- Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
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Dodecavanadate, [V12O32]4? (V12), possesses a 4.4 ? cavity entrance, and the cavity shows unique electrophilicity. Owing to the high polarizability, Br2 was inserted into V12, inducing the inversion of one of the VO5 square pyramids to form [V12O32(Br2)]4? (V12(Br2)). The inserted Br2 molecule was polarized and showed a peak at 185 cm?1 in the IR spectrum. The reaction of V12(Br2) and toluene yielded bromination of toluene at the ring, showing the electrophilicity of the inserted Br2 molecule. Compound V12(Br2) also reacted with propane, n-butane, and n-pentane to give brominated alkanes. Bromination with V12(Br2) showed high selectivity for 3-bromopentane (64 %) among the monobromopentane products and preferred threo isomer among 2-,3-dibromobutane and 2,3-dibromopenane. The unique inorganic cavity traps Br2 leading the polarization of the diatomic molecule. Owing to its new reaction field, the trapped Br2 shows selective functionalization of alkanes.
- Hayashi, Yoshihito,Inada, Yasuhiro,Katayama, Misaki,Kikukawa, Yuji,Kitajima, Hiromasa,Seto, Kensuke,Watanabe, Daiki,Yamashita, Shohei
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supporting information
p. 14399 - 14403
(2020/07/13)
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- METHOD FOR PRODUCING FLUORINATED HYDROCARBON
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PROBLEM TO BE SOLVED: To provide an industrially advantageous method for producing a fluorinated hydrocarbon such as 2-fluorobutane useful as etching gas for a dry etching process. SOLUTION: There is provided a method for producing a fluorinated hydrocarbon represented by formula (3) by bringing an ether compound represented by formula (1) into contact with an acid fluoride represented by formula (2) in a halogenated hydrocarbon solvent in the presence of a metal halide represented by formula (4): MX3 (M represents a metal atom; X represents a chlorine atom or a bromine atom) (R1 and R2 each independently represent an alkyl group having 1-3 carbon atoms; R1 and R2 may be bonded to form a ring structure; R3 represents H, a methyl group or an ethyl group; R4 and R5 each independently represent a methyl group or an ethyl group.) SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0054; 0076; 0077
(2017/10/31)
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- Iron-copper cooperative catalysis in the reactions of alkyl grignard reagents: Exchange reaction with alkenes and carbometalation of alkynes
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Iron-copper cooperative catalysis is shown to be effective for an alkene-Grignard exchange reaction and alkylmagnesiation of alkynes. The Grignard exchange between terminal alkenes (RCH=CH2) and cyclopentylmagnesium bromide was catalyzed by FeCl3 (2.5 mol %) and CuBr (5 mol %) in combination with PBu3 (10 mol %) to give RCH2CH 2MgBr in high yields. 1-Alkyl Grignard reagents add to alkynes in the presence of a catalyst system consisting of Fe(acac)3, CuBr, PBu3, and N,N,N″,N″-tetramethylethylenediamine to give β-alkylvinyl Grignard reagents. The exchange reaction and carbometalation take place on iron, whereas copper assists with the exchange of organic groups between organoiron and organomagnesium species through transmetalation with these species. Sequential reactions consisting of the alkene-Grignard exchange and the alkylmagnesiation of alkynes were successfully conducted by adding an alkyne to a mixture of the first reaction. Isomerization of Grignard reagents from 2-alkyl to 1-alkyl catalyzed by Fe-Cu also is applicable as the first 1-alkyl Grignard formation step.
- Shirakawa, Eiji,Ikeda, Daiji,Masui, Seiji,Yoshida, Masatoshi,Hayashi, Tamio
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scheme or table
p. 272 - 279
(2012/03/07)
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- Enantioselectivity of haloalkane dehalogenases and its modulation by surface loop engineering
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In the loop: Engineering of the surface loop in haloalkane dehalogenases affects their enantiodiscrimination behavior. The temperature dependence of the enantioselectivity (lnE versus 1/T) of β-bromoalkanes by haloalkane dehalogenases is reversed (red data points) by deletion of the surface loop; the selectivity switches back when an additional single-point mutation is made. This behavior is not observed for -bromoesters.
