A better solvent must improve the whole process

A process-development lead may want an alternative to a problematic solvent while a manufacturing partner wants predictable operation on existing equipment. Procurement may favour availability and price; quality needs a justified impurity and residual-solvent strategy. A proposed Resource Economics comparison would bring these incentives together around a single reaction or isolation step. The first deliverable should be a shortlist with reasons for rejection, rather than a promise to replace every solvent across a portfolio.

ACS solvent tools and ICH residual-solvent guidance address different parts of the choice (American Chemical Society, n.d.; ICH, 2024). The former can inform comparative screening; the latter concerns residues and patient safety. Neither alone identifies the best process. Our proposed analysis would keep hazard, performance, supply and cost as separate dimensions. A candidate should remain visible as a trade-off when it improves one dimension but weakens another, so a development team can judge whether further work is justified.

An initial study would request the process description, current solvent charges, yield history, analytical methods, drying times and known equipment limits. Qualified partners could then design a proportionate experimental comparison of shortlisted candidates against the current process. Hold the relevant product acceptance criteria constant, record repeatability and account for every added material. The decision output would identify which uncertainties can be resolved cheaply and which need a larger development programme or specialist safety assessment.

Reject a candidate if it cannot meet the required quality, creates an unresolved handling risk, demands unavailable equipment or shifts the burden into excessive purification. Do not average a serious failure into an attractive overall score. A bounded paid screen should finish with a documented decision: retain, investigate further or discontinue. The customer gains a clearer development choice; an investor gains evidence about where additional capital would be useful, rather than a broad environmental promise.

A useful candidate comparison would let a process team see which solvent is worth its next development experiment and why. The brief would identify the limiting attribute for each candidate: impurity removal, isolation, drying, equipment compatibility or supply. The decision owner would agree the minimum acceptable performance before results are reviewed. Procurement would check whether the required grade can actually be supplied at the proposed scale. A promising laboratory candidate would therefore have a clear development question, rather than an implied permission to introduce it into a manufacturing batch.

A useful first discussion starts with one process, one accountable owner and the choice that needs evidence. Share the decision deadline, the information already available and what a credible result would allow your team to do next.