IB Chemistry HL 3.4.12 Hl Carbocation Stability Questions

Use real HL exam questions to draw and rank carbocation intermediates, explain their relative stability, and derive the major product formed from HX or water addition.

Exam points

Draw the alternative carbocations formed by protonation at either alkene carbon, preserving the correct structural connectivity and charge.
Rank primary, secondary and tertiary carbocations by alkyl-group stabilisation and use that stability comparison to justify the preferred pathway.
Predict or derive the major product from nucleophilic attack on the more stable carbocation, including the correct regioisomer and product structure.

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Study 3.4.12 (HL)—Carbocation stability conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 2]

Ethanol is obtained by the hydration of ethene, $\mathrm{C}_{2} \mathrm{H}_{4}$ .

Alternative synthetic routes exist to produce alcohols.

Explain why the major organic product is 2-bromopropane and not 1-bromopropane.

«2-bromopropane involves» formation of more stable «secondary» carbocation/carbonium ion/intermediate
OR
1-bromopropane involves formation of less stable «primary» carbocation/ carbonium ion/intermediate «increased» positive inductive/electron-releasing effect of extra -R group/- $\mathrm{CH}_{3}$ /methyl «increases stability of secondary carbocation»

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IB Chemistry HL 3.4.12 Hl Carbocation Stability Questions question 1