- Prokop, Zbynek,Sato, Yukari,Brezovsky, Jan,Mozga, Tomas,Chaloupkova, Radka,Koudelakova, Tana,Jerabek, Petr,Stepankova, Veronika,Natsume, Ryo,Van Leeuwen, Jan G. E.,Janssen, Dick B.,Florian, Jan,Nagata, Yuji,Senda, Toshiya,Damborsky, Jiri
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supporting information; experimental part
p. 6111 - 6115
(2010/11/05)
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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- A new supported reagent for the photochemical generation of radicals in solution
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matrix presented A new polymer-supported radical source was developed by loading an N-hydroxy thiazole 2(3)-thione on a Wang resin. This new supported reagent can be employed for a solid-phase version of the Hunsdiecker reaction or to liberate free alkoxy radicals, in a variant of the "catch and release" technique, under very mild conditions (irradiation with a discharge lamp) and simplifying the purification procedure.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcu, Giancarlo,Taddei, Maurizio
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p. 855 - 857
(2007/10/03)
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- Mild conversion of alcohols to alkyl halides using halide-based ionic liquids at room temperature
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Formula presented Alcohols were efficiently converted to alkyl halides using 1-n-butyl-3-methylylimidazolium halides (ionic liquids) in the presence of Bronsted acids at room temperature. The alkyl halide products were easily isolated from the reaction mixture via simple decantation or extraction, and the 1-n-butyl-3-methylimidazolium cation could be recycled for further uses.
- Ren, Rex X.,Wu, Jeff Xin
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p. 3727 - 3728
(2007/10/03)
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- Complete inversion of configuration in aliphatic nucleophilic substitution reactions with small inner-sphere stabilization
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The stereochemistry of the nucleophilic reaction of the enolate anion of 1,4-dihydro-4-methoxycarbonyl-1-methylpyridine (1-) with (R)-(-)- and (S)-(+)-2-bromobutane has been investigated and correlated with the inner-sphere stabilization of the reactions calculated from the ratio kSUB/kET, where kSUB is the rate of substitution and kET the expected rate of electron transfer. It was shown that 1- reacts with 2-bromobutane with nearly complete inversion of configuration (99.7%). A complete shift in stereochemistry of the nucleophilic reactions of 1- with alkyl halides from racemization to complete inversion is induced by a small increase in the inner-sphere stabilization of the transition state from 0 to 3 kcal mol-1. The results in this work suggest that the SN2 inversion process in general is extremely sensitive towards inner-sphere stabilization. Acta Chemica Scandinavica 1998.
- Lund, Torben,Jacobsen, Karin Bay
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p. 778 - 783
(2007/10/03)
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- Functionalization of saturated hydrocarbons by aprotic superacids 4. Ionic bromination of ethane and other alkanes and cycloalkanes with molecular bromine in the presence of systems based on polyhalomethanes and AlBr3 under mild conditions
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Aprotic organic superacids CBr4 · 2AlBr3, CBr4 · AlBr3, · CCl4 · 2AlBr3, CCl4 · 2AlBr3, and C6F5CF3 · 2AlBr3 efficiently catalyze the bromination of alkanes and cycloalkanes with Br2. Ethane is selectively brominated at 55-65 °C to give mostly 1,2-dibromoethane (stoichiometric reaction). Propane, butane, cyclopentane, cyclohexane, and methyl-cyclopentane react with Br2 at -40 to -20 °C with good selectivity affording monobromides in high yields (catalytic reactions).
- Akhrem,Orlinkov,Afanas'eva,Vol'pin
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p. 1148 - 1153
(2007/10/03)
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- Ionic Bromination of Ethane and Other Alkanes (Cycloalkanes) with Bromine Catalyzed by the Polyhalomethane*2AlBr3 Aprotic Organic Superacids under Mild Conditions
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The polyhalomethane*2AlBr3 aprotic organic superacids were shown to effectively catalyze low-temperature ionic bromination of (cyclo)alkanes.Ethane readily reacts with Br2 at 55-65 deg C, affording mainly 1,2-dibromoethane.Propane, butane, and C5-C6 cycloalkanes react at -40 - -20 deg C, resulting in monobromides with high yields and good selectivity.
- Akhrem, Irena S.,Orlinkov, Alexander V.,Afanas'eva, Lyudmila V.,Mysov, Evgenii I.,Vol'pin, Mark E.
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p. 9365 - 9368
(2007/10/02)
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- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
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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)
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- Reactivity of Alkaneselenyl Bromide: Conversion of Alcohols into the Corresponding Alkyl Bromides with Dialkylselenium Dibromide
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The reaction of alcohols with dialkylselenium dibromide gave the corresponding bromides in moderate to high yields.Alkaneselenyl bromide, produced by the thermal decomposition from dialkylselenium dibromide, acts as a brominating agent.The reaction of alcohol with dialkylselenium dichloride afforded the corresponding chlorides, although the yields were realtively low compared with those of the bromide.
