Organic Chemistry

What this covers

• Curved-arrow notation: identifying the nucleophile and electrophile in a step, drawing arrows from lone pairs or bonds to atoms, and checking each intermediate for correct formal charge and octets
• Stereochemistry in practice: assigning R/S with Cahn-Ingold-Prelog rules, distinguishing enantiomers from diastereomers and meso compounds, drawing Newman projections and cyclohexane chair flips with axial/equatorial assignments
• Deciding between SN1, SN2, E1 and E2 from substrate class, nucleophile versus base strength, solvent and temperature — and predicting the stereochemical outcome (inversion, racemisation, Zaitsev versus Hofmann)
• Carbocation stability, hydride and alkyl shifts, and Markovnikov versus anti-Markovnikov outcomes in alkene addition, hydroboration and halogenation
• Carbonyl reactivity: nucleophilic addition to aldehydes and ketones, the addition-elimination pattern in acyl substitution, and the relative reactivity ladder of acid chlorides through amides
• Reading spectra: interpreting IR functional group regions, and using 1H NMR chemical shift, integration, and splitting patterns to propose a structure from a molecular formula and degrees of unsaturation
• Retrosynthesis on short sequences: working backwards from a target, identifying which bond to disconnect, and choosing reagents that leave the rest of the molecule untouched

Where learners get stuck

Drawing curved arrows from the electrophile to the nucleophile, or treating arrows as atom movement

Students transfer the habit of drawing 'what turns into what' from general chemistry reaction equations. In organic mechanism, the arrow tracks an electron pair only, and it always starts at a lone pair or a bond and ends where that pair lands. Once the direction is reversed, every intermediate gets the wrong charge and the mechanism stops being checkable.

Treating the SN1/SN2/E1/E2 decision as a memorised table rather than a competition between species

Course summaries present these as four boxes, so students look up 'secondary substrate' and stall when two boxes apply. The reliable approach is to ask separately how stable the carbocation would be and whether the incoming species behaves more as a nucleophile or as a base — strong bulky bases push toward E2 even where SN2 looks tabulated.

Assigning R/S incorrectly when the lowest-priority group points toward the viewer, and confusing conformers with configurational isomers

The standard rule is taught for the case where the lowest priority points away, and the reversal step is easy to forget under exam pressure. Separately, chair flips and Newman rotations change nothing about the molecule's identity, but because both are drawn as different pictures, students count them as different isomers.

Believing resonance structures are things the molecule oscillates between

The double-headed arrow looks like an equilibrium arrow, and the phrase 'resonance' suggests motion. This matters because it leads to wrong predictions about where charge sits and which position on a ring is activated in electrophilic aromatic substitution.

What a session looks like

Sessions run by voice while you have paper, a whiteboard, or your problem set in front of you. A typical session starts with you describing a structure or a problem you are stuck on, then working through it out loud: naming the reactive site, saying where the electrons go, and predicting the product before checking it. Because you have to verbalise each mechanistic step, gaps that hide behind a memorised product show up quickly. The tutor will also dictate structures for you to draw, give spectral data for you to interpret step by step, and ask you to justify stereochemical outcomes rather than just state them. Sessions can be aimed at problem sets, mechanism drilling before an exam, or a slow rebuild of a chapter that did not land the first time.

Helpful to know first

• Lewis structures, formal charge, and resonance from general chemistry
• Hybridisation, VSEPR geometry, and bond polarity
• Acid-base equilibria and comfort using pKa values to compare acid strength
• Basic thermodynamics and kinetics: rate laws, activation energy, and reading a reaction coordinate diagram
• Ability to draw and interpret line-angle (skeletal) structures

Questions

How do I stop memorising organic chemistry reactions?

By reorganising them around mechanism. Most of a first-year course reduces to a small number of patterns — nucleophile attacks electrophile, leaving group departs, proton transfers in between. Sessions work through reactions by asking which atom is electron-rich and which is electron-poor, so a reaction you have never seen becomes predictable rather than something to recall.

Can voice tutoring work for a subject that is this visual?

You draw; the tutor talks and questions. Structures are described precisely enough to draw (chain length, substituent positions, stereochemical designations), and you read your work back or describe what you have drawn. Explaining a mechanism aloud is a standard way instructors check understanding, and it is what these sessions are built around.

I passed the first semester but the second one is much harder. What changed?

Second semester shifts to carbonyl chemistry, aromatics, and multi-step synthesis, where problems combine several mechanisms and require you to hold reactivity trends in mind at once. Sessions can start by tightening arrow-pushing and carbocation reasoning from the first semester, since those are usually the pieces that make the new material feel unmanageable.

Can we work on NMR problems specifically?

Yes. Structure determination is treated as its own skill: calculating degrees of unsaturation from the formula, using IR to rule functional groups in or out, then working through chemical shift, integration ratios, and splitting to assemble fragments into a structure. Bring the spectra data from your problem set and work through them out loud.