Chemistry Reference
In-Depth Information
O
O
O
C3 sugar
cat.
C
C
C
H
OH
H
H
H
CH
2
OH
aldol
OH
O
HOH
2
C
CH
2
OH
O
O
C
H
H
CH
2
OH
HOH
2
C
aldol
OH
O
OH
O
reverse aldol
2
C
OH
C
H
H
CH
2
OH
C4 sugars
C2 sugar for autocatalysis
OH
O
O
aldol
C
H
H
C
H
H
C5 sugars
C6 sugars
aldol
Fig. 2.1
The formose reaction
of C1 and C2 is glyceraldehyde (C3). Isomerization of glyceraldehyde to its ketose
isomer and condensation of the ketose with a second molecule of C1 gives a four-
carbon ketose, which can isomerize to the C4 aldose. Reverse aldol condensation of
the C4 aldose delivers two molecules of the original catalyst, C2. Thus the reaction
produces its own catalyst, i.e., it is autocatalytic. Following an induction period
as the catalyst builds up, such a reaction continues exponentially. The C4 product
also could add another molecule of formaldehyde to produce C5 products, which
could condense again to form C6 products. Hence the products are multifarious and
unstable, but are formed quickly and efficiently.
