Preparation Process And Scale-up Of Dilauryl 4-Thiapimelate

Dilauryl 4-thiapimelate(DLTP) is a kind of important fine chemical intermediate, which mainly used in polyolefin, polystyrene, ABS resin and rubber, as an important auxiliary antioxidant. In addition, since the characteristics of high efficiency and low toxicity, it has been widely used in the field of food antioxidants in the West in recent years.There are five kinds of synthesis technologies for the preparation of DLTP. Traditionally, the common method for synthesis of DLTP is the trans-esterification of dimethyl Dimethyl 4-thiapimelate with dodecanol. The dimethyl 4-thiapimelate can be easily prepared from methyl acrylate. In the process of preparation dimethyl 4-thiapimelate, the hydrogen sulfide can be obtained from our own company, which may reduce production cost, improve the profit and greatly enhance the market competitiveness of products. However, challenges still remain. The key issue is the low yield of the product. Moreover, the catalyst used in second step should be activated under high temperature. This process combined with the resource of hydrogen sulfide produced from our own company in green technology. Additionally, the second step transesterification was realized under mild reaction condition and is suitable for industrial production.In this paper, we investigated various parameters of DLTP synthetic process including temperature, catalysts, raw material and extraction agent. The optimized reaction condition for synthesis dimethyl 4-thiapimelate is as follows: the reaction temperature was 25 oC; A was used as acid binding agent; sodium dodecyl benzene sulfonate was used as catalyst and the extractant was dichloromethane. The desired product was formed in 92.5% yield and the purity was 97%. Moreover, dichloromethane can be reused for five times. The optimized reaction condition for synthesis DLTP: the reaction temperature was 100 oC; p-toluenesulfonic acid was used as catalyst; the ratio of catalyst and raw material was 1:2.1; the extractant was isopropanol. The reagent of isopropanol could also be reused for five times. The total yield of product was more than 80% and the purity was up to 99.5%.Through a systematic research on experimental conditions, the optimum temperature of the reaction was 100 oC. Due to the solvent used in the two reaction steps can be reused, the reaction conditions are mild. This synthetic method is suitable for industrial production. At the same time, the content of the product is more than 99.5%, the melting point at 40±2 ℃, the acid value is less than 1.0 mg, ash is less than 0.01. All qualities are satisfied with the United States Pharmacopoeia(USP)standard.As is well known, the auxiliary antioxidant DLTP complexed with 1010 antioxidants can be applied to ABS resin, rubber and other fields combination. However, few works have been reported about the application in the field of resin lens. In order to explore its oxidation resistance, this paper is studied in related fields. It can be found the glass transition temperature and the yellow index of products are significantly reduced by adding DLTP, and will produce no harmful effects on the tensile strength of resin products with a significant positive effect.