- 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; 0074; 0075; 0077
(2017/10/31)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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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
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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.
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Page/Page column 53; 144; 145
(2017/01/02)
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- Trichloroisocynuric acid/DMF as efficient reagent for chlorodehydration of alcohols under conventional and ultrasonic conditions
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A new and efficient method for the chlorodehydration of alcohols utilizing TCCA/DMF is described. Various alcohols can be converted smoothly into their corresponding alkyl chlorides in high yields under mild conditions with short reaction times. Taylor & Francis Group, LLC.
- Venkana, Purugula,Kumar, Mukka Satish,Rajanna, Kamatala Chinna,Ali, Mir Moazzam
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- The thermal and mass spectral fragmentation of N-butyl thiolo-, thiono-, and dithio-chloroformate
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Thermal decomposition of n-butyl thiolochloroformate at 150C follows a similar pattern to that reported previously for n-butyl chloroformate, to give butyl chloride which is largely rearranged to the s-butyl isomer. An ion-pair mechanism, involving 1,2-and 1,3-hydride shifts, is proposed. The less stable thiono-and dithio-chloroformates decompose to give lower yields of butyl chlorides (mainly without rearrangement) together with numerous other byproducts, indicating the operation of a more complex combination of reaction pathways. The mass spectra of all three thio compounds exhibit molecular ions; the most prominent fragment ions in their spectra are the n-butyl cation, and the radical cations COS+ and CS2+. Numerous chlorine-containing ions of low intensity are also observed, and their mode of formation is discussed. Copyright Taylor &Francis Group, LLC.
- Hudson, Harry R.,Koplick, Andrew J.
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experimental part
p. 1635 - 1649
(2011/10/08)
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- Direct chlorination of alcohols with chlorodimethylsilane catalyzed by a gallium trichloride/tartrate system under neutral conditions
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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)
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- FeCl3-activated oxidation of alkanes by [Os(N)O 3]-
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Although the ion [OsVIII(N)(O)3]- is a stable species and is not known to act as an oxidant for organic substrates, it is readily activated by FeCl3 in CH2Cl2/CH 3CO2H to oxidize alkanes efficiently at room temperature. The oxidation can be made catalytic by using 2,6-dichloropyridine N-oxide as the terminal oxidant. The active intermediates in stoichiometric and catalytic oxidation are proposed to be [(O)3OsVIII≡N-Fe III] and [Cl4(O)OsVIII≡N-Fe III], respectively.
- Yiu, Shek-Man,Wu, Zhi-Biao,Mak, Chi-Keung,Lau, Tai-Chu
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p. 14921 - 14929
(2007/10/03)
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- Gas-phase reactions of Cl atoms with propane, n-butane, and isobutane
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Using the relative kinetic method, rate coefficients have been determined for the gas-phase reactions of chlorine atoms with propane, n-butane, and isobutane at total pressure of 100 Torr and the temperature range of 295-469 K. The Cl2 photolysis (λ = 420 nm) was used to generate Cl atoms in the presence of ethane as the reference compound. The experiments have been carried out using GC product analysis and the following rate constant expressions (in cm3 molecule-1 s-1) have been derived: (7.4 ±0.2) × 10-11 exp [-(70 ± 11)/T], Cl + C3H8 → HCl + CH3CH2CH2; (5.1 ± 0.5) × 10-11 exp [(104±32)/T], Cl + C3H8 → HCl + CH3CHCH3; (7.3±0.2) × 10-11 exp [-(68 ± 10)/T], Cl + n-C4H10 → HCl + CH3 CH2CH2CH2; (9.9 ± 2.2) × 10-11 exp [(106 ± 75)/T], Cl + n-C4H10 → HCl + CH3CH2CHCH3; (13.0 ± 1.8) × 10-11 exp [-(104 ± 50)/T], Cl + i-C4H10 → HCl + CH3CHCH3 CH2; (2.9 ± 0.5) × 10-11 exp [(155 ± 58)/T], Cl + i-C4H10 → HCl + CH3CCH3CH3 (all error bars are ±2ρ precision). The studies provide a set of reaction rate constants allowing to determine the contribution of competing hydrogen abstractions from primary, secondary, or tertiary carbon atom in alkane molecule.
