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: He developed acute neurologic symptoms of mental confusion , disorientation and irritability , and then lapsed into a deep coma , lasting for approximately 40 hours during the first dose ( day 2 ) of 5 - fluorouracil and folinic acid infusion .
### Output Text:
He developed acute neurologic symptoms of mental confusion , disorientation and irritability , and then lapsed into a deep coma , lasting for approximately 40 hours during the first dose ( day 2 ) of <span class="chemical">5 - fluorouracil</span> and <span class="chemical">folinic acid</span> infusion . 