Ionic liquids as catalytic “green” reactants and solvents for nucleophilic conversion of fatty alcohols to alkyl halides

Understanding Organic Processes in Ionic Liquids: Achievements So Far and Challenges Remaining

“…At the extreme, the outcome of reactions may not only vary from that observed in molecular solvents, but between different ionic liquids as well (Scheme 1) [27]. While the latter effect may often be explained in terms of the reactivity of the components of the ionic liquid (demonstrated for the cation in Baylis-Hillman processes [28] and the anion in nucleophilic substitution processes [27,29] and dediazoniation [30]) it is important to recognize that there are limited reports detailing the origin of the changes in reaction outcome between molecular and ionic solvents. In contrast, the relationship between the character of a molecular solvent and the outcome of a reaction is generally well-understood [31]; undergraduates are taught these principles so they can choose appropriate solvents for a given reaction.…”

Halogenation of organic compounds in ionic liquids

“…In continuation, they investigated structurally modified PSILs for nucleophilic reactions, including bromination (Scheme 31), by varying the length of the alkyl chain linker, the IL counterion and the loading level on the PS. 18 For the bromination of 1a, they employed 3 equiv of KBr at 100 ]). The reactions utilizing the PSIL system with the longest linker procceded most efficiently, affording the bromoalkane 2e almost quantitatively (99%).…”

“…Due to the low solubility of fatty alcohols in [bmim][Br] and [Pr i mim][Br], the formation of alkyl bromides possessing longer alkyl chains (C 8 -C 18 ) requires the use of a more lipophilic IL. For such instances, 1-octyl-3-methylimidazolium bromide ([omim][Br]) in the presence of PTSA was shown to be efficient for the transformation of fatty alcohols (C 8 -C 18 ) into the corresponding alkyl bromides, either under conventional heating at around 100 C for 1 h(Table 15, entry 4), or under MW irradiation (75 W) for a few seconds to a few minutes(Table 15, entry 5) 100. Furthermore, the reagent system [omim][Br]/PTSA was efficiently utilized for the conversion of 1,u-dialcohols (C 6 -C 16 ) into the corresponding dibromides.…”

Introduction of Halogen Atoms into Organic Compounds Under Solvent- Free Reaction Conditions

“…Various other 1-alkyl-3-methylimidazolium iodides were used for transformation of fatty diols I36 under SFRC. PTSA was used as the acid (Scheme I11) and high yields of diiodides I37 were formed by either heating (110°C, 2h) or after a short MW irradiation [106,107]. Scheme I11.…”

“…Fatty diols B102 were transformed to dibromides with the 1-alkyl-3-methylimidazolium bromide/PTSA couple. Reaction was performed at 110°C for 2 hours under SFRC, but reaction times could be shortened drastically using MW irradiation [106,107].…”