How Pyridines Are Prepared & What Are Their Uses?

Pyridine was first discovered in 1849, is known as the simplest heterocycle. The structure of pyridine closely resembles that of benzene. Pyridine is a colourless & water-soluble liquid at room temperature, also has a pungent smell. Since there is an electronegative ‘N’ present, which induced different properties from that of benzene’s ring structure. All of the pyridine ring atoms are sp2 hybridized similar to that of benzene.

 

Pyridine is generally a weak base that easily reacts with acids to produce pyridinium salts. For Example, pyridine reacts with p-toluenesulfonic acid produces pyridinium p-sulfonate salt. Let’s have a look at some pyridines:

 

  • 2-CHLORO-4-METHYLPYRIDINE
  • 4,4’-BIPYRIDINE

# 2-CHLORO-4-METHYLPYRIDINE

Also known as 2 chloro 4 picoline, this pyridine is considered as halogenated heterocycle organic compound is used mostly for the acquisition and amalgamation in order to react with 4-(Trifluoromethyl)phenylboronic acid which will result in the formation of 2-(3,5-bis(trifluoromethyl)phenyl)-4-methylpyridine that uses the process of cross-coupling reaction.

 

Generally in this reaction, the percentage of the quantity of 2-chloro-4-methylpyridine is around 25 per cent, but there are other methods also available that can be used for its production.

 

2-chloro-4-methylpyridine is prepared with STR6 reaction done with 3-methylpyridine 1-oxide with phosphorus oxychloride. This complete reaction takes place while the organic nitrogen mixture is present perfectly at the presence of -50° C and +50° C temperature.

 

It’s shocking to understand that reaction of nitrogen compounds can produce higher results and products. High quality and quantity of yield is just one advantage, other advantages include low proportion of isomeric by-products are significantly low in quantity compared to other synthetic processes.

 

Other than the pure compound that is formed, it can be easily separated from the reactant products if it is required with the help of standard methods, an example here would be with distillation. This is why this method is considered very important and helpful in the chemical manufacturing industry.

Uses of 2-chloro-4-methylpyridine

  • It’s used in determining the gas-phase basicity of multiple organic molecules that are useful in the MALD process.
  • It acts as a reagent for the synthesis of mGLUR5 modulators that is known as a highly useful antipsychotic.
  • It can also be used for the production of the orally bioavailable TGR5 agonists.

# 4,4’-BIPYRIDINE

4,4′-Bipyridine is a bipyridine that is mostly used as a harbinger for [(C5H4NCH3)2]2+, which is also called paraquat. Known as a species of paraquat, it’s toxic in nature which occurs due to transfer of biological electrons. Due to its structure, it easily bridges between metal centres to produce coordination polymers.

Uses of 4,4’-Bipyridine

  • It is used in the transition metal complex catalyst chemistry for uniform polymerization
  • Also useful for luminescence chemistry.
  • The spectrophotometric analysis uses this pyridine regularly.
  • It is also known as a ligand that is used to form a square planar geometry.
  • Data processing is also done with the help of this pyridine in the spectroscopic technique.

 

4,4’-bipyridine is electroactive in nature & is believed to intermediate electronic effects between two paramagnetic metal centres.