Stearic Acid

INCI: Stearic Acid

CAS# 57-11-4
EC#200-313-4

Acid value (mgKOH/g): 202-210
Saponification value (mgKOH/g): 204-211
Iodine value (gI2/100g): 0.5 max.
Color Lovibond 5 ¼” :0.3R 3Y max.
Fatty acid composition (%)
C12: 0-1
C14: 0-2
S16:47-53
C18: 47-50
C20: 0-1

Physical state: solid
Color : White to light yellow
Smell : Slightly mild/tallow odor
pH : Not applicable
Melting point : 53 - 63 0C
Boiling Point: 200-240 0C @ 760mmHg
Flash Point: 180-202 0C (ASTM D92, Cleveland Open Cup)

Synonyms: Stearin. acetylacetic acid sterophanic acid.
Molecular Formula: C18H36O2 (pure stearic acid)
Molecular Weight: 284.48

Description: Mixture of palmitic (hexadecanoic) and stearic (octadecanoic) acids in various proportions, usually of
vegetable (palm oil).

Physical-Chemical Data: Small white or almost white spheres and/or white or yellowish-white powder.

Practically insoluble in water, soluble in 96% ethanol, and in light petroleum ether (b.p. 50 – 70 ºC).

Melting point: 69 – 70ºC.

Properties and uses:

Stearic acid has emollient and protective properties, which prevents the desiccation of the horny layer of the skin, and is easily absorbed through it.

It is used as an emulsifier for the formation of base creams, sometimes used as vanishing emulsions, partially neutralized with an alkali (mainly triethanolamine).

The free stearic acid in these creams produces a pearly appearance. Stearic acid creams may appear cracked or lumpy due to reactions of stearic acid with zinc or calcium salts.

It is used similarly to white wax for ointments and waxes.

It is also used as a lubricant in the manufacture of tablets and capsules, and as an enteric coating for gastro-resistant pills and tablets.

Finally, it has an application as a hardening agent in suppositories.

Dosage:
As an emulsifier in ointments and creams: 1 - 20%.
As a lubricant: 1 - 3%.

Incompatibilities: Bases in general, metal hydroxides, oxidizing agents, and reducing agents.

Conservation: In tightly closed containers. PROTECT FROM LIGHT

Observations:

• Stearic acid has emollient and surfactant properties for the skin.
• It is odorless and is used to create light-colored soaps.
• Adjusts the PH of soap and produces hard soap bars.
• Due to its emulsifying property it is used to make creams and soaps.
• It is used as a substitute for palm oil.