Establishing optimal conditions for catalytic obtaining of allyl-1,3,4-trimethylcyclohex-3-encarboxylate

Abstract

Kinetics of the reaction of the catalytic cyclic addition of 2,3-dimethylbuta-1,3-diene and allyl methacrylate by the Diels-Alder reaction was studied. Reaction rate constants k=0.9·10 -3 l/(mol·s) at T=303 K; k=1.6·10 -3 l/(mol·s) at T=313 K; k=2.3·1 -3 l/(mol·s) at T=323 K; k=2.9·10 -3 l/(mole·s at T=333 K and the activation parameters of the reaction E akt =32.6 kJ/mol, ΔS=−203.7 J/(mol·K), ΔH=30.0 kJ/mol were determined. Influence of temperature, molar ratio of reagents and catalyst on the yield of the target product was investigated. At temperature increase from 303 to 333 K, ATMCGC yield increases from 58 % to 76 %. With further increase in temperature, DMB boils and AMA remains in a liquid state, accordingly it is not expected that the target product yield will materially increase. An increase in the excess of DMB:AMA=from 1.5:1 to 4:1 makes it possible to increase yield of ATMCGC from 54 % to 76 %. According to decreasing of the catalytic activity in the reactions of [4+2]-cyclic addition of DMB and esters of acrylic acids, the catalysts are placed in an order: Ag n.p. >Cu 2 Cl 2 >Pd n.p. >Au n.p. . At the established optimal conditions of catalytic production of allyl-1,3,4-trimethylcyclohex-3-enecarboxylate are: temperature of 323−333 K and molar ratio of reagents DMB:AMA=4:1 in the presence of Ag n.p. catalyst (0.25 % mol), the yield of ATMCGC reaches 72−76 % at productivity of 111−117 g/(l/h). Based on the obtained reaction rate constants and the activation parameters of the catalytic [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and allyl methacrylate, it was found that the reaction under study is subject to the kinetic law of the second order. It was established that in the presence of Agn.p. catalyst, the reaction of [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and esters of acrylic acids proceeds through a two-stage mechanism with the initial stage of formation of a catalytic complex which activates the reaction by reducing its energy barrier by 44 kJ/mol. The synthesized alkyl esters of alkylcyclohexenecarbonic acids have the ability of polymerization and can be used as a raw material for preparation of polymeric materials, compositions and hyper plasticizers for concrete mixtures. Polymer compositions made with allyl-1,3,4-trimethylcyclohex-3-enecarboxylate are recommended for manufacture of contact lenses and artificial crystalline lenses