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: Acute toxicity studies of ACC - 9653 and phenytoin sodium were carried out in mice , rats , rabbits , and dogs by i . v . , i . m . , and i . p . routes of administration .
### Output Text:
Acute toxicity studies of <span class="chemical">ACC - 9653</span> and <span class="chemical">phenytoin sodium</span> were carried out in mice , rats , rabbits , and dogs by i . v . , i . m . , and i . p . routes of administration . 