinetics and of distribution of products reveal that the electron-transfer (ET) reactivity profile of dilithium naphthalenide in its reaction with organic chlorides excludes alternative mechanisms of halogen- lithium exchange. The process generates organolithium compounds. The dianion thus emerges along with the radical anion as a suitable candidate for catalytic cycles in certain processes. Endowed with a higher redox potential than its radical anion counterpart, dilithium naphthalene displays a broader spectrum of reactivity and so increases the range of substrates suitable for lithiation. The reaction of dilithium naphthalene with THF is one example of the divergent reactivity of the radical anion and the dianion, which has been the source of apparent misinterpretation of results in the past and has now been appropriately addressed.
- Yus, Miguel,Herrera, Raquel P.,Guijarro, Albert
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p. 2574 - 2584
(2007/10/03)
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- Conversion of alcohols into alkyl chlorides using trichloroisocyanuric acid with triphenylphosphine
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Trichloroisocyanuric acid with triphenylphosphine in anhydrous acetonitrile will convert alcohols into alkyl halides.
- Hiegel, Gene A.,Rubino, Mark
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p. 2691 - 2694
(2007/10/03)
-
- The fragmentation of alkoxychlorocarbenes in hydrocarbon solvents and in low temperature argon matrixes
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Alkoxychlorocarbenes (ROCCl, R = benzyl, cyclohexyl, and 1-octyl) were generated from the corresponding diazirines in acetonitrile, dichloroethane, benzene, cyclohexane, and pentane solutions at 25°C, and the fragmentations of these carbenes were studied. A prominent product was phenacyl chloride (PhCH2CoCl), a formal rearrangement product of the carbene. In polar solvents, the two fragmentation transition states for CH3OCCl and C2H5OCCl were stabilized to the point where cis-trans isomerization, loss of CO, and concerted loss of CO + Cl all have similar activation energies. In less polar solvents, such as dichloroethane, heterolytic cleavage was probably not competitive.
- Moss, Robert A.,Ma, Yan,Zheng, Fengmei,Sauers, Ronald R.,Bally, Thomas,Maltsev, Alexander,Toscano, John P.,Showalter, Brett M.
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p. 12280 - 12291
(2007/10/03)
-
- Reactivity of bismuth(III) halides towards alcohols. A tentative to mechanistic investigation
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The reactivity of bismuth(III) halides (BiX3; X=Cl, Br and I) towards a series of alcohols has been investigated. Three different reactions have been studied, namely: halogenation, dehydration and etherification. The behaviour of these bismuth derivatives was found to depend on the nature of the halide bonded to the bismuth atom. Their reactivities can be interpreted on the basis of the Hard and Soft Acids and Bases (HSAB) principle. A mechanism is proposed which involves the formation of a complex of the alcohol with Bi(III).
- Keramane, El Mehdi,Boyer, Bernard,Roque, Jean-Pierre
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p. 1909 - 1916
(2007/10/03)
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- A comparative kinetic study of nucleophilic substitution under PTC conditions in liquid-liquid and solid-liquid systems
-
The phenomenon of initial exponential burst (IB) on kinetic curves in the reaction with solid salts was observed in the study on the S(N)2 substitution reaction of 2-octylmesylate with potassium halides under phase- transfer catalysis (PTC) conditions in liquid-liquid (l/l) and solid-liquid (s/l) systems. The mechanistic scheme describing the IB phenomenon in application to s/l PTC has been developed from the analysis of IB kinetic model known in enzyme kinetics.
- Yufit, Sergei S.,Zinovyev, Sergei S.
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p. 6319 - 6328
(2007/10/03)
-
- Kinetics of SN2 substitution reactions under conditions of phase-transfer catalysis in the systems liquid-liquid and liquid-solid. Initial jump phenomenon in reactions with solid salt
-
Comparative study of the kinetics of substitution of the mesyl group in 1-methylheptyl methanesulfonate by halogen under conditions of phase-transfer catalysis in the two-phase systems liquid-liquid and liquid-solid has revealed an initial jump on the kinetic curves for the liquid-solid system. Such phenomenon has been known previously for some complex enzymatic reactions but unknown for phase-transfer reactions. Parameters of the initial jump on kinetic curves allow one to draw some conclusions on the reaction mechanism in the system liquid-solid. The effect of reactant concentrations and temperature on the initial jump parameters has been estimated for the first time.
