Cosmic carbon chemistry

Colorless, reactive gas. Oxygen was not present in the initial atmosphere of the Earth, although at 50 % it is the most common element in the crust of the Earth (oxides, silicates, carbonates, etc.). The compound with hydrogen is remarkable. The hydrides of all other elements are unpleasant compounds, but H20 is the molecule of life. The 02 found in the air today, of which it makes up 20 %, was formed in the process of evolution by photosynthesis of algae, which then also allowed life on solid land. Oxidation with oxygen became and is still the dominant pathway of life forms for obtaining energy (respiration). Used in medicine in critical situations. Oxidations play a key role in chemistry (sulfuric acid, nitric acid, acetic acid, ethylene oxide, etc.). The ozone layer in space protects the Earth from cosmic UV radiation. Ozone (03) is used in the... 

Mechanisms by Carbon Isotope Studies, in Isotopic and Cosmic Chemistry, North Holland, Amsterdam, 1964. 

What effect do shocks have on the gas phase synthesis of complex interstellar molecules This question has been investigated at least for hydrocarbons through six carbon atoms in complexity by Mitchell (1983, 1984). He has found that if a shock passes through a dense cloud where much of the carbon is already in the form of carbon monoxide, complex hydrocarbons are not formed in high abundance. However, if a shock passes through a diffuse cloud, of density approximately 103 cm-3, where much of the cosmic abundance of carbon is in the form of C+ and to a lesser extent C, a different scenario is present. As the shock cools, the C+ and C, which remain in appreciable abundance for up to 10s yrs after the shock passage, react via many of the reactions discussed above as well as others to produce a rich hydrocarbon chemistry. The net effect is that large abundances of hydrocarbons build up as the cloud cools and eventually reaches a gas density of 3 x 104 cm-3. Do these results bear any relation to the results obtained from ambient gas phase models In both types of calculations, hydrocarbon chemistry appears to require the presence of C+ and/or C both to synthesize one-carbon hydrocarbons such as methane and then, via insertion reactions, to produce more complex hydrocarbon species. Condensation reactions do not appear to be sufficient. 

Larimer J. W. and Bartholomay M. (1979) The role of carbon and oxygen in cosmic gases some applications to the chemistry and mineralogy of enstatite chondrites. Geochim. Cosmochim. Acta 43, 1455-1466. 

It is customary to regard chemistry and chemical processes in autilitarian manner. Thus, the usual natural chemistry is one that occurs at the earth s surface, frequently in aqueous solution. We may further note, as seen in Table 17.2 below, that the cosmic abundance of the elements is strikingly different from the composition of the earth s crust. This difference is not simply reflected by that of hydrogen and helium. Of particular interest is the abundance ratio of carbon and oxygen, which is 1/2.3 cosmically and 1/250 terrestrially. (If carbon is the stuff of life, it would appear that the earth is not the optimal location for it.)... 

The carbon ion is responsible for the rich organic chemistry observed. The production of C " by the route indicated (17.6) is at least 500 times (the ratio of He/C cosmic abundance) more efficient than direct cosmic-ray ionization of CO, the predominant interstellar carbon source - hence, the rich organic chemistry observed in the interstellar medium. The efficient production of C+ has as origin the lack of... 

A good example is the molecule SiO, a cosmic precursor to silicon oxide chemistry as we now know it on earth (22). In more recent times, too, this molecule has assumed considerable significance because of its relevance to oxidation reactions taking place at the surfaces of silicon wafers and to the creation of antireflection coatings on these and other solid-state devices. Unlike its more familiar counterpart carbon monoxide, SiO is normally quick to aggregate and disproportionate [Reaction (5)] at temperatures below 1000°C ... 

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