Welcome to Chem Zipper.com......

Search This Blog

Wednesday, January 22, 2020

Why pyridine is more basic than Pyrrole?

In case of Pyrrole  the lone pair electrons of the nitrogen atom is involved in conjugated system of pi electrons of five membered ring leading to greater stability of the molecule due to acquiring aromatic character. Hence less available for donation.
While in case pyridine already has a stable conjugated system of three double bonds in an aromatic ring, like benzene. Hence the lone pair electrons on the N atom in pyridine is localized and  more available for donation and  easily donated to a H+ ions. Therefore, pyridine is a stronger base than Pyrrole.

Why pyrimidine is less basic than pyridine?



Pyrimidine is less basic than pyridine because (–I effect) negative inductive effect of nitrogen atom to another nitrogen atom that cause decreases electron density of each other. This makes it less willing to donate its lone pair. This is not count that number of lone pairs to explain basicity.


Related Questions:

Monday, January 20, 2020

How to prepare p-bromoaniline, knowing that aniline only gives the tris-brominated product; note that bromination of aniline does not stop at the monobrominated stage and cannot be moderated by using only one equivalent of bromine.

What Is Mustard Gas?

Mustard gas is a colorless oily liquid whose vapor is a powerful irritant and vesicant, used in chemical weaponsMustard gas, or sulphur mustard (Cl-CH2CH2)2S, is a chemical agent that causes severe burning of the skin, eyes and respiratory tract. It can be absorbed into the body through inhalation, ingestion or by coming into contact with the skin or eyes

Sulphur Mustard:
Nitrogen Mustard:
Related Questions:

  1. DDT- DichloroDiphenylTrichloroethane:
  2. Amoxicillin: Antibiotics:
  3. Fluoxetine: Antidepressant:
  4. AZT: Azidodeoxythymidine: Drug that treats human immunodeficiency virus (HIV):
  5. Aspirin: Acetylsalicylic acid:
  6. Capsaicin: use in pepper sprays used for personal defense and topical creams used for pain relief:
  7. What is the structure and use of Westron and Westrosol?

Sunday, January 19, 2020

Why does aqueous sodium bicarbonate solution dissolve carboxylic acids but not phenol though they are also acidic ?

In both cases the product formed is carbonic acid (pKa=6) which is stronger acid than phenols (pKa=10) but weaker than carboxylic acid(pKa=4.5).
Acid-base equilibrium in second case shift more towards backward direction. Hence phenol does not react with NaHCO3.