- Sarzynski, Dariusz,Sztuba, Barbara
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p. 651 - 658
(2007/10/03)
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- Oxidative alkoxylation of zinc phosphide in alcoholic solutions of copper(II) chloride
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Oxidative alkoxylation of Zn3P2 with the formation of valuable phosphoric and phosphorous acid esters occurred at a high rate and with a high selectivity in alcoholic solutions of CuCl2 under the action of oxygen at 30-60°C. Depending on the nature of the alcohol, two products were formed, namely, trialkyl phosphates (RO)3PO and dialkyl phosphites (RO)2HPO. Water favored the formation of dialkyl phosphates (RO)2(HO)PO. The kinetics and mechanism of the new catalytic reaction were studied, and the optimal conditions for conducting this reaction were found. The reaction proceeded in a topochemical mode by a separate redox mechanism.
- Dorfman,Ibraimova,Polimbetova
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- New aspect of nucleophilic reactivity of tertiary phosphine oxides. R3PO-POCl3 binary system
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The reaction of tertiary phosphine oxides with phosphorus oxychloride was found to give triorganylphosphonium dichlorophosphates R3PCl+PO2Cl-2 rather than phosphorylphosphonium salts R3P · OPOCl2. Mixtures of the reagents, called binary system, possess a considerable synthetic potential. They are capable of converting alcohols to the corresponding alkyl chlorides.
- Kazantseva,Timokhin,Rokhin,Blazhev,Golubin,Rybakova
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p. 1233 - 1235
(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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- 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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- Carbenes as substrates: Bimolecular fragmentation of alkoxychlorocarbenes
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Fragmentation reactions of n-butoxychlorocarbene (9), isobutoxychlorocarbene (10), and benzyloxychlorocarbene (2) were studied by product analysis and by laser flash photolysis (LFP). The carbenes were generated photochemically from 3-alkyl-3-chlorodiazirines in (1) MeCN solution; (2) 5.77 M pyridine in MeCN; (3) 0.504 M tetrabutylammonium chloride (Bu4NCl) in MeCN; or (4) 5.77 M pyridine + 0.504 M Bu4NCl in MeCN. In MeCN, 9 gave mainly HCl-capture product, n-butyl dichloromethyl ether (45.1%), carbene dimer (9.8%), and azine (14.6%). Fragmentation products 1- butene (14,4%), 2-butyl chloride (6.0%), and 1-butyl chloride (10.2%) were limited. With added pyridine. HCl was scavenged, the dichloromethyl ether was suppressed, and 1-butene (42.1%), 2-butyl chloride (7.3%), and butyl chloride (24.1%) were dominant. With added Bu4NCl, 1-butyl chloride increased to 46.4%. With both pyridine and Bu4NCl, 1-butyl choride was 63% of the product, with 1-butene at 22.8%. A similar pattern was observed with carbene 10. Products in MeCN included isobutene (23%), 1- and 2-butene (8-9%), tert- butyl chloride (1, 7%), 2-butyl chloride (5.8%), isobutyl chloride (0.4%), isobutyl dichloromethyl ether (53%), and carbene dimer (8%). The isobutyl chloride fragmentation product increased from 0.4% in MeCN, to 7.3% with pyridine, to 32% with Bu4NCl, and to 38% with both addends. With 2, benzyl chloride increased from 83% in MeCN to 91% with added pyridine and Bu4NCl. The increase in chloride displacement products are attributed to bimolecular attacks of chloride ions at the α-carbon atoms of the carbenes, particularly 9 and 10. LFP kinetic studies show that the rate constants for fragmentation of these carbenes increase linearly with the concentration of added Bu4NCl in pyridine-MeCN. Second-order rate constant (k2) as a function of [Cl-] (M-1 s-1, 24 °C) for the fragmentations are 8.2 x 106 (9), 2.7 x 106 (10), and 2.2 x 106 (2). The decrease in k2 as R in ROCCI changes from n- butyl to isobutyl to benzyl is in accord with a S(N)2-like mechanism for the carbene fragmentations in which the benzyl case involves the competitive incursion of S(N)1-like fragmentation.
