MolScript Gallery: Reaction Mechanisms Written as Text

Published: 17 Oct 2026 · Author: Scidart Academy

Each mechanism below is a few lines of MolScript and the drawing MolDraw makes from them. These are the same scripts MolDraw tests on every change: each one must draw with every curly arrow placed to the drawing rules, and its arrows must give, electron for electron, the products written after them. A mechanism appears here only if it passes.

Copy any script into the MolScript tab of the Templates panel in MolDraw, or ask the AI assistant for a mechanism, and edit it from there.

SN2

title: SN2 of bromomethane
[OH-:1] "hydroxide" + [CH3:2][Br:3] "bromomethane" ->[SN2][acetone] CO "methanol" + [Br-]
move :1 -> 1..2
move 2-3 -> 3
SN2, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

SN1

title: SN1 of tert-butyl bromide
C[C:1](C)(C)[Br:2] ->[slow] C[C+:3](C)C + [Br-]
move 1-2 -> 2
-> C[C+:4](C)C + [OH2:5]
move :5 -> 5..4
->[fast] CC(C)(C)[OH2+]
SN1, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

E2

title: E2 elimination
[OH-:1] + [H:4][CH2:2][CH:3](C)[Br:5] ->[E2] C=CC + O + [Br-]
move :1 -> 1..4; 4-2 -> 2-3; 3-5 -> 5
E2, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Cyanohydrin

title: Cyanide addition to a carbonyl
[C-:1]#N + C[CH:2]=[O:3] -> CC([O-])C#N
move :1 -> 1..2
move 2-3 -> 3
Cyanohydrin, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Hydride reduction

title: NaBH4 reduction of acetone
[H:1][BH3-:2] + C[C:3](C)=[O:4] ->[H⁻ transfer] CC([O-])C
move 1-2 -> 1..3
move 3-4 -> 4
Hydride reduction, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Ester hydrolysis (addition step)

[OH-:1] + C[C:2](=[O:3])OC ->[addition] CC([O-])(O)OC
move :1 -> 1..2
move 2-3 -> 3
Ester hydrolysis (addition step), drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Tetrahedral collapse

C[C:1]([O-:2])(O)[O:3]C ->[elimination] CC(=O)O + [O-]C
move :2 -> 2-1
move 1-3 -> 3
Tetrahedral collapse, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Aldol addition

title: Aldol addition
[CH2-:1]C(C)=O "enolate" + C[CH:2]=[O:3] "acetaldehyde" -> CC([O-])CC(C)=O
move :1 -> 1..2
move 2-3 -> 3
Aldol addition, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Michael addition

title: Michael addition
[CH2-:1]C(C)=O + [CH2:2]=[CH:3][C:4](C)=[O:5] ->[1,4-addition] CC(=O)CCC=C(C)[O-]
move :1 -> 1..2; 2-3 -> 3-4; 4-5 -> 5
Michael addition, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Enolate resonance

[CH2-:1][C:2](C)=[O:3] <-> C=C(C)[O-]
move :1 -> 1-2
move 2-3 -> 3
Enolate resonance, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Nitro resonance

C[N+:1](=[O:2])[O-:3] <-> C[N+]([O-])=O
move :3 -> 3-1
move 1-2 -> 2
Nitro resonance, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Allyl cation resonance

[CH2:1]=[CH:2][CH2+:3] <-> [CH2+]C=C
move 1-2 -> 2-3
Allyl cation resonance, drawn by MolDraw from the MolScript above
1 curly arrow, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Carbonyl protonation

[O:1]=C(C)C + [H:3][OH2+:4] ->[H⁺ transfer] [OH+]=C(C)C + O
move :1 -> 1..3
move 3-4 -> 4
Carbonyl protonation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Hemiacetal step

C[CH:1]=[OH+:2] + [OH:3]C ->[addition] CC(O)[OH+]C
move :3 -> 3..1
move 1-2 -> 2
Hemiacetal step, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Epoxide opening

