Organic Synthesis (A Level only) (AQA A Level Chemistry)

The following reaction sequence is missing two intermediates:

3 carbon alkene     →     K     →     L    →      4 carbon amine

What are the missing intermediate compounds, K and L?

Tartaric acid can occur naturally, for example in wine, and may be synthesised in the laboratory.

The laboratory synthesis occurs in 2 steps:

 

Which reagents could be used for this synthesis?

	Step 1	Step 2
A B C D	HCl (aq) H2SO4(aq) KCN (aq/alcoholic) HCN, NaCN (aq/alcoholic)	HCN (g) K2Cr2O7 / H2SO4 (aq) K2Cr2O7 / H2SO4 (aq) H2SO4 (aq)

What is the type of reaction taking place in each step?

	Step 1	Step 2	Step 3
A	addition	substitution	hydrogenation
B	acylation	nitration	reduction
C	substitution	oxidation	addition
D	acylation	substitution	hydrolysis

Propanone can be turned into 2-bromopropane in a three step synthesis via two intermediates:

 

                            Step 1                          Step 2                    Step 3    

propanone       →       propan-2-ol     →       propene      →       2-bromopropane

 

The reagents for each step could be:

 

	Step 1	Step 2	Step 3
A	NaBH4	Al2O3	HBr
B	K2Cr2O7 / H2SO4	Conc. NaOH	HBr
C	H2O / H2SO4	Al2O3	Br2
D	NaBH4	K2Cr2O7 / H2SO4	HBr

Butylamine can be prepared in two steps from 1-bromopropane

CH₃CH₂CH₂Br  →    X    → CH₃CH₂CH₂CH₂NH₂

What is the structural formula of X?

Propyl 4-aminobenzoate or risocaine is a local anesthetic that can be synthesised from 4-nitrobenzaldehyde via the following three step synthesis.

Which row contains the correct molecular formulae of compounds X and Y?

	Compound X	Compound Y
A B C D	C7H6NO3 C7H6NO4 C7H5NO4 C7H5NO3	C9H11NO4 C10H11NO3 C10H11NO4 C9H11NO3

Methyl 2-methyl propenoate can be synthesised from propanone via the following four step synthesis.

Which type of reaction is involved in each of the steps?

	Step 1	Step 2	Step 3	Step 4
A	Reduction	Elimination	Substitution	Esterification
B	Addition	Dehydration	Hydrolysis	Condensation
C	Addition	Substitution	Hydrolysis	Esterification
D	Substitution	Dehydration	Acid-base	Condensation

Mesalazine, C₇H₇NO₃, can be synthesised from salicylic acid, C₇H₆O₃, in a two step synthesis.

Which row shows the correct reagents for two steps involved in the synthesis of mesalazine?

	Step 1	Step 2
A	Sn + conc. HCl	Conc. HNO3 / H2SO4
B	Conc. NH3	Sn + conc. HCl
C	Conc. HNO3 / H2SO4	LiAlH4 / dry ether
D	Conc. HNO3 / H2SO4	Sn + conc. HCl

Which row contains the correct number of minimum steps to convert an aldehyde into the given compound?

	Amide	Primary amine	Dihalogenoalkane
A	2 steps	3 steps	4 steps
B	4 steps	2 steps	3 steps
C	3 steps	4 steps	2 steps
D	2 steps	4 steps	3 steps

1-chloropropane can be used to produce an amine via two different synthetic routes, direct and indirect.

Which pair of statements about the direct route and the indirect route is not correct?

	Direct route	Indirect route
A	The reaction mechanism is nucleophilic substitution	The product is butylamine
B	The reaction mixture needs to be heated under pressure	The reaction mechanism of the first step is nucleophilic substitution
C	The product is propylamine	The reagent for the second step is LiAlH4 in dry ether
D	The reagent is conc. NH3	The product is propylamine