- Moss, Robert A.,Johnson, Lauren A.,Merrer, Dina C.,Lee Jr., George E.
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p. 5940 - 5944
(2007/10/03)
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- Kinetics and mechanisms of the reactions of chlorine atoms with ethane, propane, and n-butane
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Absolute (flash photolysis) and relative (FTIR-smog and GC) rate techniques were used to study the gas-phase reactions of Cl atoms with ethane (k1), propane (k3), and n-butane (k2). Experiments performed at 298-540 K give k2÷k1=(2.0±0.1)exp((183±20)÷T). At 296 K the reaction of Cl atoms with propane yields of 43 % 1-propyl and 57 % 2-propyl radicals, while the reaction of Cl atoms with n-butane produces 29% 1-butyl and 71% 2-butyl radicals. Butyl radicals were found to react with Cl2 with rates which are 3 times greater than the corresponding reactions with O2.
- Tyndall,Orlando,Wallington,Dill,Kaiser
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- Synthesis and structure-activity relationships for the fungicidal activity of O,O-bisaryl sec-butylphosphonates
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Sixteen O,O-bisaryl sec-butylphosphonates have been synthesised by condensing sec-butylphosphonyl dichloride with substituted phenols. The compounds were tested against two phytopathogenic fungi, Rhizoctonia bataticola and Helminthosporium oryzae. The most active compound against R. bataticola is O,O-bis(3-methylphenyl) sec-butylphosphonate (ED50 29.56 mg litre-1) and against H. oryzae, O,O-bis(2-chlorophenyl) sec-butylphosphonate and its parachloro analogue (ED50 0.14 and 0.13 mg litre-1 respectively). Quantitative structure activity relationships on the fungicidal activity have been analysed by means of multiple regression analysis using physicochemical substituent parameters. Electronic parameters viz., σ and F have expressed significant variability in fungitoxicity against both the fungi, viz. R. bataticola and H. oryzae. Hydrophobic and steric parameters are also found to be important in the correlation studies.
- Sanyal,Roy
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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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- Reinvestigation of the SNi Reaction. The Ionization of Chlorosulfites
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The decomposition of alkyl chlorosulfites (ROSOCl) has been investigated both computationally and experimentally.Semiempirical (AM1 and PM3) as well as ab initio (HF/3-21G(*), HF/6-31G*, and MP2(full)/6-31G*//MP2(full)/6-31G*) methods were employed, and the results were confirmed experimentally by NMR spectroscopy.The computations indicated that certain alkyl sulfinyl cations (ROSO(1+)) are stable and might be involved in the decomposition of chlorosulfites.Detection of these ions by 1H and 13C NMR spectroscopy in polar solvents such as acetone-d6 and acetonitrile-d3 as well as kinetic studies allowed important conclusions to be drawn about the mechanistic details of the SNi reaction.We conclude that primary alkyl chlorosulfites ionize to yield a sulfinyl cation (ROSO(1+)) and Cl(1-), whereas tertiary chlorosulfites preferentially give a carbenium ion and a chlorosulfinyl anion (OSOCl(1-)) The generation of these ion pairs is facilitated in polar solvents where the rates of decomposition of chlorosulfites are largely accelerated.The decomposition of neopentyl chlorosulfite without rearrangement and the substitution at the bridgehead position of 7,7-dimethylbicycloheptyl 1-chlorosulfite show that the loss of SO2 from ROSO(1+) must be accompanied by the attack of the chloride ion from the front side.
- Schreiner, Peter R.,Rague Schleyer, Paul von,Hill, Richard K.
