How To Draw All Constitutional Isomers

This is a very mutual trouble type seen at the beginning of a grade in organic chemistry, and as such they have a sneaky way making it onto exams. They are of the kind in which a question is asked such as, "Depict every bit many of the structural isomers of the formula C_XH_Y as you can."

Here I depict a systematic technique for drawing the isomers for saturated hydrocarbons (the alkanes), which have the formula C_NH_North+two. First I'll describe the technique, handled in five steps, and then I'll employ it to a problem to show you how to put it to practical use.

THE FIVE STEPS FOR Drawing ISOMERS:

1. Draw the main concatenation.
2. Draw the primary chain minus 1 carbon, and add a methyl group to as many positions as possible. Never add together the methyl groups to the finish of the chain, and watch non to repeat structures (it's okay if y'all accidentally repeat structures, for they will exist caught and discarded when you exercise step 5).
3. Draw the primary concatenation minus 2 carbons, and add two one-carbon groups (two methyls) or ane 2-carbon group (an ethyl) to every bit many positions possible, trying not to echo structures.
4. Continue subtracting and adding groups in this fashion until you run out of carbons or doing so only results in repeated structures.
5. Give the IUPAC name to all the compounds y'all drew. If y'all accidentally drew the same i twice, they will have identical names, and you can cantankerous one of them off.
   

See an example problem

Source: http://www.chemhelper.com/drawingisomers.html

Posted by: kussreearly.blogspot.com

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