Phenol vs Phenyl
When phenyl group and –OH group combines, the resulted molecule is known as phenol. Both have the same aromatic ring structure.
Phenyl
Phenyl is a hydrocarbon molecule with the formula C6H5. This is derived from benzene, therefore, has similar properties as benzene. However, this differs from benzene due to lack of a hydrogen atom in one carbon. So the molecular weight of phenyl is 77 g mole-1. Phenyl is abbreviated as Ph. Usually, phenyl is attached to another phenyl group, atom or molecule (this part is known as the substituent). The carbon atoms of phenyl are sp2 hybridized like in benzene. All the carbons can form three sigma bonds. Two of the sigma bonds are formed with two adjacent carbons, so that it will give rise to a ring structure. The other sigma bond is formed with a hydrogen atom. But in one carbon in the ring, the third sigma bond is formed with another atom or molecule rather than with a hydrogen atom. The electrons in p orbitals overlap with each other to form the delocalized electron cloud. Therefore, phenyl has similar C-C bond lengths between all carbons, regardless of having alternating single and double bonds. This C-C bond length is about 1.4 Å. The ring is planar and has 120o angle between bonds around a carbon. Due to the substituent group of phenyl, the polarity and other chemical or physical properties change. If the substituent donate electrons to the delocalized electron cloud of the ring, those are known as electron donating groups. (E.g.: – OCH3, NH2) If the substituent attracts electrons from the electron cloud, they are known as electron withdrawing substituents. (E.g.: -NO2, -COOH). Phenyl groups are stable due to their aromaticity, so they don’t easily undergo oxidations or reductions. Further, they are hydrophobic and non-polar.
Phenol
Phenol is a white crystalline solid with the molecular formula C6H6OH. It has a molecular weight of 94 g mole-1. It is flammable and has a strong odor. Phenyl molecule is substituted with a –OH group to give phenol. Therefore, it has the similar aromatic ring structure as in phenyl. But its properties are different due to the –OH group. Phenol is mildly acidic (acidic than alcohols). When it loses the hydrogen of the –OH group it forms the negatively charged phenolate ion, and it is resonance stabilized, which in turn makes phenol a relatively good acid. In the resonance stabilization, the negative charge on the oxygen atom is shared with the carbon atoms in the ring.
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Phenol Vs Phenyl - Phenol is moderately soluble in water, because it can form hydrogen bonds with water. Moreover, phenol evaporates slower than water. - Phenyl and phenol differ from each other due to the presence of a –OH group in phenol. Because of this, all the properties of the two differ. - Phenyl cannot be considered as a stable molecule itself, because it is a substituent. Phenol is actually a phenyl derivative with a –OH group. - Phenyl is hydrophobic, but phenol is moderately soluble in water. - Phenyl cannot be resonance stabilized or don’t have acidic nature like phenol.
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