Process chemistry update gives more information on how chemicals are produced and what residuals may be present

Michel Dedeo | December 18, 2015 | Tools

Those of you interested in chemical residuals should take note: we just overhauled our process chemistry system for reporting the upstream chemicals in manufacturing processes and this affects the chemicals we flag as residuals.


As most of you know, the Pharos Chemical and Material Library consists of almost 38,000 chemicals and their hazards. Less well-known is a corner of the library where we show what is involved with producing the most commonly used of these chemicals. These process chemistry relationships consist of about 3000 connections such as “isooctyl alcohol is an integral reactant for diisooctyl phthalate (DIOP)”. Using rules shown below, these relationships determine whether a chemical involved in manufacturing another chemical is considered to be a likely residual. In this case, even though isooctyl alcohol is used to make diisoocytyl phthalate, it is not expected to be a residual.  This is TMI for most users, but if your work involves assessing hazards or disclosing ingredients, this process chemistry database can be a great resource. You can find this information in the Process Chemistry Research tab of each chemical’s profile.

The update involved

  1. Adding new process chemistry types (shown below in bold)
  2. Reassigning existing relationships to new process chemistry types when appropriate
  3. Changing the rules for which process chemistry types are flagged as residuals
Process Chemistry Type Residuals in Previous System Residuals in Current System
Additive (reactive) no no
Additive (non-reactive) yes yes
Byproduct no no
Catalyst (homogeneous/unknown) yes yes
Catalyst (heterogeneous/structured) NA no
Component NA yes
Initiator NA no
Monomer yes no
Product of Reversible Reaction NA yes
Pollutant/contaminant yes yes
Process Aid NA yes
Reactant no no
Solvent NA no
Unknown Role no no

These rules for residuals also determine the color of the residual hazard dot shown in the Chemicals and Materials search tab. For each chemical displayed, the system calculates which other chemicals are likely to be residuals and displays the highest hazard of these residual chemicals as a colored dot in the residual column.

For a deep dive into the new system, check out the Chemical and Material Library Description, page 23. It’s also available on our website at the bottom of the Chemicals and Materials page at It has definitions and examples of each process chemistry type and shows how to find our references.

If you have further questions feel free to send them to us using the support link below.