Phenol can be distinguished from ethyl alcohol by all of the following reagents except (a) \(\mathrm{Na}\) (b) \(\mathrm{FeCl}_{3}\) (c) \(\mathrm{Br}_{2} / \mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{NaOH}\)

Phenol is an aromatic alcohol with a hydroxyl group (-OH) directly bonded to a benzene ring. Its chemistry is rich due to the resonance stabilization of the phenoxide ion, which is formed when phenol deprotonates. When introduced to chemical reagents, phenol exhibits several distinct reactions that are indicative of its phenolic nature.

Reaction with Sodium (Na)

Upon treatment with sodium, phenol forms sodium phenoxide along with the release of hydrogen gas, a common feature it shares with ethyl alcohol.

Reaction with Ferric Chloride (FeCl3)

A classic test for phenols is their reaction with ferric chloride. Phenol forms a complex with FeCl3, resulting in a characteristic color change usually ranging from violet to green, which is a result of the formation of a phenol-iron(III) complex.

Reaction with Bromine Water (Br2/H2O)

Phenol reacts with bromine water to form a white precipitate of 2,4,6-tribromophenol. This reaction does not require a catalyst as the bromine is activated by the electron-rich aromatic ring of phenol.

Ethyl alcohol, commonly known as ethanol, is a primary alcohol with two carbon atoms. Its reactions are typical of aliphatic primary alcohols and are less complex compared to phenol.

Reaction with Sodium (Na)

Ethyl alcohol reacts with sodium to produce sodium ethoxide and hydrogen gas, similar to phenol's reaction with sodium. However, ethanol does not react significantly with other reagents that test for the presence of a phenol group.

Lack of Reaction with Ferric Chloride (FeCl3)

Unlike phenol, ethanol does not create a colored complex with FeCl3, providing a negative result for this test in distinguishing ethanol from a phenol.

Lack of Reaction with Bromine Water (Br2/H2O)

Ethanol does not react with bromine water under normal conditions, as the -OH group in ethanol is not activated in the way it is in phenol, making it unreactive towards the electrophilic bromine.

Chemical reagents play a crucial role in organic chemistry, allowing one to conduct qualitative analyses and syntheses. Understanding the reactivity of different reagents can help identify organic compounds and elucidate their structures.

Sodium (Na)

Sodium is a strong reducing agent that reacts with both phenol and alcohols to form their respective sodium salts, indicating the presence of an active hydrogen atom.

Ferric Chloride (FeCl3)

Ferric chloride is a reagent used specifically to detect phenolic groups, as it forms colored complexes only with phenols.

Bromine Water (Br2/H2O)

Bromine water is a reagent that is used for testing unsaturation and the presence of activated aromatic rings like those found in phenols, which react even under mild conditions to give tribrominated products.

Organic chemistry involves the study of carbon compounds and their properties. Key concepts such as functional groups, reactivity patterns, and mechanisms underpin this field of study.

Functional Groups

Functional groups such as hydroxyl (-OH) in alcohols and phenols define the chemical reactivity and properties of organic molecules. They are the reactive parts of the molecules that interact with chemical reagents.

Resonance Stabilization

In phenols, the aromatic ring allows for resonance stabilization, which influences how it reacts with other chemicals. Resonance stabilization in phenols is not a feature seen in simple alcohols like ethanol.

Electrophilic Aromatic Substitution

The reactions of phenols often involve electrophilic aromatic substitution mechanisms, where an electron-rich aromatic ring reacts with an electrophile, such as in the reaction with bromine water. Understanding these concepts is crucial for predicting the behavior of organic compounds in the presence of various reagents.