- THE MECHANISM OF 2-METHYLBUTENE-2 HYDROHALOGENATION IN SOLID PHASE
-
Complexes and reactions of 2-methylbutene-2 with hydrohalogen (HCl, HBr) have been studied in solid phase at 80-150 deg K.It has been found that 2-methylbutene-2 forms with HX complexes of 1:1 and 1:2 composition.Hydrohalogenation proceeds via the rearrangement of complex 2HX*C5H10 into complex of addition product with HX.Kinetic equation depends on the reagents ratio.In excess of HX (1HX:C5H1010)reaction can be described by the first order kinetic equation.If the ratio HX:C5H10 is more then 10, reaction is described by polychronous kinetic law.The effective activation energy of solid phase hydrohalogenation does not exceed 20 kJ/mole.The molecular mechanism of hydrohalogenation in solid phase has been proposed
- Sergeev, G. B.,Smirnov, V. V.,Rostovshchikova, T. N.,Komissarovan N. V.,Indoleva, Ye. V.
-
-
Read Online
- Determination and interpretation of second order rate constants for the addition of hydrogen halides to alkenes
-
An extensive range of second order rate constants for the addition of hydrogen halides to alkenes in 98% v/v ethanoic acid (acetic acid)-water have been obtained by conductivity measurements. The rate constants are in the expected order of HF HCl HBr HI. The rates with different alkenes cannot be rationalised solely by a consideration of carbocation stability and it has been necessary to consider steric effects in order to explain the observed order.
- Borgeaud, Robert,Newman, Henry,Schelpe, Arabella,Vasco, Veronica,Peter Hughes
-
-
Read Online
- Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
-
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
-
supporting information
p. 14399 - 14403
(2020/07/13)
-
- Synthesis method of tert-amylbenzene with controllable isomer content
-
The invention provides a synthesis method of tert-amylbenzene with controllable isomer content. The synthesis method comprises the following steps: 1) carrying out a substitution reaction on tert-amylalcohol and haloid acid to obtain a halopentane intermediate; 2) carrying out a Friedel-Crafts alkylation reaction on the halopentane intermediate and benzene under the catalysis of a Lewis acid to obtain tert-amylbenzene; wherein the Lewis acid is one of ZnCl2 and FeCl3 or a mixture of the ZnCl2 and the FeCl3; the temperature of the Friedel-Crafts alkylation reaction is -10 to 40 DEG C; the vacuum degree is absolute pressure of 2-75kPa; and the reaction time is 0.5-4 h. According to the synthesis method, by setting reasonable reaction steps, controlling reaction conditions, selecting a proper catalyst and the like, the isomerization ratio is reduced, and the tert-amyl product with high yield and high selectivity is obtained.
- -
-
Paragraph 0027-0028
(2020/06/17)
-
- 1,2-Dibromotetrachloroethane: An efficient reagent for many transformations by modified Appel reaction
-
An efficient and facile method has been developed for the synthesis of alkyl bromides from various alcohols under mild conditions using a triphenylphosphine (PPh 3) /1,2-dibromotetrachloroethane (DBTCE) complex in excellent yields and very short time (5 min). This method can also be applied for the transformation of chiral alcohols to their corresponding bromides in very high enantiomeric excess. The PPh 3 /DBTCE complex is also successfully applied to ring-opening reactions of cyclic ethers in mild conditions. Esterification, amidation, and formation of acid anhydrides under very mild experimental conditions are also successfully accomplished by following a modification of the Appel reaction protocol in this work.
- Essiz, Sel?uk,Da?tan, Arif
-
p. 150 - 156
(2019/05/16)
-
- BiX3 as an efficient and selective reagent for the halogen exchange reaction
-
Bismuth halides are efficient and selective reagents in the halogen exchange reactions carried out under mild conditions. This rapid, high yield reaction proceeds mainly with retention of configuration.
- Boyer, Bernard,Keramane, El Mehdi,Arpin, Severine,Montero, Jean-Louis,Roque, Jean-Pierre
-
p. 1971 - 1976
(2007/10/03)
-
- Esterification of carboxylic acid salts
-
Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
- -
-
-
- Selective C-H activation of alipathic hydrocarbons under phase-transfer conditions
-
Bromination of alipathic hydrocarbons with NaOH/CBr4 under phase-transfer conditions selectively gives the tertiary bromide. In the absence of a tertiary C-H bond in the molecule, a secondary bond will be activated (see reaction equation). This conceptionally new system for alipathic C-H activation very likely relies on the initiation of single-electron transfer followed by a radical substitution with unusually high regioselectivity.
- Schreiner, Peter R.,Lauenstein, Oliver,Kolomitsyn, Igor V.,Nadi, Suad,Fokin, Andrey A.
