250 Organic Chemistry Reactions Flashcards for Revision
In organic reactions, the condition you miss is usually the mark you lose.
250 cards
Sign up free and add it
The deck is added automatically once you finish signing up.
Nothing here is generated by AI, so the free plan is enough to add it.
See 30 sample cards
Showing a 30-card sample of 250.
| Front | Back |
|---|---|
| Aromaticity | Meaning: No bonds break. A cyclic, planar, fully conjugated pi system with 4n+2 pi electrons is unusually stable and acts as an aromatic ring. Conditions: Needs a closed loop of adjacent p orbitals and near planarity. Benzene and the cyclopentadienyl anion fit. Watch for: A single sp3 atom interrupts it. A planar 4n pi system is antiaromatic, not aromatic. |
| Boat conformation | Meaning: No bonds break. Cyclohexane can adopt a boat with eclipsed bonds and close flagpole H atoms, so it is less stable than a chair. Conditions: Occurs in cyclohexane and other six-membered rings. It appears during chair to chair interconversion. Watch for: Twist-boat is lower in energy than boat. Extra strain comes from eclipsing and transannular crowding. |
| CIP priority rules | Meaning: No bonds break. Ranking groups by atomic number gives the correct R, S, E or Z stereodescriptor. Conditions: Compare the directly attached atoms first. If tied, move outward until the first difference. Watch for: Higher isotope mass ranks higher. Multiple bonds are treated as if bonded to duplicate atoms. |
| SN2 substitution | Meaning: A nucleophile forms C-Nu as C-LG breaks in one step. The product is the substituted alkane. Conditions: Strong nucleophile such as I-, CN- or N3-. Polar aprotic solvent like DMSO or acetone. Best with methyl or primary halides. Watch for: Backside attack gives inversion at a chiral center. Tertiary halides fail. Strong base can divert to E2. |
| Good leaving group | Meaning: The group departs with the bonding pair, so C-LG breaks easily and substitution or elimination products form faster. Conditions: I-, Br-, Cl-, OTs and OMs are common. Use when the substrate must ionize or react in one step. Watch for: Better leaving groups speed both substitution and elimination. F- and OH- are poor unless activated. |
| Methyl substrate | Meaning: A nucleophile can replace the leaving group by SN2. No beta carbon exists, so elimination cannot make an alkene. Conditions: Use CH3-LG with a strong nucleophile in polar aprotic solvent. Watch for: SN1 is impossible because a methyl carbocation is too unstable. E2 cannot occur. |
| SN2 rate law | Meaning: C-Nu forms as C-LG breaks in one step to give the substitution product. Rate = k[RX][Nu-]. Conditions: Strong nucleophile. Usually methyl or primary RX in a polar aprotic solvent. Watch for: Inversion at a stereocenter. Tertiary substrates fail and strong base can divert to E2. |
| Halide leaving group order | Meaning: When C-X must break, RI and RBr give substitution or elimination products more readily than RCl, while RF is usually sluggish. Conditions: Compare simple alkyl fluorides, chlorides, bromides, and iodides under the same nucleophile or base and solvent. Watch for: Sulfonates such as OTs, OMs, and OTf are usually even better leaving groups. |
| PBr3 | Meaning: An alcohol is converted to an alkyl bromide by replacing C-O with C-Br. The product is a better substrate for later reactions. Conditions: Use PBr3, often in ether, on primary or secondary alcohols under mild, anhydrous conditions. Watch for: Reaction at a stereogenic carbon gives inversion. Tertiary alcohols are poor substrates. |
| Beta hydrogen | Meaning: A hydrogen on the carbon next to the leaving-group carbon can be removed, and the new C=C bond forms in elimination. Conditions: E2 needs a base and a beta H. E1 also needs a beta H after ionization. No beta H means no simple dehydrohalogenation. Watch for: Methyl halides cannot eliminate because they lack beta H. Which beta H is removed controls the alkene formed. |
| Hydrohalogenation | Meaning: H and X add across a C=C to form C-H and C-X bonds, giving an alkyl halide. Conditions: HX such as HCl, HBr or HI, often in ether or as concentrated solution, usually no peroxides. Watch for: Unsymmetrical alkenes usually give Markovnikov products and rearrangements can occur through carbocations. |
| Catalytic hydrogenation | Meaning: H2 adds across C=C or C≡C to form C-H bonds and reduce the pi bond, usually to an alkane. Conditions: H2 with Pd/C, Pt or Ni, often in ethanol or ethyl acetate, at room temperature or pressure. Watch for: Addition is syn on the metal surface. Alkynes usually reduce all the way unless a poisoned catalyst is used. |
