Difference Between Pyridine and Pyrimidine

Thekey difference在吡啶和嘧啶之间吡啶结构类似于苯有一个甲基group replaced by a nitrogen atom, whereas pyrimidine structure, though it too resembles the structure of benzene, has two methyl groups replaced by nitrogen atoms。

Pyridine and pyrimidine are organic compounds. These are named asheterocyclic organic compoundsbecause they are cyclic structures having two different types of atoms making the ring. These ring structures contain carbon and nitrogen atoms.

内容

1.Overview and Key Difference
2.What is Pyridine
3.What is Pyrimidine
4.并排比较 - 表格形式的吡啶与嘧啶
5.概括

What is Pyridine?

Pyridine is a heterocyclic organic compound having the chemical formula C₅H₅N. The structure of this compound resembles the structure of benzene, with one methyl group replaced by a nitrogen atom. Concerning the properties, pyridine is a weak alkaline and exists in the liquid state; it occurs as a viscous liquid. Furthermore, it is colorless and has a distinctive fish-like odor. Also, this liquid is water-soluble and is highly flammable

而且，吡啶是diamagnetic。The structure of the molecule is a hexagon. C-N bond is shorter than C-C bonds. When considering the crystallization of pyridine, it crystallizes in the orthorhombic crystal system. However, the pyridine molecule is an electron-deficient structure because of the presence of more electronegative nitrogen atom. Therefore, it tends to undergo electrophilic aromatic substitution reactions. Another reason for this ability is the presence of a lone electron pair on the nitrogen atom.

在考虑吡啶的应用时，它主要用作农药中的成分，是一种极性基础溶剂，作为Karl Fischer试剂在有机合成中，等等。

What is Pyrimidine?

嘧啶是具有化学式C的芳族杂环化合物₄H₄N₂。该化合物在1和3个位置具有氮原子。它是一个氮基碱，其中包括DNA的三个主要氮碱基：胞嘧啶，胸腺嘧啶和尿嘧啶。该化合物的摩尔质量为80 g/mol。

In pyrimidine, the pi-electron density is low because of the presence of heteroatoms in the ring. Thus, it enables the compound to undergo nucleophilic aromatic substitution. Besides, the compound is basic due to the presence of a lone electron pair on the nitrogen atom.

吡啶和嘧啶之间有什么区别？

Both the pyridine and pyrimidine are heterocyclic organic compounds. However, the key difference between pyridine and pyrimidine is that the pyridine structure resembles the structure of benzene with one methyl group replaced by a nitrogen atom, but though the pyrimidine structure too resembles the structure of benzene, it has two methyl groups replaced by nitrogen atoms. Thus, the chemical formula of pyridine is C₅H₅N, while the chemical formula of pyrimidine is C₄H₄N₂。吡啶的摩尔质量是79克/摩尔,while the molar mass of pyrimidine is 80 g/mol. Besides, the pyrimidine molecule is more pi-electron deficient than pyridine because the presence of two nitrogen atoms lowers the number of pi electrons present in the ring.

Moreover, pyrimidine is more basic than pyridine. Here, the basicity is determined by the lone electron pairs on nitrogen atoms in this molecule. Since pyrimidine has two nitrogen atoms, it is comparatively more basic.

Below infographic summarizes these differences between pyridine and pyrimidine.

概括– Pyridine vs. Pyrimidine

Both the pyridine and pyrimidine are heterocyclic organic compounds, and their structures resemble the structure of benzene. However, the key difference between pyridine and pyrimidine is that pyridine has one methyl group replaced by a nitrogen atom in the benzene ring, whereas pyrimidine has two methyl groups replaced by nitrogen atoms.

Reference

1. “Pyridine.”百科全书大不列颠, Encyclopædia Britannica, Inc., 23 Nov. 2018,Available here。
2. “Pyridine.”维基百科, Wikimedia Foundation, 29 Nov. 2019,Available here。
3.“嘧啶。”维基百科, Wikimedia Foundation, 18 Nov. 2019,Available here。

Image Courtesy:

1. “Pyridine numbers” By Yikrazuul – Own work (Public Domain) viaCommons Wikimedia
2. “Pyrimidine 2D numbers” By Jynto (talk) – Own work. The source code of this SVG is valid. This structural formula was created with ChemDraw (Public Domain) viaCommons Wikimedia