The Handbook of Soap Manufacture. H. A. Appleton

palmitin sodium hydroxide sodium palmitate glycerol

      

CH2OOC18H33						CH2OH
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CHOOC18H33	+	3NaOH	=	3NaOOC18H33	+	CHOH
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CH2OOC18H33						CH2OH
olein		sodium hydroxide		sodium oleate		glycerol

      Berthelot subsequently confirmed Chevreul's investigations by directly synthesising the fats from fatty acids and glycerol, the method he adopted consisting in heating the fatty acids with glycerol in sealed tubes. Thus, for example:—

3C18H35O2H	+	C3H5(OH)3	=	C3H5(C18H35O2)3
stearic acid		glycerol		tristearin

      Since glycerol is a trihydric alcohol, i.e., contains three hydroxyl (OH) groups, the hydrogen atoms of which are displaceable by acid radicles, the above reaction may be supposed to take place in three stages. Thus, we may have:—

(1)	C18H35O2H	+	C3H5(OH)3	=	C3H5(OH)2C18H35O2	+	H2O
					monostearin
(2)	C18H35O2H	+	C3H5(OH)2C18H35O2	=	C3H5(OH)(C18H35O2)2	+	H2O
					distearin
(3)	C18H35O2H	+	C3H5(OH)(C18H35O2)2	=	C3H5(C18H35O2)3	+	H2O
					tristearin

      There are two possible forms of monoglyceride and diglyceride, according to the relative position of the acid radicle, these being termed alpha and beta respectively, and represented by the following formulæ, where R denotes the acid radicle:—

      Monoglyceride:—

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	CH2OR			CH2OH
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(alpha)	CHOH	and	(beta)	CHOR
	|			|
	CH2OH