672-65-1Relevant articles and documents
Room temperature living cationic polymerization of styrene with HX-styrenic monomer adduct/FeCl3 systems in the presence of tetrabutylammonium halide and tetraalkylphosphonium bromide salts
Banerjee, Sanjib,Paira, Tapas K.,Kotal, Atanu,Mandal, Tarun K.
, p. 1258 - 1269 (2010)
Living cationic polymerization of styrene was achieved with a series of initiating systems consisting of a HX-styrenic monomer adduct (X?=?Br, Cl) and ferric chloride (FeCl3) in conjunction with added salts such as tetrabutylammonium halides (nBu4N+Y-; Y-?=?Br-, Cl-, I-) or tetraalkylphosphonium bromides [nR′4PBr; R′?=?CH3CH2-, CH3(CH2)2CH2-, CH3(CH2)6CH2-] or tetraphenylphosphonium bromide [(C6H5)4PBr] in dichloromethane (CH2Cl2) and in toluene. Comparison of the molecular weight distributions (MWDs) of the polystyrenes prepared at different temperatures (e.g., -25?°C, 0?°C and 25?°C) showed that the polymerization is better controlled at ambient temperature (25?°C). The polymerization was almost instantaneous (completed within 1?min) and quantitative (yield ～100%) in CH2Cl2. In CH2Cl2, polystyrenes with moderately narrow (Mw/Mn?～?1.33-1.40) and broad (Mw/Mn?～?1.5-2.4) MWDs were obtained respectively with and without nBu4N+Y-. However, in toluene, the MWDs of the polystyrenes obtained respectively with and without nBu4N+Y-/nR′4P+Br- were moderately narrow (Mw/Mn?=?1.33-1.5) and extremely narrow (Mw/Mn?=?1.05-1.17). Livingness of this polymerization in CH2Cl2 was confirmed via monomer-addition experiment as well as from the study of molecular weights of obtained polystyrenes prepared simply by varying monomer to initiator ratio. A possible mechanistic pathway for this polymerization was suggested based on the results of the 1H NMR spectroscopic analysis of the model reactions as well as the end group analysis of the obtained polymer.
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Diaz,Blanco
, p. 1313 (1974)
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The Chloroiodination of Deactivated Olefins with Antimony (V) Chloride-Iodine and Iodine Monochloride
Uemura, Sakae,Fukuzawa, Shin-ichi,Okano, Masaya,Sawada, Seiji
, p. 1390 - 1392 (1980)
By the reactions of olefins with an equimolar mixture of SbCl5 and I2 in carbon tetrachloride, various chloroiodoalkanes are obtained in fair to good yields.This method is applicable to various deactivated olefins, the reactions of which to not proceed by the reported method using a mixture of CuCl2 and I2.Iodine monocloride can also be used for this reaction, but in this case both the yield and the regiospecificity of the products are sometimes inferior.
Nickel-Catalyzed Multicomponent Coupling: Synthesis of α-Chiral Ketones by Reductive Hydrocarbonylation of Alkenes
Chen, Jian,Zhu, Shaolin
supporting information, p. 14089 - 14096 (2021/09/13)
A nickel-catalyzed, multicomponent regio- and enantioselective coupling via sequential hydroformylation and carbonylation from readily available starting materials has been developed. This modular multicomponent hydrofunctionalization strategy enables the straightforward reductive hydrocarbonylation of a broad range of unactivated alkenes to produce a wide variety of unsymmetrical dialkyl ketones bearing a functionalized α-stereocenter, including enantioenriched chiral α-aryl ketones and α-amino ketones. It uses chiral bisoxazoline as a ligand, silane as a reductant, chloroformate as a safe CO source, and a racemic secondary benzyl chloride or an N-hydroxyphthalimide (NHP) ester of a protected α-amino acid as the alkylation reagent. The benign nature of this process renders this method suitable for late-stage functionalization of complex molecules.
Lewis Base Catalysis Enables the Activation of Alcohols by means of Chloroformates as Phosgene Substitutes
Zoller, Ben,Stach, Tanja,Huy, Peter H.
, p. 5637 - 5643 (2020/09/21)
Nucleophilic substitutions (SN) are typically promoted by acid chlorides as sacrificial reagents to improve the thermodynamic driving force and lower kinetic barriers. However, the cheapest acid chloride phosgene (COCl2) is a highly toxic gas. Against this background, phenyl chloroformate (PCF) was discovered as inherently safer phosgene substitute for the SN-type formation of C?Cl and C?Br bonds using alcohols. Thereby, application of the Lewis bases 1-formylpyrroldine (FPyr) and diethylcyclopropenone (DEC) as catalysts turned out to be pivotal to shift the chemoselectivity in favor of halo alkane generation. Primary, secondary and tertiary, benzylic, allylic and aliphatic alcohols are appropriate starting materials. A variety of functional groups are tolerated, which includes even acid labile moieties such as tert-butyl esters and acetals. Since the by-product phenol can be isolated, a recycling to PCF with inexpensive phosgene would be feasible on a technical scale. Eventually, a thorough competitive study demonstrated that PCF is indeed superior to phosgene and other substitutes.
