F. Physical Organic and Reactivity Trends (3 problems) 28. Compare acidity of a series: benzylic alcohol, allylic alcohol, and simple aliphatic alcohol — rank and justify with resonance and inductive effects. 29. Predict and explain relative nucleophilicity of iodide vs bromide vs chloride in polar protic vs aprotic solvents. 30. For SN1 vs SN2 competition on a secondary benzylic substrate with heat and polar protic solvent, predict major pathway and side reactions.
Here is a curated collection of notable practice problems from 2021, drawn from various sources. We'll dissect a few illustrative examples to highlight the types of challenges you might encounter.
Draw out complete curved-arrow mechanisms to avoid missing unexpected rearrangements like hydride or alkyl shifts.
Heterocycles are ubiquitous in pharmaceutical chemistry. Understanding their reactivity is crucial. Problem 6: Reactivity of Indoles advanced organic chemistry practice problems 2021
For a horizontal allylic alcohol with the hydroxyl group on the right: (-)-DET delivers oxygen from the top face . (+)-DET delivers oxygen from the bottom face .
When faced with a daunting synthesis problem, look at the target molecule first. Break it down one bond at a time into recognizable fragments (synthons). Ask yourself: "What reaction can reliably form this specific bond?"
Mastering Advanced Organic Chemistry: 2021 Practice Problems and Solutions For SN1 vs SN2 competition on a secondary
"In this economy?" Maya countered, gesturing to the sterically hindered tertiary carbon. "There’s no way that nucleophile is getting in there without a catalyst we haven't even discovered yet."
4-week study plan (example) Week 1: Mechanisms — daily 60–90 minutes; focus on 12 mechanism problems and review. Week 2: Synthesis and retrosynthesis — 90 minutes/day; complete all retrosynthesis problems and forward syntheses. Week 3: Pericyclic + stereochemistry — alternate problem types; timed drills. Week 4: Spectroscopy + physical-organic — full practice exam (90–120 minutes) using mixed problems; review weak spots.
The (2E,4Z)-diene must rotate into the s-cis conformation to react. 2. Enantioselective Transition-Metal Catalysis
B. Retrosynthesis and Multi-step Synthesis (8 problems) 7. Retrosynthesize and propose a 5-step synthesis of trans-1,2-diphenylcyclohexane starting from benzene and common reagents. 8. Propose a convergent synthesis of (S)-(+)-1-phenylethanol in enantiopure form (≥95% ee) using asymmetric catalysts or chiral auxiliaries; include stereochemical control elements. 9. Design a retrosynthesis for methyl 3-phenylpropanoate from simple benzene derivatives; provide reagents for each forward step. 10. Synthesize a tetrasubstituted alkene (E)-2,3-diphenyl-2-butene from acetophenone in ≤6 steps; show protecting-group strategy if needed. 11. Retrosynthetic analysis for a substituted dihydropyran target; propose a forward route using oxy-Michael or Prins cyclization. 12. Plan a route to 1,4-diketone starting from 1,3-butadiene; include regioselective functionalization steps. 13. Propose synthesis of 2,3-dibromobutane with defined stereochemistry (meso and racemic pair routes) from butane derivatives. 14. Devise a synthesis of a β-lactam fused to an aromatic ring using [2+2] cycloaddition or Staudinger conditions; propose protecting groups and stereochemical considerations.
A cyclohexene derivative where the anhydride is cis to the methyl group originating from the (E) alkene, and trans to the methyl from the (Z) alkene. Section 2: Enantioselective and Asymmetric Synthesis
Controlling absolute stereochemistry at quaternary carbon centers remained a top frontier in 2021 synthetic methodology. The Problem
, yielding the final reduced tricyclic product and regenerating the radical to sustain the chain reaction. 2. Enantioselective Transition-Metal Catalysis