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We have improved the Hydrocarbons Parser, available at


The tool now computes Degrees of Unsaturation (DoU). A DoU gives the sum of the numbers of rings and pi bonds in a chemical structure. Although our tool was not originally intended for addressing formulas for polycyclic hydrocarbons, knowing the DoU value associated to a formula should to some extend help users elucidate these cases.

For instance for C14H10, DoU = 10 and the tool returns a cycloalkene result with 9 pi bonds + 1 ring. Thus, candidate results with more than one ring and containing the following counts can be proposed:

8 pi bonds + 2 rings (e.g., diphenylacetylene)
7 pi bonds + 3 rings (e.g., anthracene, phenanthrene)
6 pi bonds + 4 rings (e.g., 1,2-Dihydrocyclopenta[fg]acenaphthylene)

and a few more. You get the idea.

In upcoming updates of this tool, we expect to automate all these calculations.

Parsing chemical formulas: What a way to go! The beauty of parsing text strings of any kind is in the details.