110-53-2Relevant articles and documents
Silica Supported Acids (HClO4-SiO2, KHSO4-SiO2) as Eco-friendly Reusable Catalysts for Bromodecarboxylation of α,β-Unsaturated Carboxylic Acids using KBr under Solvothermal and Solvent-Free Conditions
Arisha, Samba Shiva Rao,Gugulothu, Yaku,Kamatala, Chinna Rajanna,Nagannagari, Maasi Reddy,Pulusu, Vijay Shekar,Utkoor, Umesh Kumar,Yelike, Hemanth Sriram
, p. 535 - 542 (2022/02/22)
A mild procedure has been developed for the bromodecarboxylation of α,β-carboxylic acids using nano silica supported SiO2-HClO4, SiO2-KHSO4 as catalysts and KBr as a bromine source in conventional solvothermal, ultrasonic assisted and solvent-free microwave assisted conditions. The α,β-unsaturated cinnamic acids were converted to corresponding β-bromo styrenes with high regioselectivity, while aliphatic α,β-unsaturated carboxylic acids afforded related β-bromo alkenes.
Rethinking Basic Concepts-Hydrogenation of Alkenes Catalyzed by Bench-Stable Alkyl Mn(I) Complexes
Weber, Stefan,St?ger, Berthold,Veiros, Luis F.,Kirchner, Karl
, p. 9715 - 9720 (2019/10/14)
An efficient additive-free manganese-catalyzed hydrogenation of alkenes to alkanes with molecular hydrogen is described. This reaction is atom economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. The most efficient precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid hydrogenolysis to form the active 16e Mn(I) hydride catalyst [Mn(dippe)(CO)2(H)]. A range of mono- A nd disubstituted alkenes were efficiently converted into alkanes in good to excellent yields. The hydrogenation of 1-alkenes and 1,1-disubstituted alkenes proceeds at 25 °C, while 1,2-disubstituted alkenes require a reaction temperature of 60 °C. In all cases, a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar were applied. A mechanism based on DFT calculations is presented, which is supported by preliminary experimental studies.
An efficient conversion of alcohols to alkyl bromides using pyridinium based ionic liquids: A green alternative to appel reaction
Das, Pranab J.,Das, Jupitara,Das, Dimpee
, p. 651 - 654 (2018/02/09)
Pyridinium based ionic liquids namely 4-alkylpyridinium bromides were prepared and used for the conversion of alcohols to alkyl bromides in the presence of p-toluenesulphonic acid in the absence of volatile organic compounds. This solvent free procedure promises to be a much improved and environmentally benign alternative to the Appel reaction.
Facile continuous process for gas phase halogen exchange over supported alkyl phosphonium salts
Sharma, Priti,Sasson, Yoel
, p. 2824 - 2828 (2018/02/06)
Chloride-bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.
A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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
, p. 420 - 430 (2015/12/31)
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.
Influence of substructures on the spreading ability and hydrolysis resistance of double-tail trisiloxane surfactants
Peng, Zhongli,Lu, Caifeng,Xu, Minling
scheme or table, p. 75 - 81 (2012/01/05)
Four types of novel double-tail trisiloxane surfactants of the general formula Me3SiOSiMeR1 OSiMe3 (R1 = -(CH2)3NR2 CH2CH(OH)CH 2(OCH2CH2)xOCH3; R 2 = -CH2CH(OH)CH2OCH2 (CH 2)yCH3, -CH2 (CH2) 3CH3, -CH2CH2CH(CH3) 2; x = 8.4, 12.9, 17.5, 22; y = 2, 6), have been synthesized. Their structures were characterized by proton and carbon nuclear magnetic resonance. Most of them are able to reduce the surface tension of water to less than 24 mN/m at concentration levels of 10-5 mol/L and 10-4 mol/L. The emphasis was on the influence of substructures on their spreading ability and hydrolysis resistance. The results showed that a weaker hydrophilicity of a surfactant molecule, a larger molar ratio of methyl to methylene in the whole hydrophobic groups, more flexible hydrophobic groups and introduction of a methyl group in the spacer can all improve the spreading ability of the double-tail trisiloxane surfactant solutions on low-energy solid surfaces. The double-tail trisiloxane surfactants 1F and 2F are stable for more than 270 days in a neutral environment (pH 7.0). The hydrolysis resistance of the double-tail trisiloxane surfactants can be improved by a weaker hydrophilicity of the surfactant molecule, and a larger volume of the hydrophobic groups. Copyright
Lithium carbenoids-ultra-reactive yet selective reagents for methylenation and halomethylenation of sulfones
Pearlman, Bruce A.,Putt, Sterling R.,Fleming, Jeffrey A.