- Yufit,Zinov'ev
-
p. 1222 - 1225
(2007/10/03)
-
- BiCl3 : An efficient agent for selective chlorination of alcohols or for halogen exchange reaction
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BiCl3 was found to be an effective reagent for an improved chlorination of alcohols and for a convenient halogen exchange reaction.
- Boyer, Bernard,Keramane, El Mehdi,Montero, Jean-Louis,Roque, Jean-Pierre
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p. 1737 - 1741
(2007/10/03)
-
- Catalytic decomposition of alkyl chloroformates by hexabutylguanidinium chloride
-
Hexabutylguanidinium chloride (0.5 molar %) efficiently decomposes alkyl chloroformates into chlorides, with low alkenes formation, via a S(N)2 mechanism as demonstrated from substituents effects and asymmetric chloride synthesis.
- Foulon, Frederique,Fixari, Bernard,Picq, Dominique,Le Perchec, Pierre
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p. 3387 - 3390
(2007/10/03)
-
- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
-
In the presence of catalytic amount of BiCl3, chloromethylsylanes can be used as chlorinating agents for alcohols, and as chloro-dealkylating agents for silyl ethers and carboxylic and sulfonic esters.The chlorination of (R)-(-)-octan-2-ol and the (R)-(-)-2-mesyloctane by TMSCl gave predominantly the (S)-(+)-2-chlorooctane with inversion of configuration at secondary carbon.According to the class of alcohol, the mechanism involves SN2, SN2' or SN1 processes.This new activation of the Si-Cl bond, probably trough a Si-Cl...BiCl3 interaction gives a hard-soft reagent that can generate a silicenium cation, was also observed with Me3SiBr, BiBr3 and Me3SiI, BiI3 systems.The reaction is also presented as a possible alcoholysis of chlorosilanes, which can lead to siloxanes in non-aqueous conditions. catalysis / halogenation / alcohol / ester / silyl ether / chlorosilane / chlorotrimethylsilane / bromotrimethylsilane / iodotrimethylsilane / siloxane / bismuth (III) halide
- Labrouillere, Mireille,Roux, Christophe Le,Oussaid, Abdelouahad,Gaspard-Iloughmane, Hafida,Dubac, Jacques
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p. 522 - 530
(2007/10/02)
-
- A Convenient Conversion of Primary Amines into the Corresponding Halides Radical Promoted Halodeamination via N-Substituted-N-Tosylhydrazines
-
Treatment of 1-substituted-1-tosylhydrazines with 2 equivalents of NCS or NBS in dry THF in presence of light affords the corresponding alkyl halides in good yields.This reaction presumably involves the initial formation of a stabilized hydrazyl radical which is halogenated in a radical chain process.Elimination of p-toluenesulfinic acid and extrusion of nitrogen leads to the corresponding alkyl halide.This route provides an improved method for halodeamination under neutral reaction conditions.
- Collazo, Luis R.,Guziec, Frank S.,Hu, Wei-Xiao Jr.,Pankayatselvan, Ratnadevi
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p. 7911 - 7914
(2007/10/02)
-
- Cobalt(II)-Porphyrin Catalyzed Selective Functionalization of Alkanes with sulfurylchloride: A Remarkable Substituent Effect
-
Cobalt(II)-porphyrin complex 1 and 2 catalyses the chlorination and sulfochlorination respectively of n-alkanes and cycloalkanes with sulfuryl chloride in benzene.The p-substituent of the benzene ring in the porphyrin complex 1 and 2 shows a remarkable chemoselectivity in these reactions.
- Khanna, Vibha,Tamilselvan, Pitchiah,Kalra, Swinder Jeet Singh,Iqbal, Javed
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p. 5935 - 5938
(2007/10/02)
-
- CHLORIERENDE METHYLIERUNG VON ALDEHYD- UND KETOGRUPPEN MIT NIOB-REAGENZIEN SOWIE AUFKLAERUNG DES MECHANISMUS
-
The reagents MeNbCl4 and Me2NbCl3, applied as isolated pure compounds, react with ketones in preparatively useful yields according to RR'CO -> RR'C(Cl)CH3.Whereas benzaldehyde reacts with MeNbCl4 analogously, the aliphatic aldehyde heptanal forms beside the expected product two cinechlorination products, indicating a mechanism via radicals.MeNbCl4 is highly aldehyde-vs.-ketone selective.Conversely, high ketone-vs.-aldehyde selectivity is achievable by application of MeNbCl4*PPh3 or NbCl5*PPh3 + 1.5 Me2Zn.
