Chemistry Reference
In-Depth Information
the tallow soaps and, because of their structures, are nonirritating to skin and eyes.
Many of the amino acid derivatives are nontoxic and have found uses in oral appli-
cations such as toothpastes and mouthwashes. Additional uses can be found in such
diverse areas as antistatic agents and lubricants for food packaging polymers, tex-
tiles, petroleum recovery, metal processing fluids, carpet cleaners, and photographic
emulsions. Acylated proteins derived from leather and bone also show good deter-
gent properties and perform well as fabric softeners and ''control'' agents in sham-
poos.
Esters of fatty acids, primarily stearic and palmitic, and distilled monoglyce-
rides with lactic, tartaric, citric, succinic, and related hydroxy acids have found wide
application as emulsifiers and improvers in the food industry. Sodium or calcium
salts of esters of stearic acid with lactic acid [sodium stearoil-2-lactylate (SSL)]
COO
Na
þ
CH
3
ð
CH
2
Þ
16
COOCH
ð
CH
3
Þ
COCH
ð
CH
3
Þ
and diacetyltartaric acid esters of monoglycerides (DATEM)
C
17
H
35
COOCH
2
CH
ð
OH
Þ
CH
2
OOCCH
ð
OOCH
3
Þ
CH
ð
OOCH
3
Þ
COOH
are widely used throughout the world in the production of bread and other bakery
products. The ''natural'' character of such products derived from lactic acid (an
a
-hydroxy acid) has led to their occasional use in skin and hair care products.
Because of the nature of the starting materials for such products, they are rather
complex mixtures of compounds ranging from free fatty acid salts to low-molecular-
weight polymers and cyclic isomers of the corresponding hydroxyl acids.
2.4.4. Phosphoric Acid Esters and Related Surfactants
The esters of phosphorus-based acids constitute a relatively uniform group of
anionic surfactants that can fill a special role in the overall scheme of surfactant
applications. The esters and diesters of phosphoric acid have the general formula
PO
3
M
þ
RO
where the R group is usually a long-chain alcohol or phenol. The materials may be
obtained as the free acid (M
H) or sodium or amine salts. In fact, they are gen-
erally found as a mixture of mono- and dibasic phosphates. The surfactant proper-
ties of the alkyl phosphates vary. They have been reported to be somewhat superior
to related sulfates and sulfonates in some applications because of their low foaming
characteristics, good solubility in water and many organic solvents, and resistance
to alkaline hydrolysis. However, their performance as detergents seems to be infer-
ior in most cases. The phosphate esters have the general disadvantage of being more
expensive than sulfonates and sulfates; but wider solubility and good activity in
harsh environments have made them useful in dry cleaning formulations, highly
alkaline cleaners, and various emulsion formulations.
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