Sustaink Green Toolkit

User Guide — Green Chemistry Calculator

How to use this guide. Fill the calculator top-to-bottom in the same order as the sections below. Every input is explained with the exact value used in the classic aspirin synthesis (salicylic acid + acetic anhydride → aspirin + acetic acid), so you always have a working reference.
Tip: click Load Aspirin Example at the top of the inputs sidebar to auto-fill the whole calculator with these values, then press Calculate Metrics to see the results.

Balanced Chemical Equation

Found at the top of the results area. Enter your fully balanced reaction equation here — it is used to calculate the theoretical Atom Economy. Each reactant and product has four boxes: Coeff, Formula, Name and MW.

Input	What to enter	Aspirin example
Coeff	Stoichiometric coefficient of the species in the balanced equation (whole number ≥ 1).	1 for all four species
Formula	Chemical formula of the species (subscripts allowed).	Reactants: C₇H₆O₃, C₄H₆O₃ Products: C₉H₈O₄, C₂H₄O₂
Name	Short display name of the species (keeps the equation readable).	Sal. acid, Ac. anhyd → Aspirin, Ac. acid
MW	Molecular weight of the species in g/mol.	138.12, 102.09 → 180.16, 60.05
Catalyst (above arrow)	Catalyst written over the reaction arrow. Leave empty if none is used.	H₂SO₄
Temp (below arrow)	Temperature / pressure conditions written under the reaction arrow.	75°C, 1 atm
Desired Product ☑	Tick only under your target product. Atom Economy = MW of desired product ÷ total MW of all reactants × 100.	✓ Aspirin only — acetic acid stays unticked (it is the by-product)
Add Reactant / Add Product	Buttons to add more species to either side of the equation.	2 reactants and 2 products in total

Aspirin reference: C₇H₆O₃ + C₄H₆O₃ —H₂SO₄, 75°C→ C₉H₈O₄ + C₂H₄O₂. Check the grey preview box below the equation, then press Calculate Atom Economy.

Reaction Name

The first field of the inputs sidebar (left panel). A free-text title that identifies your reaction in the results.

Input	What to enter	Aspirin example
Reaction Name	Any descriptive name for the reaction you are analysing.	Synthesis of Aspirin

Product

Your isolated target product with actual laboratory data (what you really obtained, not theoretical values). Use + Add Product if the reaction gives more than one product you isolate.

Input	What to enter	Aspirin example
Name	Name of the product.	aspirin
MW (g/mol)	Molecular weight of the product.	180.16
Mass (g)	Actual mass of product you isolated after purification.	10 g
Moles	Calculated automatically as Mass ÷ MW (read-only, grey box).	0.0555 (= 10 ÷ 180.16)
C atoms	Number of carbon atoms in one molecule of the product (used for carbon efficiency).	9 (aspirin is C₉H₈O₄)
Yield (%)	Actual yield as % of the theoretical yield: actual mass ÷ theoretical mass × 100.	78 %
Purity (%)	Purity of the isolated product (e.g. from melting point, titration or HPLC).	95 %

Reactants/Reagents

One card per reactant, with the amounts you actually weighed out in the lab. Use + Add Reactant to add a card for each reagent. The aspirin example uses two: salicylic acid (limiting) and acetic anhydride (in excess).

Input	What to enter	Salicylic acid	Acetic anhydride
Name	Name of the reactant or reagent.	salicylic acid	acetic anhydride
MW (g/mol)	Molecular weight.	138.12	102.09
C atoms	Carbon atoms in one molecule (used for carbon efficiency).	7	4
eq stoich	Equivalents required by the balanced equation (the theoretical ratio).	1.0	1.0
Mass (g)	Mass you actually weighed out.	7.66 g	8.5 g
Moles	Calculated automatically as Mass ÷ MW (read-only).	0.0555	0.0833
eq used	Equivalents actually used, relative to the limiting reagent (moles ÷ moles of limiting reagent).	1.0	1.5 (50% excess)
Hazardous ☑	Tick if the substance is corrosive, flammable, toxic or otherwise hazardous (feeds the hazard indicators).	✗ not hazardous	✓ corrosive, flammable
Limiting Reagent ☑	Tick the one reagent that runs out first and limits the yield.	✓ limiting	✗ in excess

Solvents

One card per solvent used in the reaction and the workup. Use + Add Solvent for each. The aspirin example uses two solvents: ethyl acetate (recrystallisation) and water.

