SARCOSINATE

Sarcosinate is an alpha-amino-acid anion that is the conjugate base of sarcosine, arising from deprotonation of the carboxy group.
Sarcosinate has a role as a human metabolite.
Sarcosinate is a conjugate base of a sarcosine.

IUPAC Name: 2-(methylamino)acetate

Molecular Formula: C3H6NO2-
Molecular Weight: 88.09 g/mol

sarcosinate, N-Methylglycocoll, (methylamino)acetate, Methylaminoethanoic acid, 2-Methylaminoethanoic acid, Methylglycocoll, CHEBI:46915, Q27120731

Sarcosinates are mild anionic surfactants with high conditioning and foaming properties.
Sarcosinates are water-soluble and stable at pH-7,5 - 9,0.
Sarcosinates can be applied in shampoos or bubble-bath formulations.

Sarcosinates are carboxylated surfactants that are also called interrupted soaps due to their similar structure to soap.
As would be expected, Sarcosinates have poor hard water tolerance but are quite mild.
Sarcosinates seem to have good cationic compatibility and thus are used in conditioning shampoos in combination with cationic polymers.
Sarcosinates have recently enjoyed good popularity in body wash preparations where they impart a silky skin feel and counteract the harshness of the alkyl sulfates.
It is quite interesting that the sarcosinate surfactants perform extremely well in the presence of sebum (hair oils) where their foam actually increases.

Sarcosinate surfactants have the general structure:

RCON(CH3)CH2COO−M+

Sarcosinates exhibit some physical and chemical properties similar to fatty acid soaps and are sometimes referred to as “interrupted” soaps.
The presence of the N-methyl amido group [–CON(CH3)–] in the carbon chain exerts a considerable influence on physical and chemical properties.
Sarcosinates are more soluble in water and are less affected by hard water than common soaps.
Unlike soap, Sarcosinates may be incorporated into formulations as low as pH 4 with very good results.

Sarcosinates produce a generous amount of rich soap-like foam, yet they exhibit mildness to skin, and according to Thau are remarkably compatible with a variety of surfactants, including cationics.
Sarcosinates are reported to be strongly absorbed on various keratin substrates like skin, hair and wool at pH 4–7.
Sarcosinates exist in equilibrium with quantities of the free N-acyl sarcosinic acid in the pH range 4–7; they are used as a blend of the free acid and its salts.
While being almost completely solubilized yielding clear solutions, the minor amount of free sarcosinic acid exhibits strong affinity for skin; thus in simple sarcosinate formulations in combination with other mild surfactants, such as sodium cocoyl isethionate, can impart a smooth and soft residual skin feel.