Conversions of various pentoses and hexoses into methyl lactate has been demonstrated for the Sn-Beta
catalyst. It is found that pentoses are converted to methyl lactate in slightly lower yields (∼40%) than
what is obtained for hexoses (∼50%), but higher yields of glycolaldehyde dimethyl acetal are observed
for the pentoses. This finding is in accordance to a reaction pathway that involves the retro aldol
condensation of the sugars to form a triose and glycolaldehyde for the pentoses, and two trioses for
hexoses. When reacting glycolaldehyde (formally a C2-sugar) in the presence of Sn-Beta, aldol
condensation occurs, leading to the formation of methyl lactate, methyl vinylglycolate and methyl
2-hydroxy-4-methoxybutanoate. In contrast, when converting the sugars in water at low temperatures
(100 °C), Sn-Beta catalyses the isomerisation of sugars (ketose–aldose epimers), rather than the formation
of lactates.