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: Diabetes was associated with an increased risk of renal impairment in all patients with CHF , but this risk was reduced in the enalapril group compared with the placebo group .
### Output Text:
Diabetes was associated with an increased risk of renal impairment in all patients with CHF , but this risk was reduced in the <span class="chemical">enalapril</span> group compared with the placebo group . 