反应设计和优化

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化学反应的设计和优化是有机合成研究的重要手段，通过改变反应参数，例如催化剂、反应体系pH值、反应溶剂、温度或时间等来节约成本、提高反应的选择性、产物的收率和纯度等。在优化化学反应时，对合成实验设备的灵活度、准确性和可重复性有一定的要求。化学反应设计侧重于从商业起始原料出发，设计目标分子的合成路径。合成人员通常采用“切断法”，以构建关键化学键为主。该过程不是从起始原料正推，而是通过多个简单步骤从目标分子逆推。虽然许多化学家可以凭借丰富的合成经验来设计这些路线，但目前不少软件，诸如SYNTHIA™可让用户根据自己设定的检索标准来分析已知和新型化合物的合成路径。

反应优化实验方法多种多样。通过大量平行实验优化反应条件，改变其中一个反应参数，控制其他参数不变，然后记录对应的反应结果，经过一系列反应后即可筛选出该参数的最佳值。然后变动另一参数，重复实验直至筛选出最优反应条件。

多反应参数同时筛选或“实验设计(DoE)”的方法可以从最低值到最高值同时改变多个参数，因而可以高效率的找到最佳反应条件。而且，同一组实验还会检测不同反应参数的组合，在高低值因素之间还会增加实验来测定反应的内在可变性。这些数据可用多维数据来表示因素和结果之间的关系，为成功优化并保证实验的可重复性，平行反应必须在可控的条件下有序地进行。

筛选出合成目标分子的可行路径后，为了优化产物、提高产率，每个化学反应都需要投入大量时间来不断优化。因此，充分利用化学反应优化设计有助于更快地实现科学突破。

图 1. 反应优化表

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