TOLUENE DIISOCYANATE

Toluene diisocyanate
(TDI; 2,4-toluene diisocyanate; 2,4-diisocyanato-1-methyl benzene)
CAS 584-84-9

C₉H₆N₂ O₂

Colorless to pale yellow liquid
bp 251 °C, mp 21 °C
Insoluble in water (reacts exothermically)

Sharp, pungent odor detectable at 0.02 to 0.4 ppm

6.0 (air = 1.0)

0.05 mmHg at 25 °C

132 °C

>619 °C

LD₅₀ oral (rat) 4130 mg/kg

LD₅₀ skin (rabbit) >10 g/kg

LC₅₀ inhal (rat) 14 ppm/4 h (100 mg/m³; 4 h)

PEL (OSHA) 0.02 ppm (ceiling 0.14 mg/m³)

TLV-TWA (ACGIH) 0.005 ppm (0.036 mg/m³)

STEL (ACGIH) 0.02 ppm (0.14 mg/m³)

Sensitizer by inhalation and skin contact; possible human carcinogen (OSHA "select carcinogen").

The acute toxicity of toluene diisocyanate by inhalation is high. Exposure to TDI can cause lung damage and decreased breathing capacity. Symptoms of exposure may include coughing, tightness of the chest, chest pain, nausea, vomiting, abdominal pain, headache, and insomnia. TDI irritates the skin, and eye contact can cause irritation with permanent damage if untreated. The oral acute toxicity of this substance is low. The odor of TDI does not provide an adequate warning to avoid overexposure.

Toluene diisocyanate has caused sensitization of the respiratory tract, manifested by acute asthmatic reaction upon return to work after a period of time away from exposure. Initial symptoms include coughing during the night, with difficult or labored breathing. Skin sensitization can also occur. Toluene diisocyanate is listed in IARC Group 2B ("possible human carcinogen"), is listed by NTP as "reasonably anticipated to be a carcinogen," and is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard.

TDI is a combustible liquid (NFPA rating = 1). Explosive limits in air are 0.9 to 9.5% by volume. Carbon dioxide or dry chemical extinguishers should be used for TDI fires.

Contact with strong oxidizers may cause fires and explosions. Contact with water, acids, bases, and amines can lead to reactions that liberate heat and CO₂ and cause violent foaming and spattering. TDI will attack some forms of plastic, rubber, and coatings.

Because of its high toxicity, carcinogenicity, and ability to cause sensitization, toluene diisocyanate should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, work with TDI should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact.

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 TDI 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, remove all ignition sources, soak up the TDI 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 TDI 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.