ChemInform Abstract: SYNTHESEN VON AROMATISCHEN HYDROXYALDEHYDEN ‐ NEUE ENTWICKLUNGEN

Oxidation of Alcohols with Molecular Oxygen on Solid Catalysts

“…The potential of these catalysts is reflected by the selective oxidation of only one OH function in complex molecules such as aldonic acids (Scheme 9) 38,84,85,136,169,179 and steroidal alcohols. 62,180 The selective oxidation of an alcoholic OH group has been attained in the presence of the following other functions: alkoxy and aryloxy groups, 83,181,182 phenolic hydroxyl, [183][184][185] CdC bond (allylic and isolated), 63,186 aromatic aldehyde, 143 amino group, 105 quaternary ammonium group, 187,188 acetamino function, 8 nitro group, 29 nitrile group, 8 aromatic Cl, 32,46,189 trifluoromethyl group, 64 N-and S-containing heteroaromatic ring, 29 and cyclopropyl group. 29 Generally, keto-carbonyl and carboxylic groups are resistant to further oxidation.…”

“…The TOF can approach 10 000 h -1 , but there are examples showing also values below 1 h -1 . , Besides the role of reactant structure, a probable reason for the big variation is the inappropriate choice of catalyst composition. For example, a 1 wt % Pt/C catalyst was completely inactive in the oxidation of phenoxyethanol, but addition of lead and cadmium nitrate promoters to the aqueous solution allowed the fast and almost quantitative transformation to phenoxyacetic acid (TOF = 840 h -1 ). , …”

“…The selective oxidation of an alcoholic OH group has been attained in the presence of the following other functions: alkoxy and aryloxy groups, ,, phenolic hydroxyl, − CC bond (allylic and isolated), , aromatic aldehyde, amino group, quaternary ammonium group, , acetamino function, nitro group, nitrile group, aromatic Cl, ,, trifluoromethyl group, N- and S-containing heteroaromatic ring, and cyclopropyl group . Generally, keto-carbonyl and carboxylic groups are resistant to further oxidation.…”

“…Promoted Pt-group metals are the most commonly used catalysts for the oxidative synthesis of carboxylic acids (as salts), including the oxidation of a broad range of functionalized alcohols ,,,, and polyhydroxy compounds. − A recent industrially important example is the oxidation of a choline salt or hydroxide over 5 wt % Pd/C to give 90% yield to betaine: ,, …”

Selective oxidation of glycerol with oxygen using mono and bimetallic catalysts based on Au, Pd and Pt metals

“…However, using an oxidation process applied to aqueous solutions using air on recyclable catalysts will lower the cost and also will be beneficial from environmental point of view. In recent years, many studies have been focused on the oxidation of alcohols [1][2][3][4][5][6][7][8] and polyols [9][10][11][12][13][14] to chemical intermediates. The big challenge associated with these catalytic oxidation reactions is to control and direct the reaction pathway to the desired products.…”