- Kauffmann, Thomas,Abel, Thomas,Neiteler, Gabriele,Schreer, Martin
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p. 503 - 506
(2007/10/02)
-
- DESIGN AND REACTIVITY OF ORGANIC FUNCTIONAL GROUPS - 2-PYRIDYLSULFONATES AS NUCLEOFUGAL ESTERS: REMARKABLY MILD TRANSFORMATIONS INTO HALIDES AND OLEFINS
-
The novel 2-pyridylsulfonate esters are excellent leaving groups for the preparation of bromides and olefins under very mild reaction conditions.Displacements occur with inversion of configuration.
- Hanessian, Stephen,Kagotani, Masahiro,Komaglou, Kossi
-
p. 1115 - 1120
(2007/10/02)
-
- REGIOSPECIFIC AND STEREOSPECIFIC SUBSTITUTION OF HYDROXYL IN ALIPHATIC ALCOHOLS BY HALOGEN
-
A new system containing triphenylphosphine and trichloro- and tribromoacetic ester makes it possible to substitute the hydroxyl group in alcohols by halogen.Regiospecific and stereospecific substitution of the hydroxyl by the halogen takes place as a result of the reaction of primary and secondary aliphatic alcohols and of 2-alkenols, susceptible to isomerization processes, with this system.
- Matveeva, E. D.,Kurts, A. L.,Yalovskaya, A. I.,Nikishova, N. G.,Bundel', Yu. G.
-
p. 642 - 646
(2007/10/02)
-
- SYNTHESIS OF ALKYL HALIDES UNDER NEUTRAL CONDITIONS
-
Primary and secondary alcohols are efficiently converted to the corresponding alkyl halides under neutral conditions.
- Munyemana, Francois,Frisque-Hesbain, Anne-Marie,Devos, Alain,Ghosez, Leon
-
p. 3077 - 3080
(2007/10/02)
-
- Triphase Catalytic Conversion of Alkenes to Organic Halides
-
Reactions of alkenes with hydrohalogenic acids (HCl and HBr) have been studied in the presence of polystyrylmethylenehexadecylbutylphosphonium bromide (1) and polystyrylmethylenehexadecyldiphenylphosphonium bromides (2) as triphase catalysts to yield organic halides by a simple product isolation.The catalysts could be recovered and recycled without loss of activity
- Khurana, Jitender M.,Tetenyi, Peter,Kodomari, Mitsuo,Regen, Steven L.
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p. 1129 - 1130
(2007/10/02)
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- A Functionalized Alkyldiphenylphosphine as an Efficient and Mild Reagent in CCl4-Promoted Substitution Reactions: Kinetics and Mechanism of the Reaction in CHCl3
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(Pyrid-2-ylethyl)diphenylphosphine can be used at 35-45 deg C in carbon tetrachloride-chloroform to give high yields of primary and secondary alkyl chlorides from the corresponding alcohols. The isolation of products is simplified by removal of the phosphorus-containing products by extraction into a dilute aqueous acid solution.The complex reaction was studied by 31P NMR.The rate constants based on the decay of phosphine are reported.The rapid conversion of alcohols proceeds equally via chlorination by CCl3 (path A) and by Cl (path B).The rates of formation and decay of an isobutoxyphosphonium intermediate, Cl, have been measured with 31P NMR.
