Метиленовый синий тригидра

Химические свойства

Methylene Blue trihydrate is a dark green crystalline powder that has a bronze-like luster. When dissolved in water or alcohol, it creates a deep blue color. Methylene blue is used as a bacteriologic stain and as an indicator. It can also inhibit guanylate cyclase and has been used to treat cyanide poisoning and lower levels of methemoglobin.

Использование

Methylene Blue trihydrate finds many uses in biology and chemistry. It acts as a GCS inhibitor, biological stain and redox indicator. It inhibits tau filament formation. Further, it is reported to bind to the M2 subtype of muscarinic receptors in rat cardiac myocytes and thus exhibit antimuscarinic effects on IK, ACh and ICa. It also inhibits endothelium-dependent relaxation of isolated blood vessels.

Подготовка

Methylene blue is synthesized commercially by oxidation of N,N-dimethyl-phenylenediamine with sodium dichromate (Na2Cr2O7) in the presence of sodium thiosulfate (Na2S2O3), followed by further oxidation in the presence of N,N-dimethylaniline (NTP, 2008). Methylene blue hydrochloride is isolated by addition of 30% hydrochloric acid and of a saturated common salt solution to the dye solution; after filtration, the product is washed with a 2% common salt solution. Instead of sodium dichromate, manganese dioxide, and catalytic amounts of copper sulfate can be used for the oxidation (Berneth, 2008).
Methylene blue of high purity can be obtained by chloroform extraction of impurities from solutions of raw dye in borate buffer at pH 9.5–10, followed by acidification of the aqueous solution and isolation of the dye (Berneth, 2008).
IARC Monographs

Общее описание

Methylene blue trihydrate appears as odorless or almost odorless dark green crystals with bronze luster or dark green crystalline powder. pH (1% solution in water) 3 to 4.5. (NTP, 1992)

Реакции воздуха и воды

Hygroscopic. Water soluble. Gives a blue solution in water.

Профиль реактивности

Methylene Blue trihydrate is incompatible with strong oxidizing agents, caustics, alkali metal iodides and reducing agents. Also incompatible with dichromates. Methylene Blue trihydrate forms double salts with many inorganic salts. Is bleached reversibly by (zinc + hydrochloric acid) or sodium hydrosulfite. In aqueous solution, Methylene Blue trihydrate is decolorized by zinc dust and dilute sulfuric acid, but the color is restored upon exposure to air and more rapidly upon addition of ammonium hydroxide.

Пожароопасность

Flash point data for Methylene Blue trihydrate are not available; however, Methylene Blue trihydrate is probably combustible.