[OH-:1] + C[CH:2]1[O:3]C1 ->[SN2] CC(O)C[O-]
move :1 -> 1..2
move 2-3 -> 3
Epoxide opening, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Alkene bromination

title: Bromination of ethene
[CH2:1]=[CH2:2] + [Br:3][Br:4] -> C1C[Br+]1 + [Br-]
move 1-2 -> 3; :3 -> 3..2
move 3-4 -> 4
Alkene bromination, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Friedel-Crafts attack

[CH:1]1=[CH:2]C=CC=C1 + C[C+:3]=O ->[SEAr] CC(=O)C1C=CC=C[CH+]1
move 1-2 -> 2..3
Friedel-Crafts attack, drawn by MolDraw from the MolScript above
1 curly arrow, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Arenium deprotonation

CC(=O)[C:1]1([H:2])C=CC=C[CH+:3]1 + [Cl-:4] ->[−H⁺] CC(=O)c1ccccc1 + Cl
move :4 -> 4..2; 2-1 -> 1-3
Arenium deprotonation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Diels-Alder

title: Diels–Alder
[CH2:1]=[CH:2][CH:3]=[CH2:4] + [CH2:5]=[CH2:6] ->[Δ] C1CC=CCC1
move 1-2 -> 2-3; 3-4 -> 4..5; 5-6 -> 6..1
Diels-Alder, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Bromine homolysis

[Br:1][Br:2] ->[hν] [Br] + [Br]
move 1-2 ~> 1; 1-2 ~> 2
Bromine homolysis, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Radical addition

title: Radical addition of Br• to propene
[Br:1] + [CH2:2]=[CH:3]C -> BrC[CH]C
move 1 ~> 1..2
move 2-3 ~> 1..2
move 2-3 ~> 3
Radical addition, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Carboxylate resonance

C[C:1](=[O:2])[O-:3] <-> CC([O-])=O
move :3 -> 3-1
move 1-2 -> 2
Carboxylate resonance, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

SN2 through its transition state

title: SN2 through its transition state
per-row: 5
[OH-:1] + [CH3:2][Br:3] {δ+=2 δ-=3} -> [OH]~C([H])([H])([H])~[Br] {ts} -> CO + [Br-]
move :1 -> 1..2; 2-3 -> 3
SN2 through its transition state, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Nucleophilic addition with R groups

title: Nucleophile adds to a ketone
[Nu-:1] + [R1][C:2](=[O:3])[R2] -> [Nu]C([R1])([R2])[O-]
move :1 -> 1..2; 2-3 -> 3
Nucleophilic addition with R groups, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

E2 with a named hydrogen

title: E2 elimination (hN names the hydrogen)
let base = [OH-:1] "hydroxide"
$base + [CH3:2][CH:3](C)[Br:5] ->[E2] C=CC + O + [Br-]
move :1 -> 1..h2; h2-2 -> 2-3; 3-5 -> 5
E2 with a named hydrogen, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Friedel-Crafts acylation with a reagent structure

title: Friedel–Crafts acylation
c1ccccc1 ->[{CC(=O)Cl}][AlCl3] CC(=O)c1ccccc1 + Cl
Friedel-Crafts acylation with a reagent structure, drawn by MolDraw from the MolScript above
1 step, no curly arrows.

Suzuki catalytic cycle

title: Suzuki coupling: catalytic cycle
layout: cycle
[Pd] "Pd(0)" ->[oxidative addition][+ ArBr] Br[Pd][Ar]
->[transmetalation][+ PhB(OH)2] [Ph][Pd][Ar]
->[reductive elimination][− Ar–Ph] [Pd]
Suzuki catalytic cycle, drawn by MolDraw from the MolScript above
3 steps, no curly arrows.

