3.3- Dimethyl-l-butyl cation

In view of these results, it is surprising that no rearrangement occurs during the aluminium chloride-catalyzed reaction of terf-butyl chloride with ethylene [97]. The intermediacy of a primary carbocation can, therefore, be ruled out and the selective formation of 18 may be rationalized by assuming the intermediacy of a bridged cation (tert-butyl-bridged ethylene). Alternatively, the attack of the /er/-butyl cation at ethylene may be nucleophilically assisted by the AIC14 ion because of the low stability of the 3,3-dimethyl-l-butyl cation (Scheme 22) [98],... 

Methyl vinyl ketone (entry 3) and the tert-butyl cation (entry 4) are also reactive toward complex 3. The naphthalenium complexes resulting from the addition of these electrophiles will add the conjugate base of dimethyl malonate (generated in situ from a combination of dimethyl malonate (DMM) and diisopropylethylamine (DIEA)) to complete the tandem additions. Oxidation of the resulting complexes yields cis-l,4-dihydronaphthalenes. The entire sequence of complexation, tandem addition, and demetalation employed for all entries in Table 4 can be performed using bench-top conditions (i.e., a non-inert atmosphere). 

Fig. 6.2 Voltammetry of the pure l-butyl-2,3-dimethyl imidazolium ionic liquids with (1) azide and (2) fluoroborate cations potential sweep rate 100 mV s, temperature 65 °C, Pt working electrode, Ag/AgCl reference electrode...

The intermediates M1-M5 were prepared according to the procedure described in Chap. 2. IIJ could be obtained by the treatment of 0,0-dimethyl l-(substimted phenoxyacetoxy)aIkylphosphonates IC with an excess of t-butylamine. In this reaction, t-butylamine could selectively and quantitatively eliminate one methyl from two MeO groups which attached to phosphorus in IC. The possible reaction mechanism for forming r-butylaminium 0-methyl phosphonate IIJ is outlined in Scheme 3.13. t-Butylamine first attacks the methyl carbon, forming intermediateiV-t-butyl-A-methyl ammonium salt, which is then deprotonated by another f-butyl-amine to form t-butylaminium and iV-methyl-Al-r-butylamine. Finally, the cation of t-butylaminium binds with the anion of phosphonate to form the IIJ. 

The mixtures of IL + water or + ethanol presented include majority of commercial ILs miscible with water or ethanol in a broad range of concentrations. There are some ILs miscible in both solvents, other do not mix with one of them, and many of them are not miscible with any of the two solvents (obviously this last will not be considered in this work). In any case, the IL mixtures measured up to now are a small part of all the millions of ILs that can be synthesized. The ILs cation presented include l-alkyl-3-methyl imidazolium, with the alkyl chain being methyl (dMIM), ethyl (EMIM), butyl (BMIM), octyl (OMIM) also the similar cation l-alkyl-2,3-dimethyl imidazolium, with the alkyl chain being propyl (PdMIM) or butyl (BdMIM). Some pyiidinium based cations are reported, the 1-alkyl-pyridinium with the alkyl chain being ethyl (EPy) or butyl (BPy) and the l-butyl-4-methyl pyiidinium (BMPy). Ammonium and phosfonium based ILs are not miscible in water or ethanol (Galan et al., 2003 Huddleston et... 

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