Question

Forming N-methyl-2-aminobutane from 2-aminobutane?

Answer 1

I would react an excess of 2-aminobutane with methyl bromide.

`underbrace("2CH"_3"CH"_2"CH"("CH"_3)"NH"_2)_color(red)("2-aminobutane") + "CH"_3"Br" → underbrace("CH"_3"CH"_2"CH"("CH"_3)"NHCH"_3)_color(red)("2-("N"-methylamino)butane") + underbrace("CH"_3"CH"_2"CH"("CH"_3) stackrel(+)("N")"H"_3color(white)(l) "Br"^"-")_color(red)("(1-methylpropyl)ammonium bromide")`

Amines can react as nucleophiles with alkyl halides in `"S"_"N"2` substitution reactions.

Yields are often poor, because the product amines are still nucleophilic and can react with more halide.

The excess of starting amine serves two functions:

• It minimizes further alkylation.
• It neutralizes the `"HBr"` that is formed.