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p. 2822 - 2829
(2007/10/02)
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- Deuterium isotope studies of the dehydration alcohols by reaction with triphenylphosphine-tetrachloromethane
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The reactions of 2-butanol, 2-butanol-2d1, erythro-2-butanol-3d1 (EB), 2-methyl-2-propranol (2M2P), and 1,1,1,3,3,3-hexadeuterio-2-methyl-2-propranol (HDMP), respectively, with CCL4, and Ph3P in a polar or non-polar solvent in the temperature range of 36-85°C was studied. For 2-butanol the fraction of dehydration products increased with temperature; the opposite temperature effect was observed for (2M2P). Dehydration was the dominant pathway for (2M2P) (85-95%) but substitution (of OH by Cl) was dominant for 2-butanol (75-95%). Deuterium retention in the butenes from the conversion of (EB) indicated that 98% or more of the dehydration followed an anti-elimination pathway, and there was a preference for Saytzeff elimination. An isotope effect for deuterium elimination (K(H)/k(D)) for the alkene-forming step for (EB) and (HDMP) was about 2.0, and neither temperature nor solvent polarity appeared to have an effect on (k(H)/k(D)) in the range investigated. Surprisingly, there was an isotope effect for the relative rate of the formation of alkyl halide from (EB) but not from (HDMP).
- Dabbagh,Franzus,Huang,Davis
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p. 949 - 960
(2007/10/02)
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- Substituted imidazolyl-alkyl-piperazine and -diazepine derivatives
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Substituted imidazolyl-alkyl-piperazine and diazepine derivatives of Formula A: STR1 wherein: R 1 is aryl, lower alkyl, cycloalkyl or hydrogen;R 2 is aryl, lower alkyl or hydrogen;R 3 is lower alkyl, hydroxy, or hydrogen;R 4 is aryl or hydrogen;R 5 is aryl or hydrogen;m is two or three;n is zero, one or two,provided that when R 3 is hydroxy, n is one or two; andq is zero, one, two, or three;and the pharmaceutically acceptable salts thereof, are calcium channel antagonists useful for treating mammals having a variety of disease states, such as stroke, epilepsy, hypertension, angina, migraine, arrhythmia, thrombosis, embolism and also for treatment of spinal injuries.
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- ORGANOBORANES FOR SYNTHESIS. 12. THE REACTION OF ORGANOBORANES WITH NITROGEN TRICHLORIDE. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO ALKYL CHLORIDES VIA HYDROBORATION
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Trialkylboranes are readily converted to the corresponding alkyl chlorides by a free radical reaction with nitrogen trichloride (NCl3).Compared to many other chlorinating agents examined, NCl3 is a superior reagent for the effective conversion of organoboranes into alkyl chlorides.Combined with the high regioselectivity inherent in the hydroboration reaction, the treatment with NCl3 allows alkenes to be transformed into pure alkyl chlorides of predictable structure.This process constitutes valuable method for the anti-Markovnikov hydrochlorination of alkenes in 66-94percent yield.Experimental evidence indicates that this reaction proceeds via free radical intermediates.The reaction of organoboranes with NCl3 is comparable to or better than other methods, such as those requiring refluxing aqueous cupric or ferric chloride, or those producing hydrogen chloride as a by-product.Consequently, this procedure could be very useful for the conversion of acid-sensitive (e.g., certain bicyclic) alkenes into alkyl chlorides where extensive skeletal rearrangements occur in hydrogen chloride additions.
- Brown, Herbert C.,de Lue, Norman R.
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p. 2785 - 2792
(2007/10/02)
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- Continuous Conversion of Alcohols into Alkyl Halides by Gas-Liquid Phase-Transfer Catalysis (G.L.-P.T.C)
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A solution of a primary alcohol (propan-1-ol, butan-1-ol, and pentan-1-ol) in an aqueous halogen acid (hydrochloric or hydrobromic acid) when passed in the gaseous state over a solid porous bed (silica gel) supporting a catalyst, affords the corresponding alkyl halide.The reagent mixture is introduced continuously into a column maintained at 170 deg C and the product is collected at the outlet.Since the process is catalytic, the bed is not consumed during the reaction.The reaction by-products depend on the type of catalyst used: Lewis acids (ZnCl2, AlCl3) lead to large quantities of alkenes and isomeric halides, while under typical g.l.- p.t.c. conditions, with a phosphonium salt as the catalyst, only the corresponding dialkyl ether, in addition to the primary alkyl halide, is obtained.The yield of the ether can be reduced progessively to zero by increasing the contact time between the reaction mixture and the catalytic bed.
