T. Arrhenius et al., ARCHEAN GEOCHEMISTRY OF FORMALDEHYDE AND CYANIDE AND THE OLIGOMERIZATION OF CYANOHYDRIN, Origins of life and evolution of the biosphere, 24(1), 1994, pp. 1-17
The sources and speciation of reduced carbon and nitrogen inferred for
the early Archean are reviewed in terms of current observations and m
odels, and known chemical reactions. Within this framework hydrogen cy
anide and cyanide ion in significant concentration would have been eli
minated by reaction with excess formaldehyde to form cyanohydrin (glyc
olonitrile), and with ferrous ion to form ferrocyanide. Natural reacti
ons of these molecules would under such conditions deserve special con
sideration in modeling of primordial organochemical processes. As a st
ep in this direction, transformation reactions have been investigated
involving glycolonitrile in the presence of water. We find that glycol
onitrile, formed from formaldehyde and hydrogen cyanide or cyanide ion
, spontaneously cyclodimerizes to 4-amino-2-hydroxymethyloxazole. The
crystalline dimer is the major product at low temperature (approximate
ly 0-degrees-C); the yield diminishes with increasing temperature at t
he expense of polymerization and hydrolysis products. Hydrolysis of gl
ycolonitrile and of oxazole yields a number of simpler organic molecul
es, including ammonia and glycolamide. The spontaneous polymerization
of glycolonitrile and its dimer gives rise to soluble, cationic oligom
ers of as yet unknown structure, and, unless arrested, to a viscous li
quid, insoluble in water. A loss of cyanide by reaction with formaldeh
yde, inferred for the early terrestrial hydrosphere and cryosphere wou
ld present a dilemma for hypotheses invoking cyanide and related compo
unds as concentrated reactants capable of forming biomolecular precurs
or species. Attempts to escape from its horns may take advantage of th
e efficient concentration and separation of cyanide as solid ferriferr
ocyanide, and most directly of reactions of glycolonitrile and its der
ivatives.