Bashkirov oxidation

The Bashkirov oxidation (liquid-phase oxidation of n-alkanes or cycloalkanes in the presence of boric acid and hydrolysis) yields the corresponding secondary alcohols [16, 17]. The reaction is used industrially for oxidation of C10 to C18 n-alkanes, providing raw materials for detergents and for oxidation of cyclododecane to cyclo-dodecanol as an intermediate for the production of Nylon 12 (Table 1, entry 8). The process is not of much commercial importance in the western world, however. Oxidation in the absence of boric acids usually leads to mixtures of alcohols, ketones, and carboxylic acids (Table 1, entry 9). 

Finally, in the Bashkirov oxidation of normal paraffins to secondary alcohols, the boric oxide introduced is often referred to as a catalyst. This material does indeed catalyse the decomposition of hydroperoxides, but by a non-radical route to alcohol and oxygen, and therefore slows down the overall rate of reaction. 

In Japan, secondary alcohols for ethoxylation are also produced by Bashkirov oxidation of -paraffins (liquid phase, in the presence of boron oxides at around 160°C). Some ethoxylates are also sulphated, while olefins can be sulphonated with SO3 or converted to sodium alkanesulphonates directly by free-radical addition of sodium bisulphite ... 

In subsequent processes, now predominating, benzene is hydrogenated to cyclohexane for aerial oxidation (cobalt catalysed) to KA oil (or Bashkirov oxidation to cyclohexanol). One or two companies appear to have substituted aerial oxidation of KA oil for the nitric acid oxidation process, while Celanese produce their 1,6-diaminohexane via 1,6-hexanediol, rather than adiponitrile. 

Bashkirov A process for making aliphatic alcohols by oxidizing paraffins. The reaction is conducted in the presence of boric acid, which scavenges the hydroperoxide intermediates. Borate esters of secondary alcohols are formed as intermediates and then hydrolyzed. Developed in the USSR in the 1950s and now operated there and in Japan. 

More reactive hydroperoxides can be converted selectively to alcohols via the method of Bashkirov (Fig. 4.44), where a boric acid ester protects the product from further oxidation and thus increases the selectivity [121]. The method is used to convert C10-C20 paraffins to alcohols which are used as detergents and surfactants, for the oxidation of cyclohexane (see elsewhere) and cyclododecane to cyclododecanol (cyclododecanone) for the manufacture of nylon-12. 

The direct oxidation of paraffin by atmospheric oxygen is a non-selective reaction which yields a complex mixture of alcohols, ketones, acids and esters. It was used in Germany during the Second World War to manufacture fatty acids. The orientation of this reaction towards the production of alcohols results from research by the Japanese Nobori and Kawai f1943) and the Russian Bashkirov 1956). Alcohol selectivity in relation to the other oxidation products derives from the use of boric acid which withdraws the secondary alkyl hydroperoxides from any subsequent oxidation by converting them to stable boric esters. ... 

The first stage in the production of adipic acid is the oxidation of liquid cyclohexane with air using a cobalt naphthenate catalyst at temperatures in the range at 140°-160°C and pressures about 8-12 bar. A mixed ketone/alcohol oil containing cyclohexanol (CeHnOH) and cyclohexanone (CeHioO) (KA oil) is produced at up to 85% selectivity, with the ketone/alcohol ratio of about 1 1. The conversion is only about 10% and unconverted cyclohexane is recycled. The process was improved by Bashkirov by the additions up to 5% boric acid to the cyclohexane and by restricting the oxygen content of the air to about 4%. The overall yield was increased to more than 90% and conversion to more than 12%. The ketone/alcohol ratio was decreased to 1 9. 

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