Points to Remember:
- Acetic acid (CHâCOOH) is a weak organic acid, readily reacting with various compounds.
- The reactions will involve the acidic hydrogen of acetic acid and the nucleophilic/electrophilic nature of the other reactants.
- Naming the products requires understanding of IUPAC nomenclature.
Introduction:
Acetic acid, also known as ethanoic acid, is a ubiquitous carboxylic acid with the formula CHâCOOH. Its reactivity stems primarily from the carboxyl group (-COOH), which contains both a carbonyl group (C=O) and a hydroxyl group (-OH). The acidic proton on the hydroxyl group is readily displaced in reactions with bases and nucleophiles. This reaction will explore the behavior of acetic acid with different reagents, focusing on the reaction mechanism and product formation.
Body:
i) Reaction with Ammonia (NHâ):
- Mechanism: Ammonia, a weak base, reacts with acetic acid in an acid-base reaction. The lone pair of electrons on the nitrogen atom in ammonia attacks the acidic proton of acetic acid, forming ammonium acetate.
- Equation: CHâCOOH + NHâ â CHâCOONHâ
- Product Name: Ammonium acetate
ii) Reaction with Phosphorus Pentachloride (PClâ ):
- Mechanism: PClâ is a powerful dehydrating agent. It replaces the hydroxyl group (-OH) of acetic acid with a chlorine atom (-Cl), forming acetyl chloride. This reaction proceeds via the formation of an intermediate.
- Equation: CHâCOOH + PClâ â CHâCOCl + POClâ + HCl
- Product Name: Acetyl chloride
iii) Reaction with Lithium Aluminum Hydride (LiAlHâ):
- Mechanism: LiAlHâ is a strong reducing agent. It reduces the carboxylic acid group (-COOH) of acetic acid to a primary alcohol group (-CHâOH). This is a two-step process involving the formation of an aldehyde intermediate.
- Equation: CHâCOOH + LiAlHâ â CHâCHâOH
- Product Name: Ethanol
iv) Reaction with Thionyl Chloride (SOClâ):
- Mechanism: Similar to PClâ , SOClâ is a dehydrating agent that converts the carboxylic acid group into an acid chloride. The reaction is often preferred over PClâ due to the easier separation of byproducts (SOâ and HCl are gases).
- Equation: CHâCOOH + SOClâ â CHâCOCl + SOâ + HCl
- Product Name: Acetyl chloride
v) Reaction with Ethanol (CâHâ OH):
- Mechanism: This reaction is an esterification reaction. The acidic proton of acetic acid reacts with the hydroxyl group of ethanol, forming an ester and water. This reaction is typically acid-catalyzed (e.g., using sulfuric acid).
- Equation: CHâCOOH + CâHâ OH â CHâCOOCâHâ + HâO
- Product Name: Ethyl acetate (This reaction is an equilibrium reaction; the yield of ethyl acetate can be improved by removing water as it is formed).
Conclusion:
Acetic acid demonstrates diverse reactivity due to the presence of the carboxyl group. It readily undergoes acid-base reactions, reductions, and substitution reactions, leading to the formation of various important derivatives like ammonium acetate, acetyl chloride, ethanol, and ethyl acetate. Understanding these reactions is crucial in organic chemistry synthesis and industrial applications. Further research could focus on optimizing reaction conditions for higher yields and exploring the use of greener reagents to minimize environmental impact. The development
of efficient and sustainable methods for the synthesis of these derivatives is vital for a more environmentally conscious chemical industry, aligning with principles of sustainable development. CGPCS Notes brings Prelims and Mains programs for CGPCS Prelims and CGPCS Mains Exam preparation. Various Programs initiated by CGPCS Notes are as follows:-