Dimethylamine, aqueous methylfuran

Dimethylamine, reaction with 2-chloro-pyrimidine, 35, 58 reaction with formaldehyde and 2-methylfuran, 35, 78 Dimethylamine (aqueous), 32, 61 33, 57... 

To 200 ml. of glacial acetic acid in a 1-1. round-bottomed flask is added slowly, with cooling in an ice bath, 151 ml. (54 g. of di-methylamine, 1.2 mole) of 40% aqueous dimethylamine solution, followed by 90 ml. (36 g. of formaldehyde, 1.2 mole) of 37% aqueous formaldehyde (formalin) solution. The flask is removed from the ice bath and equipped with a reflux condenser, through which 82 g. (90 ml., 1 mole) of 2-methylfuran (Note 1) is added all at once. Upon gentle swirling of the flask, an exothermic reaction may set in spontaneously if it does not, the flask is heated on a steam bath until reaction commences. In any event, the spontaneous reaction is allowed to proceed without further external heating. When it ceases, the reaction mixture is heated on a steam bath for another 20 minutes, cooled, and without delay poured into a cold solution of 250 g. of sodium hydroxide (Note 2) in 800 ml. of water. 

Reactions of 2-methylfuran with aqueous formaldehyde and secondary amines have been reported using a variety of procedures. Thus, 2-methylfuran, formaldehyde and dimethylamine react in aqueous acetic acid at 100 °C to give the expected product (equation 27) in 69-76% yield. Remarkably, it is reported that attempted Mannich reactions with furan itself yields no liquid amine. It has been suggested that this type of reaction can only be carried out with alkyl-substituted furans, because of the marked activating effect of methyl substitution on electrophilic substitution reactions. 

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See also in sourсe #XX -- [ , ]

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