Formose reaction

The initial dimerization of formaldehyde to give glycolaldehyde (1) occurs via an unknown mechanism, possibly promoted by light or through a free radical process and is very slow.

During this process, 3 can also react with 1 to form ribulose (4), which can isomerize to give rise to ribose (5), an important building block of ribonucleic acid.

However, these steps have been shown to proceed through a hydride shift mechanism by isotope labeling studies, instead of via an intermediate enediolate, as previously proposed.

[5] The formose reaction is of importance to the question of the origin of life, as it leads from simple formaldehyde to complex sugars like ribose, a building block of RNA.

In one experiment simulating early Earth conditions, pentoses formed from mixtures of formaldehyde, glyceraldehyde, and borate minerals such as colemanite (Ca2B6O115H2O) or kernite (Na2B4O7).