Introduction of pyrimidine – physical properties, synthesis, chemical reactions and medicinal uses in easy language

Introduction of pyrimidine

Introduction of pyrimidine, it is a 6-membered heterocyclic ring having two nitrogen atoms at 1st & 3rd position. This ring system is found to be present in many natural product (eg- nucleic acid) as well as synthetic drugs (eg- barbiturates).

It is classified as one of the building blocks of nucleic acids, namely DNA and RNA, making it an integral part of genetic information and protein synthesis. The unique properties of pyrimidine make it an indispensable component in various biochemical pathways. Its presence can be found in diverse biological molecules such as vitamins (thiamine and riboflavin), coenzymes (NAD+ and FAD), energy storage molecules (ATP), and many pharmaceutical compounds.

Physical properties of pyrimidine

1. The boiling point is 124°C &, melting point is 22.5°C of pyrimidine.

2. It has a dipole moment of up to 2.42D.

3. The Pka value for protonated pyrimidine is 1.23 in comparison 5.30 for pyrimidine.

4. It is soluble in water.

5. It is a weak base.

Synthesis of pyrimidine

1. From barbituric acid

Barbituric acid react with POCl₃ & resultant mediate further allowed to pass through zinc dust to yield pyrimidine.

2. From 1,3-dicarbonyl compound

Condensation of 1,3-dicarbonyl compound with urea in presence of C₂H₅Na gives barbituric acid, which on keto-enol tautomerism gives pyrimidine-2, 4,6-triol. Further it on treatment with POCl3 followed by treatment with zinc dust gives pyrimidine.

3. From 2,4-dichloropyrimidine

On heating 2,4-dichlorppyrimidine with hydrogen under pressure of Pd-C & magnesium oxide.

4. From formamide

Formamide on reacting with 1,1,3,3-Tetramethoxypropane yield pyrimidine.

Chemical reactions of pyrimidine

1. Electrophilic substitution reaction

Pyrimidine forms 4 resonating structure while it is subjected to attack by nucleophile. It is clear that ring is deactivated & position has a greatest electron density because there is no positive charge at the position.

2. Nucleophilic substitution reaction

The attack by nucleophilic reagent is facilitated at position.  2,4 &, 6 of pyrimidine ring. By reaction of Phosphorus oxychloride 2,4, & 6. Chloropyrimidine can made from pyrimidines.

3. Halogenation

Pyrimidine gets halogenated in the presence of AlCl₃.

4. Nitration

This reaction take place in the presence of nitric acid.

5. Sulphonation

This reaction occurs in the presence of fuming & phuric acid.

Medicinal uses of pyrimidine

1. Pyrimidine is an anti-parasite medicine that helps prevent parasites from growing & reproducing in the body.

2. Trimethoprim eliminates bacteria that cause urinary tract.

3. 5-fluorouracil is a medication used to treat colon cancer, oesophageal cancer, stomach cancer, pancreatic cancer & cervical cancer.

4. Phenobarbitone is long-acting barbiturate used as sensitive & hypnotic.

5. Other drugs having pyrimidine moiety.

6. Sulfadiazine-sulphonamide drug commonly used to treat urinary tract infection & burns.

7. Zidovudine, stavudine-nucleoside reverse transcriptase inhibitors used as to treat human immunodeficiency infections.