| Acid-catalyzed hydration of alkenes | Meaning: A C=C gains H and OH to give an alcohol. Water attacks the carbocation and deprotonation gives the neutral product. Conditions: H2O with dilute H2SO4 or H3O+, often warm. Best with alkenes that can form stable carbocations. Watch for: Hydride or alkyl shifts can rearrange the skeleton. A new stereocenter usually forms without stereocontrol. |
| Ozone cycloaddition | Meaning: O3 adds across a C=C in a 1,3-dipolar cycloaddition to form a primary ozonide and begin double-bond cleavage. Conditions: O3 in CH2Cl2 or MeOH at about -78 °C, before workup. Watch for: The first adduct is unstable. Final products are determined only after later fragmentation and workup. |
| Homolytic cleavage | Meaning: A bond breaks so each atom keeps one electron, forming two radicals. No ions are produced. Conditions: Heat or hv, especially with weak bonds such as O-O or X-X. Watch for: Use fishhook arrows. Do not confuse it with heterolysis, which gives cations and anions. |
| Gattermann-Koch formylation | Meaning: A formyl group replaces an aromatic H, forming an aryl aldehyde with a new ring-C(=O)H bond. Conditions: CO and HCl with AlCl3 and CuCl, usually on benzene or activated arenes under anhydrous conditions. Watch for: Strongly deactivated rings and basic amines fail. Polyformylation is uncommon because CHO deactivates the ring. |
| Sodium borohydride reduction | Meaning: A hydride adds to an aldehyde or ketone C=O. Protonation gives a 1° or 2° alcohol. Conditions: NaBH4 in methanol or ethanol, then aqueous workup at room temperature. Watch for: Usually stops at aldehydes and ketones. Esters and amides are normally untouched. |
| Hemiacetal formation | Meaning: An alcohol adds to an aldehyde or ketone. One C-O bond forms and the product bears OH and OR on the same carbon. Conditions: ROH, often as solvent, with mild acid catalysis. Equilibrium is usually at room temperature. Watch for: Usually unstable except in cyclic sugars or when 5- and 6-membered rings form intramolecularly. |
| Acyl chloride formation | Meaning: The OH of a carboxylic acid is replaced by Cl. The product is an acid chloride. Conditions: SOCl2, often with pyridine or catalytic DMF, in dry dichloromethane or neat reagent, then gentle heating. Watch for: Water hydrolyzes the product. HCl and SO2 are released. |
| LDA enolate formation | Meaning: A strong base removes an α-H to give a lithium enolate. This creates a nucleophile at the α-carbon. Conditions: LDA in dry THF at low temperature, commonly −78 °C, under anhydrous conditions. Watch for: Requires an α-hydrogen. LDA is bulky and usually gives the kinetic enolate. |
| Aldol addition | Meaning: An enolate adds to another aldehyde or ketone. A new C-C bond forms and the product is a β-hydroxy carbonyl. Conditions: Dilute base such as NaOH or alkoxide in alcohol or water. Keep temperature low to avoid dehydration. Watch for: Needs at least one enolizable partner. Self-condensation mixtures arise unless one partner lacks α-H. |
| Tollens oxidation | Meaning: An aldehyde is oxidized to a carboxylate, while Ag+ is reduced to metallic silver. Conditions: Ammoniacal AgNO3 in water, mildly basic, often with gentle warming. Watch for: Most ketones are negative. Alpha-hydroxy ketones can also reduce Tollens reagent. |
| Oxime formation | Meaning: Hydroxylamine adds to a carbonyl and water is lost. The C=O becomes C=N-OH. Conditions: NH2OH·HCl with base or buffer, often in ethanol-water. Mild acid and water removal help. Watch for: Ketones are slower than aldehydes. Syn and anti geometrical isomers may form. |
| Wolff-Kishner reduction | Meaning: Aldehydes and ketones are deoxygenated to methylene groups. The C=O is replaced by CH2. Conditions: H2NNH2 with KOH or NaOH in ethylene glycol or similar high-boiling solvent, strong heat. Watch for: Useful for acid-sensitive substrates. Base-sensitive or heat-sensitive groups can fail. |
| Nucleophilic acyl substitution | Meaning: A nucleophile adds to an acyl derivative, then a leaving group departs. The product is a substituted acyl compound. Conditions: Occurs with acid chlorides, anhydrides, esters or amides, often using base or acid in dry or alcoholic solvent. Watch for: Aldehydes and ketones usually stop at addition because they lack a leaving group. |
| Acid-catalyzed alpha-halogenation | Meaning: The enol of an aldehyde or ketone reacts with X2. A C-X bond forms at the alpha carbon. Conditions: Br2 or Cl2 under acidic conditions, often in acetic acid, from cold to room temperature. Watch for: Usually gives monohalogenation. Base changes the selectivity and can lead to multiple halogenations. |
