Which of the following is an anionic detergent?

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Which of the following is an anionic detergent?

Engineering

Chemistry

IUPAC Nomenclature of Organic Compound

Chemistry in everyday life

Basic concepts of organic chemistry

Question

Which of the following is an anionic detergent?

A

Glyceryl oleate

B

Sodium stearate

C

Sodium lauryl sulphate

D

Cetyltrimethyl ammonium bromide

Sodium ⁺(lauryl sulphate)^– is an anionic detergent.

An anionic detergent is a type of detergent where the hydrophilic (water-attracting) part is a negatively charged ion (anion). These detergents are commonly used in soaps and cleaning products because they are effective at removing dirt and grease.

Let's analyze each option:

Glyceryl oleate: This is an ester formed from glycerol and oleic acid. It is not a detergent; it is a non-ionic compound often used as an emollient in cosmetics.

Sodium stearate: This is a soap, which is the sodium salt of stearic acid. It ionizes in water to give stearate ions ( $C_{17}^{35} H_{35} C O O^{-}$ ) and Na⁺ ions. The stearate ion is an anion, so sodium stearate is an anionic detergent. However, it is traditionally classified as a soap rather than a synthetic detergent.

Sodium lauryl sulphate: This is a synthetic detergent. It ionizes in water to give lauryl sulphate ions ( $C_{12} H_{25} S O_{4} O^{-}$ ) and Na⁺ ions. The lauryl sulphate ion is a large anion, making sodium lauryl sulphate a classic example of an anionic detergent. It is widely used in shampoos and toothpastes.

Cetyltrimethyl ammonium bromide: This compound ionizes to give cetyltrimethyl ammonium ions ( $C_{16} H_{33} (C_{3} H_{3})_{3} N^{+}$ ) and Br^- ions. The hydrophilic part is positively charged (cation), so it is a cationic detergent, used as a germicide and antiseptic.

Therefore, sodium lauryl sulphate is the correct answer as it is a well-known synthetic anionic detergent.

Related Topics and Formulae

Types of Detergents:

Anionic Detergents: Contain a negative ion as the hydrophilic group (e.g., alkyl sulphates, alkyl benzene sulphonates).
Cationic Detergents: Contain a positive ion as the hydrophilic group (e.g., quaternary ammonium salts).
Non-ionic Detergents: Do not contain ions; hydrophilic part has groups like polyoxyethylene.

General Structure: Detergents have a hydrophobic tail (long hydrocarbon chain) and a hydrophilic head. For anionic detergents, the head is an anion such as $R - S O_{3} O^{-}$ or $R - O - S O_{3} O^{-}$ , where R is the alkyl group.