Chemistry, Derivatives, Properties and Synthesis of Purine

Chemistry of Purines

Session Objectives

By the end of this session, students will be able to:

• Discuss the chemistry, derivatives, properties and method
of synthesis of purine

PURINES AND PYRIMIDINES

PURINES AND PYRIMIDINES

The word purine (pure urine) was coined by the German chemist Emil Fischer in 1884.

He synthesized it for the first time in 1898.

The starting material for the reaction sequence was uric acid.

Uric acid was reacted with PCl5 to give 2,6,8trichloropurine, which was converted with HI and PH4I to give 2,6 diiodopurine .

The product was reduced to purine using zinc dust.

• Nucleotides are the building blocks of nucleic acids

• Building blocks of nucleic acids (RNA, DNA) with certain
heterocyclic aromatic compounds called pyrimidines and purines.

• Purine and Pyrimidine are the names of the parent compounds of two types of nitrogen-containing heterocyclic aromatic compounds.

• A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring.

• Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen containing heterocycle in nature.

Purines consist of a six-membered and a five-membered nitrogen-containing ring, fused together.

• The purine bases have a 9-membered double-ring system with four nitrogens and five carbons.

• Adenine and guanine are the principal purines of both DNA
and RNA.

Adenine (6-Aminopurine )
Guanine (2-Amino-6-oxypurine)

• The pyrimidine bases have a 6-membered ring with two
nitrogens and four carbons.

• Pyrimidines that occur in DNA are:

                Cytosine and thymine. 

                Cytosine and uracil occur in RNA.

• Cytosine (2-oxy-4-amino pyrimidine)

• Thiamine (2,4-dioxy-5-methyl pyrimidine)

• Uracil (2,4-dioxy pyrimidine)

Naturally Occuring Purines

• Caffeine (coffee) and theobromine (coffee and tea) are
naturally occurring purines.

 

Synthesis of Purines

• Formamide (45 grams) was heated with a condenser for 28 hours in an oil bath at 170-190 °C.

• After removing excess formamide (32.1 grams) by vacuum
distillation, the residue was refluxed with methanol.

• The methanol solvent was filtered, the solvent removed
from the filtrate by vacuum distillation, and almost pure purine obtained; yield 4.93 grams (71% yield from formamide consumed).

• Crystallization from acetone afforded purine as colorless
crystals; melting point 218 °C

Synthesis of Purines

Traube purine synthesis

Traube purine synthesis

Synthesis of purines

Synthesis of purines

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