Green Nitration Catalyzed By Metal Triflates And Solid Oxides

Nitration of aromatic compounds is an immensely important industrial process. The nitroaromatic compounds so produced are themselves widely utilized and act as chemical feedstocks for a great range of useful materials such as dyes, pharmaceuticals, perfumes and plastics. Unfortunately nitrations typically requires the use of potent mixture of concentrated or fuming nitric acid with sulfuric acid leading to devises corrosion, excessive acid waste steams and added expense.Furthermore, they are not very selective, and often lead to overnitration or to oxidized byproducts. The obvious disadvantages of the commercial manufacturing process currently used gas led to a substantial effort to develop viable alternatives, such as using solid-acid catalysts, other sources of NO₂⁺, other acids replacing sulfuric acid etc..The dissertation is consisted three parts. First, the study of green nitration catalyzed by lanthanide (â…¢) triflates. Second, the study of green nitration catalyzed by lanthanide (â…¢) triflates supporting on silica gel. And, third, the study of green nitration with a nitrogen dioxide-oxygen system using co-catalyst of solid oxides and lanthanide (â…¢) metal triflates.Among lanthanide (â…¢) metal triflates, Sm(OTf)₃ and Zr(OTf)₄ have better catalytic activities. When used Sm(OTf)₃ as catalyst, the optimization was as follow: toluene was reacted with 1 equiv, of 95% nitric acid and 10mol% of Sm(OTf)₃ in refluxing 1, 2-dichloroethane for 7h. The conversion of toluene was 98.7% with the isomer distributing of o : m : p=57.6 : 2.3 : 40.1.Among lanthanide (â…¢) metal triflates supporting on silica gel,Sm(OTf)₃ supporting on silica gel have better catalytic activity. When used it as catalyst, the optimization was as follow: toluene was reacted with 1 equiv, of 95% nitric acid and 2 mol% Sm(OTf)₃ supporting on silica gel (m : m=20%) in refluxing 1,2-dichloroethane for 7h. The conversion of toluene was 97.0% with the isomer distributing of o:m:p=55.4:2.4 : 42.2.Among co-catalyst of solid oxides and lanthanide (â…¢) metal triflates,HZSM-5 and Sm(OTf)₃ have better catalytic activities. When used it as catalyst, the optimization was as follow: benzene was reacted with 1 equiv, of nitrogen dioxide in 1,2-dichloroethane at 100℃for 7hours, and the catalyst was come up with HZSM-5(HZSM-5: NO₂(m:m) =1 : 3.2) and 1 mol% of Sm(OTf)₃. The yield of nitrobenzene was 72.5%.