Answers are grounded in this paper and cite their sources.
The rate of polymerization of hydrogen cyanide to aminomalononitrile and the tetramer, diaminomalonodinitrile, is quadratic in the total cyanide concentration. Since the reactions form part of a plausible prebiotic purine synthesis and since they compete with hydrolysis, concentration of cyanide may have been important. This may be achieved usefully by cooling to separate out ice.
No takes yet. Share an insight, caveat, or question.
Sanchez et al. (1966) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: