**2.5 Polymer-supported HIL**

A polymer-supported catalyst was prepared, which exhibited high catalytic activity. Copolymerization of 1-vinyl-3-butylimidazolium with styrene gave polymer supports to immobilize Pd(OAc)2 using a method of alcohol reduction. The Pd existed as NP of less than 6 nm in these copolymers. This copolymer-supported Pd was efficient and a reusable catalyst for the Heck reaction in aqueous media in the absence of any phase transfer catalysts (PTCs) or ligands (**Figure 8**). The catalyst could be reused for three cycles without depletion of yield [21].

**Figure 7.** *Ni supported on magnetic nanoparticles [20].*

**135**

**Figure 9.**

*On the Technology of Heterogenization of Transition Metal Catalysts towards the Synthetic…*

Ionic liquid hybrid materials comprising of either CNT or MWCNT were developed, where the CNT or MWCNT were covalently anchored with the

imidazolium-based ILs. The material thus obtained as per this methodology allows specific interactions between the IL thin film and the chemical composition of the MWCNT or CNT surfaces. Typically, the catalytic material was immobilized on the IL thin film. Lee et al. [22] have functionalized MWCNTs with ionic liquid moieties. Interestingly, the change of the ionic liquid anion modulates the solubility of the nanotubes in different solvents. This property makes the modified MWCNTs soluble in ionic liquid and created an IL-based catalytic system when Pd nanopar-

Palladium-containing nanoparticles were immobilized to attain heterogeneity on the mesoporous nanoparticles, namely SBA-15 using an ionic liquid, namely 1.1.3.3-tetramethylguanidinium lactate. Very interestingly, this immobilized Pd catalyst was exploited for solvent-free Heck-type coupling reactions and showed excellent activity and reusability. No deactivation was observed even after six recycles. High yields were achieved even with very low catalyst loading 0.001% of Pd, which is remarkable. Leaching occurs during the reaction, but the Pd gets redeposited on the surface at the end of the reaction with the help of TMG (1,1,3,3-tetramethylguanidine) moiety, excellent stabilizer for metallic NPs [23]. Pd acetate was immobilized on amorphous silica with the aid of an IL, namely [bmim]PF6. This immobilized catalyst was highly efficient for the Mizoroki-Heck reaction of various aryl halides with cyclohexyl acrylate in dodecane as solvent. A TON of 68,400 and

were achieved in the reaction of iodobenzene with cyclohexyl

acrylate. The recyclability of the catalyst was lost after three cycles. Leaching studies showed loss of less than 0.24% Pd [9]. This methodology is presented in **Figure 9**.

Pd(OAc)2 was immobilized on amorphous silica or alumina with the aid of an ionic liquid (Pd-SILC—Pd supported ionic liquid catalyst). The catalytic materials immobilized on N,N-diethylamino propylated (NDEAP) alumina or silica with or without bmimPF6 gave the best results for the Suzuki-Miyaura coupling of aryl halides with arylboronic to yield the respective biphenyls. The synthesis of the encapsulated heterogeneous ionic liquid and the reaction were represented below (**Figure 10**). It was found out that the immobilization with the aid of an IL, bmimPF6 was essential for inhibiting leaching of Pd(OAc)2. The catalyst gave 95%

**2.6 Heterogenous ionic liquids (HILs) on carbon nanotubes (CNT) and** 

*DOI: http://dx.doi.org/10.5772/intechopen.86846*

ticles are immobilized on them.

*2.6.1 HIL on mesoporous solids*

TOF of 8000 h<sup>−</sup><sup>1</sup>

*2.6.2 Encapsulated heterogenous ionic liquids*

*HIL on mesoporous solids—Mizoroki-Heck reaction.*

**multiwalled carbon nanotubes (MWCNT)**

**Figure 8.** *Polymer-supported HIL [21].*

*On the Technology of Heterogenization of Transition Metal Catalysts towards the Synthetic… DOI: http://dx.doi.org/10.5772/intechopen.86846*
