DodecaGreen The Green Chemistry Portal

Solvent intensity calculator.

Calculate the Solvent Intensity of any chemical process from the actual masses of solvents and auxiliaries used and the mass of product isolated. Results update live as you type — and every session stays in your browser, never on a server.

Principle 5 guide
01

What is Solvent Intensity — and why does it matter?

+

Solvent Intensity (SI) is a direct experimental measure of how much solvent and auxiliary material a chemical process consumes per unit of desired product isolated. Expressed as grams of solvent per gram of product (g/g), SI isolates the solvent burden from the broader Process Mass Intensity (PMI) calculation, shining a direct light on Principle 5 of Green Chemistry — Safer Solvents and Auxiliaries.

GoalMinimise the mass of solvents and auxiliary substances consumed per gram of isolated product — the ideal is zero (solvent-free operation). Every reduction in SI directly lowers the environmental and safety footprint of a process.
WhySolvents typically account for 50–80% of the total mass used in a batch chemical process and 70–80% of its lifecycle environmental impact. A high SI signals a process that wastes resources, generates hazardous waste, increases cost, and amplifies exposure risk for workers.
HowRun reactions at higher concentration; substitute hazardous solvents with greener alternatives (water, bio-derived alcohols, ethyl acetate); recover and recycle solvents; replace chromatographic purification with crystallisation; use flow chemistry or mechanochemistry to eliminate solvents entirely.

The formula

$$\text{SI} = \frac{\displaystyle\sum_{i} \left( m_{\text{solvent},i} - m_{\text{recovered},i} \right)}{m_{\text{product}}}$$
SymbolTermUnits
\(\text{SI}\)Solvent Intensityg g−1; ideal value = 0
\(m_{\text{solvent},i}\)Mass of each solvent or auxiliary used (enter volume × density, or mass directly)g
\(m_{\text{recovered},i}\)Mass of solvent i recovered and recycled (credits recycling)g
\(m_{\text{product}}\)Mass of isolated desired productg

SI uses net solvent mass (used minus recovered) to reward recycling and recovery. All solvents and auxiliary substances — reaction solvents, extraction solvents, wash solvents, recrystallisation solvents, chromatography eluents, drying agents — should be included. A lower SI is always better; SI = 0 represents a fully solvent-free process.

Typical SI values by process type

Process typeTypical SI (g/g)Key driver
Industrial bulk chemicals (highly optimised)< 5Minimal auxiliary solvent; continuous processing
Academic synthesis (simple, 1–2 solvents)5–20Reaction solvent + recrystallisation only
Pharmaceutical fine chemicals (multi-step)20–50Multiple solvent exchanges, workup, chromatography
Complex API synthesis or chiral resolution> 50Many steps, large excess reagents, heavy purification

Strengths and limitations

Strengths

  • Directly targets Principle 5 — isolates solvent use from all other waste streams
  • Simple to calculate from lab records; no molecular weights needed
  • Rewards recovery and recycling — net solvent mass penalises waste, not reuse
  • Identifies "hot spots" in multi-step processes (e.g. chromatography steps)
  • Easy to communicate to non-chemists; units (g/g) are intuitive

Limitations

  • Requires experimental data — cannot be calculated at the design stage
  • Treats all solvents equally: 1 g of water = 1 g of dichloromethane (use solvent guides to complement)
  • Does not capture hazard, toxicity, energy for evaporation, or life-cycle impacts
  • SI alone does not distinguish between a process using 1 g of a carcinogen and 1 g of water
  • Dependent on scale; lab-scale SI is often higher than pilot or manufacturing scale

SI in context: complementary green metrics

MetricWhat it measuresStage
Solvent Intensity (SI)Net solvent & auxiliary mass per unit product mass — the focus of this toolExperimental
Atom Economy (AE)Theoretical fraction of reactant mass in desired product (from balanced equation)Design
% YieldFraction of theoretical product actually isolatedExperimental
E-factorTotal waste mass per unit product (includes all inputs: reagents, solvents, workup)Experimental
PMI (Process Mass Intensity)Total input mass per unit product; PMI = E-factor + 1; SI is a component of PMIExperimental
02

Experiment details

03

Solvents & auxiliaries

Enter every solvent and auxiliary substance used: reaction solvents, extraction solvents, wash solvents, recrystallisation solvents, chromatography eluents, drying agents, etc. Enter volume and density to auto-calculate mass, or enter mass directly. Enter any mass recovered to give credit for recycling — net mass = used − recovered.

