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CHEMISTRY, M8 2023 HSC 36

An organic reaction pathway involving compounds and is shown in the flow chart.
 

The molar mass of is 84.156 g mol.

A chemist obtained some spectral data for the compounds as shown.
 

 
 δ
 
 

Identify the functional group present in each of compounds to and draw the structure of each compound. Justify your answer with reference to the information provided.  (9 marks) 

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Compound : Alkene
 

Compound : Secondary alcohol
 

Compound : Ketone
 

Reasoning as follows:

→ Compound is able to undergo an addition reaction to add water across a bond    Alkene

→ Compound is the product of the above hydration reaction and is therefore an alcohol.

→ The spectrum of Compound confirms it is an alkene (132 ppm peak corresponding to the atoms). 3 spectrum peaks indicate 3 carbon environments. The molar mass of compound is 84.156 g mol which suggests symmetry within the molecule.

→ The Infrared Spectrum of Compound has a broad peak at approximately 3400 cm. This indicates the presence of an hydroxyl group and confirms is an alcohol.

→ Compound is produced by the oxidation of Compound with acidified potassium permanganate.

→ Compound is a carboxylic acid if is a primary alcohol or a ketone if is a secondary alcohol.

→ Since the spectrum of does not show any peaks between 9.0 − 13.0 ppm, it cannot be a carboxylic acid. Compound is therefore a ketone and Compound is a secondary alcohol.

→ The spectrum shows 5 peaks 5 hydrogen environments.

→ Chemical shift and splitting patterns information indicate:

1.01 ppm – 1.05 ppm: (next to a )

1.65 ppm: (with multiple neighbouring hydrogens)

2.42 ppm: (next to the ketone and a )

2.46 ppm: (next to the ketone and a )

Show Worked Solution

Compound : Alkene
 

Compound : Secondary alcohol
 

Compound : Ketone
 

Reasoning as follows:

→ Compound is able to undergo an addition reaction to add water across a bond    Alkene

→ Compound is the product of the above hydration reaction and is therefore an alcohol.

→ The spectrum of Compound confirms it is an alkene (132 ppm peak corresponding to the atoms). 3 spectrum peaks indicate 3 carbon environments. The molar mass of compound is 84.156 g mol which suggests symmetry within the molecule.

→ The Infrared Spectrum of Compound has a broad peak at approximately 3400 cm. This indicates the presence of an hydroxyl group and confirms is an alcohol.

→ Compound is produced by the oxidation of Compound with acidified potassium permanganate.

→ Compound is a carboxylic acid if is a primary alcohol or a ketone if is a secondary alcohol.

→ Since the spectrum of does not show any peaks between 9.0 − 13.0 ppm, it cannot be a carboxylic acid. Compound is therefore a ketone and Compound is a secondary alcohol.

→ The spectrum shows 5 peaks 5 hydrogen environments.

→ Chemical shift and splitting patterns information indicate:

1.01 ppm – 1.05 ppm: (next to a )

1.65 ppm: (with multiple neighbouring hydrogens)

2.42 ppm: (next to the ketone and a )

2.46 ppm: (next to the ketone and a )

CHEMISTRY, M8 2019 HSC 19 MC

Compound shows three signals in its spectrum.

Treatment of with hot acidified potassium permanganate produces a compound . Compound turns blue litmus red.

Compound produces compound upon reaction with hot concentrated sulfuric acid.

Which of the following correctly identifies compounds , and ?
 

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Show Worked Solution

→ The given information suggests that compound is a carboxylic acid because it is produced through the oxidation of compound , a primary alcohol, with an oxidising agent and turns blue litmus red.

→ The treatment of compound with hot concentrated sulfuric acid results in a dehydration reaction.

→ In summary, the information provided suggests that compound is a carboxylic acid and compound is a primary alcohol, and that the treatment of compound with hot concentrated sulfuric acid results in a dehydration reaction.


♦♦♦ Mean mark 33%.