- Soaps: Sodium or potassium salts of long-chain fatty acids (e.g., \(RCOO^-Na^+\)).
- Synthetic Detergents:
- Anionic: Long alkyl chain with a sulfonate (\(-\text{SO}_3^-\)) or sulfate (\(-\text{OSO}_3^-\)) head group. E.g., Sodium dodecylbenzenesulfonate, Sodium lauryl sulfate.
- Cationic: Long alkyl chain with a quaternary ammonium (\(-\text{N}^+R_3\)) head group. E.g., Cetyltrimethylammonium bromide. Used in hair conditioners, germicides.
- Non-ionic: Long alkyl chain or alkylphenol with a polyoxyethylene chain (-\text{O}-\text{CH}_2\text{CH}_2\text{O}-)\(_n\)H. No ionic group. E.g., detergents made from reaction of polyethylene glycol with long chain alcohols or alkylphenols.
- Fats/Oils (Triglycerides): Esters of glycerol and three fatty acids. Example: \( (\text{RCOO})_3\text{C}_3\text{H}_5 \). These are not detergents themselves but are raw materials for soap.
Synthetic detergents are cleansing agents that have a soap-like action but are not soaps (salts of fatty acids). They typically have a long hydrophobic hydrocarbon tail and a hydrophilic head group. They are classified as anionic, cationic, or non-ionic.
A) \( \text{C}_9\text{H}_{19} - \text{Ph} - \text{O}(\text{CH}_2\text{CH}_2\text{O})_6\text{CH}_2\text{CH}_2\text{OH} \)
This is a non-ionic detergent. The long hydrocarbon chain (\(\text{C}_9\text{H}_{19}\)-Ph-) provides the hydrophobic part. The polyoxyethylene chain (-\text{O}(\text{CH}_2\text{CH}_2\text{O})_6\text{CH}_2\text{CH}_2\text{OH}\)) provides the hydrophilic part due to ether linkages and the terminal -OH group capable of hydrogen bonding. Example: detergents formed by reaction of polyethylene glycol with alkylphenols. This is a synthetic detergent.
B) \( \text{CH}_3(\text{CH}_2)_{10}\text{CH}_2\text{OSO}_3\text{Na} \) (Sodium lauryl sulfate or sodium dodecyl sulfate, SDS)
This is an anionic detergent. The \( \text{CH}_3(\text{CH}_2)_{10}\text{CH}_2- \) is the hydrophobic tail. The \( -\text{OSO}_3^-\text{Na}^+ \) is the hydrophilic head group (sulfate group). This is a common synthetic detergent.
C) \( \text{CH}_3(\text{CH}_2)_{15}\text{N(CH}_3\text{)}_3\text{Br} \) (Cetyltrimethylammonium bromide, CTAB)
This is a cationic detergent. The \( \text{CH}_3(\text{CH}_2)_{15}- \) is the hydrophobic tail. The \( -\text{N}^+\text{(CH}_3\text{)}_3\text{Br}^- \) is the quaternary ammonium hydrophilic head group. This is a synthetic detergent.
D) \( (\text{C}_{15}\text{H}_{31}\text{COO})_3\text{C}_3\text{H}_5 \) (Glyceryl tripalmitate, a triglyceride)
This is a fat or oil (specifically, tripalmitin). Fats and oils are triglycerides, which are esters of glycerol and fatty acids. Soaps are made by saponification (hydrolysis with alkali) of fats/oils. This compound itself is a fat, not a detergent.
Therefore, A, B, and C are synthetic detergents.
This matches option (1).
