Study On The Preparation And Cyclization Reaction Of 5-o-tolyl-2-pentene

5-o-tolyl-2-pentene(OTP) is a useful intermediate for synthesizing 2,6-naphthalenedicarboxylic acid (2,6-NDCA), a raw material used to make polyethylene naphthalate(PEN) which is a high performance engineering plastics with good thermal and mechanical stability. OTP can be obtained from o-xylene with 1,3-butadiene through side-chain alkenylation reaction over liquild NaK eutectic mixture catalyist. Then 1,5-Dimethyltetralin (1,5-DMT) is obtained from OTP throuth cyclization reaction over acidic zeolite catalyst. After cyclization, 1,5-DMT undergoes dehydrogenation to produce 1,5-dimethylnaphthalene (1,5-DMN), isomerization to produce 2,6-DMN, and finally oxidation to 2,6-NDCA. In this thesis, the process of side-chain alkenylation and cyclization reaction have been studied. NaK eutectic mixture is seldom used as acatalyst, not to mention the sonochemical treatment of it in a catalytic system. In this paper, we report the effect of ultrasonic irradiation of the NaK eutectic mixture catalyst on side-chain alkenylation of o-xylene with 1,3-butadiene for the synthesis of OTP.Effects of the pretreatment of catalysis, reaction temperature, the ratio of the reactants, the substrate-catalyst ratio and the content of the promoter on the reaction properties of NaK catalysts has been studied in a wide range. The sonochemical pretreatment of the NaK eutectic mixture catalyst resulted in excellent 1, 3-butadiene conversion (up to 83.16%). It was found experimentally that the optimal parameters are ultrasound frequency 30 kHz, insonation time 3 hours, sonication power 80W, reaction temperature 150°C,the ratio of the reactants 5:1, the substrate-catalyst ratio 400:1. The introduction of N,N,N',N'-tetramethylethylenediamine (TMEDA) with the optimum content of 1 % can give rise to a further considerable of 1, 3-butadiene conversion (up to 89.4%).Moreover, various zeolites were investigated and the evaluation results showed that Pt/USY catalysts had a better activity and excellent selectivity for OTP to target product 1,5-DMT. The Pt loading has an obvious effect on the excellent selectivity of cyclization reaction. The Pt/USY catalyst with 1wt% Pt and 2 wt% Cu performed best, when the reaction temperature 240°C and the amount of catalyst 1 wt%, giving conversion of 84% and selectivity of 90.04%.By means of BET, XRD, XPS and FT-IR analysis of adsorbedpyridine, it can be concluded that the catalytic activities of Pt/USY were correlated with the state of Pt...