The process of diene cyclization of 2,3-dimethylbutadiene with allyl methacrylicate was investigated. Effects of temperature, reaction duration, and ratio of reagents on the yield of 1,3,4-trimethylcyclohex-3-en-1-carboxylic acid allyl ester was studied. Optimal conditions of passing the process were found.Esters of alkyl-substutited cyclohexenecarboxylic acids are valuable raw material for the synthesis of a number of compounds including medical preparations, some of which inhibit cholesterin biosynthesis and noticeably reduce its level in blood [1]. Furthermore esters of alkylsubstutited cyclohexenecarboxylic acids are used for the synthesis of tertiary alcohols applied in perfumery compositions [2]. Owing to the dielectric anisotropy, esters are used as components of liquid-crystal compositions for electro-optical instruments. They are also widely applied as softening modifi ers of epoxy resins. Multifunctional monomers of various structures with a certain complex physicochemical characteristics are obtained on the basis of esters of alkyl-substutited cyclohexenecarboxylic acids [3].In the literature there are data on the cyclization of some dienes with acrylates. Ethyl ester of 3,4-dimethylcyclohex-3-en-1-carboxylic acid is obtained by the reaction of 2,3-dimethylbutadiene (DMB) with ethyl acrylate by the Diels-Alder reaction [2]. Methyl ester of 2-methylcyclohex-3-en-1-carboxylic acid is obtained by the condensation of piperylene with methyl acrylate, using equimolar amounts of piperylene and methyl acrylate. The mixture is stirred, put in an autoclave, and heated up for 6 h at 200°С in the presence of hydroquinone. The yield of the ester is 65% [1]. Methyl ester of 1,3,4-trimethylcyclohex-3-en-1-carboxylic acid is obtained by the cyclization of DMB with methyl metacrylate, using a solution of methyl metacrylate and DMB in toluene. The mixture is stirred, put in a glass ampoule, and heated up within 12 h at 140°С in the presence of pyrogallol. The yield of the ester is 70% [3]. No published information on the procedures of preparation of 1,3,4-trimethylcyclohex-3-en-1-carboxylic acid allyl esters (TMCHC AE) is available.The aim of this work was the extension of the assortment of esters of cyclohexenecarboxylic acids due to obtaining new monomers, unsaturated esters of alkylsubstutited cyclohexenecarboxylic acids.To prepare TMCHC AE, we have chosen its synthesis from DMB with methacrylic acid allyl ester (MA AE) has been selected. EXPERIMENTALIn the work we have studied the process of TMCHC AE preparation by DMB diene cyclization with MA AE according to the reaction according to the scheme To obtain TMCHC AE, we used DMB synthesized by a catalytic dehydration of 2,3-dimethyl-2,3-butanediol [4, 5] and chemically-pure grade MA AE.Reaction products were analyzed on a "Chrom-5" chromatograph with a DTP thermal conduction detector and a chromatograph column of 1 m in length and diam-
Based on experimental studies and mathematical modeling method, the effectiveness of technological process for the production of allyl 1,3,4-trimethylcyclohex-3-en-1-carboxylate was forecasted. The optimal conditions of the process were revealed.The allyl 1,3,4-trimethylcyclohex-3-en-1-carboxylate was synthesized by the cyclization of 2,3-dimethylbuta-1,3-diene (dimethylbutadiene) with allyl methacrylate in the Diels-Alder reaction. To optimize the experimental studies and to determine the optimum process conditions, we applied a method of full factorial experiment. For the mathematical description of the process by this method [1, 2] with three factors we choose the regression equation (1). where Y is a response function (the process efficiency parameter) on the individual technological parameters; X are the coded independent variables (the process parameters).Based on previous studies [3] of reactivity in the 2,3-dimethylbuta-1,3-diene cyclization with allyl methacrylate, we chose three factors as the technological parameters: the temperature in the range of 120-170°C, the reaction duration in the range of 2-5 h, and the molar ratio of the starting materials, 1:1 to 1:2. The response functions were: the productivity of the process with respect to allyl trimethylcyclohexanoate, and the yield of the product.The experiment reproducibility was checked by carrying out two parallel experiments (k = 2) for each combination of the process parameters in this local region of the factor space. Table 1 shows the results of the reproducibility checking in eight experiments for the given response functions. For each series of parallel experiments the estimate for the variance was calculated by Eq. (2).Estimates of the uniform variance in the several series of parallel experiments were averaged, and the estimates of the reproducibility variance were found by Eq. (3). N S y 2 = 1/N Σ S j 2 , N = 8.(3) j=1
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