Carbon secondary production

The chromatograms of the liquid phase show the presence of smaller and larger hydrocarbons than the parent one. Nevertheless, the main products are n-alkanes and 1-alkenes with a carbon number between 3 to 9 and an equimolar distribution is obtained. The product distribution can be explained by the F-S-S mechanism. Between the peaks of these hydrocarbons, it is possible to observe numerous smaller peaks. They have been identified by mass spectrometry as X-alkenes, dienes and also cyclic compounds (saturated, partially saturated and aromatic). These secondary products start to appear at 400 °C. Of course, their quantities increase at 425 °C. As these hydrocarbons are not seen for the lower temperature, it is possible to imagine that they are secondary reaction products. The analysis of the gaseous phase shows the presence of hydrogen, light alkanes and 1-alkenes. 

At 375°C with the ZSM-5, the main products formed are n-alkanes. Other products are observed ramified alkanes and alkenes, 1-alkenes, aromatics and cyclic saturated hydrocarbons. The majority of hydrocarbons formed have a carbon number between 3 to 6. In the case of the zeolite Y, the n-alkanes and similar secondary products are formed but their repartition is different i.e. the normal and ramified alkanes are the main products and no cyclic compound can be observed. All these products are in higher quantity with the ZSM-5 than with the zeolite Y. This is in agreement with the calculated n-dodecane conversions. With the increase of the temperature, the same products are formed but their quantities increase. The analysis of the gaseous phase shows the presence of hydrogen, light normal and ramified alkanes and 1-alkenes. 

The Fischer-Tropsch synthesis, which may be broadly defined as the reductive polymerization of carbon monoxide, can be schematically represented as shown in Eq. (1). The CHO products in Eq. (1) are any organic molecules containing carbon, hydrogen, and oxygen which are stable under the reaction conditions employed in the synthesis. With most heterogeneous catalysts the primary products of the reaction are straight-chain alkanes, while the secondary products include branched-chain hydrocarbons, alkenes, alcohols, aldehydes, and carboxylic acids. The distribution of the various products depends on both the type of catalyst and the reaction conditions employed (4). 

Single-compound carbon isotope analysis has proved extremely valuable in documenting a hitherto invisible dietary component in European prehistory. Although some chemical analyses had been conducted by the time Andrew Sherratt wrote of the secondary products revolution , it is only in the past... 

The Pt/C catalyst, compared with Pd/C, showed not only enhanced activity (vide supra) but also reduced selectivity for glyceric acid (only 55% at 90% conversion), favoring dihydroxyacetone formation up to 12%, compared with 8% for the Pd case [48]. The Pt/C catalyst promoted with Bi showed superior yields of dihydroxyacetone (up to 33%), at lower pHs. Glyceric and hydroxypyruvic acids, apparently, are formed as by-product and secondary product, respectively [48], The addition of Bi seems to switch the susceptibility of glycerol oxidation from the primary towards the secondary carbon atoms. 

The simple procedure for the carbonylation of allyl halides has been extended in the high yielding solid-liquid two-phase conversion of allyl phosphates into amides (60-80%) under the influence of a rhodium carbonyl cluster in the presence of primary or secondary amines (Scheme 8.8). A secondary product of the reaction is the allylamine, the concentration of which increases as the pressure of the carbon monoxide is reduced, such that it is the sole product (ca. 80%) in the absence of carbon monoxide [28],... 

The first coupling reaction of this type studied utilized a 3-methoxyphenyl ring as the aryl coupling partner (Scheme 36) [47a, c]. The reaction employed constant current electrolysis conditions and a reticulated vitreous carbon anode (RVC). A good yield of cyclized material was obtained. However, the reaction was plagued by the formation of secondary products derived from over-oxidation (35 and 36) of the initially formed cyclization products (33 and 34). The amount of over-oxidized material could be greatly reduced with the use of controlled potential electrolysis conditions. 

By analogy, the formation of a double bond between carbon and phosphorus, which in our opinion, however is improbable, is assumed to be the third stage. Finally, this is followed by the addition of water and tautomeric rearrangement to the primary phosphine. In this way, phosphine, which is present in technical acetylene, and because of its good solubility in actone concentrates in the commercial steel cylinders, forms with acetone, isopropylphosphine oxide and possibly, secondary products... 

All manipulations should be carried out in a wel1-ventilated hood. The preparation requires the use of formaldehyde solution, and gives rise to ethyl acrylate as a secondary product, the amount of which increases if the addition of the carbonate solution is too rapid and the temperature rises to 45°C. 

IVom that period a constant race was kept up between soap-making and the artificial production of soda. Every improvement in Leblanc s system was followed by an extension of the soap trade and it is a curious fact, that tho seaport of Liverpool exports annually more soap at present, than did all tire ports of Great Britain previous to the conversion by Mr, Muspratt, on tho large scale, of chloride of sodium into crude carbonate of soda. The manufacture of soap has, on the other hand, been a powerful stimulus to the preparation of soda, and of the important secondary product—chloroxide of calcium, or bleaching powder —two substances which are so intimately allied with almost all branches of chemical manufactures. Thus soap occupies one of the most important pages in tho, history of applied chemistry. The increase ta the consumption of this article has led, moreover, to the dis-... 

Sulfur fulfills many diverse roles in lakes. As the sixth most abundant element in biomass, it is required as a major nutrient by all organisms. For most algae, S is abundant in the form of sulfate in the water column however, in dilute glacial lakes in Alaska (I) and in some central African lakes (2) low concentrations of sulfate may limit primary production. Sulfur also serves the dual role of electron acceptor for respiration and, in reduced forms, source of energy for chemolithotrophic secondary production. Net sulfate reduction can account for 10-80% of anaerobic carbon oxidation in lakes (3-5), and hence this process is important in carbon and energy flow. Sulfate reduction, whether associated with uptake of sulfate and incorpo-... 

All these cyclodehydration products are the result mainly of an inside chain oxygen attack on a primary carbon the chiral carbon configurations remain unchanged. The only exception to this rule concerns the secondary products obtained from glucitol. 

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