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NSWChemistryQuick questions
Module 7: Organic Chemistry
Quick questions on Organic reaction pathways and retrosynthesis explained: HSC Chemistry Module 7
13short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the most common one-step reaction that produces this functional group?Show answer
3. What is the precursor (the synthon) for that step? 4.
What is the master synthesis tree (Module 7)?Show answer
Going forward (oxidation direction or chain growth):
What is retrosynthesis?Show answer
To plan a synthesis, work backwards from the target. At each step, ask:
What is strategies for planning?Show answer
Count the carbons. The target and starting material must have compatible carbon skeletons. HSC does not include carbon-skeleton-changing reactions (no $C-C$ bond formation), so the carbon count is preserved through every step.
What is count the carbons?Show answer
The target and starting material must have compatible carbon skeletons. HSC does not include carbon-skeleton-changing reactions (no $C-C$ bond formation), so the carbon count is preserved through every step.
What is check the oxidation level?Show answer
Alkane and alkene are at the same level for the carbon involved. Alcohol is one step up. Aldehyde and ketone are another step.
What is identify the limiting step?Show answer
Markovnikov hydration always gives the more substituted alcohol. To get the less substituted alcohol, use a haloalkane route (HBr addition followed by hydrolysis) or accept the Markovnikov product and work from there.
What is use reflux when stated?Show answer
Esterification, oxidation to acid, hydrolysis, and base hydrolysis all require reflux. Distillation only is for collecting an aldehyde or separating an ester after the reaction.
What is forgetting conditions?Show answer
"Oxidise to a carboxylic acid" without saying "reflux with excess acidified dichromate" loses marks.
What is markovnikov going the wrong way?Show answer
Hydration of propene gives propan-2-ol (Markovnikov), not propan-1-ol. State the regiochemistry explicitly.
What is trying to build $C-C$ bonds?Show answer
HSC does not include Grignards or coupling reactions. Carbon count must match.
What is stopping a primary alcohol at the aldehyde under reflux?Show answer
Under reflux with excess oxidant, you get the acid. To isolate the aldehyde, distil it off as it forms.
What is writing esterification with dilute $H_2SO_4$?Show answer
It must be concentrated, both for catalysis and for water removal.