Question

A fruity smell is produced by the reaction of \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) with (a) \(\mathrm{PCl}_{5}\) (b) \(\mathrm{CH}_{3} \mathrm{COOH}\) (c) \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) (d) none of these

Short answer

(b) \(\mathrm{CH}_{3}\mathrm{COOH}\) produces a fruity smell.

Step-by-step solution

Identify the Compounds

First, we need to identify the compounds involved in the reaction with ethanol (\(\mathrm{C}_{2} \mathrm{H}_{5}\mathrm{OH}\)). Options include \(\mathrm{PCl}_{5}\), \(\mathrm{CH}_{3}\mathrm{COOH}\), and \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\).

Determine the Type of Reactions

Ethanol can react with these compounds in different ways: - With \(\mathrm{PCl}_{5}\): This reaction typically produces ethyl chloride (a halogenated compound).- With \(\mathrm{CH}_{3}\mathrm{COOH}\): This reaction produces an ester, specifically ethyl acetate, characterised by a fruity smell.- With \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\): No typical fruity-smelling compound is formed in this reaction.

Identify the Fruity Smell-Producing Reaction

The fruity smell is due to the production of esters. In the given options, the reaction between \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\) and \(\mathrm{CH}_{3} \mathrm{COOH}\) (acetic acid) produces ethyl acetate, a compound known for its fruity smell. This reaction is termed esterification.

Select the Correct Option

Based on the analysis, the compound that reacts with ethanol to produce a fruity smell is \(\mathrm{CH}_{3}\mathrm{COOH}\) (option b).

Key concepts

Ethanol Reactions

Ethanol is a versatile organic compound often used as a reactant in various chemical reactions. It can participate in substitution, esterification, and oxidation reactions. When ethanol reacts with

• PCl₅: A substitution reaction occurs, producing ethyl chloride, which doesn't exhibit a fruity aroma.
• CH₃COOH: An esterification reaction takes place, forming ethyl acetate, which is renowned for its distinctive fruity scent.
• CH₃COCH₃: This reaction doesn't typically create any products with a fruity smell, as ethanol acts merely as a solvent here.

In esterification, ethanol reacts specifically with acetic acid (CH₃COOH) to produce an ester. Ethyl acetate, a common ester, results from the combination of ethanol and acetic acid, marking a classic example of such a process.
The general reaction for an esterification can be written as:\[ R-OH + R'-COOH \rightarrow R'-COO-R + H_2O \] Here, \(R\) is the ethyl group from ethanol, and \(R'\) is the acetate group from acetic acid.

Fruity Smell in Chemistry

The fruity smell is often associated with esters, a class of organic compounds formed in the reaction between an alcohol and a carboxylic acid. Esters have distinct smells, often reminiscent of fruits and flowers. This makes them essential for use in fragrances and flavorings.

• Why Esters Smell Fruity: The volatile nature of esters allows them to vaporize quickly, reaching our olfactory receptors effectively, thus providing a perception of fragrance.
• Common Fruity Esters: Some common esters such as ethyl acetate, isoamyl acetate, and methyl butyrate contribute smells similar to apple, banana, and pineapple, respectively.

The ability to produce these distinct scents has led to the widespread use of esters in perfumes and scented products. Moreover, many natural flavors and aromas contain esters, adding to their appeal.
While the esterification reaction creating these compounds primarily involves alcohols and acids, many factors like the specific reactants and reaction conditions can influence the exact scent of the resulting ester.

Ethyl Acetate

Ethyl acetate is a widely known ester, famous for its sweet, fruity smell. It emerges from the esterification reaction between ethanol and acetic acid, and its chemical formula is C₄H₈O₂. This compound doesn't just stop at being aromatic; it serves multiple purposes across different industries.

• Uses: Ethyl acetate finds application as a solvent in paints, coatings, and nail polish remover due to its ability to dissolve many resins and plastics.
• Production: Large-scale production of ethyl acetate typically involves ethanol and acetic acid under acidic conditions, employing a catalyst such as sulfuric acid or an acid chloride.

The allure of ethyl acetate extends to its simple synthesis and broad applicability. Though its main claim to fame is the fruity aroma, this ester’s functional versatility keeps it in demand. In labs, it’s a handy solvent, and in the consumer world, it’s key to making pleasant-smelling, effective products.