, p. 5646 - 5657 (2007/10/03)
The first efficient, one-pot method for methylenation of p-toluyl sulfones (i.e., the transformation of p-MePhSO2CHR2 into R 2CCH2) is described. Methods for effecting that transformation involving alkylation of sulfones with reagents of the general formula MCH2X, where M = SiMe3, SnR3, and MgCl (the Julia method) have been previously described. However, the silicon reagent is completely unreactive toward many sulfones, the tin reagent typically affords only moderate yields, and the magnesium reagent typically gives incomplete reaction (9-40% starting material). This article reports that excellent yields are obtained by alkylating the sulfone with the more ionic lithium methylene carbenoids (LiCH2X, where X = Cl, Br, and I). For example, treatment of sulfone 1 with 3 equiv of n-BuLi (THF, -100 °C) followed by 2 equiv of CH2Br2 affords olefin 2 in 96% yield. Although the carbenoid is generated in the presence of a 1:2 mixture of α-lithio- sulfone and n-BuLi, it reacts selectively with the α-lithio-sulfone (Krel = 9.6 ± 0.8 with LiCH2Br). The chlorocarbenoid LiCH2Cl reacts somewhat less selectively (K rel = 3.5). The alkylsubstituted carbenoid n-BuCHBrLi reacts ≥ 40 times more slowly than LiCH2Br, suggesting that olefination occurs by the SN2 mechanism rather than by metal-assisted ionization (MAI), the mechanism by which cyclopropyl and vinylidene carbenoids react with nucleophiles. Finally, sulfones can be transformed into vinyl halides by treatment with 3 equiv of n-BuLi (THF, -78 °C), followed by >2 equiv of diisopropylamine, followed by 3 equiv of dihalomethane (CH2X 2, where X2 = Cl2, BrCl, Br2, or I2). All products are formed in high yield and purity.
Direct bromination and iodination of non-activated alkanes by hypohalite reagents
Montoro, Raul,Wirth, Thomas
, p. 1473 - 1478 (2007/10/03)
The direct functionalisation of alkanes through bromination and iodination has been successfully achieved. The combination of stoichiometric mixtures of elemental halogen and sodium alkoxides leads to the formation of alkyl hypobromites and hypoiodites as reagents. The halogenation occurs without external photostimulation under thermal reaction conditions. Georg Thieme Verlag Stuttgart.
Direct halogenation of alcohols and their derivatives with tert-Butyl halides in the ionic liquid [pmIm]Br under sonication conditions - A novel, efficient and green methodology
Ranu, Brindaban C.,Jana, Ranjan
, p. 755 - 758 (2007/10/03)
A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert-Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one-pot fashion by this procedure. A plausible rationale for this transformation is also presented. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
Synthesis of 2-γ-N-(aminoethyl)aminopropyl-2-methyl-6-alkyl(aryl,H)-1,3-dioxa-6- aza-2-silacyclooctanes
Yang,Lin,Li
, p. 2817 - 2822 (2007/10/03)
Some new 2-γ-N-(aminoethyl)aminopropyl-2-methyl-1,3-dioxa-6-aza-2- silacyclooctane and 2-γ-N-(aminoethyl)aminopropyl-2-methyl-6-alkyl(aryl)-1,3-dioxa-6-aza- 2-silacyclooctanes have been synthesized from γ-chloropropyldimethoxymethyl silane by ethylenediamine substitution and diethanolamine or N-alkyl(aryl)diethanolamines substitution. The resulting silocanes have been characterized by elemental analyses, IR, and 1H NMR.