Input	What to enter	Ethyl acetate	Water
Solvent	Name of the solvent.	ethyl acetate	water
Mass (g)	Total mass of solvent used (volume × density if you measured by volume).	25.0 g	80 g
B.P. (°C)	Boiling point — used to estimate the energy needed for solvent recovery.	77	100
% rec	Percentage of the solvent you recover and can reuse (e.g. by distillation). Enter 0 if it is discarded.	80 % recovered	0 % (discarded)
Hazardous ☑	Tick if the solvent is hazardous or environmentally harmful.	✓ flammable, irritant	✗ benign

Catalysts

One card per catalyst. Leave the section empty if no catalyst is used. The aspirin synthesis uses a few drops of concentrated sulfuric acid.

Input	What to enter	Aspirin example
Name	Name of the catalyst.	sulfuric acid
MW (g/mol)	Molecular weight of the catalyst.	98.08
Mass (g)	Mass of catalyst used (usually small).	0.2 g (a few drops)
Recovery (%)	Percentage of the catalyst recovered and reusable after the reaction.	0 % (neutralised during workup)
Hazardous ☑	Tick if the catalyst is hazardous or environmentally harmful.	✓ highly corrosive

Water & Workup

Auxiliary materials consumed while isolating the product. They count towards the total mass input (PMI / E-Factor), so do not forget them.

Input	What to enter	Aspirin example
Aqueous washes (g)	Total mass of water used to wash the crude product (1 mL ≈ 1 g).	100 g of cold-water washes
Drying agents (g)	Mass of drying agent used (e.g. MgSO₄, Na₂SO₄, CaCl₂).	1.5 g

Conditions

How the reaction is driven. These values feed the energy and CO₂ (carbon footprint) estimates.

Input	What to enter	Aspirin example
Energy Sources	Select the heating / cooling / activation method from the dropdown (grouped by type). Choose Other to type a custom method in the extra field that appears.	Water / Steam Bath
Time (h)	Total reaction time in hours.	1.5 h
Temp (°C)	Reaction temperature in degrees Celsius.	75 °C
Pressure (atm)	Reaction pressure in atmospheres (1 = open flask at ambient pressure).	1 atm

Separation/Purification

How the product is isolated and purified. Greener techniques are marked (green) in the dropdown and score better in the sustainability indicators.

Input	What to enter	Aspirin example
Method	Select the separation method from the dropdown (filtration, extraction, distillation, crystallization, chromatography, evaporation/drying, other). Choose Other to type a custom method in the extra field that appears.	Aqueous or Ethanol Recrystallization (green)

Include recovered solvent in PMI numerator

The last input before the buttons. PMI (Process Mass Intensity) = total mass of all materials ÷ mass of product. This checkbox decides how recovered solvent is counted:

Setting	Effect on PMI	Aspirin example
Unchecked (default)	Recovered solvent is subtracted from the mass input — recycling is rewarded with a lower (better) PMI.	✗ left unchecked — the 80% of ethyl acetate recovered (20 g) is credited, lowering the PMI
Checked	All solvent mass is counted even if recovered — a stricter, more conservative (higher) PMI.

All done? Press Calculate Metrics at the bottom of the sidebar to compute all green chemistry metrics, or Reset to clear every field and start over.

How to use

Goal

Results

Contents

Balanced Chemical Equation

Reaction Name

Product

Reactants/Reagents

Solvents

Catalysts

Water & Workup

Conditions

Separation/Purification

Include recovered solvent in PMI numerator

Desired Product

Reactants/Reagents

Solvents

Catalysts

Water & Workup

Conditions

Separation/Purification

Balanced Chemical Equation