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

2020 ◽  
Vol 19 (5) ◽  
pp. 369-378 ◽  
Author(s):  
Saúl A. Villafañe-Barajas ◽  
María Colín-García ◽  
Alicia Negrón-Mendoza ◽  
Marta Ruiz-Bermejo
Keyword(s):  
Chemical Evolution ◽  
Hydrogen Cyanide ◽  
Organic Molecules ◽  
Chemical Species ◽  
Hydrothermal Systems ◽  
Raw Material ◽  
Complex Molecules ◽  
Prebiotic Molecules ◽  
The Stability

AbstractHydrogen cyanide (HCN) is considered a fundamental molecule in prebiotic chemistry experiments due to the fact that it could have an important role as raw material to form more complex molecules, as well as it could be an intermediate molecule in chemical reactions. However, the primitive scenarios in which this molecule might be available have been widely discussed. Hydrothermal systems have been considered as abiotic reactors and ideal niches for chemical evolution. Nevertheless, several experiments have shown that high temperatures and pressures could be adverse to the stability of organic molecules. Thus, it is necessary to carry out systematic experiments to study the synthesis, stability and fate of organic molecules in hydrothermal scenarios. In this work, we performed experiments focused on the stability and fate of HCN under a simple hydrothermal system scenario: the thermolysis of HCN at 100°C, at acidic and basic pH and in the presence of Mg-montmorillonite. Furthermore, we analysed the products from HCN thermolysis and highlighted the role of these chemical species as prebiotic molecules under a hydrothermal scenario.

scholarly journals A Lizardite–HCN Interaction Leading the Increasing of Molecular Complexity in an Alkaline Hydrothermal Scenario: Implications for Origin of Life Studies

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 661
Author(s):  
Saúl A. Villafañe-Barajas ◽  
Marta Ruiz-Bermejo ◽  
Pedro Rayo-Pizarroso ◽  
Santos Gálvez-Martínez ◽  
Eva Mateo-Martí ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Hydrogen Cyanide ◽  
Organic Molecule ◽  
Organic Molecules ◽  
Analytical Techniques ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Molecular Complexity ◽  
Molecule Production

Hydrogen cyanide, HCN, is considered a fundamental molecule in chemical evolution. The named HCN polymers have been suggested as precursors of important bioorganics. Some novel researches have focused on the role of mineral surfaces in the hydrolysis and/or polymerization of cyanide species, but until now, their role has been unclear. Understanding the role of minerals in chemical evolution processes is crucial because minerals undoubtedly interacted with the organic molecules formed on the early Earth by different process. Therefore, we simulated the probable interactions between HCN and a serpentinite-hosted alkaline hydrothermal system. We studied the effect of serpentinite during the thermolysis of HCN at basic conditions (i.e., HCN 0.15 M, 50 h, 100 °C, pH > 10). The HCN-derived thermal polymer and supernatant formed after treatment were analyzed by several complementary analytical techniques. The results obtained suggest that: I) the mineral surfaces can act as mediators in the mechanisms of organic molecule production such as the polymerization of HCN; II) the thermal and physicochemical properties of the HCN polymer produced are affected by the presence of the mineral surface; and III) serpentinite seems to inhibit the formation of bioorganic molecules compared with the control (without mineral).

Concerning the chemical structure of the dicyanogen photopolymer and its presence in certain bodies of the Solar system. Implications on the synthesis of some prebiotic molecules

2002 ◽  
Vol 1 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Franco Cataldo
Keyword(s):  
Solar System ◽  
Ultraviolet Light ◽  
Hydrogen Cyanide ◽  
Chemical Structure ◽  
Organic Molecules ◽  
Cometary Nuclei ◽  
Prebiotic Molecules ◽  
Jovian Atmosphere

The chemical structure of the dicyanogen photopolymer (CN)x, also known as paracyanogen, prepared in different solvents from dicyanogen (CN)2 photopolymerization under the action of ultraviolet light, is shown to be very similar to the polymer derived from hydrogen cyanide (HCN) and from certain tholins obtained from a simulated Jovian atmosphere. The implications of dicyanogen and its polymer as a precursor of some organic molecules already detected in cometary comas and tails and in meteorites are discussed. In particular, paracyanogen may be present in the cometary nuclei and in the surface of certain low-albedo objects in the Solar system.

scholarly journals The dielectric coefficients of gases III—Allene, allylene, butanes, butylenes, cyanogen, and hydrogen cyanide—IV— Fluorides of boron, nitrogen, and carbon

1936 ◽  
Vol 156 (887) ◽  
pp. 130-143 ◽  
Keyword(s):  
Hydrogen Cyanide ◽  
Boron Trifluoride ◽  
The Other ◽  
Raw Material ◽  
Nitrogen Trifluoride ◽  
Carbon Tetrafluoride ◽  
Dielectric Coefficient ◽  
The Stability ◽  
Boron Nitrogen

Measurements of dielectric coefficient similar to those recorded in Parts I and II have now been made for the gases allene CH 2 = C = CH 2 , CH 3 —C≡CH, n - and iso -butane, α-, β-, and iso -butylene, cyanogen, hydrogen cyanide, boron trifluoride, nitrogen trifluoride, and carbon tetrafluoride, using the same apparatus as before. Owing to the stability and the ease of working with parallel condensor described in Part II, this was employed exclusively, the condeser G 4 being used to contain the gases. Of these, allylene, iso -butylene, and hydrogen cyanide have appreciable moments, while α-butylene, nitrogen trifluoride, and possibly allene appear to be very slightly polar. The other gases are electrically neutral. β-butylene is of interest since it affords a rather rare example of a gas exhibiting cis-trans isomerism. Unfortunately, the raw material required for making the cis form could not be obtained while the experiments were in progress, so that the measurements have had to be deferred.

