931-78-2Relevant academic research and scientific papers
Metal-free regioselective hydrochlorination of unactivated alkenes via a combined acid catalytic system
Liang, Shengzong,Hammond, Gerald B.,Xu, Bo
supporting information, p. 680 - 684 (2018/02/14)
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.
Silica gel-mediated hydrohalogenation of unactivated alkenes using hydrohalogenic acids under organic solvent-free conditions
Tanemura, Kiyoshi
supporting information, p. 4293 - 4298 (2018/11/10)
Silica gel-mediated hydrochlorination of unactivated alkenes using 35% hydrochloric acid under organic solvent-free conditions proceeded to give the corresponding chlorides in good yields. Hydrobromination or hydriodination using 47% hydrobromic acid or 55% hydriodic acid afforded the corresponding halides, respectively. Silica gel could be recycled five times without any significant loss of activities.
Site-Selective Aliphatic C-H Chlorination Using N-Chloroamides Enables a Synthesis of Chlorolissoclimide
Quinn, Ryan K.,K?nst, Zef A.,Michalak, Sharon E.,Schmidt, Yvonne,Szklarski, Anne R.,Flores, Alex R.,Nam, Sangkil,Horne, David A.,Vanderwal, Christopher D.,Alexanian, Erik J.
, p. 696 - 702 (2016/02/03)
Methods for the practical, intermolecular functionalization of aliphatic C-H bonds remain a paramount goal of organic synthesis. Free radical alkane chlorination is an important industrial process for the production of small molecule chloroalkanes from simple hydrocarbons, yet applications to fine chemical synthesis are rare. Herein, we report a site-selective chlorination of aliphatic C-H bonds using readily available N-chloroamides and apply this transformation to a synthesis of chlorolissoclimide, a potently cytotoxic labdane diterpenoid. These reactions deliver alkyl chlorides in useful chemical yields with substrate as the limiting reagent. Notably, this approach tolerates substrate unsaturation that normally poses major challenges in chemoselective, aliphatic C-H functionalization. The sterically and electronically dictated site selectivities of the C-H chlorination are among the most selective alkane functionalizations known, providing a unique tool for chemical synthesis. The short synthesis of chlorolissoclimide features a high yielding, gram-scale radical C-H chlorination of sclareolide and a three-step/two-pot process for the introduction of the β-hydroxysuccinimide that is salient to all the lissoclimides and haterumaimides. Preliminary assays indicate that chlorolissoclimide and analogues are moderately active against aggressive melanoma and prostate cancer cell lines.
Synthesizing method of pesticide intermediate 1-methylcyclohexanecarboxylic acid
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Paragraph 0019; 0020, (2017/06/02)
The invention discloses a synthesizing method of a pesticide intermediate 1-methylcyclohexanecarboxylic acid. The 1-methylcyclohexanecarboxylic acid is prepared by taking 2-methylcyclohexanol, formic acid and an R-Cl halogenating reagent as the raw materials through halogenation and substitution reactions by means of a one-pot method. The synthesizing method is novel, the defects in a traditional production process can be overcome, emission of waste acid water is reduced, the production capacity is enlarged, and the synthesizing method is green and environmentally friendly.
Kinetics and mechanism of unimolecular heterolysis of cage-like compounds: XIX. Effect of the nucleofuge nature on the activation parameters of heterolysis of 1-halo-1-methylcyclohexanes in cyclohexane. Heterolysis rate ratio in aprotic and protic solvents
Dvorko,Koshchii,Ponomareva
, p. 50 - 55 (2007/10/03)
Heterolysis of 1-bromo-1-methylcyclohexane in cyclohexane (E1 reaction) involves solvation of the transition state (ΔS≠ = -81 J mol-1K-1), while heterolysis of 1-chloro-1- methylcyclohexane is characterized by desolvation of the transition state (ΔS≠ = 92 J mol-1K-1). The probability for the formation of transition state (interaction between cationoid intermediate and solvent cavity) increases in the first case due to enhanced stability of the solvated intermediate, and in the second, due to reduction in its size. The bromide/chloride heterolysis rate ratio decreases as the ionizing power of aprotic solvent decreases and that of protic solvent increases.
