Chemistry question

[adamrose]

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I understand basicity follows the periodic table trend of up and to the left which makes C2H5O- a weaker base than C2H5N-
so why is N3- considered a weak base compared to OH- or OCH3-?

does it have to do with having charges on most electronegative atoms lead to a more stable molecule (weaker base?)

 

[Weakfart]

I understand basicity follows the periodic table trend of up and to the left which makes C2H5O- a weaker base than C2H5N-
so why is N3- considered a weak base compared to OH- or OCH3-?

does it have to do with having charges on most electronegative atoms lead to a more stable molecule (weaker base?)

Probably because the delocalization of the charge on the azide ion. Any time you have delocalization, you're gonna have a weaker base than expected.

 

[pulltheleverkronk]

It has to do more with resonance and what you said- with the negative charge being on more electronegative atoms. Nitrogen atoms are more stabilized with a positive charge on them anyway.

 

[DAT Destroyer]

I understand basicity follows the periodic table trend of up and to the left which makes C2H5O- a weaker base than C2H5N-
so why is N3- considered a weak base compared to OH- or OCH3-?

does it have to do with having charges on most electronegative atoms lead to a more stable molecule (weaker base?)

I want you to remember this....AZIDE....N3- is a strong nucleophile.......but a weak base. My dear friend......I am awarding you the #1 question EVER ASKED on SDN !!!! Ask it to virtually any Organic Chemistry professor on earth.......and he or she will likely tremble...... This is a very sophisticated question.....debated by some of the Worlds best Organic and Quantum chemists. Nucleophilicity usually parallels Basicity.....but ALAS.....not always.

In Advanced Organic Chemistry.....we have what is known as Hard acids, and Hard bases......as well as Soft Acids and Soft Bases. The Hard species are dependent more on Charge than orbitals......Soft species depend on Orbitals. EVIDENTLY.......the Azide will react with a halide and function as a great nucleophile because the orbital energy is favorable for the interaction. The reason that it acts as poor base ...is different. The H+ ion is a Hard Acid,,,,,,and will react poorly with the moderately soft azide ion.

This is well beyond the scope of the DAT...... but since you asked, Sorry for the punishment !

The Dark Dungeon of Advanced Organic Chemistry is a lonely dark place.

Keep up the good work.......Dr Romano