Edexcel A-Level Chemistry A2 20.3 Knowledge of Organic Chemistry Contained Given in This Specification to Solve Problems Such As I Predicting the Properties Questions

Practise Edexcel IAL Chemistry 20.3 by planning unfamiliar routes with functional-group tests, named reagents, essential conditions and intermediate structures.

Exam points

Plan up to four synthesis steps with reagents, conditions and intermediate structures.
Use functional-group tests to predict observations with bromine water, PCl5 or Brady's reagent.
Evaluate synthesis choices by step count, purification, reagent cost, toxicity or yield.

[Maximum number: 7]

This question is about benzene and some of its compounds.

Devise a synthesis to convert bromobenzene into benzamide.

Include reagents, conditions and the structures of the intermediate compounds.

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An answer that makes reference to the following points:

- (M1) reagent for step 1 - magnesium and (dry) ether

(1) (reacting with bromobenzene)

- (M2) first intermediate - phenyl magnesium bromide

(1)

- (M3) reagent for step 2 - phenyl magnesium bromide with carbon dioxide / $\mathrm{CO}_{2}$ and (followed by hydrolysis with) dilute acid / $\mathrm{H}^{+}$ or methanal and dilute acid / $\mathrm{H}^{+}$ then oxidation

(1)

- (M4) second intermediate - benzoic acid

(1)

- (M5) reagent for step 3 - phosphorus(V) chloride /

(1) $\mathrm{PCl}_{5}$

(1)

- (M6) third intermediate - benzoyl chloride

-(M7) reagent for step 4 - ammonia / $\mathrm{NH}_{3}$ added to an

(1) acyl chloride

COMMENT Allow the use of ammonia with benzoic acid if there is clear evidence of the ammonium salt being dehydrated. M5 to M7 can then be awarded, otherwise the do not award applies

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Allow displayed / structural / skeletal formulae or any combination of these

Ignore any references to heat/ incorrect inorganic products

Examples of structures of intermediates:

Do not award

Allow (1) for M3 for the acid hydrolysis of benzonitrile

Allow thionyl chloride/ $\mathrm{SOCl}_{2}$

Do not award dilute ammonia or ammonia added to benzoic acid

M4 to M7 from scheme above can be awarded from benzoic acid however produced

(7)

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Edexcel A-Level Chemistry A2 20.3 Knowledge of Organic Chemistry Contained Given in This Specification to Solve Problems Such As I Predicting the Properties Questions question 1