scholarly journals Astrochemistry and Astrobiology: Materials Sciencein Wonderland?

2019 ◽  
Vol 20 (17) ◽  
pp. 4079 ◽  
Author(s):  
Marco d'Ischia ◽  
Paola Manini ◽  
Marco Moracci ◽  
Raffaele Saladino ◽  
Vincent Ball ◽  
...  
Keyword(s):  
Material Design ◽  
Reaction Pathways ◽  
Mineral Surfaces ◽  
Thermal Transformations ◽  
Reaction Conditions ◽  
Organic Systems ◽  
Polycyclic Aromatic ◽  
Broad Variety ◽  
The Origin Of Life ◽  
Complex Organic

Astrochemistry and astrobiology, the fascinating disciplines that strive to unravel the origin of life, have opened unprecedented and unpredicted vistas into exotic compounds as well as extreme or complex reaction conditions of potential relevance for a broad variety of applications. Representative, and so far little explored sources of inspiration include complex organic systems, such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives; hydrogen cyanide (HCN) and formamide (HCONH2) oligomers and polymers, like aminomalononitrile (AMN)-derived species; and exotic processes, such as solid-state photoreactions on mineral surfaces, phosphorylation by minerals, cold ice irradiation and proton bombardment, and thermal transformations in fumaroles. In addition, meteorites and minerals like forsterite, which dominate dust chemistry in the interstellar medium, may open new avenues for the discovery of innovative catalytic processes and unconventional methodologies. The aim of this review was to offer concise and inspiring, rather than comprehensive, examples of astrochemistry-related materials and systems that may be of relevance in areas such as surface functionalization, nanostructures, and hybrid material design, and for innovative technological solutions. The potential of computational methods to predict new properties from spectroscopic data and to assess plausible reaction pathways on both kinetic and thermodynamic grounds has also been highlighted.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

Gold Catalyzed Hydroamination of Propargylic Alcohols: Controlling Divergent Reaction Pathways to Access 1,3-Aminoalcohols, 3-Hydroxyketones or 3-Aminoketones

2018 ◽  
Author(s):  
Victor Laserna ◽  
Tom Sheppard
Keyword(s):  
Gold Catalysis ◽  
Reaction Pathways ◽  
High Yield ◽  
Reaction Conditions ◽  
Propargylic Alcohols ◽  
Catalytic Quantity ◽  
Selective Formation ◽  
General Method

A versatile approach to the valorization of propargylic alcohols is reported, enabling controlled access to three different products from the same starting materials. Firstly, a general method for the hydroamination of propargylic alcohols with anilines is described using gold catalysis to give 3-hydroxy imines with complete regioselectivity. These 3-hydroxyimines can be reduced to give 1,3-aminoalcohols with high syn seletivity. Alternatively, by using a catalytic quantity of aniline, 3-hydroxyketones can be obtained in high yield directly from propargylic alcohols. Further manipulation of the reaction conditions enables the selective formation of 3-aminoketones via a rearrangement/hydroamination pathway.<br>

scholarly journals A Sustainable Improvement of ω-Bromoalkylphosphonates Synthesis to Access Novel KuQuinones

Organics ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 107-117
Author(s):  
Mattia Forchetta ◽  
Valeria Conte ◽  
Giulia Fiorani ◽  
Pierluca Galloni ◽  
Federica Sabuzi
Keyword(s):  
Metal Oxides ◽  
Phosphonic Acid ◽  
Organic Molecules ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Phosphonic Acids ◽  
Sustainable Improvement ◽  
Phosphonate Esters ◽  
First Time ◽  
Complex Organic

Owing to the attractiveness of organic phosphonic acids and esters in the pharmacological field and in the functionalization of conductive metal-oxides, the research of effective synthetic protocols is pivotal. Among the others, ω-bromoalkylphosphonates are gaining particular attention because they are useful building blocks for the tailored functionalization of complex organic molecules. Hence, in this work, the optimization of Michaelis–Arbuzov reaction conditions for ω-bromoalkylphosphonates has been performed, to improve process sustainability while maintaining good yields. Synthesized ω-bromoalkylphosphonates have been successfully adopted for the synthesis of new KuQuinone phosphonate esters and, by hydrolysis, phosphonic acid KuQuinone derivatives have been obtained for the first time. Considering the high affinity with metal-oxides, KuQuinones bearing phosphonic acid terminal groups are promising candidates for biomedical and photo(electro)chemical applications.

