Why are imines important?

1 Answer
Feb 11, 2017

Because imine formation represents #C-N# bond formation.........

Explanation:

From your organic chemistry course, you know that there relatively few ways to make #C-C# and #C-N# and #C-"heteroatom"# bonds in general. Of course, we may represent the formation of imines by the reaction:

#"Imine formation:"#

#R_1C(=O)R_2 + R_3NH_2 rarr R_1C(=NR_3)R_2 + H_2O#

These reactions are reasonably simple to accomplish by various (and straightforward) means. The fact that the reaction spits out water (i.e. it is a condensation reaction) provides a thermodynamic driving force to the reaction. And thus we have formed a carbon-heteroatom bond (of course, here, the bond is unsaturated). In the best circumstances we may reduce the imine function to give secondary amines.

#"Imine reduction:"#

#R_1C(=NR_3)R_2 + H^(-) rarr R_1C(H)(NR_3)R_2#

The hydride transfer reagent may by #LiAlH_4# or #KBEt_3H# or even #H_2# with transition metal catalysis.

Sometimes, this can be done with stereocontrol; of course we'd need a special hydride transfer agent, likely a chiral transition metal complex under dihydrogen.