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: Of the 20 animals that received subarachnoid injection of 2 - chloroprocaine - CE seven ( 35 % ) developed hind - limb paralysis .
### Output Text:
Of the 20 animals that received subarachnoid injection of <span class="chemical">2 - chloroprocaine - CE</span> seven ( 35 % ) developed hind - limb paralysis . 