New technological breakthrough: A green and efficient synthesis process for biphenyldichlorobenzene, contributing to the upgrading of the fluorescent brightener and high-end materials industries

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New technological breakthrough: A green and efficient synthesis process for biphenyldichlorobenzene, contributing to the upgrading of the fluorescent brightener and high-end materials industries. In the field of fine chemicals, biphenyldichlorobenzene, with the chemical name 4,4’–bis(chloromethyl)biphenyl, is an essential key intermediate. It functions like a sophisticated \"molecular bridge\" and is widely used in the synthesis of biphenyl-biphenylethyne-type fluorescent brighteners (such as CBS-X, CBS-127). These brighteners are key ingredients in industries such as washing, textiles, and plastics for enhancing the whiteness and brightness of products. At the same time, it is also an important cornerstone for synthesizing certain special drugs and high-performance engineering resins. As a white crystalline powder, its melting point of 126°C and good solubility in polar solvents enable it to perform excellently in subsequent processing steps. However, the process of building this “bridge” – namely the industrial synthesis of biphenyldichlorobenzene – has long been plagued by industry-related issues such as low yields and insufficient purity, which hinder the quality and cost control of downstream products. I. Industry pain points: The constraints of traditional processes. Currently, catalytic processes are used in China. This process uses biphenyl and similar substances as raw materials, and the reaction takes place in a solvent. To mitigate side effects, dispersants and polymerization inhibitors must also be added to the system. Nevertheless, this process still has significant drawbacks: low reaction efficiency, as the reaction takes up to 20 hours and requires high energy consumption. The yield is unsatisfactory: for every 1 ton of biphenyl used, only about 900 kilograms of product can be obtained, with a molar yield as low as 55%. This means that nearly half of the valuable raw material fails to be converted into the desired product, resulting in a waste of resources. Purity remains stagnant: The purity of the product is typically between 98% and 98.5%, which fails to meet the strict requirements regarding impurity levels in high-end application areas. Complex process: Multiple additives need to be added, increasing the complexity and cost of the production process. II. Technical breakthrough: To address the aforementioned industry challenges, a domestic research team has delved deeply into reaction mechanisms, drawing fully on cutting-edge research findings from home and abroad, and successfully developed a new green, efficient, and low-cost process for the synthesis of biphenyldichlorobenzene. (1) Core innovation: Composite catalyst system. The greatest breakthrough of this process lies in the abandonment of traditional single catalysts, with an innovative use of a composite catalyst system. It not only significantly enhances the acidity of the reaction system but also facilitates the depolymerization of paraformaldehyde to produce key active intermediates. It can also improve the dispersion and dissolution of the reactants, making the reaction more uniform and efficient, thereby eliminating the need to add additional dispersants. It further increased the polarity and acidity of the system, greatly promoting dissolution in the reaction solution and ensuring that the reaction site remained saturated with high concentrations of reactants. More importantly, it can effectively reduce the activation energy of the reaction, making it easier for collisions between molecules to result in products; this accelerates the reaction at its root level and suppresses the formation of by-products, thus eliminating the need to use inhibitors. (II) Process optimization: Dual improvement in reaction efficiency and quality. Driven by the new catalyst system, the entire production process has been comprehensively optimized: the reaction time has been significantly reduced, from 20 hours to around 10 hours, resulting in nearly double the production efficiency. The reaction conditions are more gentle: the maximum reaction temperature is maintained at 37±2°C, which is lower than the 45°C used in the original process; this leads to lower energy consumption and fewer side reactions. The yield and purity of the product are significantly improved: the molar yield of this process remains above 70%, which is higher than the company’s current level of 55% ； The product purity exceeds 99%, meeting the requirements of the high-end market. Simplified process, more environmentally friendly: the use of dispersants and polymerization inhibitors is eliminated, reducing the generation of waste materials, making the process more environmentally sustainable. (III) Strict quality control to ensure product consistency. In addition to the core synthesis process, the research team has also developed purification methods. Residual catalysts and acidic impurities are removed through treatment, followed by recrystallization, to ultimately obtain high-purity white crystals. At the same time, we can use advanced analysis and testing equipment to conduct a comprehensive quality assessment of the products, particularly to accurately measure the content of metal ions, ensuring that they meet the strict standards required in fields such as pharmaceuticals and high-end resins. III. Market Prospects and Economic Analysis: The successful adoption of this technology will bring significant economic benefits to the relevant enterprises. Taking the production of 1 ton of biphenyldichlorobenzene as an example, the new process (with a yield of 70%) can significantly reduce the consumption of key raw materials such as biphenyl compared to the original process (with a yield of 55%). Based on preliminary calculations, by using the new process, the raw material cost per ton of product can be kept at around 15,600 yuan. The cost advantage stems mainly from the savings in raw materials resulting from improved yield. IV. Conclusion The new synthesis process for biphenyldichlorobenzene developed by this research team has successfully addressed the long-standing problems of yield and purity that have hindered industrial application, through an innovative reconfiguration of the catalyst system. It represents a breakthrough technology that combines technical advancement, economic viability, and environmental friendliness. It not only brings immediate economic benefits to enterprises, but also helps the downstream industries of fluorescent brighteners, pharmaceuticals, and new materials enhance the competitiveness of their products and achieve transformation and upgrading.