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: The first case involved a 59 - year - old man who used Dormex , which contains hydrogen cyanamide , without protection after consuming a large amount of alcohol during a meal .
### Output Text:
The first case involved a 59 - year - old man who used <span class="chemical">Dormex</span> , which contains <span class="chemical">hydrogen cyanamide</span> , without protection after consuming a large amount of <span class="chemical">alcohol</span> during a meal . 