| 词条 | Chromium(VI) oxide peroxide | |||
| 释义 |
| Verifiedfields = changed | verifiedrevid = 434965124 | ImageFile = CrO5-2D.png | ImageAlt = | ImageFile1 = | IUPACName = | OtherNames = chromium(VI) oxide peroxide, chromium pentoxide |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|changed|??}} | CASNo = 35262-77-2 | PubChem = 22222816 | SMILES = [O-2].[O-][Cr]([O-])(=O)=O | InChI = 1/Cr.5O/q;;;-2;2*-1/rCrO4.O/c2-1(3,4)5;/q2*-2 | InChIKey = ZWPVWTIRZYDPKW-NIUFNKCUAY }} |Section2={{Chembox Properties | Cr=1 | O=5 | Density = | MeltingPt = | BoilingPt = | Solubility = soluble (decomposes without stabilisers)}} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} Chromium(VI) peroxide (CrO5) or chromium oxide peroxide is an unstable compound formed by the addition of acidified hydrogen peroxide solutions to solutions of metal chromates or dichromates, such as sodium chromate or potassium dichromate. The generally yellow chromates or orange dichromates turn to dark blue as chromium(VI) peroxide is formed. Chromate or dichromate reacts with hydrogen peroxide and an acid to give chromium peroxide and water. CrO42− + 2 H2O2 + 2 H+ → CrO5 + 3 H2O After a few seconds, the chromium(VI) peroxide decomposes to turn green as chromium(III) compounds are formed.[1] To avoid this decomposition, it is possible to stabilize chromium(VI) oxide peroxide in a water-immiscible organic solvent such as diethyl ether, butan-1-ol or amyl acetate by adding a layer of the organic solvent above the chromate/dichromate solution and shaking during the addition of hydrogen peroxide. In this way, the chromium(VI) peroxide (unstable in the aqueous phase in which newly formed) is dissolved in the immiscible organic solvent. In this condition it can be observed over a much longer period. 2 CrO5 + 7 H2O2 + 6 H+ → 2 Cr3+ + 10 H2O + 7 O2 This compound contains one oxo ligand and two peroxo ligands, making a total of five oxygen atoms per chromium atom. CrO5 is unstable and decomposes on standing to form CrO3. It is incompatible with ketones and primary alcohols as it oxidizes them to aldehydes and carboxylic acids and itself gets reduced to Cr3+.Therefore, CrO5 is a good oxidizing agent (even better than chromates and dichromates due to the presence of two reactive peroxo ligands) but due to its low stability it is never used in organic syntheses. DerivativesThe etherate, bipyridyl and pyridyl complexes of this compound have been found to be effective oxidants in organic chemistry.[2] The structure of the pyridyl complex has been determined crystallographically.[3] {{clear|left}}GalleryReferences1. ^Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils; (1985). "Chromium" (in German). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1081–1095. {{ISBN|3-11-007511-3}}." 2. ^{{cite journal | doi = 10.1016/S0040-4020(01)87476-7 | title = Chromium(VI) based oxidants-1 Chromium peroxide complexes as versatile, mild, and efficient oxidants in organic synthesis | year = 1986 | last1 = Firouzabadi | first1 = H. | last2 = Iranpoor | first2 = N. | last3 = Kiaeezadeh | first3 = F. | last4 = Toofan | first4 = J. | journal = Tetrahedron | volume = 42 | pages = 719 }} 3. ^{{cite journal | doi = 10.1038/196570b0 | title = Crystal Structure of Peroxochromates, CrO5⋅C5H5N | year = 1962 | last1 = Stomberg | first1 = Rolf | journal = Nature | volume = 196 | pages = 570 | issue=4854}} External links
3 : Peroxides|Chromates|Oxides |
|||
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。