Диметил сульфаты: қасиеттері, қолданылуы және қауіптері

Chembox
|Watchedfields = changed
|verifiedrevid = 443690412
|ImageFile Ref =
|ImageFile = Dimethyl sulfate. svg
|ImageFile1 = Dimethyl sulfate from xtal 3D balls. png
|PIN = Dimethyl sulfate
|OtherNames = Dimethyl sulphate; Sulfuric acid dimethyl ester; Me2SO4; DMSO4; Dimethyl ester of sulfuric acid; Methyl sulfate, di
|Section1=
|Section2=Chembox Properties
|Formula = C2H6O4S
|MolarMass = 126.13 g/mol
|Appearance = Colorless, oily liquid
|Odor = faint, onion like
|REL = Ca TWA 0.1 ppm (0.5 mg/m3) [skin]
|LCLo = 97 ppm (human, 10 min) J. P. Claesson later extensively studied its preparation. It was investigated as a candidate for possible use in chemical warfare in World War I in 75% to 25% mixture with methyl chlorosulfonate (CH3ClO3S) called "C stoff" in Germany, or with chlorosulfonic acid called "Rationite" in France.

Dimethyl sulfate is a reagent for the methylation of phenols, amines, and thiols. One methyl group is transferred more quickly than the second. Methyl transfer is assumed to occur via an SN2 reaction. Compared to other methylating agents, dimethyl sulfate is preferred by the industry because of its low cost and high reactivity.

Dimethyl sulfate (DMS) is used to determine the secondary structure of RNA. At neutral pH, DMS methylates unpaired adenine and cytosine residues at their canonical Watson–Crick faces, but it cannot methylate base paired nucleotides. Using the method known as DMS MaPseq, RNA is incubated with DMS to methylate unpaired bases. Then the RNA is reverse transcribed; the reverse transcriptase frequently adds an incorrect DNA base when it encounters a methylated RNA base. These mutations can be detected via sequencing, and the RNA is inferred to be single stranded at bases with above background mutation rates. Dimethyl sulfate can effect the base specific cleavage of DNA by attacking the imidazole rings present in guanine. Dimethyl sulfate also methylates adenine in single stranded portions of DNA (for example, those with proteins like RNA polymerase progressively melting and re annealing the DNA). Upon re annealing, these methyl groups interfere with adenine guanine base pairing. Nuclease S1 can then be used to cut the DNA in single stranded regions (anywhere with a methylated adenine). This is an important technique for analyzing protein DNA interactions.

Although dimethyl sulfate is highly effective and affordable, its toxicity has encouraged the use of other methylating reagents. Methyl iodide is a reagent used for O methylation, like dimethyl sulfate, but is less hazardous and more expensive. High pressure can be used to accelerate methylation by dimethyl carbonate. In general, the toxicity of methylating agents is correlated with their efficiency as methyl transfer reagents.

Dimethyl sulfate is carcinogenic It is absorbed through the skin, mucous membranes, and gastrointestinal tract, and can cause a fatal delayed respiratory tract reaction. An ocular reaction is also common. There is no strong odor or immediate irritation to warn of lethal concentration in the air. The LD50 (acute, oral) is 205 mg/kg (rat) and 140 mg/kg (mouse), and LC50 (acute) is 45 ppm per 4 hours (rat). The vapor pressure of 65 Pa is sufficiently large to produce a lethal concentration in air by evaporation at 20 °C. Delayed toxicity allows potentially fatal exposures to occur prior to development of any warning symptoms.