- Akabori, Sadatoshi,Takanohashi, Yoshinori
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p. 3482 - 3484
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 10. THE BASE-INDUCED REACTION OF BROMINE WITH ORGANOBORNES. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO ALKYL BROMIDES VIA HYDROBORATION
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The reaction of trialkylboranes with bromine is greatly accelerated by base.Bromination in the presence of sodium hydroxide provides alkyl bromide along with a large amount of the corresponding alcohol.The use of sodium methoxide as a base eliminates this undesirable side reaction and provides an improved yield of alkyl bromide.Consequently, hydroboration, followed by bromination in the presence of sodium methoxide, provides a convenient new procedure for the conversion of alkenes into alkyl bromides.The organoboranes, obtained via hydroboration of terminal alkenes, react with the utilization of all three alkyl groups attached to boron, providing nearly quantitative yields of alkyl bromides. This procedure also accommodates common organic functional groups, as demonstrated by the preparation of methyl 11-bromoundecanoate and 11-bromoundecyl acetate from the corresponding functionally substituted alkenes.Under these conditions, secondary and bulky primary alkyl groups react more sluggishly.However, a procedure involving simultaneous addition of bromine and methanolic sodium methoxide provides improved results for such derivatives.Surprisingly, the base-induced bromination of tri-exo-nobornylborane results in an inversion of configuration at the reaction center to give predominantly endo-2-bromonorbornane.A mechanism is proposed to account for this remarkable inversion.
- Brown, Herbert C.,Lane, Clinton F.
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p. 2763 - 2772
(2007/10/02)
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- Stereochemistries and mechanisms of reactions of electrophiles with organotin compounds
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The effect of solvent and electrophile on halodemetalation reactions of carbon-tin bonds has been investigated. Both stereochemical results and 119Sn NMR have been used as mechanistic probes. The effect of solvent is extreme; reactions performed in polar solvents such as acetonitrile and dimethylformamide yield cleavage products with predominantly inversion of configuration, whereas nonpolar solvents yield products with predominantly retention. Polar-aprotic solvents appear to be highly efficient in promoting inversion stereochemistry. Polar-protic solvents are not as efficient. This is explained in terms of some very specific solvation phenomena. Also, 119Sn NMR studies of several trialkyltin halides in various solvents show that these specific solvation phenomena can be qualitatively assessed. The nature of the electrophile also plays an important role in eventual stereochemistry; Br2, I2, ICl, and IBr are compared and discussed.
- Fukuto, Jon M.,Newman, David A.,Jensen, Frederick R.
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p. 415 - 420
(2008/10/08)
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- Efficient Conversion of Alkyl Chlorides into Bromides
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The convenient and selective catalytic conversion of secondary and tertiary alkyl chlorides into bromides with hydrogen bromide in the presence of small amounts of anhydrous iron(III) bromide is described.
- Yoon, K. B.,Kochi, J. K.
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p. 1013 - 1014
(2007/10/02)
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- HYDROALUMINATION OF OLEFINS BY THE LiAlH4/UCl4 SYSTEM
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LiAlH4 reacts with olefins in the presence of catalytic amount of UCl4 or UCl3 to give alkylaluminate compounds.The active species in these reactions is thought to be U(AlH4)3.
- Marechal, Jean-Francois Le,Ephritikhine, Michel,Folcher, Gerard
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- New Reagents, XXXVII - (α-Lithioalkyl)diphenylarsane Oxides: Synthesis and Application for the Indirect Nucleophilic Haloalkylation
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Due to ready accessibility and high nucleophilicity (α-lithioalkyl)diphenylarsane oxides (2) are favorable reagents for the synthesis of many organoarsenic compounds.In organic synthesis they are recommendable as reagents for indirect nucleophilic haloalkylation reactions (Hal = Cl, Br, I).
- Kauffmann, Thomas,Joussen, Rolf,Woltermann, Annegret
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p. 2135 - 2142
(2007/10/02)
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- RHODIUM(I) CATALYZED CARBONYLATION REACTIONS OF HALIDES AND ETHERS
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Benzylic bromides and methyl ioide react with ethers, carbon monoxide, potassium iodide, and the dimer of chloro(1,5-hexadiene)rhodium(I) to give esters in good yields.
- Buchan, Caroline,Hamel, Nathalie,Woell, James B.,Alper, Howard
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p. 5743 - 5746
(2007/10/02)
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- Chemical process
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Novel bis(3',5'-mono or dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketones are prepared by reacting a (3',5'-mono or dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketone with an N,N-dihydrocarbyl-2,6-mono or dihydrocarbyl-4-aminomethylphenol and an alkyl halide in the presence of an alkaline earth metal halide. The products are useful as antioxidants.
