The key difference between borazine and benzene is that the borazine contains three boron atoms and three nitrogen atoms in the ring structure whereas the benzene contains six carbon atoms in the ring structure.
Both borazine and benzene have similar structures with a six-membered ring, and these two compounds are isoelectronic. That means, both borazine and benzene have the same numbers of electrons or the same electronic structure. However, they have completely different chemical and physical properties because the rings of these compounds consist of different atoms.
CONTENTS
1. Overview and Key Difference
2. What is Borazine
3. What is Benzene
4. Similarities Between Borazine and Benzene
5. Side by Side Comparison – Borazine vs Benzene in Tabular Form
6. Summary
What is Borazine?
Borazine is an inorganic compound having the chemical formula B3H6N3. It is a cyclic compound with a six-membered ring structure. That is, it has three B-H units and three N-H units in an alternating pattern. Thus, we can write its chemical formula as (BH3)(NH3). Also, this structure is isoelectronic with the benzene ring. As like benzene, this too is a colourless liquid at room temperature. Therefore, we sometimes name it as “inorganic benzene”.
Figure 01: Chemical Structure of Borazine
Furthermore, the molar mass of borazine is 80.50 g/mol. The melting point and boiling points are −58 °C and 53 °C respectively. Also, it has an aromatic smell. Moreover, this is a synthetic compound that we can produce from diborane and ammonia at 1:2 ratio.
The chemical reaction involved in this process is as follows:
3 B2H6 + 6 NH3 → 2 B3H6N3 + 12 H2
Above all, if we add borazine to water, it will hydrolyze to give boric acid, ammonia and hydrogen gas. Besides, this compound is thermally very stable due to its low standard enthalpy change of formation; −531 kJ/mol. Also, compared to benzene, borazine is far more reactive. For example, it can react with hydrogen chloride while benzene cannot.
According to the X-ray crystallographic determinations, the bond lengths in the ring structure of borazine are equal. However, it cannot form a perfect hexagon because the alternating pattern of nitrogen and boron gives different bond angles and thus, a distinct molecular symmetry.
What is Benzene?
Benzene is an organic compound having the chemical formula C6H6. It has a six-membered ring structure with all members are carbon atoms. Here, each of this carbon atom is attached to a hydrogen atom. Since this compound contains only carbon and hydrogen atoms, it is a hydrocarbon. Above all, this compound naturally occurs as a constituent of crude oil.
Figure 02: Various Representations of Benzene
Looking at their properties, the molar mass of benzene is 78.11 g/mol. The melting point and boiling points are 5.53 °C and 80.1 °C respectively. Also, it is a colourless liquid at room temperature. Furthermore, it is an aromatic hydrocarbon. As a result, it has an aromatic odour. Moreover, according to the X-ray diffraction determinations, all the bonds between the six carbon atoms have similar lengths. Therefore, it has an intermediate structure. We call it a “hybrid structure” because according to the bond formation, there should be alternating single bonds and double bonds between the carbon atoms. Subsequently, the actual benzene structure is a result of several resonance structures of the benzene molecule.
What are the Similarities Between Borazine and Benzene?
- Both are cyclic structures.
- Also, both, borazine and benzene, have a six-membered ring.
- Moreover, both have equal bond lengths between the atoms of the ring.
- Furthermore, both are colourless liquids at room temperature.
- Both are isoelectronic as well.
What is the Difference Between Borazine and Benzene?
Borazine is an inorganic compound having the chemical formula B3H6N3 whereas Benzene is an organic compound having the chemical formula C6H6. Therefore, the key difference between borazine and benzene is that the borazine contains three boron atoms and three nitrogen atoms in the ring structure whereas benzene contains six carbon atoms in the ring structure. In borazine, the boron and nitrogen atoms are in an alternating pattern. As a result, the borazine molecule is not a perfect hexagon, but benzene has only carbon atoms in the ring. Thus, it can form a perfect hexagon. Hence, we can consider this as another difference between borazine and benzene.
Above all, a significant difference between borazine and benzene is that the borazine is a synthetic compound whereas the benzene naturally occurs in crude oil as a major constituent. Also, we can identify a difference between borazine and benzene based on their reactivity as well. Comparatively, borazine is more reactive than benzene.
Summary – Borazine vs Benzene
Borazine and benzene are isoelectronic; meaning that they have the same numbers of electrons or the same electronic structure. But, they are two different compounds. And, the key difference between borazine and benzene is that the borazine contains three boron atoms and three nitrogen atoms in ring structure whereas the benzene contains six carbon atoms in the ring structure.
Reference:
1. Mn2555 Follow. “BORAZINE- Structure, Preparation and Properties.” LinkedIn SlideShare, 24 Nov. 2015. Available here
2. “Benzene.” Wikipedia, Wikimedia Foundation, 27 Sept. 2018. Available here
Image Courtesy:
1.”Borazine-dimensions-2D”By Hbf878 – Own work, (CC0) via Commons Wikimedia
2.”Benzene Representations”By Vladsinger – Own work (CC BY-SA 3.0) via Commons Wikimedia