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: OBJECTIVE : Quetiapine is a dibenzothiazepine derivative , similar to clozapine , which has the highest risk of causing blood dyscrasias , especially neutropenia .
### Output Text:
OBJECTIVE : <span class="chemical">Quetiapine</span> is a dibenzothiazepine derivative , similar to <span class="chemical">clozapine</span> , which has the highest risk of causing blood dyscrasias , especially neutropenia . 