Dimethyl sulfate

• Dimethyl sulphate
• DMS

Colorless liquid with a sweet odor

Liquid

1.33 g · cm -3

-31.8 ° C

188.5 ° C ( decomposition)

0.35 hPa ( 20 ° C)

Poorly in water ( 28 g · l-1 at 18 ° C )

1.3874 (20 ° C)

Risk

Not determined, as carcinogenic

205 mg · kg -1 ( LD50, rat, oral)

-735.5 KJ / mol

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Dimethyl sulfate is a colorless, sweet-smelling very toxic liquid. It is the dimethyl ester of sulfuric acid and available in modest yield of methanol and H2SO4. In chemical synthesis, it is an extremely potent alkylating agent. Its toxicity is based on the alkylation of DNA and proteins.

The abbreviation DMS often used is not clear, since it is also used for dimethyl sulfide, dimethyl sulfone and dimethyl sulfite. A mix of substances is dangerous because of their different characteristics.

Synthesis

The synthesis is carried out by the reaction of dimethyl ether with sulfur trioxide ( SO3). Until the 1980s, this was the main use of dimethyl ether, 1998, of the 50,000 tonnes produced in Central Europe about 15,000 tonnes converted to dimethyl sulfate.

Responsiveness

The sulfate ion is a very weak nucleophile, and thus an excellent leaving group in an SN reaction. This is the basis, the strong ability of the dimethyl sulfate methylation. At room temperature at first reacts only one methyl group, wherein heating both of the methyl groups can be used. As an example of such methylation of this is the reaction mentioned with a carboxylic acid:

Use

Dimethyl sulfate is used in laboratory and technique for methylation of carboxylic acids, amines, phenols, and other compounds. It is a raw material for the manufacture of cosmetics, paints, pharmaceuticals and agricultural products.

Safety

Dimethyl sulfate is classified as clearly carcinogenic and mutagenic presumably in humans. It can quickly diffuse through intact skin. Due to the alkylating action of dimethyl sulfate is a strong mucosal and lung poison. This is the basis, the carcinogenic effect of dimethyl sulfate: The DNA is methylated and thus can not be read, the poisoned cell dies or mutates. Also, liver, kidneys, heart and nervous system are attacked. Due to the sulfuric acid formed in the hydrolysis of dimethyl sulfate also highly corrosive. The substance is classified as very dangerous carcinogenic substance in Annex II, No. 6 of the Hazardous Substances Ordinance ( Ordinance on Hazardous Substances ) and may be produced or used in closed systems.

When working with the substance extreme caution. As a warning effect is missing ( odorless, No acute irritant effect ), it can easily get unnoticed for receiving hazardous quantities. After an approximately six-to twelve-hour latency period following severe burns of the respiratory tract. The wearing of special protective gloves and work in a fume hood is essential. Remains of dimethyl sulfate are to be destroyed with a surplus of 10 % ammonia.