Question

Acetic acid reacts with $PC{l_5}$ to form-
A. $LiAl{H_4}$
B. $CHC{l_2}COOH$
C. $C{H_3}COCl$
D. $C{H_3}COOCl$

Answer 1

Phosphorous penta-chloride $PC{l_5}$ is a pale yellow crystalline solid which has a characteristic smell. It is generally used as a chlorinating agent. Acetic acid is an organic acid with carboxylic functional group which is for its many properties like antibacterial and antifungal properties.

Step-by-Step Solution-
Acetic acid is an organic acid with formula ${\text{C}}{{\text{H}}_3}{\text{COOH}}$. It is a clear and colorless liquid with vinegar like smell. When it reacts with $PC{l_5}$ it produces acetyl chloride and hydrochloric acid. The reaction is as follows-
${\text{C}}{{\text{H}}_3}{\text{COOH}} + {\text{PC}}{{\text{l}}_{\text{5}}} \to {\text{C}}{{\text{H}}_3}{\text{COCl + HCl + POC}}{{\text{l}}_3}$
In this reaction hydroxyl group of acetic acid is replaced by chloride ion and acetyl chloride is formed. Acetyl chloride is a colourless fuming liquid. It has a characteristic pungent smell. It is an important compound because-
- It is used as acetylating agent in preparation of ester and amide from alcohol and amine compounds.
- It is used in the synthesis of dyes and in manufacture of aspirin, acetaminophen, aceto-phenone and acetanilide like pharmaceuticals.
- It is used in the testing of cholesterol.
- It is also used in composition of liquid crystals which are used in our watches, calculators, optical displays and memory devices.

Hence the correct answer is C.

Note: The uses of Acetic acid are-
- It is used in biochemistry analysis and as a reagent in the lab during chemical reactions.
- It is used as an acidifying and neutralizing agent.
- It is used as a food additive or flavoring agent for food.
- It is used in the textile industry in printing and as a deliming agent during leather tanning.
- It is used in production of nylon and other acrylic fibres and in manufacture of acetyl compounds.