How many and what are the isomers of C_4H_8?

Feb 20, 2016

A formula of ${C}_{4} {H}_{8}$ specifies 1 degree of unsaturation.

Explanation:

One degree of unsaturation involves the presence of an unsaturated bond OR a ring.

So I can count 5 structural isomers: 2 rings, and 3 olefins. One of the olefins has 2 geometric isomers.

As regards the degree of unsaturation, this is a useful reference when we compare the formula to a saturated molecule, ${C}_{n} {H}_{2 n + 2}$, i.e. butane if $n$ $=$ $4$. How many isomers can butane, ${C}_{4} {H}_{10}$, generate?

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