Benzenecarboxylic acid, from oxidation

In 1931 Ing pointed out that formula (II) and (III) do not contain methyl or potential methyl groups in j ositions 6 and 8 which they occupy in cytisoline. Further, a partially reduced quinoline ought to oxidise easily to a benzenecarboxylic acid and so far the only simple oxidation, products recorded from cytisine were ammonia, oxalic acid and isovaleric acid. Distillation of cytisine with zinc dust or soda-lime yields pyrrole and pyridine, but no quinoline. On these grounds Ing suggested that cytisine should be formulated without a quinoline nucleus, and that the reactions which indicate the presence of an aromatic nucleus in the alkaloid can be accounted for by an a-pyridone ring. This a-pyridone nucleus can... 

Important derivatives are obtained from PMBs by oxidation (see Phthalic acid and OTHER benzenecarboxylic acids). For example, hemimellitene is oxidized to hemimellitic acid dihydrate [36362-97-7] or hemimellitic acid [569-51-7] which can be dehydrated to hemimellitic anhydride [3786-39-8]. 

It is likely that the benzenecarboxylic acids are derived from lignin units where the a-carbon of the side-chain has been oxidized to a carboxyl group (52), and different studies have interpreted the structures and distributions of the methyl esters of benzenecarboxylic acids as indicating that these structural units exist as either free or ester-bound structures in the HA 10,16,17,24)- However, it has recently become clear that certain benzenecarboxylic acids are produced from unoxidized lignin moieties by the TM AH reagent in the course of the reaction at elevated temperatures 41), Examination of the products from the TMAH thermochemolysis of a model lignin dimer, free of any carboxylic functionality, showed the production of relatively large amounts of methylated benzenecarboxylic acid derivatives. These authors... 

Scheme 9.4. The Caimizzaro reaction. The oxidation-reduction of benzenecarbaldehyde (benzaldehyde) to benzenecarboxylic acid (benzoic acid) and phenylmethanol (benzyl alcohol). Note the transfer of a hydride (H ) ion from one carbon to another, accounts for the oxidation (hydrogen, H, loss), and reduction (hydrogen, H , gain). (See Cannizzaro, S. Liebigs Ann. Chem., 1853,88, 129.)...

Recently, we have developed a versatile aqueous medium self-assembly method for the generation of diverse multicopper(II) complexes and coordination polymers derived from cheap and commercially available ligands such as aminoalcohols and benzenecarboxylates [6-15]. The obtained compounds were applied as highly efficient and versatile catalysts or catalyst precursors in two different alkane functionalization reactions. These include the mild oxidation of alkanes (typically cyclohexane as a model substrate) by hydrogen peroxide into alkyl hydroperoxides, alcohols, and ketones [6-9, 11, 16, 17], as well as the hydrocarboxylation of gaseous and liquid C ( = 2 - 9) alkanes, by carbon monoxide, water, and potassium peroxodisulfate into the corresponding carboxylic acids [12-15, 18-22]. 

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