9701 · 16.1
Alcohols flashcards
Revision flashcards for Cambridge 9701 Alcohols (syllabus 16.1). Flip, recall, then mark a real past-paper question.
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What is the functional group of an alcohol?
The hydroxyl group, –OH.
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How is a primary (1°) alcohol defined?
The carbon atom bonded to the –OH group is attached to only one other alkyl group (or no alkyl groups, as in methanol).
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How is a secondary (2°) alcohol defined?
The carbon atom bonded to the –OH group is attached to two other alkyl groups.
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How is a tertiary (3°) alcohol defined?
The carbon atom bonded to the –OH group is attached to three other alkyl groups.
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What are the reagents and conditions for oxidising a primary alcohol to an aldehyde?
Reagent: Acidified potassium dichromate(VI), $K_2Cr_2O_7/H^+$. Conditions: Gentle heating and immediate distillation of the product.
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What are the reagents and conditions for oxidising a primary alcohol to a carboxylic acid?
Reagent: Acidified potassium dichromate(VI), $K_2Cr_2O_7/H^+$. Conditions: Heating under reflux.
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What is the observable colour change when an alcohol is successfully oxidised with acidified dichromate(VI)?
The solution turns from orange (due to the $Cr_2O_7^{2-}$ ion) to green (due to the $Cr^{3+}$ ion).
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What is the product of oxidising a secondary alcohol like propan-2-ol?
A ketone. Propan-2-ol oxidises to propanone.
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Why do tertiary alcohols resist oxidation by acidified dichromate(VI)?
The carbon atom bonded to the –OH group has no hydrogen atoms attached. Oxidation requires the removal of a hydrogen atom from this carbon, which is not possible without breaking a C-C bond.
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What are the conditions for esterification?
Heating a mixture of an alcohol and a carboxylic acid with a strong acid catalyst, typically concentrated sulfuric acid.
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What are the products of the dehydration of an alcohol?
An alkene and water.
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What reagent is used for the dehydration of an alcohol?
A concentrated acid catalyst, such as concentrated sulfuric acid ($H_2SO_4$) or concentrated phosphoric acid ($H_3PO_4$), with heating.