Continuous processing is now commonly used in the manufacturing of fine chemicals including agrochemicals and pharmaceuticals. Datasets are now available, including some on environmental sustainability aspects, that enable more direct comparison between related batch and flow processes. This article examines six continuous processes where an environmental sustainability concept or metric (e.g. process mass intensity) can be compared to that from a closely-related batch process in order to assess the impact that continuous manufacturing has on that theme. Some current case studies where additional Green Chemistry concepts are exemplified are shared along with how continuous processing impacts the manufacture. We illustrate situations where continuous processing can reasonably be expected to show sustainability advantages over batch, as well as a scenario where increased solvent usage in flow mode worsened the environmental profile. While we believe that continuous processing can provide sustainability benefits, there are cases where its application can have a negative effect on environmental metrics. Our hope is to provide impartial guidance for development and manufacturing scientists so they may best utilize continuous technologies in an environmentally responsible way.

• Eli Lilly and Company

• API

1. Continuous manufacturing Green chemistry
2. Pharmaceutical Manufacturing
3. Process mass intensity
4. small volume continuous