-
p. 1895 - 1897
(2007/10/03)
-
- Reactivity of Alkaneselenyl Bromide: Conversion of Alcohols into the Corresponding Alkyl Bromides with Dialkylselenium Dibromide
-
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
-
p. 3482 - 3484
(2007/10/02)
-
- A CONVENIENT AND EFFICIENT METHOD FOR THE CONVERSION OF ALKYL CHLORIDES TO THE CORRESPONDING BROMIDES
-
Reaction of representative alkyl chlorides (involving primary, secondary and tertiary substrates as also a dichloide) with stoechiometric amount of lithium bromide in the presence of a transfer agent (5percent Aliquat 336) without any added solvent, resulted in high conversions into the corresponding bromides under convenient and economical conditions.
- Loupy, Andre,Pardo, Claude
-
p. 1275 - 1282
(2007/10/02)
-
- SELECTIVE HYDROBROMINATION OF BRANCHED ALCOHOLS USING PHASE TRANSFER CATALYSIS
-
In the presence of quaternary ammonium phase transfer catalysts hydrobromination of branched alcohols proceed via selective SN2 mechanism practically without rearrangements.
- Dakka, Gihad,Sasson, Yoel
-
p. 1223 - 1224
(2007/10/02)
-
- ANOMALOUS ORIENTATION EFFECTS DURING BENZOYLOXYLATIONS BY "SILVER BROMIDE DIBENZOATE"
-
The solid complex formed from bromine and silver benzoate reacts with both arenes and alkenes to form aryl and alkyl benzoates, respectively.Highly unusual substituent effects are observed in the benzoyloxylations of arenes.Electron-withdrawing groups (e.g. -NO2, -CN,-CO-) on the aromatic ring facilitate reaction though directing the attacking reagent exclusively to the meta position.In alkanes, tertiary positions are most prone to attack.
- Bryce-Smith, Derek,Isaacs, Neil S.,Tumi, Seddeg O.
-
p. 1471 - 1472
(2007/10/02)
-
- Silylaminyl Radicals. Part 2. Free Radical Chain Halogenation of Hydrocarbons using N-Halogenobis(trialkylsilyl)amines
-
The liquid-phase halogenation of a number of hydrocarbons and of 1-chlorobutane by N-halogenobis(trialkylsilyl)amines has been studied using product analysis techniques.The reactions take place by free radical chain mechanisms which involve the propagation steps generalised in equations (A) and (B) (X=Br or Cl).At 353 K, the molar reactivities of toluene (benzylic C-H) and cyclohexane towards (R3Si)2N+RH(R3Si)2NH+R (A) R+(R3Si)2NXRX+(R3Si)2N (B) (Me3Si)2N are approximately equal and toluene is 5.2 times more reactive than perdeuteriotoluene.The relative rates of hydrogen abstraction by (Me3Si)2N and (ButMe2Si)2N from the primary, secondary, and tertiary C-H groups in 2-methylbutane show that the silylaminyl radicals are not only highly reactive but also sterically demanding.Thus, at 333 K the average primary C-H reactivity is 0.6 times that of the tertiary C-H towards attack by (Me3Si)2N, but 4.2 times that of the tertiary C-H towards attack by the more bulky (ButMe2Si)2N.Silylaminyl radicals are much more reactive in hydrogen abstraction than are analogous dialkylaminyl radicals and this difference is interpreted in terms of thermodynamic and polar effects which arise because of the ?-donor-?-acceptor nature of the trialkylsilyl substituent.
- Cook, Malcolm D.,Roberts, Brian P.,Singh, Karamjit
-
p. 635 - 644
(2007/10/02)
-
- Arbuzov Reaction of Alkyl and Silyl Phosphites with Halogens involving Four- and Five-co-ordinate Intermediates
-
Low temperature 31P n.m.r. spectroscopy and chemical data have been applied to elucidate the mechanism of the Arbuzov-type reaction between phosphites and halogens.Simple and substituted trialkyl, alkyl 1,2-phenylene, and trisilyl phosphites have been allowed to react with chlorine, bromine, and iodine.In some cases intermediate halogenophosphonium salt (2) and in others halogenophosphoranes (3) are observed which then decompose into the corresponding pure highly reactive phosphorohalidates (4).It was possible to prepare stable phosphonium salts from halogenophosphonium salts (2) and halogenophosphoranes (3).
- Michalski, Jan,Pakulski, Marek,Skowronska, Aleksandra
-
p. 833 - 836
(2007/10/02)
-
- A Convenient Method for the Preparation of Highly Pure t-Alkyl Bromides and Iodides
-
Highly pure (99-100 percent) t-butyl and t-pentyl bromides and iodides, and 3-bromo-3-ethylpentane were readily prepared in 83-95 percent yields by the reactions of the corresponding alcohols with hydrobromic or hydroiodic acid, using lithium or calcium halide.The metal halides remarkably increased the yield and the purity of the products.
- Masada, Hiromitsu,Murotani, Yoshiharu
-
p. 1181 - 1182
(2007/10/02)
-
