メチルレッド 化学特性,用途語,生産方法
外観
赤紫色～暗紫色, 結晶～結晶性粉末
溶解性
水及びエタノール、アセトン等の有機溶媒と任意の割合で混和する。
解説
〘名〙 (methyl red) 赤～紫色の結晶。化学式は C15H15N3O2 酸塩基指示薬の一つ。酸性側で赤、塩基性側で黄色。変色域は pH4.4～6.2 塩素で酸化をうけ無色になるため、塩素検出にも用いられる。MR と略記される。
精選版 日本国語大辞典 精選版
用途
ｐH測定用、中和滴定用指示薬(弱塩基-強酸系)。
用途
酸塩基中和滴定指示薬。
特長
100ml包装は滴下用褐色ガラス瓶を使用しています。
化学的特性
dark red crystalline powder
使用
As indicator in 0.1% alcoholic solution; pH: 4.4 red, 6.2 yellow. Used for titrating NH3, weak organic bases, e.g., alkaloids; not suitable for organic acids, except oxalic and picric acid. Methyl red is easily reduced, thereby losing its color, and readings should be made promptly. It is gradually being replaced by sulfonphthalein indicators, such as bromcresol green, which are more stable and exhibit a sharper change in color.
製造方法
2-Aminobenzoic acid?diazo, and N,N-dimethylaniline coupling.
定義
An acid–base indicator that is
red in solutions below a pH of 4.2 and yellow
above a pH of 6.3. It is often used for
the same types of titration as methyl orange
but the transition range of methyl red
is nearer neutral (pH7) than that of methyl
orange. The two molecules are structurally
similar.
一般的な説明
Methyl red solution is an azo dye which turns to red when pH is below 4.4 (yellow pH < 6.2, orange pH 4.4-6.2). Some bacteria utilize glucose to form large amounts of acid with the result that the pH value of the medium falls distinct. Other species produce no or less free acid. This difference can be visualized by using methyl red. This test is used to differentiate enteric bacteria.
危険性
Questionable carcinogen.
安全性プロファイル
Questionable
carcinogen with experimental tumorigenic
data. Mutation data reported. When heated
to decomposition it emits toxic fumes of
NOx.
純化方法
The acid is extracted with boiling toluene using a Soxhlet apparatus. The crystals which separate on slow cooling to room temperature are filtered off, washed with a little toluene and recrystallised from glacial acetic acid, *benzene or toluene followed by pyridine/water. Alternatively, dissolve it in aqueous 5% NaHCO3 solution, and precipitate it from a hot solution by dropwise addition of aqueous HCl. Repeat this until the extinction coefficients do not increase. [Beilstein 16 IV 504.]
メチルレッド 上流と下流の製品情報
原材料
準備製品