Tris(dimethylamino)methane (TDAM) is the simplest representative of the tris(dialkylamino)methanes of the general formula (R2N)3CH in which three of the four of methane's hydrogen atoms are replaced by dimethylamino groups (−N(CH3)2). Tris(dimethylamino)methane can be regarded as both an amine and an orthoamide.
Tris(dimethylamino)methane is a strong base and can be used as a formylation agent, as aminomethylenation reagent and as a source for the basic bis(dimethylamino)carbene of the formula (R2N)2C:.
Preparation Tris(dimethylamino)methane is generally formed from dimethylaminating electron-rich formamide derivatives. For example, N,N,N′,N′-Tetramethylformamidinium chloride or bis(dimethylamino)acetonitrile react with dimethylamide salts to give TDAM:
Likewise dimethylformamide (DMF) dimethylacetal, HC(OCH3)2N(CH3)2, reacts with dimethylamine in the presence of the acidic catalyst 2,4,6-tri-tert-butylphenol to give the same product:
TDAM can be produced directly from DMF with tetrakis(dimethylamino)titanium(IV):
Red-Al and other hydride reductants reduce hexamethylguanidinium chloride to TDAM:
Properties Tris(dimethylamino)methane is a clear, colorless or pale yellow liquid with a strong ammoniacal odor. The compound is freely miscible with many non-polar aprotic and water-free solvents. However, when heated tris(dimethylamino)methane reacts with protic solvents (such as water or alcohols) but also with weak CH-acidic substances, such as acetone or acetonitrile.
Upon heating to 150–190 °C decomposition occurs to tetrakis(dimethylamino)ethylene, a strong electron donor.
Applications Tris(dimethylamino)methane dissociates into N,N,N,N-tetramethylformamidinium cations and dimethylamide anions, which abstract protons from CH- and NH-acidic compounds. The anions thus formed add to the formamidinium cations which in turn eliminate dimethylamine and react to form dimethylaminomethylene compounds (= CH−N(CH3)2) or amidines by aminomethyleneation.
Reaction to form a methyl α-cyano-β-dimethylaminoacrylate:
Reaction to form N,N-dimethyl-N-p-nitrophenylformamidine:
Aminomethylenation provides intermediates for the synthesis of heterocycles such as pyrimidines, pyrazoles, 1,4-dihydropyridines and indoles.
N,N,N,N-Tetramethylselenourea is accessible by the extended heating of tris(dimethylamino)methane with selenium in xylene; bis(dimethylamino)carbene is suggested as an intermediate.
Related reagent Bis(dimethylamino)methane
References