HEXAMETHYLPHOSPHORAMIDE

Hexamethylphosphoramide
(Hexamethylphosphoric triamide, HMPA, HMPT)
CAS 680-31-9

(Me₂ N)₃P=O

Colorless liquid
bp 233 °C, mp 6 °C
Completely miscible with water

Spicy odor (no threshold data)

6.2 (air = 1.0)

0.07 mmHg at 25 °C

105 °C

LD₅₀ oral (rat) 2525 mg/kg

LD₅₀ skin (rabbit) 2600 mg/kg

Possible human carcinogen (OSHA "select carcinogen")

The acute toxicity of hexamethylphosphoramide is low. HMPA can cause irritation upon contact with the skin and eyes.

Hexamethylphosphoramide has been found to cause cancer in laboratory animals exposed by inhalation and meets the criteria for classification as an OSHA "select carcinogen." Chronic exposure to HMPA can cause damage to the lungs and kidneys. Reproductive effects in male animals treated with hexamethylphosphoramide have been observed. HMPA should be regarded as a substance with poor warning properties.

Combustible liquid. Its decomposition at high temperatures or in a fire can produce phosphine, phosphorus oxides, and oxides of nitrogen, which are extremely toxic. Carbon dioxide or dry chemical extinguishers should be used for HMPA fires.

Incompatible with strong oxidizing agents and strong acids.

Because of its carcinogenicity, hexamethylphosphoramide should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high chronic toxicity (Chapter 5.D). In particular, this compound should be handled only in a fume hood, using appropriate impermeable gloves and splash goggles to prevent skin and eye contact. Containers of this substance should be stored in secondary containers.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If hexamethylphosphoramide is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, soak up the hexamethylphosphoramide with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Excess hexamethylphosphoramide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.