Oil-Water Interfacial Synthesis as a Benign and Safer Alternativ to Conventional Liquid-Phase Syntheses

有机合成通常在有机溶剂中进行，其中一些是有毒的，有害的，或对环境有害的。对于均相合成反应，溶剂的选择常常受到溶剂所要求的多种功能的限制。其中两个更重要的功能是：(1)反应物、反应中间体和催化剂的增溶作用；(2)通过溶剂作为碱或催化剂配体的参与，提高反应的速率或选择性。2,6-二甲基苯酚的好氧偶联是商业生产聚（2,6-二甲基-1,4-苯基氧化物）（PPO）的基础，吡啶和硝基苯因其对二甲基苯酚、PPO和氯化亚铜（偶联催化剂）的高溶解度而常被用作反应介质。但吡啶和硝基苯等溶剂是剧毒和有毒的。它们的使用带来了健康、安全和环境问题，需要探索替代溶剂和技术。本研究的目的是开发油水界面合成作为一种良性替代需要使用有毒溶剂的传统合成。这项技术涉及到用无害油和水相的组合来代替有毒的有机溶剂。以前限制溶剂选择的多种功能在这里解耦，并由双相混合物单独满足。通过表面活性配合物和水相的pH控制，在油水界面上实现所需的反应。本项目将进一步发展界面技术，使其可以(1)优化并应用于商业PPO合成，(2)扩展到其他具有商业潜力的合成反应。该研究将得到Mallinckrodt特种化学品公司的智力投入和可能的长期财政支持。

Organic syntheses are often carried out in organic solvents, some of which are toxic, hazardous, or environmentally troublesome. The choice of a solvent for a homogeneous synthesis reaction is often limited by the multiple functions required of the solvent. Two of the more important functions are: (1) solubilization of the reactants, reaction intermediates, and catalyst, and (2) rate or selectivity enhancement through the participation of the solvent as a base or as a catalyst ligand. In the aerobic coupling of 2,6- dimethylphenol, which is the basis of the commercial production of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), pyridine and nitrobenzene are often used as the reaction media because of their high solubilities for dimethylphenol, PPO, and cuprous chloride (the coupling catalyst). But solvents such as pyridine and nitrobenzene are highly toxic and noxious. Their use presents health, safety and environmental concerns and alternate solvents and technology need to be explored. The objective of this research is to develop oil-water interfacial synthesis as a benign alternative to conventional syntheses that require the use of toxic solvents. This technique involves a combination of innocuous oil and aqueous phases in place of the toxic organic solvent. The multiple functions which previously limited the choice of solvent are here decoupled and are met separately by a biphasic mixture. The desired reaction is effected at the oil-water interface by means of a surface-active complex and by pH control of the aqueous phase. This project will further develop the interfacial technique so that it may be (1) optimized and adopted for commercial PPO synthesis and (2) extended to other synthesis reactions that have commercial potential. The research will receive intellectual input and possible long- term financial support from Mallinckrodt Specialty Chemicals Company.