Vapor phase oxidation of methylpyridine aldehydes

A study is made of the contact oxidation of -, ß- and -methylpyridines by air, over the temperature range 390°–490° C, contact time 0.17–1.0 sec, mole ratio oxygenmethylpyridine 0.5 to 401, with dilution of the air-vapor mixture with water in the ratio 15–103 mole water per mole methylpyridine, using two vanadium oxide catalysts differing in respect of sizes of specific surface areas.Use of the low specific surface area catalyst increases the selectivity of the process, by diminishing the proportion of secondary reaction products of the aldehydes and decreasing the complete oxidation of the methylpyridines.     

A mild oxidation of aldehydes to α,β-unsaturated aldehydes

Phenylselenenyl chloride reacts with enamines at ?110° C to give α-phenylselenoaldehydes, and oxidative elimination yields α,β-unsaturated aldehydes.     

Efficient N-p-methoxyphenyl amine deprotection through anodic oxidation

[reaction: see text] A new method of deprotection of N-p-methoxyphenylamines using anodic oxidation in acidic medium is presented. The process furnishes a high yield of amine and is compatible with several oxidable functional groups.     

First aromatic ring acetamidation by anodic oxidation

Anodic oxidation of 1-(trifluoromethyl)benzene in dry acetonitrile/Bu₄NBF₄ under constant potential conditions led to 2-(trifluoromethyl) acetanilide in 86% yield. Other experimental conditions, as the use of constant current or the change in the supporting electrolyte were considered.     

Organocatalyzed asymmetric α-hydroxyamination of α-branched aldehydes: asymmetric synthesis of optically active N-protected α,α-disubstituted amino aldehydes and amino alcohols

Enantioselective direct α-hydroxyamination and α-aminoxylation of α-branched aldehydes using a proline-derived tetrazole catalyst is described herein. α-Hydroxyamination adducts with up to 90% ee were obtained by the reaction of nitrosobenzene with unactivated α-branched aldehydes under mild reaction conditions.     

The anodic oxidation of gold + palladium alloys

The anodic oxidation of Au+Pd alloys has been studied in solutions of 1 M H₂SO₄ and 0.1 M K₂SO₄ by voltammetric methods. A linear relationship between oxide reduction maximum and bulk alloy composition, often used to determine the surface composition of homogeneous alloys, could be shown to hold only for alloys up to 60 at% gold. At higher gold content the Au oxide peak must be additionally evaluated. With continuous cycling in acid solution the anodic dissolution of Pd, especially from gold-rich places, leads to a rather heterogeneous surface. The O--chemisorption is not governed by a transfer mechanism from Pd to Au surface atoms. The alloys are able to absorb the oxygen species generated in the positive potential region; however, this ability decreases with increase of the gold content.     

Magnesium-oppenauer oxidation of alcohols to aldehydes and ketones

Using a magnesium-Oppenauer oxidation aldehydes and ketones are prepared from halomagnesium alkoxides, which in turn are the products of Grignard reactions.     

Aerobic oxidation of aldehydes by visible light photocatalysis

An efficient and environmentally benign method for the oxidation of aldehydes to carboxylic acids has been developed. Singlet oxygen, generated by visible light in the presence of a Ru or Ir photocatalyst, reacted with aldehydes to give the corresponding carboxylic acids in excellent yields. The reaction is highly chemo-selective, in which only an aldehyde moiety is reactive even in the presence of other photo-oxidation active sites. This method is an example of an ideal green chemical reaction in the sense that molecular oxygen and visible light are key sources for the transformation.     

Catalyzed oxidation of alcohols and aldehydes with iodosylbenzene

RuCl₂(PPh₃)₃ catalyzes oxidation of alcohols to carbonyi compounds by iodosylbenzene and that of aldehydes to carboxylic acids. Catalyzed oxidation of primary alcohols with phenyliodosodiacetate affords aldehydes.     

A new oxidation of aldehydes to carboxylic acids

2-Hydroperoxyhexafluoro-2-propanol (HPHI) is a selective catalytic and stoichiometric reagent for the oxidation of aldehydes to acids under mildly basic conditions.     

N-heterocyclic carbene-catalyzed oxidation of unactivated aldehydes to esters

N-Heterocyclic carbenes catalyze the oxidation of unactivated aldehydes to esters with manganese(IV) oxide in excellent yield. The reaction proceeds through a transient activated alcohol, which when generated in situ allows for the selective oxidation of the aldehyde under mild conditions. These conditions successfully oxidize potentially epimerizable aldehydes and alcohols while preserving stereochemical integrity. A variety of ester derivatives can be synthesized with variation of the acylated alcohol as well as the unactivated aldehyde.     

Montmorillonite clay-catalyzed cyclotrimerization and oxidation of aliphatic aldehydes

A temperature-dependent equilibrium is observed for the cyclotrimerization of aliphatic aldehydes in the presence of Montmorillonite K10 clay, while aerobic oxidation of aliphatic aldehydes to the corresponding carboxylic acids is favored at room temperature in the presence of Montmorillonite KSF clay.