Final answer:
Vacuum distillation is carried out under reduced pressure to prevent the degradation of the product by reducing its boiling point and minimizing thermal degradation.
Step-by-step explanation:
In vacuum distillation, the process of distilling is carried out under reduced pressure, typically in a vacuum. This reduces the boiling point of the products, which helps prevent their degradation.
By lowering the pressure, the temperature required to vaporize the components is decreased, which reduces the chances of thermal degradation.
For example, in the distillation of petroleum, vacuum distillation is used to separate the different fractions (such as gasoline and diesel) without causing significant thermal decomposition of the products.