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: Both compounds are metabolised in the same way as 1 - bromo - 1 - chloro - 2 , 2 , 2 - trifluoroethane ( halothane ) to form reactive trifluoroacetyl halide intermediates , which have been implicated in the hepatotoxicity of halothane .
### Output Text:
Both compounds are metabolised in the same way as <span class="chemical">1 - bromo - 1 - chloro - 2 , 2 , 2 - trifluoroethane</span> ( <span class="chemical">halothane</span> ) to form reactive <span class="chemical">trifluoroacetyl</span> halide intermediates , which have been implicated in the hepatotoxicity of <span class="chemical">halothane</span> . 