Chemistry

Difference Between Benzene and Phenyl

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Main Difference

The main difference between Benzene and Phenyl is that Benzene is made up of six hydrogen atoms, whereas Phenyl is made up of five hydrogen atoms.

Benzene vs. Phenyl

Benzene is known as a colorless, liquid, volatile hydrocarbon existing in petroleum; on the other hand, the phenyl is known as a group that is derived from benzene and usually combines with other molecules. Benzene consists of six hydrogen atoms; on the contrary, the phenyl consists of five carbon atoms.

The stability of benzene is very high when it is alone and not combined with other molecules; on the flip side, the phenyl has low stability when it is alone. C6H is the chemical formula of benzene; on the other hand, C6H5 is the chemical formula that is written for phenyl.

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Benzene is considered as a functional group which contains a benzene ring which is usually attached to the CH2 group; on the contrary, a phenyl is also a functional group which consists of six C atoms usually bonded in a hexagonal ring in which one C atom is further bonded to a substituent, and the other remaining five C atoms are bonded to hydrogen atoms.

The abbreviation of benzene is “Bn” which is used to represent the benzyl group such as BnOH is marked for benzyl alcohol; on the flip side, the abbreviation of phenyl is “Ph” which is used to represent the phenyl group such as PhH is used to donate the benzene.

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The bond dissociation energy, which is necessary for the detachment of the benzyl C-H bond is 90 kcal/mol, whereas the energy which is needed for the dissociation of phenyl C-H bond is 113 kcal/mol. The benzyl is widely used in the organic synthesis as a safety group for carboxylic acids and alcohols; on the other hand, the phenyls containing compounds are widely used in the medicines such as Atorvastatin is used to minimize the cholesterol level, and Fexofenadine is used to cure the allergies.

The enhanced reactivity characterized the benzylic positions because of the low bond dissociation energy of the benzyl C-H bonds, but benzylic substitutions show increased reactivity in free radical oxidation, halogenation, hydrogenolysis, etc. While the lower reactivity characterized the phenylic positions because of high bond dissociation energy, phenyl substances are hydrophobic and resist oxidation.

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Comparison Chart

BenzenePhenyl
The functional group, which consists of a benzene ring which is directly attached to the CH2 group, is known as benzene.The functional group consists of six C atoms in which one is attached to the substituent, and others are attached to the hydrogen atom.
Properties
A colorless, liquid, volatile hydrocarbon existing in petroleumA group which is derived from benzene and usually combines with other molecules
Number of Hydrogen Atoms
Consists of six hydrogen atomsConsists of five carbon atoms
Stability
The stability is very high when it is alone and not combined with other moleculesHas low stability when it is alone
Chemical Formula
C6HC6H5
Abbreviation
“Bn” which is used to represent the benzyl group such as BnOH is marked for benzyl alcohol“Ph” which is used to represent the phenyl group such as PhH is used to donate the benzene
Bond Dissociation Energy
The bond dissociation energy which is necessary for the detachment of the benzyl C-H bond is 90 kcal/molThe energy which is needed for the dissociation of phenyl C-H bond is 113 kcal/mol
Use
Widely used in organic synthesis as a safety group for carboxylic acids and alcoholsWidely used in medicines such as Atorvastatin is used to minimize the cholesterol level, and Fexofenadine is used to cure the allergies
Reactivity
The enhanced reactivity characterized the benzylic positions because of the low bond dissociation energy of the benzyl C-H bonds, but benzylic substitutions show increased reactivity in free radical oxidation, halogenation, hydrogenolysis, etcThe lower reactivity characterized the phenylic positions because of high bond dissociation energy, phenyl substances are hydrophobic and resist oxidation

What is Benzene?

The property of benzene is that it is an unstable, colorless liquid hydrocarbon which is found in petroleum. Benzene is considered a ring structure, and its formula is C6H6.

Total carbon atoms of benzene are usually attached through single bonds, and these three bonds are arranged in discontinuous manners. One each carbon atom is attached with the one hydrogen atom, and in this way, all the six hydrogen atoms are attached with the six carbon atoms.

Because of the existence of double bonds in benzene, the π bond electrons joined to form two electron clouds that are present in the benzene ring, on the upper or lowest of the ring. The electron cloud is considered parallel to the plane of the benzene ring, and this particular structure of the benzene ring was first proposed by the Kekule (1872); that’s why benzene structure is also known as Kekule structure.

What is Phenyl?

Phenyl is a functional group that is the resultant of the benzene and then further joined with the other molecules. The phenyl molecular formula is C6H5. The phenyl is made up of alternating double bonds, which are the same present in benzene.

The reason for the high reactivity of phenyl is that it consists of a vacant point where one hydrogen atom is not present. So the phenyl group is attached with other different molecules through the vacant point, which enhances the reactivity of phenyl.

Normally some consider that the benzyl or phenyl group is the same, but it is not. These two groups are very different from each other due to the presence of –CH2– group in benzene, which is attached to the benzene ring. The phenyl is present in the form of phenol, which is the most common molecule in the phenyl group, and from there, the phenyl group is attached to the –OH group.

The energy which is needed for the dissociation of phenyl C-H bond is 113 kcal/mol. Some common examples of phenyl are triphenylmethane, chlorobenzene, phenol, etc.

Key Differences

  1. Benzene is a compound that consists of all paired electrons, whereas phenyl is a radical which consists of unpaired electrons.
  2. The molecular formula of benzene is C6H6; on the other hand, the molecular formula of phenyl is C6H5.
  3. Benzene forms the precipitation in water, while the phenyl is soluble in water and forms the heterogeneous mixture.
  4. The abbreviation of benzene is “Bn,” for instance; benzyl alcohol is normally denoted as BnOH; on the other hand, the abbreviation of phenyl is “Ph,” for example benzene can be denoted as PhH.
  5. 90 kcal/mol is the bond dissociation energy, which is used to break down the benzyl C-H bond; on the contrary, 113 kcal/mol is the bond dissociation energy which is used to dissociate the phenyl C-H bond.
  6. Benzene is importantly used in the synthesis of organic compounds, which is a protecting group for carboxylic acids and alcohols. On the contrary, the compounds containing phenyl are used in the medicinal purpose; for example, Atorvastatin is used for lowering the cholesterol level, and Fexofenadine is used for curing the allergies.

Conclusion

The above discussion concludes that the benzene and phenyl are widely used in the different important compounds, but many precautions should be taken while choosing the benzene products. The particular difference present between benzene and phenyl is that benzene consists of six hydrogen atoms, while phenyl consists of five hydrogen atoms.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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