HydrocarbonsEasy

Degrees of unsaturation

Compute the degrees of unsaturation (DoU) of styrene C₈H₈.

Given data

C = 8H = 8

Steps

0 / 1

Degrees of unsaturation count how many rings and multiple bonds a molecule has: each ring or double bond 'removes' 2 H atoms compared with the corresponding saturated alkane. Comparing the real H with those of an alkane (2C+2) gives DoU = (2C + 2 − H)/2 (no N or halogens here).
Write your working — the numerical result must appear in the text

Full worked solution

Degrees of unsaturation count how many rings and multiple bonds a molecule has: each ring or double bond 'removes' 2 H atoms compared with the corresponding saturated alkane. Comparing the real H with those of an alkane (2C+2) gives DoU = (2C + 2 − H)/2 (no N or halogens here).
$DoU = \frac{2\cdot8 + 2 - 8}{2}$
$DoU = (16+2-8)/2 = 10/2 = \mathbf{5}$ . 4 from the aromatic ring (3 double bonds + 1 ring) + 1 from the vinyl double bond.

Result:

DoU = 5

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