A remarkably efficient Markovnikov hydrochlorination of olefins and transformation of nitriles into imidates by use of AcCl and an alcohol
Yadav, Veejendra K.,Babu, K. Ganesh
, p. 452 - 456 (2007/10/03)
HCl generated by mixing AcCl with EtOH brings about Markovnikov hydrochlorination of olefins in excellent yields. The products are isolated in states of high purity simply by removal of the volatile components under reduced pressure. Further, nitriles are transformed into imidate hydrochlorides on similar treatment with AcCl and an alcohol. This procedure for nitrile-imidate transformation is much more efficient than that used previously, which involved continuous passing of HCl gas into the solution of a nitrile in a solvent such as Et2O or benzene and an alcohol until one equivalent had been absorbed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
Reactivity of bismuth(III) halides towards alcohols. A tentative to mechanistic investigation
Keramane, El Mehdi,Boyer, Bernard,Roque, Jean-Pierre
, p. 1909 - 1916 (2007/10/03)
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).
Formation of three-membered rings by SHi displacement. Reverse of cyclopropyl ring opening
Tanner, Dennis D.,Zhang, Liying,Hu, Li Qing,Kandanarachchi, Pramod
, p. 6818 - 6824 (2007/10/03)
The general methods, photoinitiated or peroxide-initiated free radical chain additions of halomethanes to olefins, yield 1,2-addition products at temperatures ranging from 20 to 100°C. At lower temperatures, -42 to -104°C, a competitive reaction, subsequent to the addition of CCl2X., yields alkylcyclopropanes. The reactions of 1-octene or 1-hexene and 1-methylcyclohexene with atomic hydrogen carried out in the presence of several transfer agents (CCl4, CCl3Br, CCl2Br2) initiate a radical chain addition of CCl2X. and yield cyclized materials resulting from the SHi displacement of halogen by a carbon-centered radical. The radical displacement of a halogen on carbon, the reverse of homolytic displacement on cyclopropyl carbon, is dominant at low temperatures. The rate constants for cyclization (kc) vs transfer with halomethane (kt) showed isokinetic temperatures of -46°C (CCl4, 1-hexene); -35°C (CCl4, 1-methylcyclohexene). The isokinetic temperatures for the reactions of the two substrates carried out in the presence of BrCCl3 were calculated as -204 °C (1-octene) and -109°C (1-methylcyclohexene).
The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
, p. 217 - 254 (2007/10/02)
In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
Surface-mediated reactions. 3. Hydrohalogenation of alkenes
Kropp, Paul J.,Daus, Kimberlee A.,Tubergen, Mark W.,Kepler, Keith D.,Wilson, Vincent P.,Craig, Stephen L.,Baillargeon, Michelle M.,Breton, Gary W.
, p. 3071 - 3079 (2007/10/02)
Appropriately prepared silica gel and alumina have been found to mediate the addition of HCl, HBr, and HI to alkenes. The technique has been rendered even more convenient by the use of various organic and inorganic halides that undergo hydrolysis in the presence of silica gel or alumina to generate hydrogen halides in situ. Under these conditions alkenes such as cycloheptene (1), 1-octene (7), and 3,3-dimethyl-1-butene (15), which react with HCl only very slowly in solution, underwent rapid addition. 1-Octene (7) underwent ionic addition of HBr without competing radical addition. 1,2-Dimethylcyclohexane (24) afforded the syn addition product 25c, which underwent equilibration with the thermodynamically more stable isomer 25t. A mechanism for surface-mediated addition/elimination is proposed involving a stepwise transfer of H+ and X- from or to the surface in syn fashion, as shown in Scheme II.
