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: In anesthetized dogs , a high dose of ACC - 9653 ( 31 mg / kg ) was infused over 15 , 20 , and 30 min and the responses were compared to an equimolar dose of phenytoin sodium ( 21 mg / kg ) .
### Output Text:
In anesthetized dogs , a high dose of <span class="chemical">ACC - 9653</span> ( 31 mg / kg ) was infused over 15 , 20 , and 30 min and the responses were compared to an equimolar dose of <span class="chemical">phenytoin sodium</span> ( 21 mg / kg ) . 