Potential Explosion Hazard Of -Lithiated Amines
Michael K. Denk, Gurmit Singh, and Nachhattarpal K. Gill
Chemical & Engineering News (30 June 2003) Vol. 81, No. 26, p. 2
We want to report on the potential hazardous nature of the doubly lithiated bis(dimethylamino)-methane LiCH2N(CH3)CH2N(CH3)CH2Li (1), a compound that has recently been described in the literature [Chem. Ber., 129, 483 (1996)]. Compound 1 was prepared as described in the reference above by lithiation of the aminal (CH3)2NCH2N(CH3)2 with tert-butyllithium and was isolated as a colorless crystalline solid with matching spectroscopic data. Upon using the full amounts given in the literature procedure (5.6 g of isolated 1 instead of 1 g obtained in a test run), the compound detonated during drying in vacuo, shattering the Schlenk frit used for its isolation. The researcher monitoring the experiment was protected by a lab coat and safety glasses but received a deep cut on the cheek from flying glass splinters as well as minor cuts on one hand, but luckily did not sustain other injuries.
While the explosive nature of 1 seems surprising at first, the compound does contain the LiCH2N< fragment and is thus related to carbenoids LiCR2X (X = halogen), which are known to decompose in a strongly exothermic fashion to give, inter alia, the carbenes R2C: and the salts LiX.
Irrespective of the mechanism of the decomposition, we believe that 1 and related compounds should be regarded as potentially explosive and treated accordingly. Drying of the compound may have been a contributing factor by removing intracrystalline solvent and should thus be avoided wherever possible.
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