Study the reaction scheme and answer the questions that follow - Leaving Cert Chemistry - Question 8 - 2012
Question 8
Study the reaction scheme and answer the questions that follow.
- Give the systematic (IUPAC) name for (i) the alcohol A, (ii) the ester B.
- Alcohol A and propan-... show full transcript
Worked Solution & Example Answer:Study the reaction scheme and answer the questions that follow - Leaving Cert Chemistry - Question 8 - 2012
Step 1
Give the systematic (IUPAC) name for (i) the alcohol A, (ii) the ester B.
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Answer
The IUPAC name for the alcohol A is propan-2-ol (or 2-propanol), and the IUPAC name for the ester B is propyl methanoate (or methanoic acid propyl ester).
Step 2
Alcohol A and propan-1-ol are structural isomers. Explain.
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Structural isomers are compounds that have the same molecular formula but differ in the arrangement of atoms, resulting in different structural formulas. In this case, alcohol A (propan-2-ol) and propan-1-ol both have the formula C3H8O but differ in the position of the hydroxyl (–OH) group.
Step 3
What is the structural difference between a primary alcohol and a secondary alcohol?
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A primary alcohol has the hydroxyl (-OH) group attached to a carbon atom that is connected to only one other carbon (e.g., in propan-1-ol), while a secondary alcohol has the hydroxyl group attached to a carbon atom that is bonded to two other carbons (e.g., in propan-2-ol).
Step 4
Identify another pair of structural isomers from the reaction scheme.
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Another pair of structural isomers from the reaction scheme is propanal and propanone, which differ in the placement of the carbonyl (C=O) group.
Step 5
Identify a compound in the scheme whose carbon atoms are in tetrahedral geometry.
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In the reaction scheme, the compound propan-2-ol has a carbon atom in tetrahedral geometry due to the presence of four substituents around it.
Step 6
Name the reagent and catalyst used to bring about the conversions labelled R.
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The reagent used for the conversions labelled R is hydrogen, and the catalyst can be nickel, palladium, or platinum.
Step 7
Propyl alcohol is oxidised by Fehling's reagent. Describe how this reaction is carried out.
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The oxidation of propyl alcohol using Fehling's reagent involves mixing Fehling's solution A and B, heating the mixture, and adding the alcohol to be oxidised. The solution will turn from blue to a brick-red precipitate of copper(I) oxide (Cu2O) as the alcohol is oxidised.
Step 8
Why does propanone not react with Fehling's reagent?
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Propanone does not react with Fehling's reagent because it is a ketone, and ketones are typically not easily oxidised by Fehling's reagent, which is a reducing agent.
Step 9
Which compound in the scheme would you expect to have a fruity odour?
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The compound expected to have a fruity odour is the ester B, propyl methanoate, which is known for its characteristic scent similar to fruits.
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