Naming organic compounds

Which compound is alicyclic and unsaturated?

The skeletal structure of a medicinal drug is shown below.

How many hydrogen atoms are in its molecular formula?

This question is about hydrocarbons with six carbon atoms.

Compound A is a hydrocarbon:

Compound A

What is the systematic name of compound A ?

The table below shows incomplete information about two hydrocarbons.

Complete the table.

Compound B, CH₃CH=C(CH₃)CH₂CH₃, exists as E and Z stereoisomers.

Draw the structures of the E and Z stereoisomers of compound B.

Explain why compound B can form E and Z stereoisomers.

Hexane, C₆H₁₄, is used as a fuel.

1.0 mol of hexane is mixed with 6.0 mol of oxygen and combusted.

Construct an equation for the incomplete combustion of 1.0 mol of hexane with 6.0 mol of oxygen.

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 different compounds that each contain O and H atoms covalently bonded together.

The alcohol 2,3‑dimethylhexan‑1‑ol has the molecular formula C₈H₁₈O.

Draw the skeletal formula of 2,3‑dimethylhexan‑1‑ol.

What is the number of H atoms in 8.45 g of 2,3‑dimethylhexan‑1‑ol?

Give your answer to 3 significant figures and in standard form.

Why does paracetamol not react with Na₂CO₃(aq)?

The student uses the reaction of nuromol tablets with Na₂CO₃(aq) to determine the mass of ibuprofen and the mass of paracetomol in one nuromol tablet.

The student’s method is outlined below.

• Weigh four nuromol tablets.

• Add the tablets to an excess of aqueous sodium carbonate.

• Collect the gas produced and measure its volume.

Results Mass of four nuromol tablets = 2.80 g Volume of gas collected at RTP = 48.0 cm³

Assume that ibuprofen is the only compound in nuromol tablets that reacts with Na₂CO₃(aq).

Determine the mass of ibuprofen and the mass of paracetomol, in mg, in one nuromol tablet.

Barium hydroxide, Ba(OH)₂, is an alkali. A student is supplied with a solution of Ba(OH)₂ with a concentration of 46.80 g dm^–3 at 25 °C.

The student dilutes 20.0 cm³ of this solution of Ba(OH)₂ with water and the solution is made up to 100.0 cm³ at 25 °C.

Calculate the pH of the diluted solution of Ba(OH)₂ at 25 °C.

Give your answer to 2 decimal places.

Which hydrocarbons are unsaturated?

Which hydrocarbons are alicyclic?

Which hydrocarbons have the general formula C_nH_2n?

What is the systematic name of hydrocarbon C ?

Explain why hydrocarbon D is a Z-stereoisomer.

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).

Propyne, CH₃C≡CH, is a member of the alkynes homologous series with the C≡C functional group.

What is the general formula of the alkynes?

A C_nH_2n–4

B C_nH_2n–2

C C_nH_2n

D C_nH_2n+2

Oxymetazoline, shown below, is used as a decongestant in the treatment of colds.

How many H atoms are in one molecule of oxymetazoline?

A 23

B 24

C 25

D 26

What is the systematic name for the compound below?

A 3,5-dimethylocta-1,3,6-triene

B 3,5-dimethylocta-2,5,7-triene

C 4,6-dimethylocta-1,3,6-triene

D 4,6-dimethylocta-2,5,7-triene

Which compound(s) is/are aliphatic?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

This question is about -amino acids.

The general formula of an -amino acid is RCH(NH₂)COOH.

Most -amino acids show optical isomerism.

Explain the term optical isomerism.

The -amino acid valine has the R group of –CH(CH₃)₂.

What is the systematic name of valine?

Draw diagrams to show 3D structures of the optical isomers of valine.

How many optical isomers are possible for compound E ?

A student hydrolyses compound E with dilute hydrochloric acid, HC l (aq).

Draw the structures of the organic products formed by this hydrolysis.

This question is about unsaturated hydrocarbons.

What is the systematic name of hydrocarbon A ?

Compounds B and C are branched hydrocarbons that are structural isomers of C₆H₁₂.

Compounds B and C both have stereoisomers.

• Compound B has cis and trans isomers but does not have optical isomers.

• Compound C has optical isomers but does not have cis and trans isomers.

What is meant by the term structural isomers ?

