Acylation and nucleophilic addition-elimination

Which reagents could a student use to prepare the ester shown?

This question is about carbonyl compounds.

The three compounds below each contain a ketone and one other functional group.

Pyruvic acid
Methylglyoxal
Acetol

What is a functional group ?

A chemical test is carried out which gives a positive result for all three compounds.

Suggest the reagent and observation of this chemical test.

Reagent........

Observation........

A student is provided with three unlabelled sample tubes, containing either pyruvic acid, methylglyoxal or acetol.

The student carries out three chemical tests on each sample.

Complete the table with the expected observations, including ‘no change’ where appropriate.

Complete the flowchart for the reactions of pyruvic acid.

This question is about organic acids.

-Amino acids have the general formula RCH(NH₂)COOH.

Compound S is made of two -amino acids bonded together.

Compound S is hydrolysed into its component -amino acids.

The resulting mixture is analysed using TLC to produce a chromatogram:

The R group and the R_f value is shown for some -amino acids.

Determine the R_f values of the two -amino acids in the chromatogram.

Compound S has two possible structures.

Draw both of these structures.

This part is about compounds called -keto acids.

The equation shows the decomposition of a -keto acid.

Draw the structures of the organic products you would expect from the decomposition of the two other -keto acids below.

-Amino acids have the NH₂ group bonded to the carbon atom adjacent to the carboxylic acid group.

Suggest the difference between an -keto acid and a -keto acid.

Which compound is a secondary amide?

This question is about carboxylic acids and esters.

Short-chain carboxylic acids, such as methanoic acid, HCOOH, are soluble in water.

Explain, with a labelled diagram, how HCOOH interacts with water when it dissolves.

Ester F has the structure shown below.

What is the systematic name for this ester?

Ester F can be prepared from a carboxylic acid in two steps.

Step 1 The carboxylic acid is converted into an acyl chloride.

Step 2 The acyl chloride is converted into ester F.

Write equations for Step 1 and Step 2.

Show organic compounds as structures.

Step 1

Step 2

The repeat unit of a polyester is shown below.

Draw the structures of monomers required to form this polyester.

The compound below contains an ester and an amide group.

Draw the structures of the organic products formed by the complete alkaline hydrolysis of this compound using NaOH(aq).

Which compound reacts with ethanoyl chloride?

This question is about reactions of acrolein, H₂C=CHCHO.

Acrolein reacts with sodium cyanide in acidic conditions, NaCN(aq) / H + (aq).

Outline the reaction mechanism for this reaction, showing the intermediate and the organic product.

The structure of acrolein has been provided.

Include curly arrows and relevant dipoles.

Name this type of mechanism.

This question is about organic acids.

Table 18.1 shows the R groups in four amino acids.

Most amino acids show optical isomerism.

Explain the term optical isomerism.

Draw 3-D diagrams to show the optical isomers of alanine.

How many optical isomers does threonine have?

Ibuprofen, shown below, is used as a painkiller.

What is the molecular formula of ibuprofen?

One ibuprofen tablet contains 400 mg of ibuprofen.

Calculate the number of ibuprofen molecules in one ibuprofen tablet.

Give your answer to 3 significant figures.

Tablets based on ibuprofen and lysine are now available from pharmacies.

These tablets are claimed to act faster than ibuprofen by being absorbed into the body more quickly than ibuprofen alone.

One type of these tablets contains a salt of ibuprofen and the amino acid lysine (R = –(CH₂)₄NH₂) in a 1:1 molar proportion.

Suggest why tablets based on a salt of ibuprofen should act faster in the body than ibuprofen.

Compounds B and C, shown below, are unsaturated hydrocarbons containing nine carbon atoms.

Compound B reacts with chlorine at room temperature, but compound C requires the presence of a halogen carrier.

In both reactions, the organic compound reacts with chlorine in a 1:1 molar ratio.

Draw the structures of the organic product of each reaction.

Outline the mechanism for the reaction of compound C with chlorine.

Show the role of the halogen carrier.

Compound C can be prepared by ‘trimerisation’ of propanone using concentrated sulfuric acid as a catalyst.

