Secondary nucleus production

The 14N atom is the fourth mostabundantnucleus that is produced by nucleosynthesis in the stars (after l60,12C and 20Ne). Its nucleosynthesis occurs primarily in stars of insufficient mass to become supernovae, especially in AGB stars (see Glossary). It is the natural byproduct of the fusion of hydrogen into helium in the carbon-nitrogen cycle. The 14N is created by proton-capture reactions transmuting the initial C and O within the star to 14N during the CN cycle. Production from intial C and O makes 14N a secondary nucleus, since it can be made only in proportion to the amount of C... 

Epoxides are often encountered in nature, both as intermediates in key biosynthetic pathways and as secondary metabolites. The selective epoxidation of squa-lene, resulting in 2,3-squalene oxide, for example, is the prelude to the remarkable olefin oligomerization cascade that creates the steroid nucleus [7]. Tetrahydrodiols, the ultimate products of metabolism of polycyclic aromatic hydrocarbons, bind to the nucleic acids of mammalian cells and are implicated in carcinogenesis [8], In organic synthesis, epoxides are invaluable building blocks for introduction of diverse functionality into the hydrocarbon backbone in a 1,2-fashion. It is therefore not surprising that chemistry of epoxides has received much attention [9]. 

With most primary amines this is virtually the sole product, but with secondary amines (i.e. N-alkylanilines) some coupling may also take place on a carbon atom of the nucleus, while with tertiary amines (i.e. N,N-dialkylanilines) only the product coupled on carbon (34) is... 

Spallation occurs when a high-energy cosmic ray breaks a target nucleus into two or more pieces. These interactions commonly eject neutrons. The secondary neutrons slow down to thermal energies and eventually react with other nuclei in the target material to generate heavier species. Production of cosmogenic nuclides by secondary neutrons increases with depth to a peak at between 0.5 and 1 m below the surface. Therefore, in order to get an... 

The perchlorates of various secondary amines, such as diphenylamine and indole derivatives, are colorless.64 The similarity of colors produced in the presence of hydrochloric acid also attests to the non-auxochromic character of the perchlorate ion in the production of the colored derivative. Consequently, the only role attributable to the perchloric acid in this test is that with nucleic acids it leads to more effective hydrolysis and releases more 2-desoxyribose for reaction with tryptophan. This reaction leads to the production of a substance of the type represented by XV and XVI (R " = H), and the increase in the number of conjugated double bonds results in the product being colored. With ribose, which has a free hydroxyl group at carbon atom 2, a ketone of the type shown in XVII can be formed, and in this case the net result is no increase in the number of double bonds conjugated with the indole nucleus and no comparable increase in color. Hence the test will distinguish between ribose and 2-desoxyribose. 

Alkylation of the aromatic nucleus has been discussed previously (method 1), Phenols are alkylated chiefly in the para position by tertiary alcoholsor olefins. The yields of product range from 24% to 64%. Primary alkyl radicals isomerize to secondary alkyl groups. The best method for the preparation of n-alkyl phenols is by reduction of the corresponding acyl derivatives (method... 

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