Chemical evolution. XIV. Oxidation of diaminomaleonitrile and its possible role in hydrogen cyanide oligomerization

Abstract

A,A'-Diisopropyldiaminomaleonitrile (4) is oxidized by oxygen to , '-diisopropyldüminosuccmonitrile (5) in 47% yield in acetonitrile solution. The yield of 5 is much less in aqueous solution at pH 9.2 with monoisopropylurea as the other reaction product. Ammoniacal hydrolysis of 5 (0.1 mmol) gives urea (0.076 mmol) as the only reaction product, while hydrolysis in the presence of a 30-fold excess of cyanide gives an enhanced yield of urea (0.28 mmol). These results may be explained by the reduction of 5 to 4 by cyanide with the subsequent formation of cyanogen or cyanate which in turn reacts with ammonia to give urea. Oxygen oxidizes 4 to 5, thus completing the cycle. Diaminomaleonitrile (3) is air oxidized in aqueous ammonia (pH 9.2) and urea was detected as a reaction product. Diiminosuccinonitrile ( 6) is the most likely initial oxidation product of 3. A 50% yield of urea is obtained on hydrolysis of 6 in ammonical solution. However, this yield did not increase when the hydrolysis was performed in the presence of cyanide. A pH 9.2 solution of cyanide in the presence of oxygen decomposes more rapidly than one which has been degassed. The detection of urea and amino acids (after acid hydrolysis) from the degassed cyanide solution demonstrates that oxidation and reduction leading to urea and the amino acid precursors are taking place in the absence of oxygen, suggesting that these reactions were feasible on the primitive earth.

Chemical evolution. 31. Mechanism of the condensation of cyanide to hydrogen cyanide oligomers

“…This is attributed to the oxidation of diaminomaleonitrile to diiminosuccinonitrile (4), a compound which is rapidly hydrolyzed to urea by dilute NH4OH. 17 The observation that the amounts of diaminomaleonitrile are significantly less in the presence of molecular oxygen (Figure 2) is consistent with the above result. The principal effect of molecular oxygen is apparently the oxidation of diaminomaleonitrile since the rate of oligomerization of HCN, as monitored by the loss of cyanide, was not significantly different in the absence or presence of oxygen in the early stages of the reaction (Figure 3).…”

Characterization of HCN-Derived Thermal Polymer: Implications for Chemical Evolution

“…The synthesis of HCN-DTP was performed under argon atmosphere, and furthermore, the polymerization reaction was performed under depleted oxygen conditions. The higher hydrophilicity of our sample may be related with moisture directly acquired from aqueous medium resulted from hydrolysis reactions (e.g., hydrolysis of nitriles, urea, and/or diiminosuccinonitrile, DISN [32,33]). Hence, the peak at 124 • C in our sample could be linked with another thermal event, the degradation of other organic molecules, such as urea, which are ionically adsorbed on the polymer backbone.…”

“…There is robust information about the mechanisms and chemical conditions that lead to the formation of DAMN from HCN, cyanide ( -CN), and intermediate species, such as AMN [31][32][33][34]. There are also some proposals about their polymeric structure [18,20,28,[35][36][37][38][39].…”

An experimental study of the thermolysis of hydrogen cyanide: the role of hydrothermal systems in chemical evolution

“…Several researches have shown that urea is a product of HCN oligomerization. Specifically, it may be a product of oxidation/hydrolysis of DAMN (Ferris et al ., 1973, 1974b; Ferris and Ryan, 1973; Ferris and Edelson, 1978; Ferris and Hagan, 1984). Our experiments showed that urea is formed only by thermolysis of slightly basic HCN solutions (pH = 8.5) and even in the presence of Mg-Mont (Fig.…”