Q28-15E - Organic Chemistry (Mcmurry)

Question

Question: Amine bases in nucleic acids can react with alkylating agents in typical S_N2 reactions. Look at the following electrostatic potential maps, and tell which is the better nucleophile, guanine or adenine. The reactive positions in each are indicated.

Step-by-Step Solution

Answer

Guanine is the better nucleophile compared to adenine and favors the reaction mechanism of S_N2.

Explaining the solitary pair

The thing about electron of solitary pair on nitrogen will add aromaticity or reverberation. This will make it less nucleophile and less receptive to alkylation. Then N7, guanine is in the orbital of sp₃ hybridization and will not contribute to the aromaticity of electrons and guanine. Guanine on N₁ has solitary pair is in the orbital of p will add guanine aromaticity.

Explaining the solitary pair and its aromaticity

The N₁ solitary pair is an aromaticity piece that will lead to diminishes reactivity and, moving the capacity, becomes alkylated. The gathering of essential amine will join carbon two and cyclic six rings of guanine. It will be less responsive and partake in reverberation.