Oxidations with chromium(VI) oxide. VII. The mechanism of oxidation of secondary alcohols

1958 ◽  
Vol 23 (11) ◽  
pp. 2068-2080 ◽  
Author(s):  
J. Roček ◽  
J. Krupička
Keyword(s):  
Secondary Alcohols ◽  
Chromium Vi ◽  
Mechanism Of Oxidation

Compounds of chromium(VI): The pyridine – chromic anhydride complex, benzimidazolinium dichromate, and three 2-alkyl-1H-benzimida -zolinium dichromates

2003 ◽  
Vol 81 (6) ◽  
pp. 612-619 ◽  
Author(s):  
T Stanley Cameron ◽  
Jason AC Clyburne ◽  
Pramod K Dubey ◽  
J Stuart Grossert ◽  
K Ramaiah ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Chromium Trioxide ◽  
Aqueous Acetic Acid ◽  
Secondary Alcohols ◽  
Chromic Anhydride ◽  
Acid Base ◽  
Chromium Vi ◽  
Oxidation Of Alcohols ◽  
Dichromate Anions

Pyridine, when allowed to react with chromic anhydride under strictly anhydrous conditions, gives the known, very air-sensitive, crystalline 2:1 Lewis acid–base complex 1. The crystal structure has now been successfully determined. When benzimidazole and three 2-alkyl-1H-benzimidazoles were treated with chromium trioxide in aqueous acetic acid, crystalline dichromate salts (2–5) were readily formed. These salts consist of dichromate anions linked to the cations by hydrogen bonds of the type N—H···O. The chromium atoms have distorted tetrahedral environments, with the Cr—O distances being typical for dichromate anions. In the cases of the 2-methyl and 2-ethyl salts, the anions are disordered about a centre of inversion. The hydrogen bonding arrangements are discussed and the structures are compared with other oxygenated chromium(VI) species. The dichromate salts are useful selective oxidants for a range of primary and secondary alcohols; examples of these reactions are reported.Key words: chromium(VI), pyridine – chromium trioxide complex, benzimidazolinium dichromate salts, controlled oxidation of alcohols.

Mechanism of oxidation of alcohols with N-bromo succinimide

1969 ◽  
Vol 47 (4) ◽  
pp. 694-697 ◽  
Author(s):  
N. Venkatasubramanian ◽  
V. Thiagarajan
Keyword(s):  
Secondary Alcohols ◽  
Cyclic Mechanism ◽  
Oxidation Of Alcohols ◽  
Mechanism Of Oxidation ◽  
Cis And Trans ◽  
Kinetics Of ◽  
Electron Withdrawing Substituents

The kinetics of the oxidation of a number of aliphatic and aromatic secondary alcohols with N-bromo succinimide has been investigated. Electron-withdrawing substituents retard the reaction considerably and electron-releasing substituents increase the rate of oxidation. The Taft ρ* value is −2.56. Cis- and trans-4-t-butyl cyclohexanols are oxidized at nearly the same rates. There is also a good correlation between the rates of the NBS oxidations and Br2 oxidations of these alcohols. The results are interpreted in terms of a cyclic mechanism involving a rate-determining abstraction of the alpha hydrogen as a hydride anion.

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