What is meant by the term stereoisomers ?

Draw structures for the cis and trans isomers of the branched hydrocarbon B.

Draw 3D structures for the optical isomers of compound C.

Compounds D and E are two more structural isomers of C₆H₁₂.

Compounds D and E do not show stereoisomerism.

Table 16.1 shows NMR and infrared (IR) spectral data for D and E.

Draw the structures of D and E and explain how the spectral data in Table 16.1 provides evidence for the structures.

Draw the structures of the products you would expect from the ozonolysis of the two compounds below.

This question is about organic synthesis.

Prenal, shown below, is used in the synthesis of some pharmaceuticals.

What is the systematic name for prenal?

* A student intends to synthesise compound A using the two-stage route below.

(chloromethyl)benzene Compound A

Plan a two-stage synthesis to prepare 5.44 g of compound A starting from (chloromethyl)benzene, C₆H₅CH₂Cl. Assume that the overall percentage yield of compound A from (chloromethyl)benzene is 25%.

In your answer, include the mass of C₆H₅CH₂Cl required, reagents, and equations where appropriate.

Purification details are not required.

What is the name of the compound below?

H₃C CH₂CH₃

A E-3-bromopent-2-ene

B E-3-bromopent-3-ene

C Z-3-bromopent-2-ene

D Z-3-bromopent-3-ene

What is the structural formula of ethyl 3-methylbutanoate?

A CH₃CH₂COOCH₂CH₂CH(CH₃)₂

B CH₃CH₂COOCH(CH₃)CH₂CH₃

C CH₃CH₂CH(CH₃)COOCH₂CH₃

D (CH₃)₂CHCH₂COOCH₂CH₃

What is the number of alicyclic structural isomers of C₅H₁₀?

A 3

B 4

C 5

D 6

What is the molecular formula of the steroid molecule below?

Hydrocarbon A can be reacted with bromine in the presence of ultraviolet radiation to prepare (CH₃)₃CCHBrCH₃.

What is the systematic name for (CH₃)₃CCHBrCH₃?

(CH₃)₃CCHBrCH₃has stereoisomers.

Explain the term stereoisomers and name this type of stereoisomerism.

Explanation:........

Type of stereoisomerism:........

Draw 3D diagrams for the stereoisomers of (CH₃)₃CCHBrCH₃.

Complete the table to show the mechanism for the reaction of hydrocarbon A with Br₂ to form (CH₃)₃CCHBrCH₃.

Use skeletal formulae for all organic compounds. Use ‘dots’ (●) to show the position of unpaired electrons.

State two limitations of using radical substitution in organic synthesis.

The carbonyl compounds, F and G, shown below, contribute to the flavour of coffee.

Compound F is a member of a homologous series.

Explain the term homologous series.

Predict the molecular formula for the member of this homologous series containing 24 carbon atoms.

Describe suitable chemical tests, with observations, that would confirm the presence of the functional groups in F and G.

Explain why the mechanism in (c)(i) involves heterolytic fission.

This question is about esters.

The structure of ester A is shown below.

What is the systematic name of ester A ?

Name the type of reactions of ester A shown in (ii).

A polyester is formed from 200 molecules of 4-hydroxybenzoic acid.

What is the relative molecular mass, M_r, of the polyester?

M_r =........ g mol⁻¹

* A student intends to synthesise ester C.

Plan a two-stage synthesis to prepare 12.75 g of ester C starting from 2-methylpropanal, (CH₃)₂CHCHO. Assume the overall percentage yield of ester C from 2-methylpropanal is 40%.

In your answer include the mass of 2-methylpropanal required, reagents, conditions and equations where appropriate.

Purification details are not required.

Which structure represents an alicyclic compound?

This question is about reactions of organic compounds containing carbon, hydrogen and oxygen.

A chemist investigates two reactions of alcohol A, shown below.

What is the systematic name of alcohol A ?

What is the structural formula of alcohol A ?

The chemist heats alcohol A with an acid catalyst to form a mixture containing alkenes.

Draw the structures of the two alkenes formed in this reaction.

The chemist heats alcohol A with sodium chloride and sulfuric acid.

Construct a balanced equation for this reaction. Show structures for the organic compounds in your equation.