- Tundo, Pietro,Venturello, Paolo,Angeletti, Enrico
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p. 2157 - 2158
(2007/10/02)
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- Experimental evidence for AcO-7 neighboring group participation
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The reaction of diol diacetates with anhydrous aluminium chloride at ca 100° leads to displacement of only one of the acetoxy groups by chlorine. An oxygen-18 label study has shown that these displacements take place via acetoxonium intermediates and has provided direct evidence for the intervention of a seven-membered ring acetoxonium ion in the displacement of acetate by chlorine in 1,4-butanediol diacetate.
- Wilen, Samuel H.,Delguzzo, Luciano,Saferstein, Richard
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p. 5089 - 5094
(2007/10/02)
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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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- Absolute Rate Constants for the Reactions of α-Toluenesulfonyl Chloride with Carbon-Centered Radicals
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The absolute rate constants for the reaction of some carbon-centered radicals with α-toluenesulfonyl chloride have been measured in solution by using laser flash photolysis techniques.At 298 K, the rate constants are 1.3*106, 1.2*106, and 1.0*108 M-1s-1 for n-butyl, sec-butyl, and phenyl radicals respectively.Arrhenius parameters were determined for n-butyl and sec-butyl radicals.Evidence that suggests the involvement of charge-transfer interactions is presented.Such rate-enhancing interactions have been shown to have a greater influence on the preexponential factor than on the activation energy.
- Chatgilialoglu, C.
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p. 2871 - 2873
(2007/10/02)
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- Hydrochlorination of Alkenes. 3. Reaction of the Gases Hydrogen Chloride and (E)- and (Z)-2-Butene
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Mixtures of the gases hydrogen chloride and (E)-2-butene, hydrogen chloride and (Z)-2-butene, and hydrogen chloride and (Z)-2H2>-2-butene at total pressures up to 7 atm and temperatures between 283 and 313 K react to yield, exclusively, 2-chlorobutane (erythro- and threo-2H2>-2-chlorobutane in the case of the labeled alkene).Kinetic measurements for the reaction of all three gaseous alkenes with gaseous hydrogen chloride have been made by infrared spectroscopy.Elimination stadies were performed on the 2H2>-2-chlorobutane formed.It is concluded that sur face catalysis is required for product formation and that surface adsorption of both hydrohen chloride and butene is required to consummate the reaction.
- Tierney, John,Costello, Francis,Dalton, David R.
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p. 5191 - 5196
(2007/10/02)
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- REACTION OF ALKYL 2-CHLORO-1,1,2-TRIFLUOROETHYL ETHERS WITH LEWIS ACIDS
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Ethyl 2-chloro-1,1,2-trifluoroethyl ether heated with boron trifluoride etherate gave ethyl fluoride and chlorofluoroacetyl fluoride.When heated with aluminium chloride, it afforded a mixture of ethyl fluoride, ethyl chloride, chlorofluoroacetyl fluoride, and chlorofluoroacetyl chloride.Treatment of the acyl halides with ethanol yielded ethyl chlorofluoroacetate.Butyl and octyl 2-chloro-1,1,2-trifluoroethyl ethers gave directly butyl and octyl chlorofluoroacetates, respectively, under similar conditions.
- Hudlicky, Milos
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p. 349 - 354
(2007/10/02)
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- SN2 Reactions in the Gas Phase. Temperature Dependence of the Rate Constants and Energies of the Transition States. Comparison with Solution
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The rate constants for the gas-phase reactions Cl- + RBr = ClR + Br-, where R = Me, Et, n-Bu, i-Pr, and i-Bu, were determined for temperatures between 25 and 390 deg C with a pulsed electron beam high ion source pressure mass spectrometer.The rate constants for Me decreased with an increase of temperature (negative temperature dependence).Et and n-Bu had almost no temperature dependence while i-Pr and i-Bu had positive temperature dependence.An analysis of the data on the basis of theory provides approximate values for ΔE0, the energy of the transition state relative to the energy of the reactants.These ΔE0 values are as follows: Me, -2.5; Et, 0.8; n-Bu, -0.5; i-Pr, +5.1; i-Bu, +5.7 kcal/mol.The δΔE0 are compared with relative activation energies: δEa in solution (C.K.Ingold and A.J.Parker) and calculated strain energies δΔEstrain due to steric repulsions in the transition state (C.K.Ingold and D.F.DeTar).An approximate agreement between the three sets of data is found.This finding supports the assumption of Ingold that steric effects in the transition state dominate the relative rates of this reaction series.The temperature dependence of the rate constants in the gas phase is of interest to ion-molecule reaction theory.It provides a graphic demonstration for the effect of the central barrier in the double-well reaction coordinate.When ΔE0 is negative, negative temperature dependence is observed.When -ΔE0 is small (Me, n-Bu) the reaction proceeds with chemical activation at the very low pressures used in ion cyclotron resonance but with near Boltzmann transition-state distribution at the higher pressures used in high-pressure mass spectrometry.When ΔE0 is positive, the reaction proceeds with positive temperature dependence and boltzmann transition-state distribution.
