An Introduction to AS Level Organic Chemistry (CIE AS Chemistry)

A chemist is analysing a collection of organic compounds.

Some of these compounds are shown in Table 1.1.

Compound	IUPAC name	Displayed formula	Skeletal formula
1	Z-2-chloro-but-2-en-1-ol
2	2-chloropropanal
3
4

  

Complete Table 1.1.

State the empirical formula of compound 1.

Explain why compound 1 exists as two stereoisomers, but compound 4 does not.

Compounds 2 and 3 both exhibit the same type of isomerism.

Explain how the concept of hybridisation can be used to explain the triple bond present in propyne.

Consider the molecule shown in Fig. 2.1 which contains both sigma and pi bonds.

State the number of carbon atoms that exhibit sp² hybridisation in this molecule.

Complete Table 2.1 to show the hybridisation of the nitrogen atoms in NF₄⁺, N₂H₂ and N₂H₄.

This question is about the structure and reactions of organic compounds.

Fig. 3.1 shows the displayed formula of a type of fuel known as gasoline. 

The gasoline shown in Fig. 3.1 can react with chlorine in the presence of UV light to form various chlorinated products.

There are two possible reactions of 1-bromopropane with sodium hydroxide.

Fig. 3.2 shows the mechanism for the reaction of aqueous sodium hydroxide with 1-bromopropane.

Pentanal reacts with hydrogen cyanide ions to form 2-hydroxyhexanenitrile as outlined in Fig. 3.3. 

There are many different chemicals with the same molecular formulae but different arrangements of atoms in three-dimensional space. 

C₄H₈ exists as several isomers.

Draw the displayed formulae of the following compounds and, where appropriate, identify any chiral centres. 

• 2,4-dimethylhexan-3-ol
• 2,4-dimethyl-3-chloropentane
• 2-aminobutane

1-bromopropan-1-ol exhibits optical isomerism.

Draw 3D representations of the two enantiomers of 1-bromopropan-1-ol.

Hybridisation of the s and p orbitals can be used to explain the shapes observed in molecules.

Explain why cyclohexane C₆H₁₂ has a puckered, non-planar shape by making reference to the C–C–C bond angles and the type of hybridisation of carbon in the molecule. 

Urea, CO(NH₂)₂, is present in solution in animal urine. 

Describe the hybridisation of C and N in the molecule, giving approximate bond angles.

Describe the hybridisation of the carbon atom in methane and explain how the concept of hybridisation can be used to explain the shape of the methane molecule.

A molecule of ethanol is shown in Fig. 5.1.

Deduce the hybridisation of the carbon atom marked in the diagram below.

This question is about organic compounds found in living organisms.

Terpenes are a class of organic compounds widely used as fragrances in products such as perfumes. For example, one of the simpler terpenes, nerol is found in many essential oils such as lemongrass and hops. The structure of nerol is shown in Fig 1.1.

Explain whether nerol shows geometrical (cis-trans) and optical isomerism. In your answer, identify any relevant points in the structure of nerol.

Two structural isomers of nerol are linalool and geraniol. They are unsaturated alcohols with similar chemical properties that are both used in perfumes. 

The IUPAC names for both linalool and geraniol are shown in Table 1.1.

Draw the skeletal formulae for these two isomeric alcohols.

The organic compounds in Fig 2.1 are all made by living organisms.

Fig. 2.1

Compounds B, C, D and E all show the same type of isomerism.

Circle the functional group(s) responsible for this isomerism on the molecules in Fig 2.1.

Compound D reacts with hydrogen chloride to form two products.

Name the type of reaction occurring when compound E reacts to form methanol and deca-2,4-dienoic acid.

Ibuprofen is a common non-steroidal anti-inflammatory drug (NSAID). It contains a benzene ring and a carboxylic acid at the end of one of the branches as shown in Fig 3.1.

Fig 3.1

Deduce the number of sigma (σ) and pi (π) bonds in ibuprofen.

The ibuprofen molecule contains both sp² and sp³ hybridised carbon atoms.

State the number of sp² and sp³ hybridised carbon atoms in a molecule of ibuprofen.

Explain why the benzene ring is a planar hexagon.