Carbonization in Titan Tholins: implication for low albedo on surfaces of Centaurs and trans-Neptunian objects

2015 ◽  
Vol 15 (3) ◽  
pp. 231-238 ◽  
Author(s):  
Chaitanya Giri ◽  
Christopher P. McKay ◽  
Fred Goesmann ◽  
Nadine Schäfer ◽  
Xiang Li ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Organic Material ◽  
Near Infrared ◽  
Proof Of Concept ◽  
Astronomical Observations ◽  
Polycyclic Aromatic ◽  
Large Polycyclic Aromatic Hydrocarbons ◽  
Characteristic Features ◽  
Complex Organic ◽  
Geometric Albedo

AbstractAstronomical observations of Centaurs and trans-Neptunian objects (TNOs) yield two characteristic features – near-infrared (NIR) reflectance and low geometric albedo. The first feature apparently originates due to complex organic material on their surfaces, but the origin of the material contributing to low albedo is not well understood. Titan tholins synthesized to simulate aerosols in the atmosphere of Saturn's moon Titan have also been used for simulating the NIR reflectances of several Centaurs and TNOs. Here, we report novel detections of large polycyclic aromatic hydrocarbons, nanoscopic soot aggregates and cauliflower-like graphite within Titan tholins. We put forth a proof of concept stating the surfaces of Centaurs and TNOs may perhaps comprise of highly ‘carbonized’ complex organic material, analogous to the tholins we investigated. Such material would apparently be capable of contributing to the NIR reflectances and to the low geometric albedos simultaneously.

scholarly journals Recent Advances in Photocatalytic Transformation of Carbohydrates Into Valuable Platform Chemicals

2021 ◽  
Vol 3 ◽  
Author(s):  
Huan Chen ◽  
Kun Wan ◽  
Fangjuan Zheng ◽  
Zhuo Zhang ◽  
Hongyu Zhang ◽  
...  
Keyword(s):  
Solar Energy ◽  
Scientific Community ◽  
Value Added ◽  
Reaction Pathways ◽  
Future Perspective ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
Selective Transformation ◽  
Platform Chemicals ◽  
Broad Interest

In response to the less accessible fossil resources and deteriorating environmental problems, catalytic conversion of the abundant and renewable lignocellulosic biomass to replace fossil resources for the production of value-added chemicals and fuels is of great importance. Depolymerization of carbohydrate and its derivatives can obtain a series of C5-C6 monosaccharides (e.g., glucose and xylose) and their derived platform compounds (e.g., HMF and furfural). Selective transformation of lignocellulose using sustainable solar energy via photocatalysis has attract broad interest from a growing scientific community. The unique photogenerated reactive species (e.g., h+, e−, •OH, •O2−, and 1O2), novel reaction pathways as well as the mild reaction conditions make photocatalysis a “dream reaction.” This review is aimed to provide an overview of the up-to-date contributions achieved in the selective photocatalytic transformation of carbohydrate and its derivatives. Photocatalytic methods, properties and merits of different catalytic systems are well summarized. We then put forward future perspective and challenges in this field.

Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth

Science ◽  
2018 ◽  
Vol 361 (6406) ◽  
pp. 997-1000 ◽  
Author(s):  
K. O. Johansson ◽  
M. P. Head-Gordon ◽  
P. E. Schrader ◽  
K. R. Wilson ◽  
H. A. Michelsen
Keyword(s):  
Interstellar Dust ◽  
Hydrogen Abstraction ◽  
Particle Formation ◽  
Reaction Pathways ◽  
Radical Chain ◽  
Carbonaceous Particle ◽  
Carbonaceous Particles ◽  
Chain Reactions ◽  
Polycyclic Aromatic ◽  
Covalently Bound

Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) are known precursors to high-temperature carbonaceous-particle formation, the molecular pathways that initiate particle formation are unknown. We present experimental and theoretical evidence for rapid molecular clustering–reaction pathways involving radicals with extended conjugation. These radicals react with other hydrocarbon species to form covalently bound complexes that promote further growth and clustering by regenerating resonance-stabilized radicals through low-barrier hydrogen-abstraction and hydrogen-ejection reactions. Such radical–chain reaction pathways may lead to covalently bound clusters of PAHs and other hydrocarbons that would otherwise be too small to condense at high temperatures, thus providing the key mechanistic steps for rapid particle formation and surface growth by hydrocarbon chemisorption.

Functional Analysis and the Species Design

2017 ◽  
Author(s):  
Karen Neander
Keyword(s):  
Mental Content ◽  
Functional Explanation ◽  
Organic System ◽  
Organic Systems ◽  
Etiological Theory ◽  
Normal Human ◽  
Human Immune ◽  
Proper Functions ◽  
Complex Organic

Chapter 3 is about functional explanation in biology, rather than directly about mental content, but in this chapter the author defends a controversial premise of the methodological argument for teleosemantics (given in chapter 4). The premise is that physiologists and neurophysiologists ascribe normal-proper functions in explaining how bodies and brains operate for significant scientific reasons. How an organic system operates in the here and now depends on the actual causal contributions its components make in the here and now, and yet biologists also describe the normal-proper functions of components when explaining how (and not just why) complex organic systems operate or function the way they do. Central to the biologists’ task is describing systems that are functioning normally or properly (e.g., normal human visual systems, or normal human immune systems). The author explains how this role of a malfunction-permitting notion of function (sometimes called a “normative” notion) is consistent with the etiological theory of functions, but the aim here is not to establish the truth of the etiological theory of functions (which is defended in other works).

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