Small change–large effect: An added para-methyl group on the aryl ring in the 1-aryl-3-alkyl-imidazolium motif of TAAILs leads to well-separated metal nanoparticles.
As et of new tunable aryl alkyl ionic liquids (TAAILs) based on the 1-aryl-3-alkyli midazolium motif has been synthesized, in which the following variables were systematically changed:a lkyl chain length, aryl substitution (group and position), and counter ion. TAAILs with dicyanamide (DCA) and bis(trifluoromethylsulfonyl)imide (N(SO 2 CF 3 ) 2 ,N Tf 2 )a nions showed remarkable differences of their physical properties:N Tf 2 ionic liquidsw ere found to have high decomposition temperatures andv iscositiesw ell below those of the DCA TAAILs. In contrast, the dicyanamide anion increased the electrochemical stabilityl eadingt o TAAILs with an extremely wide electrochemical window of up to 7.17 V. Additionally,b oth classes of TAAILs extract transition metalsf rom aqueous solutions:T AAILs with the DCA anion extract both platinum andc opperw hile TAAILs with the NTf 2 anion are selective towards platinum. Thisd emonstratest hat minor changes of the molecular structure lead to TAAILs with drastically changed physicochemical properties.
Tunable aryl alkyl ionic liquids (TAAILs) are a promising class of imidazolium-or triazolium-based ionic liquids. Contrary to "standard" all-alkyl ionic liquids, these carry an aryl ring together with a linear or branched alkyl chain. Their application in the cobalt-catalyzed hydroarylation/hydroamination of alkenes and anilines is presented. The catalytic system is tolerant toward air and is scalable and reusable. It has been successfully used for the synthesis of pharmacologically relevant primary to tertiary aryl amines.
Substituted imidazolium ionic liquids (ILs) were investigated for their reactivity towards Na12Ge17 as a model system containing redox‐sensitive Zintl cluster anions. The ILs proved widely inert for imidazolium cations with a 1,2,3‐trisubstitution at least by alkyl groups, and for the anion bis(trifluoromethylsulfonyl)azanide (TFSI). A minute conversion of Na12Ge17 observed on long‐time contact with such ILs was not caused by dissolution of the salt‐like compound, and did thus not provide dissolved Ge clusters. Rather, a cation exchange led to the transfer of Na+ ions into solution. In contrast, by using benzophenone as an oxidizer, heterogeneous redox reactions of Na12Ge17 were initiated, transferring a considerable part of Na+ into solution. At optimized conditions, an X‐ray amorphous product NaGe6.25 was obtained, which was thermally convertible to the crystalline type‐II clathrate Na24–δGe136 with almost completely Na‐filled polyhedral cages, and α‐Ge. The presented method thus provides unexpected access to Na24–δGe136 in bulk quantities.
Vaporization enthalpies of five different imidazolium based Tunable Aryl Alkyl Ionic Liquids (TAAILs) with a common bis(trifluoromethylsulfonyl)imide ([NTf2]) anion were measured using a Quartz Crystalline Microbalance (QCM) and by Thermogravimetric Analysis (TGA). The counter anion and the alkyl chain of these imidazolium‐based ionic liquids with one N‐aryl and one N‐alkyl substituent were kept constant to study the influence of the ortho‐ and para‐substituted aryl moieties on the vaporization enthalpies of these ionic liquids. For comparison, enthalpies of vaporization measured at elevated temperatures were adjusted to the reference temperature 298 K. Structure‐property relations between TAAILs and similarly shaped corresponding 1‐(R‐phenyl)‐imidazoles were analyzed. An incremental approach to predict vaporization enthalpies of ionic liquids by group contributions was suggested. The procedure is based on vaporization enthalpy of a starting IL and group contributions well established from molecular compounds.
Tunable aryl alkyl ionic liquids (TAAILs) based on the imidazolium cation were first reported in 2009. Since then, a series of TAAILs with different properties due to the electron-donating or -withdrawing effect of the substituents at the aryl ring has been developed. Herein, a wide variety of those ionic liquids (ILs) is presented in terms of their cation structure. The authors synthesized ILs containing the bromide or bis(trifluoromethane)sulfonimide anion and 1-aryl-3-alkyl imidazolium cations with various substituents in the ortho and/ or para position of the phenyl ring and alkyl chains of different lengths varying from butyl to dodecyl. The differences of their physical properties (melting point, thermal decomposition, viscosity, electro-chemical window) of these ILs are reported according to their structure.
The
anionic complex [NBu4][Pd(DMSO)Cl3],
which can be synthesized on a gram scale in a single step starting
from commercially available starting materials, has been shown to
be an active catalyst in the Mizoroki–Heck reaction of aryl
halides. We present two new catalytic applications of this complex:
the base-free oxidative Heck reaction and the reductive homodimerization
of aryl halides. This complex outperformed other palladium salts.
In the latter reaction, the catalyst loading could be reduced to 0.01
mol %. The scope of the reactions has been explored, demonstrating
the potential of the anionic palladium complex in these catalytic
transformations.
Functionalized imidazolium cations were combined with the hexacyanidosilicate anion, [Si(CN) 6 ] 2-, by salt metathesis reactions with K 2 [Si(CN) 6 ], yielding novel ionic compounds of the general formula [R-Ph(nBu)Im] 2 [Si(CN) 6 ] {R = 2-Me (1), 4-Me (2), 2,4,6-Me = Mes (3), 2-MeO (4), 2,4-F (5), 4-Br (6); Im = imidazolium}. All synthesized imidazolium hexacyanidosilicates decompose upon thermal treatment above 95°C (96-164°C).
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