CH_{2}OOC_{18}H_{33} CH_{2}OH
| |
CHOOC_{18}H_{33} + 3NaOH = 3NaOOC_{18}H_{33} + CHOH
| |
CH_{2}OOC_{18}H_{33} CH_{2}OH

olein sodium sodium glycerol
hydroxide oleate

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:--

3C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{3} = C_{3}H_{5}(C_{18}H_{35}O_{2})_{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) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{3} =
C_{3}H_{5}(OH)_{2}C_{18}H_{35}O_{2} + H_{2}O
monostearin

(2) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)_{2}C_{18}H_{35}O_{2} =
C_{3}H_{5}(OH)(C_{18}H_{35}O_{2})_{2} + H_{2}O
distearin

(3) C_{18}H_{35}O_{2}H + C_{3}H_{5}(OH)(C_{18}H_{35}O_{2})_{2} =
C_{3}H_{5}(C_{18}H_{35}O_{2})_{3} + H_{2}O
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 formulae, where R
denotes the acid radicle:--

_Monoglyceride_:--

CH_{2}OR CH_{2}OH
| |
(alpha) CHOH and (beta) CHOR
| |
CH_{2}OH CH_{2}OH

_Diglyceride_:--

CH_{2}OR CH_{2}OR
| |
(alpha) CHOH and (beta) CHOR
| |
CH_{2}OR CH_{2}OH

According to the relative proportions of fatty acid and glycerol u