| PCC oxidation | Meaning: A primary alcohol is oxidized to an aldehyde and a secondary alcohol to a ketone without going on to the acid. Conditions: Use PCC in CH2Cl2 under anhydrous conditions at room temperature. Watch for: Water promotes overoxidation or messy mixtures. It does not oxidize isolated alkenes. |
| MOM ether protection | Meaning: An alcohol O-H is converted into a methoxymethyl ether by forming an O-CH2OCH3 bond. Conditions: MOMCl with DIPEA or Et3N in CH2Cl2, usually 0 °C to rt under dry conditions. Watch for: MOM is acid-labile. Phenols and amines can also be alkylated if chemoselectivity is poor. |
| Luche reduction | Meaning: An alpha,beta-unsaturated carbonyl is reduced at C=O to give an allylic alcohol. The C=C bond is retained. Conditions: NaBH4 with CeCl3·7H2O in MeOH, usually 0 °C to rt. Watch for: Without CeCl3, selectivity drops. Saturated carbonyls gain little from this method. |
| DEPT-135 | Meaning: In a 13C NMR DEPT-135 spectrum, CH and CH3 signals point up, CH2 signals point down, and quaternary carbons vanish. Conditions: Run DEPT-135 with a normal proton-decoupled 13C spectrum in a deuterated solvent such as CDCl3. Watch for: Quaternary carbons give no peak. Overlap can hide phase, so use the regular 13C trace to count carbons. |
About this deck
Organic chemistry reactions go wrong in revision for a simple reason: the same substrate can substitute, eliminate, add, rearrange, or do nothing useful depending on the conditions. You half remember a reagent, miss the heat, forget the solvent, or overlook the competing pathway, and suddenly near-identical questions have different answers. The slip is usually not a big idea. It is the detail that changes the outcome. This deck turns that into cards you can rehearse fast. It has 250 cards split across structure and bonding (35), substitution and elimination (45), alkenes alkynes and radicals (45), aromatics (35), carbonyls (55), and synthesis and analysis (35). Each card covers a single reaction or concept, with Meaning on the back for what it is, Conditions for when it happens, and Watch for to flag the rival pathway or common trap. So hybridisation, antiaromaticity, and alpha cleavage sit beside core reaction patterns in the same format. On a spaced repetition schedule, the cards you can answer cleanly stop showing up so often, while the ones you still confuse keep returning until the conditions and alternatives separate in your head. The deck leaves out long mechanism walk-throughs and broad spectroscopy tables on purpose, so your reviews stay focused on deciding what happens, when it happens, and what else could happen instead.
Frequently asked
- Why does a reactions deck start with structure and bonding?
- Because reactivity depends on the basics. The structure and bonding section (35) puts hybridisation, resonance, acidity, basicity, conformations, and stereochemistry into the same Meaning, Conditions, and Watch for format as the reaction cards, so later choices make more sense.
- How are substitution and elimination reactions handled in this deck?
- The substitution and elimination section (45) is built around the fact that the same substrate can go different ways. Cards separate what happens from the conditions that favour it and use Watch for to flag the rival pathway, leaving group issue, or selectivity trap that usually causes the mistake.
- What is covered in synthesis and analysis?
- It mixes route-planning and interpretation cards, so you review how to choose a transformation and how to read clues from products or fragments. That is where alpha cleavage sits, alongside synthesis decisions that depend on conditions rather than memorised lists.
- Can I import the whole deck on the free plan?
- Yes. Importing a saved deck runs no new AI generation and spends no AI credits, so the free plan imports all 250 cards. You can study, edit and delete them afterwards.
- Will importing it twice create duplicates?
- No. Cards you already have are skipped and only cards added in a revision come through. Including re-imports after deleting it, one official deck can be imported three times per account.
- Can I use it on the web and in the mobile app?
- Yes. The deck is added to your account rather than to a device, so the same cards and the same progress are there on the web, on iOS and on Android.
- Can I edit the cards after importing?
- Yes. Imported cards are yours: you can edit both sides, delete cards you do not need, change tags, and move cards to another deck.
No official exam questions are reproduced. Every card was written for this deck.Editorial reference date 2026-08-30.