Adsorption of HCN onto sodium montmorillonite dependent on the pH as a component to chemical evolution

2014 ◽  
Vol 13 (4) ◽  
pp. 310-318 ◽  
Author(s):  
M. Colin-Garcia ◽  
A. Heredia ◽  
A. Negron-Mendoza ◽  
F. Ortega ◽  
T. Pi ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Molecular Model ◽  
Three Dimensional ◽  
Channel Structure ◽  
Mineral Surfaces ◽  
Sodium Montmorillonite ◽  
Complex Molecules ◽  
Prebiotic Chemical ◽  
Physical And Chemical

AbstractThe aim of this work is to study the behaviour of hydrogen cyanide (HCN) adsorbed onto mineral surfaces (sodium montmorillonite, a clay mineral) in different pH environments as a possible prebiotic process for complexation of organics. Our experimental results show that specific sites on the surface of the clay increased the concentration of HCN molecules dependent on the pH values. Moreover, this adsorption can occur through physical and chemical interactions enhanced by the channel structure of the sodium montmorillonite. The three-dimensional channelling structure of the clay accumulates the organics, hindering the releasing (desorption) of the organic molecules. A molecular model developed here also confirms the role of the pH as a regulating factor in the adsorption of HCN onto the inorganic surfaces and the possibility for further reactions forming more complex molecules, as an abiotic mechanism important in prebiotic chemical evolution processes.

Stability of α-ketoglutaric acid simulating an impact-generated hydrothermal system: implications for prebiotic chemistry studies

2020 ◽  
Vol 19 (3) ◽  
pp. 253-259
Author(s):  
L. Ramírez-Vázquez ◽  
A. Negrón-Mendoza
Keyword(s):  
Chemical Reactions ◽  
Chemical Evolution ◽  
Hydrothermal System ◽  
Krebs Cycle ◽  
Physicochemical Process ◽  
Energy Sources ◽  
Mineral Surfaces ◽  
The Past ◽  
The Stability

AbstractLife originated on Earth possibly as a physicochemical process; thus, geological environments and their hypothetical characteristics on early Earth are essential for chemical evolution studies. Also, it is necessary to consider the energy sources that were available in the past and the components that could have contributed to promote chemical reactions. It has been proposed that the components could have been mineral surfaces. The aim of this work is to determine the possible role of mineral surfaces on chemical evolution, and to study of the stability of relevant molecules for metabolism, such as α-ketoglutaric acid (α-keto acid, Krebs cycle participant), using ionizing radiation and thermal energy as energy sources and mineral surfaces to promote chemical reactions. Preliminary results show α-ketoglutaric acid can be relatively stable at the simulated conditions of an impact-generated hydrothermal system; thus, those systems might have been plausible environments for chemical evolution on Earth.

The concept of ‘doping’ of conducting polymers: the role of reduction potentials

1985 ◽  
Vol 314 (1528) ◽  
pp. 3-15 ◽  
Keyword(s):  
Conducting Polymer ◽  
Chemical Species ◽  
Nucleophilic Attack ◽  
Organic Polymer ◽  
Organic Polymers ◽  
Spontaneous Reduction ◽  
Reduction Potentials ◽  
N Doping ◽  
The Stability

The conductivity of certain organic polymers can be raised to metallic levels by chemical or electrochemical ߢp-doping’ (oxidation), or ‘n-doping’ (reduction). Polyacetylene, (CH) x , the prototype conducting polymer, has been studied more extensively than any other conducting polymer and the doping concepts involved appear to be applicable to other polymer systems. The doping of an organic polymer to achieve certain metallic properties is phenomenologically similar to the doping of a classical inorganic semiconductor in that very large increases in conductivity are observed when the material takes up very small amounts of certain chemical species. However, mechanistically it is different in that the doping of an organic polymer involves simply the partial oxidation or reduction of the polymer, each oxidation state exhibiting its own characteristic reduction potential. The dopant ion incorporated may be derived from the chemical dopant species or it may be completely unrelated to it. The reduction potentials of neutral trans -(CH) x its various oxidized or reduced states, and also the band gap of cis - and trans -(CH) x have been determined electrochemically. The reduction potentials have been used, together with known standard reduction potentials of a variety of redox couples, to rationalize the doping of (CH) x to achieve metallic conductivity by using a number of dopant species, including I 2 , Li, AgClO 4 , gaseous O 2 , H 2 O 2 or benzoquinone (the last three species in aqueous HBF 4 ) and aqueous HClO 4 , etc. The stability of p-doped polyacetylene in aqueous acidic media is ascribed to the fact that a positive charge on a CH unit in trans -(CH) x is delocalized over approximately fifteen carbon atoms in what is termed a ‘positive soliton’. This reduces the ease of nucleophilic attack of the partly oxidized polymer chain. The O 2 -doping of (CH) x permits the use of (CH) x as an electrocatalytic electrode for the spontaneous reduction of oxygen at one atmosphere pressure and at room temperature in strong aqueous HBF 4 solutions. It is concluded that reduction potentials can be used to rationalize the ability of certain dopants to increase the conductivity of selected organic polymers by many orders of magnitude and that they may also be used to predict new chemical species that are therm odynamically capable of acting as p- or n-dopants.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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