Ionic lithium amides

The Diels-Alder reaction is an important and widely used reaction in organic synthesis (Sauer and Sustmann, 1980), and in the chemical industry (Griffiths and Previdoli, 1993). Rate enhancement of this reaction has been achieved by the use of solvents such as water, surfactants, very high pressure, lithium amides, alkylammonium nitrate salts, and macrocyclic hosts (Sherman et ak, 1998). Diels-Alder reactions can be ran in neutral ionic liquids (such as 1-butyl-3-methylimidazolium trifluoromethanesulfo-nate, l-butyl-3-methylimidazolium hexafluorophophate, l-butyl-3-methylimidazolium tetrafluoroborate, and l-butyl-3-methylimidazolium lactate). Rate enhancements and selectivities are similar to those of reactions performed in lithium perchlorate-diethyl ether mixtures. 

The two chiral lithium amides were found to form symmetrically solvated dimers in diethyl ether (DEE). The addition of tetrahydrofuran (THF) and of l,3-dimethyl-3,4,5,6-tetrahydro-2-(l//)-pyrimidinone (DMPU) did not affect the Li NMR chemical shift due to a very strong internal coordination. The Li and Li MAS-NMR signals of fast ionic conducting Li2 2xMgi+xCl4 have... 

The resulting ionic compound is a white solid which melts between 373 and 375 °C (and decomposes to the imide and ammonia above this upper limit as noted above, eventually decomposing to lithium nitride). Experimentally, the standard enthalpy of formation for lithium amide, AHf, is -176 kJ mol ... 

Lithium amides are strong dipoles since the bond between the nitrogen anion and the lithium cation is mainly ionic. Therefore, they are rarely... 

In 2002, Leadbeater and Torenius reported the base-catalyzed Michael addition of methyl acrylate to imidazole using ionic liquid-doped toluene as a reaction medium (Scheme 6.133 a) [190], A 75% product yield was obtained after 5 min of microwave irradiation at 200 °C employing equimolar amounts of Michael acceptor/donor and triethylamine base. As for the Diels-Alder reaction studied by the same group (see Scheme 6.91), l-(2-propyl)-3-methylimidazolium hexafluorophosphate (pmimPF6) was the ionic liquid utilized (see Table 4.3). Related microwave-promoted Michael additions studied by Jennings and coworkers involving indoles as heterocyclic amines are shown in Schemes 6.133 b [230] and 6.133 c [268], Here, either lithium bis(trimethylsilyl)amide (LiHMDS) or potassium tert-butoxide (KOtBu) was em-... 

A number of other methods exist for the a halogenation of carboxylic acids or their derivatives.134 The acids or their chlorides or anhydrides can be a chlorinated by treatment with CuCl in polar inert solvents (e.g., sulfolane).135 Acyl halides can be a brominated or chlorinated by use of N-bromo- or N-chlorosuccinimide and HBr or HC1.136 The latter is an ionic, not a free-radical halogenation (see 4-2). Direct iodination of carboxylic acids has been achieved with L-Cu(II) acetate in HO Ac.137 Acyl chlorides can be a iodinated with L and a trace of HI.138 Carboxylic esters can be a halogenated by conversion to their enolate ions with lithium N-isopropylcyclohexylamide in THF and treatment of this solution at - 78° with I2138 or with a carbon tetrahalide.139 Carboxylic acids, esters, and amides have been a fluorinated at -78°C with F2 diluted in Ni.,4°... 

A solid-state solar cell was assembled with an ionic liquid—l-ethyl-3-methylimidazolium bis(trifluoromethanesulfone)amide (EMITFSA) containing 0.2 M lithium bis(trifluoromethanesulfone)amide and 0.2 M 4-tert-butylpyridine—as the electrolyte and Au or Pt sputtered film as the cathode.51,52 The in situ PEP of polypyrrole and PEDOT allows efficient hole transport between the ruthenium dye and the hole conducting polymer, which was facilitated by the improved electronic interaction of the HOMO of the ruthenium dye and the conduction band of the hole transport material. The best photovoltaic result ( 7p=0.62 %, 7SC=104 pA/cm2, FOC=0.716 V, and FF=0.78) was obtained from the ruthenium dye 5 with polypyrrole as the hole transport layer and the carbon-based counterelectrode under 10 mW/cm2 illumination. The use of carbon-based materials has improved the electric connectivity between the hole transport layer and the electrode.51... 

A solution of lithium bis(trifluoromethylsulfonyl)amide is made up at 0.5molkg 1 in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoro-methylsulfonyl)amide. Both the salt and the ionic liquid are dried prior to use at 100°C or above, under vacuum for 12 h or more, which gives water values at least below 10 ppm. These materials must be handled only in an argon-filled dry... 

Simple examples of cyclic oligomers formed through ionic interactions are the trimer of lithium bis(trimethylsilyl)amide, [LiN(SiMe3)2]3 (Scheme 13), " and hexameric [LilSCeHs (CH2NMe2)2-2,6 ]6 More intricate cage, ladder, and other polycyclic structures are formed in various other compounds. " ... 

Matsumoto H, Sakaebe H, Tatsumi K. Preparation of room temperature ionic liquids based on aliphatic onium cations and asymmetric amide anions and their electrochemical properties as a lithium battery electrolyte. J. Power Sources. 2005. 146, 45-50. 

K. Hayamizu, S. Tsuzuki, S. Seki, Y. Umebayashi, J. Chem. Phys. 2011, 135, 084505/ 1-084505/11. Nuclear magnetic resonance studies on the rotational and translational motions of ionic liquids composed of l-ethyl-3-methylimidazolium cation and bis (trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts. 

Howlett PC, Brack N, Hollenkamp AF, Forsyth M, MacFarlane DR (2006) Characterization of the lithium surface in N-methyl-N-alkylpyrrolidinium bls(trifluoromethanesulfonyl)amide room-temperature ionic liquid electrolytes. J Electrochem Soc 153(3) A595-A606. doi 10. 1149/1.2164726... 

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