Lithium methylamine

Solutions containing a high concentration of excess electrons display a transition to the metallic state. Thus, for sodium-ammonia solutions in the concentration region 1-6 M the specific conductance increases by about three orders of magnitude, and the temperature coefficient of the conductance is very small (27). Similar behavior is exhibited by other metal-ammonia solutions (but surprisingly, not by concentrated lithium-methylamine solutions ) (10) and by metal-molten salt solutions (17). 

Section IV gives an overall view of concentrated solutions and the nonmetal-metal (NM-M) transition. Here again, the majority of data are for metal-ammonia solutions. However, in the past decade a substantial body of experimental data has emerged for the NM-M transition in lithium-methylamine solutions, which allows a direct comparison with the situation existing in metal-ammonia solutions (60). This section also considers recent developments in the study of the "expanded-metal compounds, as typified by LilNHs),, Ca(NH3)8 (82), and Li(CH3NH2)4 66), and formed by slow cooling of the concentrated metal solutions. 

Na-NH3, 1.02 x 108 ohm-1 cm2 mol-1 for Hg, 0°C, 0.16 x 10 ohm-1 cm2 mol-1). In the intermediate composition range 1 to 7 MPM, a NM-M transition occurs, and changes in the electronic, thermodynamic, and mechanical properties of the system are equally impressive (35, 37, 124, 154). A detailed discussion of the concentration dependence of various properties of metal-ammonia solutions is given in the book by Thompson (164). In addition, a recent review (60) at Colloque Weyl V also summarizes the available data for lithium-methylamine solutions (10, 11, 63, 127, 128, 166). 

Edwards, Lusis, and Sienko have recently reported an ESR study (60) of frozen lithium-methylamine solutions which suggests the existence of a compound tetramethylaminelithium(O), Li(CH3NH2)4, bearing all the traits (60) of a highly expanded metal lying extremely close to the metal-nonmetal transition. Specifically, both the nuclear-spin and electron-spin relaxation characteristics of the compound, although nominally metallic, cannot be described in terms of the conventional theories of conduction ESR (6,15, 71) and NMR in pure metals (60, 96, 169). 

Prolin-Peptid-Bindungen als Beispiel fiir tert. Amide konnen ebenfalls im System Lithium/Methylamin bei -70° gespalten werden204 ... 

Wahrend 2-Methyl-furan und Furfurylalkohol mit Lithium/Methylamin lediglich Ge-mische (mit 2-Methylimino-pentan als Hauptprodukt)4 liefert, erhalt man aus 3-Carboxy-furan unter klassischen Birch-Bedingungen in Isopropanol bei nachfolgender Behandlung mit Diazomethan 3-Methoxycarbonyl-2,3-dihydro-furan5 (85% d.Th. Kp30 83 - 84°) ... 

Didecyl- bzw. Dibenzyl-sulfon werden durch Lithium/Methylamin zu Decansulfinsaure (92% d.Th.) und Decan bzw. Phenylmethansulfinsdure und Toluol gespalten1. 

Diphenylsulfid reagiert mit Lithium/Methylamin zu Thiophenol2 (80% d.Th.), und l,2-Bis-[butylthio]-benzol wird durch Natrium/fl. Ammoniak zu 1,2-Dimercapto-benzol (56-85% d.Th, Kp5 95°) reduziert5. 

Reduziert man z.B. N-Methyl-N-phenyl-acetamid mit Natrium/fl. Ammoniak/Atha-nol, so erhalt man in 56%-iger Ausbeute Acetaldehyd2. Hexansaure-diathylamid wird durch Natrium/fl. Ammoniak/Essigsaure in 53%-iger Ausbeute zu Hexanal reduziert3 und 1-Acetyl- bzw. l-(3-Phenyl-propanoyl)-2-carboxy-pyrrolidin bilden bei Reduktion mit Lithium/Methylamin/-70°2-Carboxy-pyrrolidin (Prolin)4 ... 

Aldehydes are also obtained in variable yields from the lithium-methylamine reduction of carboxamides/ Cinnamaldehyde or 3-phenylpropanal can be prepared by the Raney nickel-catalysed hydrogenation of cinnamonitrile, though the generality of the method is not reported/ ... 

---