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- Chemical process for preparing 1,3-diketones
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Novel (3',5'-dihydrocarbyl-4'-hydroxybenzyl)-1,3-diketones are prepared by reacting an N,N-dihydrocarbyl-2,6-dihydrocarbyl-4-aminomethylphenol with a 1,3-diketone and an alkyl halide in the presence of an alkali or an alkaline earth metal hydride. The products are useful as antioxidants.
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- Chemical process
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Novel 2,4-dihydrocarbylspiro[5.5]undeca-1,4,8-trien-3-one compounds are prepared by reacting an N,N-dihydrocarbyl,2,6-dihydrocarbyl-4-aminomethylphenol with a conjugated diene and an alkyl halide in a liquid solvent medium.
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- SELECTIVITIES OF pi - AND sigma -SUCCINIMIDYL RADICALS IN SUBSTITUTION AND ADDITION REACTIONS. APPENDIX: RESPONSE TO WALLING, EL-TALIAWI, AND ZHAO.
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A new method for studies of pi -succinimidyl (S// pi ) radicals is described, one that makes possible the study of reactions of this radical with a variety of substrates not accessible by the use of Br//2-NBS. NBS systems containing BrCCl//3 at mole fractions greater than 0. 3 show all the characteristics associated with S// pi behavior, and they function in the presence of olefins which serve as Br//2 scavengers. If CCl//4 is substituted for BrCCl//3, the system is clearly S// sigma . The S// pi behavior is contrasted with S// sigma and Br multiplied by (times) reactivities for H abstractions from a variety of substrates and for additions to tert-butylethylene, isobutylene, and 1,3-butadiene. In early-transition-state systems, for H transfer, the strength of the bond being broken and the strength of the bond being made are not the major factors in determining reactivities. The behavior in late-transition-state systems is influenced by both bond strengths. The S// pi radical shows intermediate behavior. These conclusions are supported by primary deuterium isotope effects for methylene chloride and chlororoform. The Appendix addresses a number of questions raised by the preliminary study of NBS reactions by Walling et al.
- Skell,Tlumak,Seshadri
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p. 5125 - 5131
(2007/10/02)
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- Reactions of a Graded Set of Radicals with N-Bromosuccinimide; Two Transition States
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The reactions of N-bromosuccinimide with a series of radicals have been studied.These reactions fall into two categories, the more reactive radicals producing ?-succinimidyl and the less reactive radicals producing ?-succinimidyl.The threshold for the changeover from one reaction domain to the other occurs with radicals less reactive than secondary alkyls.These results are interpreted with two transition states, an in-line transition state for the more reactive radicals and an out-of-plane transition state for the less reactive radicals. An upper limit of 18 kcal/mol is established for the enthalpy difference, HS? - HS?.Two new methods for generating S? radicals are indicated.
- Tlumak, Robert L.,Skell Philip S.
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p. 7267 - 7274
(2007/10/02)
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- Relative Bond Dissociation Energies for Two-Ligand Complexes of Cu+ with Organic Molecules in the Gas Phase
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Ralative two-ligand dissociation enthalpies, δD(Cu+-2L), for Cu+ with 43 organic molecules are determined.A pulsed-laser volatilization/ionization sourse is used to generate Cu+ which reacts with EtCl and/or other molecules to give Cu(ligand)2+ species.Equilibrium constants are measured for the ligand-exchange reactions which occur when pairs of ligand molecules are present.Free energies for two-ligand exchange are obtained from the equilibrium constant for the reaction Cu(A)2+ + 2B ->/+ + 2A.The free-energiy differences are added to give a scale of relative free energies for ligand exchange.These are converted to enthalpies to give δD(Cu+-2L) scale with the assumption that enthropy changes are small and can be neglected except for symmetry corrections which are made in appropriate cases.Dependence of δD(Cu+-2L) on functional group and substituent effects is analyzed.These results for Cu+ are compared to available results for other reference acids: H+, Al+, Mn+, Li+, and CpNi+.These comparisons show that Cu+ is a softer acid than the other reference acids.This is apparent from the relative preference of Cu+ for mercaptans and HCN compared to alcohols and other oxygen bases.
- Jones, Roger W.,Staley, Ralph H.
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p. 2296 - 2300
(2007/10/02)
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- Bulky trialkylborohydrides
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Borohydride hydrogenations using agents of the formula M[RR'R"BH] wherein M is a metal and R, R', and R" are each organic groups, at least one of them being a secondary or tertiary alkyl group, are described herein. These compounds are active hydrogenating agents which are particularly useful because they permit steric control of the hydrogenation of carbonyl groups, they permit selective hydrogenation of functional groups or, where one of the R groups is optically active, they permit stereoselective hydrogenation.
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