Pseudo Halide Chemistry in Ionic Liquids with Decomposable Anions

Abstract

Several pseudohalide containing ionic liquids with quarternary ammonium counter cations of the general formula [R3MeN]X [R = ethyl (1X), n‐butyl (2X) with X– = CN–, N3–, OCN–, and SCN–] were synthesized by decomposition of the corresponding trialkylammonium methylcarbonate in the reaction with Me3Si–X. We also treated 2CN with OP(OMe)3, yielding [nBu3MeN][O2P(OMe)2] and acetonitrile (Me‐CN). The double salt [nBu3MeN]2{[B(OMe)3(CN)](CN)} was obtained from the reaction of 2CN with B(OMe)3, featuring the formation of the monocyanotrimethoxyborate anion, [B(OMe)3(CN)]–, co‐crystallized with [nBu3MeN]CN. [nBu3MeN]2{[B(OMe)3(CN)](CN)} was fully characterized including structure elucidation.

Synthesis of trans-stilbenes via phosphine-catalyzed coupling reactions of benzylic halides

“…These signals are assigned to a [B(OMe) x F 4− x ] − base complex. 26 The formation of [B(OMe) x F 4− x ] − is slow and the amount is small due to the low solubility of CsF in 1,4-dioxane. [B(OMe) x F 4− x ] − is regarded as a base with steric hindrance and can slowly release methoxyl ions.…”

The dialkylcarbonate route to ionic liquids: purer, safer, greener?

“…The methylcarbonate ionic liquids were then reacted with trimethylsilyl-X compounds to give ([N 2221 ][X]) and ([N 4441 ][X]) ionic liquids in a quantitative yield, avoiding residual water and halide. 97,98…”

Pseudohalogen Chemistry in Ionic Liquids with Non‐innocent Cations and Anions

“…[125] They were formed in autoclave reactions at autogenous pressure (Scheme 1), due to a modified reaction, which was first described by Werntz [126] and taken up again in later years by various working groups. [127][128][129] In a subsequent reaction we synthesized the pseudohalides of the type [R 3 MeN]X (R = Et, nBu: X = CN, N 3 , OCN, SCN; [123] R = nPr: X = CN) [124] and [Ph 3 MeP]CN, [125] by nucleophilic desilylation of trimethylpseudohalosilanes Me 3 Si-X with the reactive and non-innocent [CO 3 Me] À anion (Scheme 2), a reaction developed by Sundermeyer et al [129] Besides the pseudohalide salt, Me 3 Si-OMe and CO 2 were formed, whereby the latter can be removed from the reaction solution, which shifted the reaction equilibrium in favor of the products. The formation of the stable SiÀ O bond (444 kJ/mol) [130] is also a driving force of this reaction.…”

“…ILs from ILs with Decomposable Anions [123][124][125] We started this project with the synthesis of various trialkylmethylammonium-([R 3 MeN]: R = Et, nPr, nBu) [123,124] and methyltriphenylphosphonium methylcarbonates. [125] They were formed in autoclave reactions at autogenous pressure (Scheme 1), due to a modified reaction, which was first described by Werntz [126] and taken up again in later years by various working groups.…”

“…ILs [123] The Lewis acidities of trimethyl phosphate OP(OMe) 3 and trimethyl borate B(OMe) 3 were investigated towards the pure ILs [nBu 3 MeN]X (X = CN, N 3 , OCN, SCN), hopefully leading to new pseudohalide phosphates or borates. However, a reaction of [nBu 3 MeN]X with OP(OMe) 3 did not lead to the formation of new pseudohalide phosphates as hoped (Scheme 8, route A), but in all cases to methylation of the pseudohalide and to formation of [nBu 3 MeN][O 2 P(OMe) 2 ], which could be shown clearly by means of NMR spectroscopy (Scheme 8, route B).…”