Suggest an equation for this reaction, using molecular formulae.

An organic chemist is investigating compound D for possible use as a medicine.

The chemist proposes a synthesis of compound D from compound C.

The chemist develops a three-stage synthesis of compound D from compound C.

Complete the flowchart. Show structures for organic compounds.

Alcohols can be used to prepare organic compounds with different functional groups.

HO(CH₂)₄OH can be oxidised to form HOOC(CH₂)₂COOH.

State the reagents and conditions and write an equation for this oxidation.

In the equation, use [O] for the oxidising agent.

Reagents and conditions:........

Equation:

HOOC(CH₂)₂COOH is soluble in water.

Explain, using a labelled diagram, why HOOC(CH₂)₂COOH is soluble in water.

HOOC(CH₂)₂COOH and HO(CH₂)₄OH react together to form polymer E.

Draw one repeat unit of polymer E.

The functional groups should be clearly displayed.

Governments are encouraging the development of biodegradable polymers to reduce dependency on persistent plastic waste derived from fossil fuels.

Polymer E is a biodegradable polymer.

Suggest why polymer E is able to biodegrade.

This question is about organic chemistry.

This part is about two practical techniques used in organic preparations.

Complete the missing labels on the diagram and name the technique.

Name of technique:........

Draw a labelled diagram to show apparatus set up for filtration under reduced pressure (vacuum filtration).

This part is about amines.

Amine A is a liquid at room temperature and pressure.

When vaporised, 0.202 g of the amine produces 72.0 cm³ of gas at 1.00 × 10⁵ Pa and 100 °C. The¹³C NMR spectrum of amine A has 3 peaks.

Determine the molecular formula of A and suggest a possible structure for amine A.

Molecular formula of A........

Structure of A

Which chemical(s) can react with phenol?

1 Potassium hydroxide

2 Ethanoyl chloride

3 Nitric acid

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about -amino acids, RCH(NH₂)COOH.

Table 17.1 shows the R groups in four amino acids.

In the boxes, draw the organic products for the reactions of serine shown below.

What is the R_f value of serine (ser) in solvent W?

Analyse the chromatograms to identify the unknown amino acid.

Explain your reasoning.

Name of unknown amino acid........

Explanation........

This question is about reaction mechanisms.

Chemists use curly arrows in reaction mechanisms.

What does a curly arrow show in a reaction mechanism?

Draw structures to show the products in the reaction mechanism below.

Use the mechanism in (ii) to explain what is meant by heterolytic fission.

An incomplete reaction mechanism is shown below.

What is the role of OH − in this mechanism?

Which compound is a secondary amide?

This question is about aromatic carboxylic acids and their derivatives.

The concentration of ester K in the cosmetic product is 9.13 × 10⁻² g dm⁻³.

Using the results, calculate the concentration, in mol dm⁻³, of ester M in the cosmetic product.

Give your answer to two significant figures.

concentration of ester M =........ mol dm⁻³

This question is about two compounds used in medicine.

Cis-platin, PtCl₂(NH₃)₂, is a complex of platinum which is used in cancer treatment.

What is the oxidation number of platinum in cis-platin?

Cis-platin is prepared in a ligand substitution reaction which takes place in multiple steps.

The equation for the final step forming cis-platin is shown below.

cis-platin

In the box, outline the mechanism for the formation of cis-platin from [PtCl₃(NH₃)]^–. Use curly arrows and lone pairs where appropriate.

cis-platin

Paracetamol is a solid organic compound used in tablets as a painkiller.

Name the functional groups present in paracetamol.

Equal amounts of the four compounds are added to the same volume of water.

Which compound would produce the most acidic solution?

A CH₃CONH₂

B CH₃COOH

C CH₃COOCH₃

D CH₃COCl

Which reagents could be used to prepare CH₃CH₂CONHCH₃?

A CH₃CH₂COCl + CH₃NH₂

B CH₃CH₂CONH₂ + CH₃Br

C CH₃CH₂COONa + CH₃NH₂

D CH₃CH₂COCH₃ + NH₃