Glycolaldehyde is the second most abundant compound formed when preparing
pyrolysis oil (up to 10% by weight). Glycolaldehyde can be synthesized by the oxidation of
ethylene glycol using
hydrogen peroxide in the presence of
iron(II) sulfate.
Biosynthesis It can form by action of
ketolase on
fructose 1,6-bisphosphate in an alternate glycolysis pathway. This compound is transferred by
thiamine pyrophosphate during the
pentose phosphate shunt. In
purine catabolism,
xanthine is first converted to
urate. This is converted to
5-hydroxyisourate, which decarboxylates to
allantoin and
allantoic acid. After hydrolyzing one
urea, this leaves
glycolureate. After hydrolyzing the second urea, glycolaldehyde is left. Two glycolaldehydes condense to form
erythrose 4-phosphate, which goes to the pentose phosphate shunt again.
Role in formose reaction Glycolaldehyde is an intermediate in the
formose reaction. In the formose reaction, two
formaldehyde molecules condense to make glycolaldehyde. Glycolaldehyde then is converted to
glyceraldehyde, presumably via initial tautomerization. The presence of this glycolaldehyde in this reaction demonstrates how it might play an important role in the formation of the chemical building blocks of life.
Nucleotides, for example, rely on the formose reaction to attain its sugar unit. Nucleotides are essential for life, because they compose the genetic information and coding for life.
Theorized role in abiogenesis It is often invoked in theories of
abiogenesis. In the laboratory, amino acids and short dipeptides have been shown to catalyze the formation of complex sugars from glycolaldehyde. For example, L-valyl-L-valine was used as a catalyst to form tetroses from glycolaldehyde. Theoretical calculations have additionally shown the feasibility of dipeptide-catalyzed synthesis of pentoses. This formation showed stereospecific, catalytic synthesis of D-ribose, the only naturally occurring enantiomer of ribose. Since the detection of this organic compound, many theories have been developed related various chemical routes to explain its formation in stellar systems. It was found that UV-irradiation of methanol ices containing CO yielded organic compounds such as glycolaldehyde and
methyl formate, the more abundant isomer of glycolaldehyde. The abundances of the products slightly disagree with the observed values found in IRAS 16293-2422, but this can be accounted for by temperature changes.
Ethylene glycol and glycolaldehyde require temperatures above 30 K. The general consensus among the astrochemistry research community is in favor of the grain surface reaction hypothesis. However, some scientists believe the reaction occurs within denser and colder parts of the core. The dense core will not allow for irradiation as stated before. This change will completely alter the reaction forming glycolaldehyde. ==Formation in space==