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: Hypersensitivity immune reaction as a mechanism for dilevalol - associated hepatitis .
### Output Text:
Hypersensitivity immune reaction as a mechanism for <span class="chemical">dilevalol</span> - associated hepatitis . 