Main Difference – Benzene vs Phenyl
Aromatic compounds are compounds having ring structures composed of alternating single and double bonds in that ring. Most of the aromatic compounds are composed of benzene rings. Phenyl is a derivative of benzene. The main difference between benzene and phenyl is that benzene is composed of six hydrogen atoms whereas phenyl is composed of five hydrogen atoms.
Key Areas Covered
1. What is Benzene
– Definition, Structure, Properties, Applications
2. What is Phenyl
– Definition, Structure, Properties, Applications
3. What are the similarities between Benzene and Phenyl
– Outline of Common Features
4. What is the difference between Benzene and Phenyl
– Comparison of Key Differences
Key Terms: Aromatic Compounds, Benzene, Electrophilic, Nucleophilic, Phenol, Phenyl
What is Benzene
Benzene is a colorless, volatile, liquid hydrocarbon present in petroleum. It is a ring structure. The chemical formula of benzene is C6H6. All the carbon atoms are bonded with each other through three single bonds and three double bonds which are arranged in an alternating manner. The six hydrogen atoms are attached to the six carbon atoms, one per each carbon. Due to the presence of double bonds, the electrons in the π bonds are combined together, forming two electron clouds located on the top and the bottom of the benzene ring. The electron cloud is parallel to the plane of the benzene ring. This structure of benzene was first proposed by Kekule (1872), so it is called as Kekule structure.
Figure 1: Structure of Benzene
All carbon atoms in the benzene ring are sp2 hybridized. Although the bond length of C-C single bond is larger than C=C double bond in general, all the bonds in benzene are of the same length. Due to the formation of electron clouds, the bond length of Benzene is somewhere between the length of a single bond and a double bond. Benzene is a planar structure and it can be used for the synthesis of many other advanced compounds due to its availability for substitutions on the ring.
Figure 2: Two Electron Clouds of Benzene
The benzene ring is rich with electrons. Thus, benzene is sufficiently nucleophilic. Therefore, the major reaction that benzene can undergo is electrophilic substitution. Benzene can share its electrons with electrophiles. Electrophilic components are molecules that lack electrons in order to become stable.
What is Phenyl
Phenyl is a group derived from benzene and it can be combined with another molecule. The chemical formula of phenyl group is C6H5. It is also composed of alternating double bonds as same as in benzene ring. Phenyl group has a vacant point where a hydrogen atom is missing. Therefore this group can get attached to a different molecule through this point. This makes the phenyl group very reactive.
Some people think the phenyl group and the benzyl group are the same. But they are very different because benzyl group has a –CH2– group attached to the benzene ring.
The most common molecule in which the phenyl group is found is phenol. There, the phenyl group is bonded with –OH group.
Figure 3: Phenyl Group (in blue color)
- Figure 3: Phenyl Group (in blue color)
Similarities Between Benzene and Phenyl
- Both molecules are composed of six carbon atoms.
- Both are ring structures.
- Both are planar structures.
- Hybridization of carbon atom is sp2 in both benzene and phenyl.
- The bond length between carbon atoms are equal (1.4 A0).
Difference Between Benzene and Phenyl
Definition
Benzene: Benzene is a colorless, volatile, liquid hydrocarbon present in petroleum.
Phenyl: Phenyl is a group derived from benzene and it can be combined with another molecule.
Number of Hydrogen Atoms
Benzene: Benzene has six hydrogen atoms.
Phenyl: Phenyl has five carbon atoms.
Stability
Benzene: Benzene is stable when alone.
Phenyl: Phenyl is not stable alone.
Chemical Formula
Benzene: The chemical formula of benzene is C6H6.
Phenyl: The chemical formula of phenyl is C6H5.
Conclusion
Benzene is widely used in the synthesis of different important compounds. But care should be taken when choosing benzene for products which have close relations to the human consumption. That is because it has been discovered that benzene has carcinogenic effects. Phenyl is a substituent derived from benzene. The main difference between benzene and phenyl is that benzene is composed of six hydrogen atoms whereas phenyl is composed of five hydrogen atoms.
References:
1. “The Phenyl Group.” Chemistry LibreTexts. N.p., 21 July 2016. Web. Available here. 21 June 2017.
2. “Phenyl or benzyl?” Hunt, Ian R. Benzene as a substitutent. N.p., n.d. Web. Available here. 21 June 2017.
Image Courtesy:
1. “Benzene Structural diagram” By Vladsinger – Own work (Public Domain) via Commons Wikimedia
2. “Phenyl Group General Formulae V” Von Jü – Eigenes Werk (CC0) via Commons Wikimedia
3. “Benzene Quadrupole” By Michael.hell at the English language Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
Leave a Reply