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Organic Chemistry · Part 1 of 4
15 exam-style questions with model answers, plus 20 quick multi-choice questions — every question on this part of the standard, grouped by the 5 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
Name the functional group present in each of: (a) CH3CH2CHO, (b) CH3COCH3, (c) CH3CH2COCl, (d) CH3CH2CONH2.
Explain how you can tell from its structure whether a compound containing a C=O group is an aldehyde or a ketone, and explain why this distinction affects how the compound reacts with acidified dichromate.
Consider the three compounds CH3CH2COOH, CH3CH2COOCH3 and CH3CH2CONH2. All three contain a carbonyl carbon bonded to a second heteroatom. Compare and contrast their structures, and justify why only one of them will produce bubbles of carbon dioxide when sodium carbonate solution is added.
Give the IUPAC name of (a) CH3CH2CH2CHO and (b) CH3COCH2CH3, and draw the structural formula of propanoyl chloride.
Name the compound CH3CH(OH)CH2COOH, and explain how you decided which functional group provides the suffix and which becomes a prefix.
A student names the compound CH3CH2COOCH2CH2CH3 as 'propyl propanoate' and the compound CH3CH2CH2COOCH2CH3 as 'propyl ethanoate'. One name is correct and one is not. Identify the error, give the correct name, and explain the general rule that the student has misapplied. Support your answer by drawing both compounds.
Define the term 'constitutional isomer' and draw two constitutional isomers of C3H8O.
Propanal and propanone are constitutional isomers with the molecular formula C3H6O. Explain how a simple chemical test could distinguish between them, and explain why the test works.
Draw all four constitutional isomers of C4H9Br, name each, and classify each as primary, secondary or tertiary. Predict which isomers would give the same organic product on treatment with KOH in alcohol, and justify your prediction.
State the two conditions a molecule must meet to show cis–trans isomerism, and state whether but-1-ene, CH2=CHCH2CH3, meets them.
Explain why but-2-ene exists as cis and trans isomers but butane does not, even though both have four carbons in a chain.
The compound CH3CH=CHCOOH exists as cis and trans isomers. The trans isomer melts at 72 °C and the cis isomer at 14 °C, and the cis isomer is the more soluble in water. Justify both observations in terms of the structures of the two isomers, and explain why a chemical test could not be used to distinguish them.
Define a chiral carbon, and identify the chiral carbon in CH3CH2CH(NH2)COOH.
Explain why 2-bromobutane exists as enantiomers but 1-bromobutane does not.
A chemist synthesises 2-chlorobutane from but-1-ene and obtains a product that does not rotate plane-polarised light at all. A colleague concludes that the product cannot contain a chiral carbon and must therefore be 1-chlorobutane. Evaluate this conclusion, and explain how the two possibilities could be distinguished experimentally.