Alkane catalytic nitration with

Several metal oxides could be used as acid catalysts, although zeolites and zeo-types are mainly preferred as an alternative to liquid acids (Figure 13.1). This is a consequence of the possibility of tuning the acidity of microporous materials as well as the shape selectivity observed with zeolites that have favored their use in new catalytic processes. However, a solid with similar or higher acid strength than 100% sulfuric acid (the so-called superacid materials) could be preferred in some processes. From these solid catalysts, nation, heteropolyoxometalates, or sulfated metal oxides have been extensively studied in the last ten years (Figure 13.2). Their so-called superacid character has favored their use in a large number of acid reactions alkane isomerization, alkylation of isobutene, or aromatic hydrocarbons with olefins, acylation, nitrations, and so forth. 

Efficient catalytic alkane nitrations can be performed with the assistance of N-hydroxyphthalimide (NHPI) with N02 in air [Eq. (10.57)]298 or with HNO3.299 NHPI may also be used to form alkanesulfonic acids by reacting alkanes with S02 300... 

The catalytic oxidation of cyclohexane is performed in the liquid phase with air as reactant and in the presence of a catalyst. The resulting product is a mixture of alcohol and ketone (Table 1, entry 12) [19]. To limit formation of side-products (adipic, glutaric, and succinic acids) conversion is limited to 10-12 %. In a process developed by To ray a gas mixture containing HC1 and nitrosyl chloride is reacted with cyclohexane, with initiation by light, forming the oxime directly (Table 1, entry 12). The corrosiveness of the nitrosyl chloride causes massive problems, however [20]. The nitration of alkanes (Table 1, entry 13) became important in a liquid-phase reaction producing nitrocyclohexane which was further catalytically hydrated forming the oxime. 

Interestingly, this reaction could be performed with catalytic amounts of silver provided that the nitrate counterion was present. The latter could be obtained from silver nitrate or by addition of lithium nitrate to silver bromide. Mixtures of alkanes were obtained starting from two different organomagnesiums, suggesting radical formation. 

Vicinal oxyamination. In the presence of catalytic amounts (1%) of osmium tetroxide the trihydrate of chloramine-T reacts with alkanes to form vicinal hydroxy />-toluenesulfonamides (equation I). The effective reagent is considered to be (1). In some instances addition of silver nitrate was found to be advantageous. ... 

In the course of gas-phase nitration of alkanes with NO, increase in the yield of nitroalkane can be attained by increase in the rate of radical formation and retardation of oxidative reactions in which the free radicals take part. It is probable that the catalytic effect of molecnlar iodine on the nitration of propane with NO is associated mainly with the tendency of inactive iodine atoms to retard the oxidation of hydrocarbons [11]. In the presence of 0.15% I, the CO content of the reaction products is reduced from 22.1 % to 5.2%. Simultaneously, the yield of nitro compounds is increased by 10%. 

A wide variety of alkanes were successfully nitrated by the NHPI/NO2 system (Figure 6.6). In addition, nitric acid instead of NO2 was found to act as an efficient nitrating reagent. For example, the reaction ofadamantane with concentrated HNO3 in the presence of catalytic amounts of NHPI in PhCFs at 60 °C under Ar afforded nitroadamantane and 1,3-dinitroadamantane in 64 and 3% yields, respectively (Eq. (6.26)). 

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