トリオキソクロム(VI)

解説二クロム酸カリウム，または二クロム酸ナトリウム，酸化クロム(Ⅵ)の水溶液と濃硫酸との混合物．強い酸化力があり，理化学用ガラス器具の洗浄，とくに有機物による汚れの除去に利用される．液ははじめ赤橙色であるが，使用するにつれて，CrⅢを生じて赤褐色になり，さらに緑色に近づく．CrⅥの毒性と硫酸の腐食性という問題点があるため，現在ではほかの界面活性洗剤にとってかわられて使用は減っている．森北出版「化学辞典（第2版）

用途酸化剤、有機合成原料、触媒。

用途金属表面仕上げ剤

説明Chromium hydroxide (Cr2O(OH)4) is a bright bluish-green pigment prepared by the calcinations of bichromate with boric acid at 500°C. The mass during cooling is hydrolyzed with water, which yields the hydrate.

使用Chromium(VI) oxide is widely used in chromium electroplating, and as protective coatings in corrosion/oxidation resistance of metals. It is also employed in CDs and DVDs. It is useful as an oxidant in Jones oxidation in acetic acid or acetone. It is used in the oxidation of primary alcohols into carboxylic acids, and secondary alcohols into ketones. With phosphoric acid, it is used as a stripping agent for anodic coatings of all types and in the production of syntheric rubies.

一般的な説明Chromium(VI) oxide (CrO3) is a hexavalent chromium that is majorly used as an oxidizing agent. It oxidizes the C-H bonds in the aromatic rings to form benzoic acid from alkyl benzene. It can be prepared by adding concentrated sulphuric acid in potassium dichromate.

使用用途主に用の工業原料として使用され、や、その他の金属と反応させ、耐腐食性のクロム保護膜を形成する方法がよく用いられます。 また、赤外域に透過波長域を持つという特徴があり、光学系材料として、吸収膜、エレクトロクロミック用途などに使われます。光学特性 (屈折率、透過率) は基板の温度によって、強い影響を受けます。三酸化クロムの膜質は丈夫で、耐腐蝕、酸化防止、耐磨耗性、密着力を付与するためにも使用可能です。

製造方法Chromium(VI) oxide is prepared by heating sodium dichromate dihydrate with a slight excess of sulfuric acid in a steel tank or cast iron container: Na2Cr2O7 + 2H2SO4 → 2CrO3 + 2NaHSO4 + H2O The temperature of the mixture is kept above the melting point of chromium(VI) oxide to evaporate water and separate the top layer of sodium bisulfate from the molten chromium(VI) oxide at the bottom. Temperature control and duration of heating is very crucial in the process. Temperatures over 197°C (melting point), or allowing the molten mass to stand for a longer time, may result in decomposition of the product.

純化方法It separates when potassium or sodium dichromate are dissolved in conc H2SO4. Dry it in a vacuum desiccator over NaOH pellets. It is a hygroscopic, powerful oxidant and can ignite with organic compounds. It is a skin and pulmonary IRRITANT. [Keyes et al. Industrial Chemicals (Lowenheim & Moran eds.) 4th edn J. Wiley pp 270-274 1975.] CANCER SUSPECT.