In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The most commonly reported toxic effects of capecitabine are diarrhea , nausea , vomiting , stomatitis and hand - foot syndrome .
### Output Text:
The most commonly reported toxic effects of <span class="chemical">capecitabine</span> are diarrhea , nausea , vomiting , stomatitis and hand - foot syndrome . 