DIMETHYL SULFATE

Dimethyl sulfate
(Methyl sulfate; DMS)
CAS 77-78-1

(CH₃)₂ SO₄

Colorless, oily liquid
bp 189 °C, mp -32 °C
Soluble in water (2.8 g/100 mL at 20 °C); reacts slowly with water to form sulfuric acid and methanol

Almost odorless

4.3 (air = 1.0)

0.5 mmHg at 20 °C

83 °C

495 °C

LD₅₀ oral (rat) 205 mg/kg

LC₅₀ inhal (rat) 9 ppm (45 mg/m³;4 h)

PEL (OSHA) 1 ppm (5 mg/m³)--skin

TLV-TWA (ACGIH) 0.1 ppm (0.52 mg/m³)--skin

Liquid and vapor can cause severe burns to the skin, eyes, and respiratory tract; corrosive and moderately toxic by ingestion; probable human carcinogen (OSHA "select carcinogen").

Dimethyl sulfate is extremely hazardous because of its lack of warning properties and delayed toxic effects. The vapor of this compound is extremely irritating to the skin, eyes, and respiratory tract, and contact with the liquid can cause very severe burns to the eyes and skin. Ingestion of dimethyl sulfate causes burns to the mouth, throat, and gastrointestinal tract. The effects of overexposure to dimethyl sulfate vapor may be delayed. After a latent period of 10 hours or more, headache and severe pain to the eyes upon exposure to light may occur, followed by cough, tightness of the chest, shortness of breath, difficulty in swallowing and speaking, vomiting, diarrhea, and painful urination. Fatal pulmonary edema may develop. Systemic effects of dimethyl sulfate include damage to the liver and kidneys.

Dimethyl sulfate is listed by IARC in Group 2A ("probable human carcinogen") and is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard. Data indicate that dimethyl sulfate does not specifically harm unborn animals; dimethyl sulfate is not a developmental toxin. It is a strong alkylating agent and does produce genetic damage in animals and in bacterial and mammalian cell cultures.

Dimethyl sulfate is a combustible liquid (NFPA rating = 2). Toxic dimethyl sulfate vapors are produced in a fire. Carbon dioxide or dry chemical extinguishers should be used to fight dimethyl sulfate fires.

Dimethyl sulfate can react violently with ammonium hydroxide, sodium azide, and strong oxidizers.

Because of its carcinogenicity, dimethyl sulfate 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, work with dimethyl sulfate should be conducted in a fume hood to prevent exposure by inhalation, and appropriate impermeable gloves and safety goggles should be worn at all times to prevent skin and eye 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 dimethyl sulfate is ingested, obtain medical attention immediately. If 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 dimethyl sulfate 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 dimethyl sulfate and waste material containing this substance should be placed in a covered metal 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.