Phosgene (carbonyl dichloride, 281211), phosphorus oxychloride (281212), phosphorus trichloride (281213), and phosphorus pentachloride (281214) are listed CWC Schedule 3 or Schedule 2 precursors. US importers must comply with Commerce Department export/import authorization requirements and may need to file end-use certificates depending on origin and quantity.

Thionyl chloride (SOCl₂) classifies under subheading 281217 and is primarily used as a chlorinating agent in pharmaceutical and agrochemical synthesis, particularly for converting carboxylic acids to acid chlorides. It is a highly reactive, moisture-sensitive liquid requiring specialized packaging and DOT hazmat compliance on import.