# NIOSH Pocket Guide to Chemical Hazards
Hexamethyl phosphoramide | CAS 680-31-9
[(CH3)2N]3PO | RTECS TD0875000
Synonyms & Trade Names Hexamethylphosphoric triamide, Hexamethylphosphorotriamide, HMPA, Tris(dimethylamino)phosphine oxide | DOT ID & Guide
Exposure Limits | NIOSH REL: Ca See Appendix A
OSHA PEL: none
IDLH Ca [N.D.] | Conversion
Physical Description Clear, colorless liquid with an aromatic or mild, amine-like odor. [Note: A solid below 43°F.]
MW: 179.2 | BP: 451°F | FRZ: 43°F | Sol: Miscible
VP: 0.03 mmHg | IP: ? |  | Sp.Gr: 1.03
Fl.P: 220°F | UEL: ? | LEL: ? |
Class IIIB Combustible Liquid: Fl.P. at or above 200°F.
Incompatibilities & Reactivities Oxidizers, strong acids, chemically-active metals (e.g., potassium, sodium, magnesium, zinc)
Measurement Methods None available
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: No recommendation Provide: Eyewash, Quick drench | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure- demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, respiratory system; dyspnea (breathing difficulty); abdominal pain; [potential occupational carcinogen]
Target Organs Eyes, skin, respiratory system, central nervous system, gastrointestinal tract Cancer Site [in animals: cancer of the nasal cavity]
See also: INTRODUCTION