Organic Chemistry Lab 3D — Rotate real molecules to learn mechanisms, chirality and spectra

The useful test is whether an app computes its 3D models and verdicts live, or just plays a pre-rendered animation for each case. Organic Chemistry Lab 3D computes every angle, energy, R/S label and mechanism outcome with its own chemistry engine, so dragging a bond in the Conformation Lab or setting conditions in the Reaction Bench produces a result worked out on the spot. It covers 41 lessons across six units, free on iOS and Android, and works fully offline.

SN2 is a single concerted step: a strong nucleophile attacks the opposite face from the leaving group, favoured by a primary substrate and a polar aprotic solvent. SN1 goes through a flat carbocation intermediate, favoured by a tertiary substrate and a polar protic solvent, and loses the original stereochemistry in the process. E1 and E2 are their elimination counterparts, forming a double bond instead of a new substituent, with E2 needing the departing hydrogen positioned anti-periplanar to the leaving group. The Reaction Bench lets you set a substrate, reagent, solvent and temperature, predict which of the four wins, then run it and see the mechanism unfold.

R and S are labels for the two possible arrangements at a chiral centre — a carbon bonded to four different groups. You rank the four groups by the CIP priority rules, based on atomic number, then check whether the sequence from highest to lowest priority runs clockwise (R, from the Latin rectus) or counterclockwise (S, sinister) when the lowest-priority group points away from you. Chirality Lab asks you to commit to R or S before showing the priorities, so you have to reason through the geometry rather than pattern-match the answer.

A cyclohexane ring in its lowest-energy chair conformation keeps every carbon's bond angles close to the ideal 109.5°, but the hydrogens (or substituents) on each carbon still point in two distinct directions: axial, roughly perpendicular to the ring, and equatorial, roughly in the ring's plane. A ring flip swaps every axial position for equatorial and vice versa, and because a bulky substituent prefers the roomier equatorial position, which chair is favoured depends on what's attached. Conformation Lab's cyclohexane model lets you find the axial groups and watch the flip decide which chair wins.

They are predicted from standard correlation tables rather than recorded on a real instrument, and the app says so wherever they appear. That makes them reliable for what structure elucidation actually depends on — how many signals appear, how they split, how they integrate, and which carbonyl type is present — while being approximate in the finer decimal places of an exact chemical shift. Spectra Lab is built around identifying a compound from exactly that kind of qualitative reading, the way a real problem set asks you to.

Yes. Unit 1 in full, the first lesson of every other unit, all four labs with no restrictions, the entire 54-molecule library and three AI explanations a day are free on both the App Store and Google Play. Pro adds the remaining 30 lessons, unlimited AI explanations and removes ads, and the paywall is skippable everywhere it appears.

Yes, entirely. Every shape, angle, energy value, name, mechanism verdict and predicted spectrum is computed by the app's own chemistry engine on your device rather than fetched from a server, so lessons, labs and the molecule library all work on a train, in a basement with no signal, or in airplane mode.

It explains, in plain language, why a computed answer is the answer — for example, why a particular mechanism won under the conditions you set. It is never asked to decide what the answer is; the chemistry engine has already worked that out deterministically, and the AI only puts it into words, which keeps a fluent-sounding wrong explanation from substituting for a correct one.

Anyone taking a first or second organic chemistry course — high school, university or exam preparation — and anyone who found the subject difficult on paper and suspects it might make more sense in three dimensions. The course assumes the kind of general chemistry background a student has going into organic chemistry, then builds from hybridisation and functional groups up to full structure elucidation.