Mechanistic Studies on Dimerization of Olens and Subsequent Alkylation of Phenol

Abstract

Production of less toxic alkylphenol ethoxylates, a subset of the family of non-ionic surfactants has been a topic of extensive research since adverse eects of detergent toxicology have been seen on aquatic life and their propagation in entire food cycle through means of water, soil and air has been observed, this led to ban on various non-ionic surfactants in several countries. When alkylphenol ethoxylate waste enters the environment it metabolizes into lower ethoxylated alkylphenols or alkylphenols at the end of anaerobic/ aerobic digestion. These lower metabolities are found to mimic the hormone oestradiol in shes, birds and mammals. In the present study attempts are made to produce alkylphenols with modied the structure. Dimers of olens viz. 1-Octene, 2-Octene, 1-Decene, 2-Heptene and Dodecene are produced to alkylate phenol. At industrial level linear olens are also found in cracked renery streams having 6-24 carbon atoms, these are oligomerized by contacting with activated Y-zeolites. Detailed characterization of various grades of cationic zeolite catalyst is done for the selection of the optimum catalyst for obtaining high dimer yield and selectivity. Reaction operating parameters viz. temperature of the reaction, moisture content of the reactant, amount of catalyst used and duration of the reaction are also varied to nd out the best operating conditions for all the reactions. Kinetics study is performed for all the reactions and the data obtained from the study has been used to t to various rate equations which gives important information about the mechanism of the reaction. 13C NMR of the pure dimers and nal alkylphenols is obtained in order to understand the product composition at atomic levels. Zeolite CBV 720 is found to be the best catalyst for dimerization of olens used in this work due to its ability to give high dimer yield along with ability to minimize formation of higher oligomers. Rate of dimerization of 2-Octene if found to be fastest among other olens under same operating conditions, this behavior is explained through various experiments and studies while discussing the results. The13C NMR study also give a brief insight of the ortho/para distribution in the nal alkylphenols.