설명(영) |
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The Betaine group of cosmetic raw materials includes the quaternized alkyl or substituted alkyl derivatives of N,N-dimethyl glycine. The Betaines have the structure:
in which the nitrogen atom always carries a positive charge regardless of pH. At pHs normally encountered in cosmetics this charge is counterbalanced by a negative charge on the carboxyl group (zwitterion). Betaines are not truly amphoteric compounds because they do not exhibit exclusively anionic characteristics even at high pH. R represents an alkyl group, e.g., C14H29- in Myristyl Betaine, or an amide-interrupted alkyl group, e.g., C17H35CONH(CH2)3-, in Stearamidopropyl Betaine. Related amphoteric compounds are derived from amino propane sulfonic acids (see Sulfonic Acids), e.g., Lauryl Sultaine.
The Betaines are zwitterionic, surface-active compounds which are employed as emulsifiers, detergents, foam boosters, aqueous viscosity increasing agents, and skin and hair conditioners. |