Sarcosinates

Generic Nomenclature

Sarcosinates

N-Acyl derivatives of sarcosine

Example:

Lauryl sarcosine

Description

Made from a fatty acid chloride and N-methyl glycine:

RCOCI + CH₃NHCH₂COOH    →   RCON(CH₃) CH₂COOH (catalyzed by alkali) + NaCl

The product as made contains sodium chloride which can be removed. Most commercial products contain considerable amounts of sodium chloride.

General properties

• General

More acidic than fatty acids and therefore there is less need to avoid free acid and pH control is easier; similar properties to isethionates.

• Solubility

Sodium salt not very soluble in acid or neutral pH but quite soluble in alkali; TEA salt more soluble at neutral pH.

• Compatibility
• with other surfactants: Good compatibility with anionic, non-ionic, and cationics where they do not adversely affect the bactericidal properties; compatible with quaternaries and phenolic biocides.
• with aqueous ions: Excellent, e.g. good foam with TEA salt in hard water.
• Chemical stability

Stable in acid and moderate acid at normal temperatures; unstable in strong acid or acid at high temperatures, loses foaming characteristics and thickens appreciably.

• Functional properties

Foams well even in presence of sebum and oils; foams better in hard water than soft water; good lime soap dispersant; some bacteriostatic activity claimed.

Applications

• Household products

Toothpaste ingredient, enzyme inhibiting, strong foamer, good detergent; liquid soaps.

• Personal care

Foaming agent in shampoos, boosts lather of alkyl sulfates in presence of sebum and good foaming in the presence of soaps; detoxifying agent in shampoos; addition to anionics improves mildness, conditioning and foaming; shaving preparations; foam baths; facial cleansers.

• Surgical scrubs
• Corrosion inhibitor

Specification

Activity	30% for Na salt40% for TEA salt
Acid value	50-60 mg KOH/g
Sodium chloride	1-5%