NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Trimethyl phosphite

CAS
121-45-9

(CH3O)3P

RTECS
TH1400000
Synonyms & Trade Names

Methyl phosphite, Trimethoxyphosphine, Trimethyl ester of phosphorous acid
DOT ID & Guide
2329 / 129

Exposure
Limits

NIOSH REL: TWA 2 ppm (10 mg/m3)
OSHA PEL: none
IDLH
N.D. See: IDLH INDEX
Conversion
1 ppm = 5.08 mg/m3
Physical Description
Colorless liquid with a distinctive, pungent odor.
MW: 124.1
BP: 232°F
FRZ: -108°F
Sol: Reacts
VP(77°F): 24 mmHg
IP: ?

Sp.Gr: 1.05
Fl.P: 82°F
UEL: ?
LEL: ?

Class IC Flammable Liquid: Fl.P. at or above 73F and below 100F.
Incompatibilities & Reactivities

Magnesium perchlorate, water [Note: Reacts (hydrolyzes) with water.]
Measurement Methods
None available
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet (flammable)
Change: No recommendation
Provide: Quick drench
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Soap flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
Not available.
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
Irritation eyes, skin, upper respiratory system; dermatitis; in animals: teratogenic effects
Target Organs
Eyes, skin, respiratory system, reproductive system
See also: INTRODUCTION