- Caldwell, Gary,Magnera, Tom F.,Kebarle, Paul
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p. 959 - 966
(2007/10/02)
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- Kinetics of Cl(2PJ) Reactions with the Chloroethanes CH3CH2Cl, CH3CHCl2, CH2ClCH2Cl and CH2ClCHCl2
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The kinetics of the reactions Cl(2PJ) + RHCl -> RCl + HCl were investigated over the temperature range 257-426 K for RHCl = CH3CH2Cl (k2), CH3CHCl2 (k3), CH2ClCH2Cl (k4), and CH2ClCHCl2 (k5).Cl(2PJ) was produced by 355 nm pulsed laser photolysis of Cl2 and monitored by time-resolved resonance fluorescence spectroscopy.The data are adequately described by the following Arrhenius expressions (units are cm3 molecule-1 s-1, errors are 2? and refer to precision only): k2=(2.34+/-0.42)E-11exp, k3=(8.19+/-1.84)E-12exp,k4=(2.21+/-0.51)E-11exp, and k5=(4.88+/-1.41)E-12exp.Under some experimental conditions evidence for Cl(2PJ) regeneration via a secondary reaction was observed.At 258+/-1 K, deviations of Cl(2PJ) temporal profiles from first-order behavior were attributable to the reactions RCl + Cl2 -> RCl2 + Cl(2PJ)(kj).By modeling the observed C(2PJ) temporal profiles, we found the rate constant kj to lie in the range (5-12)E-14 cm3 molecule-1 s-1 for all RCl investigated.The reactivity trends observed in reactions of Cl2PJ) with C2HXCl(6-x), x=3-6, are discussed.
- Wine, P. H.,Semmes, D. H.
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p. 3572 - 3578
(2007/10/02)
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- Free Radical Substitution. Part 37. The Effect of Solvent on the Atomic Chlorination of 1-Substituted Butanes and Related Compounds
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Experimental results reported in this paper show that the relative selectivity of atomic chlorination of 1-substituted butanes and related compounds is greatly influenced by the phase and by solvents.Solvents can be divided into three classes: (a) inert, (b) solvents which decrease the selectivity, and (c) solvents which increase the selectivity.The second group solvate the transition state and the third group solvate the chlorine atoms.
- Potter, Alan,Tedder, John M.
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p. 1689 - 1692
(2007/10/02)
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- Synthesis and transformations of phosphorus imidazolidines (1,3-diaza-2-phospholidines)
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Four new derivatives of the phosphorus imidazolidine ring system have been prepared by animation of dichlorophosphines with variously N,N′-disubstituted ethylenediamines. The nmr spectra of the N-CH3 substituted rings show a sharp doublet for these protons and a multiplet for the methylene bridge protons, while the N-phenyl derivatives show a sharp doublet for the methylene bridge protons at 60 and 100 MHz contrary to expectations on the basis of the pyramidal stereochemistry of phosphorus(III). These observations are interpreted in terms of the stereochemistry and dynamics of the diazaphos-pholidine heterocycles. The phosphorus imidazolidines are transformed to their boron analogs in an exothermic reaction with phenylboron dichloride with the release of dichlorophosphine, but the reaction is not reversible. Treatment of the phosphorus ring with arsenic trichloride yields a solid whose mass spectrum shows a peak at the highest mass corresponding to the ten-membered ring dimer of the known arsenic imidazolidine.
- Das,Zuckerman
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p. 1028 - 1030
(2007/10/08)
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