Imine formation: amine addition

title: Imine formation, step 1
C[CH:1]=[O:2] + [NH2:3]C ->[addition] CC([O-])[NH2+]C
move :3 -> 3..1; 1-2 -> 2
Imine formation: amine addition, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Oxocarbenium formation (acetal)

title: Acetal formation: loss of water
C[CH:1]([O:2]C)[OH2+:3] -> C[CH]=[O+]C + O
move :2 -> 2-1; 1-3 -> 3
Oxocarbenium formation (acetal), drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

E1 deprotonation

title: E1: water removes a proton
C[C+:1](C)[CH3:2] + [OH2:3] -> C=C(C)C + [OH3+]
move :3 -> 3..h2; h2-2 -> 2-1
E1 deprotonation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Claisen condensation addition

title: Claisen condensation: enolate addition
[CH2-:1]C(=O)OC + C[C:2](=[O:3])OC -> COC(=O)CC(C)([O-])OC
move :1 -> 1..2; 2-3 -> 3
Claisen condensation addition, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Halohydrin formation

title: Water opens a bromonium ion
[CH2:2]1[CH2:3][Br+:1]1 + [OH2:4] -> [OH2+]CCBr
move :4 -> 4..2; 2-1 -> 1
Halohydrin formation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Radical chlorination propagation

title: Chlorination of methane: propagation
[Cl:1] + [H:2][CH3:3] ->[hν] Cl + [CH3]
move 1 ~> 1..2; 2-3 ~> 1..2; 2-3 ~> 3
Radical chlorination propagation, drawn by MolDraw from the MolScript above
3 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Methyl radical coupling

title: Radical termination
[CH3:1] + [CH3:2] -> CC
move 1 ~> 1..2; 2 ~> 1..2
Methyl radical coupling, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Carboxylic acid deprotonation

title: Hydroxide deprotonates acetic acid
[OH-:1] + CC(=O)[OH:2] -> CC(=O)[O-] + O
move :1 -> 1..h2; h2-2 -> 2
Carboxylic acid deprotonation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Amide resonance

C[C:1](=[O:2])[NH2:3] <-> CC([O-])=[NH2+]
move :3 -> 3-1; 1-2 -> 2
Amide resonance, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

SN1 without map numbers

title: SN1 with element ends, numbered, snake rows
number: both
wrap: snake
per-row: 3
CC(C)(C)Br ->[slow] C[C+](C)C + [Br-]
move C-Br -> Br
-> C[C+](C)C + O
move :O -> O..C+
->[fast] CC(C)(C)[OH2+]
SN1 without map numbers, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Highlighted SN2

title: SN2 with the reacting atoms highlighted
[OH-:1] {highlight=1:blue} + [CH3:2][Br:3] {highlight=2/2-3:red} -> CO + [Br-]
move :1 -> 1..2; 2-3 -> 3
Highlighted SN2, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Pd cycle with oxidation states

title: Cross-coupling cycle with oxidation states
layout: cycle
[Pd:1] {ox=1:0} ->[oxidative addition][+ ArX] [X][Pd:2][Ar] {ox=2:II}
->[transmetalation][+ R–M] [R][Pd:3][Ar] {ox=3:II}
->[reductive elimination][− Ar–R] [Pd:1]
Pd cycle with oxidation states, drawn by MolDraw from the MolScript above
3 steps, no curly arrows.

Grignard addition (ion pair)

title: Grignard addition to a ketone
[CH3:1][Mg:2]Br + C[C:3](C)=[O:4] -> CC(C)(C)[O-] + [Mg+]Br
move 1-2 -> 1..3; 3-4 -> 4
Grignard addition (ion pair), drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Alkoxide protonation

title: Work-up: the alkoxide is protonated
CC(C)(C)[O-:1] + [H:2][OH2+:3] -> CC(C)(C)O + O
move :1 -> 1..2; 2-3 -> 3
Alkoxide protonation, drawn by MolDraw from the MolScript above
2 curly arrows, every one placed to the drawing rules; the electron bookkeeping gives exactly the products drawn.

Related guides

MolScript: the language guide chemfig mechanism samples Chemical reaction drawer All articles

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