Number of rings and unsaturations

An aliphatic hydrocarbon has a formula C H2 + 2. Each ring or unsaturation that is present in a hydrocarbon decreases the number of hydrogen atoms by two units. Let x be the number of hydrogen atoms observed then, if N, is the number of rings and unsaturations, we have... 

We have seen a series of methods that allow us to work our way from a spectrum back to the molecular structure information on the elemental composition, the molecular mass, the number of rings and unsaturations, the relationships between the structure and the... 

International Union of Pure and Applied Chemists (lUPAC) nomenclature rules and the rings and unsaturations formula are based on graph theory. The number of rings and unsaturations in any chemical structure is also known as the cyclomatic number. 

Unsaturated hydrocarbons and cyclic hydrocarbons have characteristic empirical formulae. The general formula of hydrocarbons is Cx 2x+2-2m while that of alcohols is C H2x-n-2m y (where m represents the number of rings and unsaturated bonds in the molecular structure). An important characteristic of molecules composed of C, H, O, and S is that their presence results in an even number molecular weight. This characteristic, however, disappears at the presence of a nitrogen atom, which relates to the so-called nitrogen rule . 

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See also in sourсe #XX -- [ ]

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