Cocamidopropyl betaine (CAPB), a widely used surfactant in personal care products, is manufactured through a two-step process:
Step 1: Formation of Intermediate Amide
In the first step, dimethylaminopropylamine (DMAPA) undergoes a reaction with fatty acids sourced primarily from coconut or palm kernel oil. This reaction occurs through a cold blend process. Specifically, the primary amine group within DMAPA exhibits higher reactivity and consequently reacts with the carboxylic group present in lauric acid, a predominant constituent of these fatty acid sources. The outcome of this reaction is the formation of an intermediate amide compound.
Step 1 Reaction:
CH3(CH2)10COOH + H2NCH2CH2CH2N(CH3)2 → CH3(CH2)10CONHCH2CH2CH2N(CH3)2
Lauric acid + DMAPA Intermediate Amide
Step 2: Quaternization Reaction to Yield CAPB
Following the formation of the intermediate amide, the subsequent step involves the reaction of chloroacetic acid with the intermediate amide under basic conditions. This reaction, known as quaternization, occurs between the chloroacetic acid and the tertiary amine group within the intermediate amide, resulting in the formation of a quaternary ammonium center. This pivotal reaction yields the final product, Cocamidopropyl betaine (CAPB).
Step 2 Reaction:
CH3(CH2)10CONHCH2CH2CH2N(CH3)2 + ClCH2CO2H + NaOH →
Intermediate Amide + Chloroacetic acid + Sodium Hydroxide
CH3(CH2)10CONHCH2CH2CH2N+(CH3)2CH2CO2− + NaCl + H2O
Cocamido Propyl Betaine (CAPB) + Sodium Chloride + Water
This two-step process ensures the production of high-quality CAPB, which finds extensive application in various personal care formulations for its exceptional surfactant properties.
CAPB Upstream Tree:
