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: Consequently , carmofur - induced leukoencephalopathy may uncommonly result in organic personality syndrome in the residual state .
### Output Text:
Consequently , <span class="chemical">carmofur</span> - induced leukoencephalopathy may uncommonly result in organic personality syndrome in the residual state . 