21 topics
Organic chemistry help, mechanism first
Organic chemistry punishes memorisation harder than any other science course, because there are only about a dozen mechanisms and several hundred reactions that are those mechanisms wearing different substituents. Curved arrows always start where the electrons are and point at where they are going. Draw them that way consistently and a reaction you have never seen before becomes something you can predict rather than recall.
Where students get stuck
SN1 or SN2 — how am I supposed to decide?
Look at the substrate first, because it settles most cases on its own. Methyl and primary carbons go SN2, since backside attack needs room and there is no cation stable enough for the alternative. Tertiary goes SN1, because the carbocation is stabilised and the back side is blocked. Secondary is where the other factors actually decide: a strong nucleophile in a polar aprotic solvent pushes SN2, while a weak nucleophile that is also the solvent pushes SN1. The stereochemistry then tells you which one happened after the fact — SN2 inverts the centre cleanly, SN1 gives a roughly even mixture because the flat cation can be attacked from either face.
I keep drawing the arrows backwards
There is one rule and it fixes nearly every case: an arrow starts at electrons and ends where those electrons end up. Electrons live in lone pairs, in pi bonds, and occasionally in sigma bonds. They never live on a positive charge, so an arrow must never start at H+ or at a carbocation. When a base takes a proton, the arrow runs from the lone pair on the base to the hydrogen, and a second arrow runs from the bond being broken onto the atom keeping it. After each step, count the bonds on every atom you touched. If a carbon has five, you have drawn an arrow into a full octet and skipped the arrow that should have left at the same time.
Resonance versus isomers, and which structure is the real one?
Neither structure is real and the molecule is not flipping between them. Resonance forms are two incomplete drawings of one thing, because a single Lewis structure cannot show electrons spread over three atoms. Isomers are genuinely different compounds with atoms in different places. The test is simple: if anything moved except electrons, it is an isomer, not a resonance form. To rank contributors, prefer full octets first, then negative charge sitting on the more electronegative atom, then the least separation of charge. This matters because delocalisation stabilises intermediates, which is exactly why allylic and benzylic cations behave like tertiary ones despite being drawn on a primary carbon.
R and S, especially when the lowest priority points at me
Rank the four groups by the atomic number of the atom directly attached, and where two tie, walk outward one bond at a time until they differ at a first point of difference. Duplicate atoms count for double bonds. Then orient the molecule with the lowest priority pointing away and read one to two to three: clockwise is R, anticlockwise is S. When the lowest priority is pointing toward you instead, do not rotate the drawing. Read the direction as it stands and reverse the answer, which is faster and far less error-prone. Then check for internal mirror symmetry, because a molecule with two stereocentres that mirror each other is meso and has no optical activity at all.
Multi-step synthesis: I have no idea where to begin
Work backwards from the product, not forwards from the starting material. Look at the target and ask which bond in it is the one you cannot make by any reaction you know, then find the disconnection that produces two fragments you could actually buy or build. Keep going until every fragment is something simple. Only then write the sequence forwards and check the order for conflicts: protecting groups go on before the step that would destroy the sensitive functional group and come off after, and directing effects on an aromatic ring mean nitrating before or after alkylation gives completely different products. Most failed syntheses on an exam are the right reactions in the wrong order.
What's covered
Organic Chemistry topics you can work through with a tutor, generate practice on, or turn into flashcards and a study plan.
Structure and bonding
- Hybridisation, sigma and pi bonds
- Formal charge and skeletal structures
- Resonance and delocalisation
- Acidity, basicity and reasoning from pKa
- Inductive and resonance effects on stability
Stereochemistry and conformation
- Chirality, R and S assignment, Fischer projections
- Enantiomers, diastereomers and meso compounds
- Newman projections and conformational energy
- Cyclohexane chairs and axial versus equatorial preference
Core reactions and mechanisms
- SN1, SN2, E1, E2 and the competition between them
- Alkene addition, Markovnikov and anti-Markovnikov outcomes
- Alkyne reactions and selective reduction
- Radical halogenation and selectivity
- Electrophilic aromatic substitution and directing effects
- Carbonyl addition: aldehydes, ketones and Grignard reagents
- Nucleophilic acyl substitution in carboxylic acid derivatives
Spectroscopy and synthesis
- Degrees of unsaturation from a molecular formula
- IR and functional group identification
- NMR: chemical shift, integration and splitting
- Mass spectrometry and fragmentation patterns
- Retrosynthesis and multi-step planning
Organic Chemistry questions
Can it check a mechanism I drew on paper?
Yes. Hold the page up to the camera and it reads your structures and arrows, then tells you which specific arrow is wrong and why — starting on a positive charge, breaking a bond that was not there, an intermediate with a five-bonded carbon. Redrawing your own mechanism after that correction is what makes the next one stick.
Will it just give me the products so I can finish the problem set?
No. It asks you which site is electrophilic and what the nucleophile is before it draws anything, because a product handed over teaches nothing that survives to the exam. If you already have an answer and want it verified, it will confirm or point to the step that went wrong instead of working the question again from the start.
Can it help me interpret an NMR spectrum from my lab?
Yes. Share the spectrum on screen and it goes through it in the order that works: degrees of unsaturation from the formula first, then integration for how many hydrogens each signal covers, then shift for the environment, then splitting for the neighbours. It walks you to a structure rather than announcing one, so you can repeat the method on the next spectrum.
I did badly on the first midterm. What should I change before the next one?
Usually the study method rather than the hours. Rewriting notes and rereading reaction lists feels productive and predicts very little. What correlates is drawing mechanisms from a blank page under time pressure, then checking them. Generated practice sets here come back with full worked solutions, so you can do that loop repeatedly without waiting for a marker. No one can promise you a mark, but this is the practice that separates the two groups.
Stuck on organic chemistry right now?
Talk it through out loud, share your screen, and watch it worked out step by step on a whiteboard.
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