Monocyclic arenes hydrogenation

In summary, partial hydrogenation of anisole to 1-methylcyclohexene by polyoxoanion-stabilized Rh(0) nanoclusters is very modest but could in the future be an interesting additive study in the monocyclic arene hydrogenation research area. 

The total hydrogenation of benzene derivatives represents an important industrial catalytic transformation, in particular with the conversion of benzene into cyclohexane, a key intermediate in adipic acid synthesis, which is used in the production of Nylon-6,6 (Scheme 1). This reaction is still the most important industrial hydrogenation reaction of monocyclic arenes [1]. 

In the past five years, the use of nanoparticles in this active research area has received increased attention since some homogeneous catalysts have been shown to be nanoheterogeneous [24-26]. Today, soluble noble metal nanoparticles are considered as reference in monocyclic arene catalytic hydrogenation under mild conditions and several stabilized systems have been reported [27,28]. 

As judiciously reported by the authors, the yields are too low for technical appUcations but this reaction represents the second example of partial hydrogenation of monocyclic arene by soluble transition metal nanoparticles. 

Scheme 9.9 Total hydrogenation of monocyclic arene compounds by various zerovalent noble-metal nanoparticles.

A particularly active catalyst for the hydrogenation of polycylic arenes has been generated from the anionic hydridoruthenium precatalyst in Figure 15.18, discovered by Grey and Fez. This system catalyzes the hydrogenation of antliracene to 1,2,3,4-tetrahydroanthracene under relatively mild conditions with a turnover frequency of > 50 h" and a turnover number of > 100 (Equation 15.96). Both anthracene and naphthalene are partially hydrogenated in the presence of tlais catalyst, but monocyclic arenes do not react. 

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