<a href="https://en.wikipedia.org/wiki/Skeletal_structure" class="extiw" title="en:Skeletal structure">Skeletal structure</a> of a generic <a href="https://en.wikipedia.org/wiki/carboxylic_acid_anhydride" class="extiw" title="en:carboxylic acid anhydride">carboxylic acid anhydride</a>. It implies a <i>symmetric</i> case—derived from two of the same <a href="https://en.wikipedia.org/wiki/carboxylic_acid" class="extiw" title="en:carboxylic acid">carboxylic acid</a> compounds—giving the two "R" groups are the same as each other.
<a href="//commons.wikimedia.org/wiki/User:DMacks" title="User:DMacks">DMacks</a> (<a href="//commons.wikimedia.org/wiki/User_talk:DMacks" title="User talk:DMacks"><span class="signature-talk">talk</span></a>)
<span class="int-own-work" lang="en">Own work</span>