Solvent / auxiliary Category Vol. (mL) Density (g/mL) Mass used (g) Recovered (g) Net mass (g)
Σ Net solvent mass g numerator of SI

Tip: Mass = Volume (mL) × Density (g/mL). Common densities: water 1.000, ethanol 0.789, ethyl acetate 0.902, DCM 1.325, acetone 0.791, toluene 0.867, hexane 0.659, THF 0.889, DMF 0.944.

04

Isolated product

Enter the mass of product actually isolated at the end of the process (after all workup and purification). This is the denominator of the SI calculation.

Product mass g denominator of SI
05

Results

Solvent Intensity (SI)
g solvent / g product
Total Solvent Used
grams
Solvent Recovered
grams
Product Mass
grams isolated
Solvent Intensity — burden gauge (lower bar = greener; capped at 50 g/g)
0 (ideal)1020304050+

Solvent mass contributions

Solvent burden vs. product

06

Detailed breakdown & interpretation

Solvent / auxiliary Category Used (g) Recovered (g) Net (g) % of Σ net Visual
Enter solvents and product mass above to see breakdown.

Interpretation

Enter solvents and product mass above to generate an interpretation.
07

Save & load sessions

Sessions are stored in your browser only. No data leaves your device.

No saved sessions yet.
08

Export

Export your Solvent Intensity calculation as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.

09

Where can I read more?

+

References are sorted alphabetically by first author.

  1. P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998. ISBN 978-0-19-850698-0. — Original statement of the 12 Principles; frames Principle 5 on solvents and auxiliaries.
  2. C. Capello, U. Fischer and K. Hungerbühler, "What is a green solvent? A comprehensive framework for the environmental assessment of solvents," Green Chem., 2007, 9, 927–934. DOI: 10.1039/B617536H. — Framework for evaluating solvent greenness beyond mass alone.
  3. D. J. C. Constable, C. Jiménez-González and R. K. Henderson, "Perspective on Solvent Use in the Pharmaceutical Industry," Org. Process Res. Dev., 2007, 11, 133–137. DOI: 10.1021/op060170h. — Industry data on solvent dominance in pharmaceutical process mass.
  4. R. K. Henderson et al., "Expanding GSK's solvent selection guide — embedding sustainability into solvent selection starting at medicinal chemistry," Green Chem., 2011, 13, 854–862. DOI: 10.1039/C0GC00918K. — GSK solvent selection guide; basis for comparing SI with solvent hazard.
  5. C. Jiménez-González et al., "Using the Right Green Yardstick: Why Process Mass Intensity Is Used in the Pharmaceutical Industry to Drive More Sustainable Processes," Org. Process Res. Dev., 2011, 15, 912–917. DOI: 10.1021/op200097d. — Introduces PMI; shows SI as a key PMI component.
  6. R. A. Sheldon, "The E-Factor 25 years on: the rise of green chemistry and sustainability," Green Chem., 2017, 19, 18–43. DOI: 10.1039/C6GC02157C. — Updated review of waste metrics including solvent intensity across sectors.
10

Contributors

Roles follow the CRediT taxonomy (Contributor Roles Taxonomy), adapted for educational software. Hover a contributor's name for a summary, or a column header for the definition of that role.

Contributor

© 2024– DodecaGreen Project. All rights reserved. · Last updated: 06/06/2026

This portal was built with the assistance of a large language model (Claude, Anthropic), which was used to generate and refine code, articulate and structure contributed ideas within the defined page format, and support iterative design decisions. All scientific content, conceptual frameworks, pedagogical choices, and final outputs were directed, reviewed, and verified by the contributors listed above.

11

How do I cite this page?

+

If you use this tool in teaching or published work, please cite the DodecaGreen portal as the source.

Reference
BibTeX