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Reaction Scale Calculator

Pick a stored reaction, fix one reagent's amount, get every other reagent's quantity by stoichiometric equivalents. Solvent volume derived from your substrate concentration. Densities + molar masses come from our molecule database.

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Wittig olefination: methyltriphenylphosphonium bromide + benzaldehyde → styrene

[Ph3P=CH2] + Ar–CHO → Ar–CH=CH2 + Ph3P=O

Canonical Wittig olefination — the textbook 'make an alkene from an aldehyde' demo. The ylide (methylenetriphenylphosphorane) is generated in situ from methyltriphenylphosphonium bromide + base (typically n-BuLi at −78 °C, or NaH in DMSO), then reacts with benzaldehyde to give styrene. The triphenylphosphine oxide byproduct precipitates from cold ether and is the diagnostic end-of-reaction signal.

Conditions: Step 1 — Suspend Ph3P+CH3 Br− (1.05 equiv) in dry THF under N2; cool to −78 °C; add n-BuLi (1.05 equiv, 2.5 M in hexanes) dropwise. Stir 30 min — solution turns yellow-orange (ylide formation). Step 2 — Add benzaldehyde (1.0 equiv) dropwise; warm to RT over 1–2 h; stir 4–12 h. Workup — Quench with sat. NH4Cl; extract with Et2O; wash brine; dry MgSO4. Concentrate carefully (styrene is volatile, bp 145 °C). Triphenylphosphine oxide precipitates from cold pentane/ether — filter off. Distil residue under reduced pressure for clean styrene.

Expected yield
70–88 %
Expected duration
4–12 h at RT after −78 °C ylide formation

Mechanism reference ↗

Scale inputs

Anchor reagent + concentration

Total reactant moles divided by this concentration sets the solvent volume.

Anchor amount

Updates as you type · the URL captures every input.

Computed quantities

Reactants

Reactants for Wittig olefination: methyltriphenylphosphonium bromide + benzaldehyde → styrene: stoichiometric quantities derived from the anchor amount.
Reagent Equiv Moles · mmol Mass · g Volume · mL
1779-49-3
1779-49-3 · C19H18BrP

density unavailable — volume not calculable.

1.05 1.05 0.375
Benzaldehyde
100-52-7 · C7H6O
1.0 1.00 0.106 0.10

Solvent

Solvent for Wittig olefination: methyltriphenylphosphonium bromide + benzaldehyde → styrene: stoichiometric quantities derived from the anchor amount.
Reagent Equiv Moles · mmol Mass · g Volume · mL
109-99-9
109-99-9 · C4H8O
50.60 3.649 4.10

Product

Product for Wittig olefination: methyltriphenylphosphonium bromide + benzaldehyde → styrene: stoichiometric quantities derived from the anchor amount.
Reagent Equiv Moles · mmol Mass · g Volume · mL
Styrene
100-42-5 · C8H8
1.0 1.00 0.104 0.11

Expected isolated yield

What you should actually weigh out of the recrystallisation flask, scaled from the limiting reactant via the canonical-procedure yield window.

Product
Styrene 100-42-5 · C8H8
Theoretical max
0.10 g (1.00 mmol)
Expected isolated · 70–88 % yield
0.07 – 0.09 g

Stoichiometry: moles_X = (moles_anchor / equiv_anchor) × equiv_X. Mass = moles × MW; volume = mass / ρ. Solvent volume = total reactant moles ÷ substrate concentration.

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