Colligative properties are the properties like the vapor pressure, lowering when you have a mixture in a liquid, instead of having a pure substance you have amixture of substances here.

依数现象是这样一种现象,当你把物质混合在一起的时候,你不会得到纯物质,而是得到混合物质。

youdao

That slows the next reaction, a problem because the substance that will become the drug is highly unstable and decomposing, sharply lowering the yield.

WSJ: Researchers Manipulate HIV Drug's Chemistry to Lower Cost