[6] For drying, the salt is dissolved in dichloromethane and the solution is treated with solid anhydrous sodium sulfate.
After several dissolutions in dichloromethane and acetone, and precipitations with tetrahydrofuran, a colorless solid is obtained, which is stable under air and moisture sealing.
Therefore, also syntheses of the much better processible salts N,N,N′,N′-tetramethylformamidinium methylsulfate[6] (from the dimethylformamide–dimethylsulfate complex[8]) and of N,N,N′,N′-tetramethylformamidinium p-toluenesulfonate (from dimethylformamide and p-toluenesulfonyl chloride) were investigated.
From N,N,N′,N′-tetramethylformamidinium chloride and sodium ethoxide in ethanol, dimethylformamide diethyl acetal is formed in 68% yield.
[18] Strong bases (such as phenyllithium) can abstract a proton from the formamidinium cation of N,N,N′,N′-tetramethylformamidinium forming bis(dimethylamino)carbene.