A student carries out two experiments in the laboratory based on succinic acid (butanedioic acid), (CH₂COOH)₂.

Succinic acid is esterified by ethanol, C₂H₅OH, in the presence of an acid catalyst to form an equilibrium mixture.

The equilibrium constant, K_c, for this equilibrium can be calculated using the amounts, in moles, of the components in the equilibrium mixture, using expression 5.1.

A student carries out an experiment to determine the value of K_c for this equilibrium.

• The student mixes together 0.0500 mol of succinic acid and 0.150 mol of ethanol, with a small amount of an acid catalyst.

• The mixture is allowed to reach equilibrium.

• The student determines that 0.0200 mol of succinic acid are present in the equilibrium mixture.

Which technique could be used to determine the equilibrium amount of succinic acid?

Write the equation for the equilibrium reaction that takes place.

Draw the skeletal formula of the ester present in the equilibrium mixture.

K_c is the equilibrium constant in terms of equilibrium concentrations.

Why can expression 5.1 be used to calculate K_c for this equilibrium?

Calculate the value of K_c for this reaction.

Show your working.

This question is about organic reactions.

Give the systematic name for compound A.

What type of reaction has taken place?

A similar reaction takes place when propanone, (CH₃)₂CO, is mixed with OH^–(aq) ions.

Draw the structure of the organic product of this reaction.

* Many organic reactions use electrophiles as reagents.

Explain the role of electrophiles in organic chemistry.

Your answer should include one reaction of an aliphatic compound and one reaction of an

aromatic compound, including relevant mechanisms.

How can the molecule below be described?

A Aromatic and alicyclic

B Aliphatic and unsaturated

C Aromatic and unsaturated

D Alicyclic and saturated

What is the molecular formula of the compound below?

This question is about unsaturated hydrocarbons.

Compound A and compound B are isomers.

Compound A has a lower melting point than compound B.

Suggest why.

Compound C, CH₃CH₂CH=CHCH₂CH₂OH, exists as cis and trans stereoisomers.

Name compound C.

Define the term stereoisomers.

Draw the structures of the cis and trans stereoisomers of compound C.

The C=C group in an alkene contains a -bond.

Complete the diagram below to show how p-orbitals are involved in the formation of a -bond.

Compound D, shown below, reacts with hydrogen bromide by electrophilic addition. A mixture of two organic compounds, E and F, is formed.

compound D

Suggest how an HBr molecule can act as an electrophile.

Draw the structures of the two organic compounds E and F.

Outline the mechanism of the reaction between compound D and hydrogen bromide to form either compound E or compound F.

Include curly arrows and relevant dipoles.

Which of E or F is the major organic product?

Explain your answer.

Major organic product........

Explanation........

Myrcene, C₁₀H₁₆, is a naturally occurring hydrocarbon containing more than one carbon-carbon double bond.

Reaction of 204 mg of myrcene with hydrogen gas produces a saturated alkane.

Calculate the volume of hydrogen gas, in cm³ and measured at RTP, needed for this reaction.

Show your working.

-Carotene is a naturally occurring unsaturated hydrocarbon found in carrots. A -carotene molecule contains 40 carbon atoms, has two rings, and a branched chain.

0.0200 mol of -carotene reacts with 5.28 dm³ of hydrogen gas to form a saturated hydrocarbon.

Using molecular formulae, construct a balanced equation for this reaction.

Include relevant calculations and reasoning.

Equation........

This question is about alcohols.

Construct an equation for the complete combustion of an unsaturated alcohol with 5 carbon atoms.

Many alcohols, including ethanol, are soluble in water.

Explain, with the aid of a diagram, why ethanol is soluble in water.

Include relevant dipoles and lone pairs.

The solubility of hexan-1-ol and hexane-1,6-diol in water is shown below in Table 19.1

Explain the difference in solubility of hexan-1-ol and hexane-1,6-diol.

Alcohols are important in organic synthesis and can be formed by the reduction of carbonyl compounds.

Complete the flowchart by filling in each box.

What is the name of compound K ?

Butan-1-ol can be oxidised to form two different organic products, depending on the reaction conditions used.

Describe both oxidation reactions of butan-1-ol.

For each reaction include

• the structure of the organic product

• a balanced equation

• the essential reaction conditions.

In your equations you may use [O] to represent the oxidising agent.