19^th GREEN Open Seminar

           There is a need for environmentally benign processes for the synthesis of fine and specialty chemicals. In general, fine chemical synthesis requires various successive steps, and many of them are carried out in homogeneous phase using stoichiometric amount of acid catalyst such as H₂SO₄, HF, AlCl_3, etc. These acids are not reusable and have to be neutralized, which generate large amount of waste posing environmental problems. Therefore, new processes in the production of fine and specialty chemicals materials play an important role in the development of clean and efficient processes for the production of fine chemicals and pharmaceuticals. Alkylation of phenol and m-cresol is an industrially important reaction because many alkylated and acylated products have commercial applications.

Hexagonal mesoporous pure AlPO, MgAPO and CoAPO were successfully synthesised at room temperature using cetyltrimethylammonium bromide as the structure directing agent. Al,Zn-MCM-41 was synthesized by hydrothermal method using cetyltrimethylammonium bromide as the structure directing agent. Hexagonal mesoporous Co,Al-MCM-41 and Fe,Al-MCM-41 were synthesised by hydrothermal method using tetradecyltrimethylammonium bromide as the template. All these materials were characterized extensively. The catalytic activity of these materials was evaluated for different alkylation reactions. tert-Butylation of m-cresol with tert-butanol was carried out over mesoporous AlPOs. High conversion of m-cresol was observed over mesoporous CoAPO due to high acid sites present in the catalyst. A novel route to produce thymol by vapour phase reaction of m-cresol with isopropyl acetate was studied over Al-MCM-41 and Al,Zn-MCM-41. Fe, Al-MCM-41 and Co, Al-MCM-41 was used as catalysts for tert-butylation of phenol using tert-butanol and isobutanol respectively as the alkylating agents. Thus solid acid catalysts such as mesoporous AlPOs, MCM-41 could be viable and ecofriendly alternative to mineral acid catalysts in the synthesis of fine and specialty chemicals.