- Toto, Susan D.,Doi, Joyce Takahashi
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p. 4999 - 5003
(2007/10/02)
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- Selenium and Tellurium Tetrachlorides as Reagents for the Conversion of Alcohols to Alkyl Chlorides and Tellurium Tetrachloride as a Lewis Acid Catalyst for Aromatic Alkylation
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Selenium tetrachloride(SeCl4) reacts smoothly with alcohols in various nonpolar solvents to give the corresponding alkyl chlorides in 44-97percent yield.Similar reaction also proceeds with tellurium tetrachloride(TeCl4), while the treatement of benzyl, 1-phenylethyl, and t-butyl alcohols with TeCl4 in aromatic solvents results in a high yield formation of alkylated aromatics instead of alkyl chlorides.Such Friedel-Crafts aromatic alkylation hardly occurs in the SeCl4 case.The chlorination species is not chlorine which might be evolved by dissociation of SeCl4 or TeCl4, but the metal chloride itself.The conversion of optically active R-(+)-1- phenylethanol to 1-phenylethyl chloride proceeds with nearly complete racemisation.
- Yamauchi, Takayoshi,Hattori, Kaneaki,Mizutaki, Shoichi,Tamaki, Kentaro,Uemura, Sakae
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p. 3617 - 3620
(2007/10/02)
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- Preparation of Alkyl Chlorides, Acid Chlorides, and Amides Using Polymer-Supported Phosphines and Carbon Tetrachloride: Mechanism of These Reactions
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Alcohols and thiols were converted into alkyl chlorides, carboxylic acids were converted into acid chlorides, and mixtures of carboxylic acids and amines were converted into amides by reaction with carbon tetrachloride and 1percent cross-linked polystyrenes containing phosphine residues.Some of these conversions were also effected by using a linear polymer containing phosphine residues.The reactions proceed in high yield, and isolation of the products is facilitated by the ready removal of all the polymer-supported species.The mechanism of the reactions between triphenylphosphine, carbon tetrachloride, and alcohols is complex, but the polymer-supported reactions appear to follow analogous pathways to the low molecular weight reactions as judged by the yields of chloroform and the number of equivalents of phosphine consumed per mole of alkyl chloride produced.The mechanism requires polymer-supported groups reacting together.The slow step in the reactions appears to be the generation of the chlorinating species.The polymer-supported reactions are faster than those using triphenylphosphine or 4-(diphenylphosphinyl)isopropylbenzene.It is suggested that this is due to a microenvironmental effect.
- Harrison, Charles R.,Hodge, Philip,Hunt, Barry J.,Khoshdel, Ezzatollah,Richardson, Graham
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p. 3721 - 3728
(2007/10/02)
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- New Procedure for the Transformation of Alcohols to Alkyl Halides via Xanthate Esters and Free-Radical Intermediates
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O-Alkyl-S-methyl xanthates have been used to convert alcohols to alkyl halides via free-radical pathways.The xanthate esters were readily prepared in high yields and were converted in 8-80percent yields to the corresponding alkyl halides by (a) photolysis with 254-nm light in carbon tetrachloride or bromotrichloromethane and (b) by treatment with Cu(I)-Cu(II) halide in acetonitrile.The photochemical transformation gave low yields with highly aliphathic compounds due to carbon tetrachloride-mediated free-radical halogenation reactions.The transformation promoted by Cu(I)-Cu(II) halide competed with an electron-transfer oxidation process.The reaction could not be induced with AIBN or benzoyl peroxide or by treatment with molybdenum pentachloride.Mechanistic implications are discussed.
- Cristol, Stanley J.,Seapy, Dave G.
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p. 132 - 136
(2007/10/02)
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- Mechanism of the Triphenylphosphine-Tetrachloromethane-Alcohol Reaction: Pericyclic or Clustered Ion Pairs?
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The intermediate formed from tetrachloromethane-triphenylphosphine and neopentyl alcohol decomposes bimolecularly in acetonitrile and not unimolecularly as in CDCl3.This kinetic order is not consistent with a pericyclic pathway but is consistent with an ion-pair mechanism.Consistent with the ion-pair mechanism in acetonitrile is the incorporation of external nucleophiles in the neopentyl skeleton by addition of added nucleophiles to the system.Consistent with the enhanced polarity of acetonitrile is the increased amount of carbon-oxygen cleavage resulting in extensive racemization of the reaction product from (R)-(+)-2-octanol.The preparation of neopentyl thiocyanate and neopentyl isothiocyanate from the corresponding alcohol illustrates the synthetic utility of this reaction in more polar solvents.
- Slagle, J. D.,Huang, T. T.-S.,Franzus, B.
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p. 3526 - 3530
(2007/10/02)
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