Facile Fabrication of Organic‐Inorganic Hybrid Material Based on Well‐Dispersed AuNPs on Organo‐Functionalised Zn‐Al‐Layered Double Hydroxides for Hydroamination of 1‐Hexene

Abstract

AbstractA pioneering technique has been developed to design an organic‐inorganic hybrid material where small sized gold nano particles (2‐5 nm AuNPs) are uniformly dispersed on organo functionalized Zn−Al layered double hydroxide (LDH). Primarily a novel clay based hybrid material can be synthesized by grafting of organo silane groups (i. e. amino propyl triethoxy silane (APTS) and (3‐Mercaptopropyl) trimethoxy silane (MPTS)) onto the LDH layer. This hybrid material can control the crystal growth of AuNPs to generate a very small particle size and lock the position of consecutive AuNPs which prevent agglomeration. A regular characterisation was performed by various techniques. The TEM image revealed the formation of well dispersed AuNPs (having average particle sizes is 2–5 nm) on functionalised LDH. Diffuse reflectance spectra confirmed that the nucleation of AuNPs forms without any aggregation. Successful grafting of APTS and MPTS onto the LDH layers is confirmed from FTIR and NMR spectroscopy. The heterogeneous catalyst proves an excellent catalytic activity towards hydroamination reaction of 1‐hexene (addition of amine to inactivated alkenes). Interestingly AuNPs on organo functionalised LDH showed better catalytic activity and stability as compared to that of parent ZnAl‐LDH. Superior catalytic activity was generally endorsed to the small particle size of gold which is due to the synergistic effect between AuNPs with amine or thiol pendant of organic moiety APTS or MPTS respectively. The heterogeneous catalysts, i. e. AuNPs on thiol functionalized LDH, show 92% product yield and AuNPs on amine functionalized afford 95% product yield towards hydroamination reaction without the requisite of any acid promoters. The hybrid material can be recovered and reused, which is a green and economical process for commercial application.