3.1 Introduction to Organic Chemistry

Ethers are a homologous series of organic compounds containing the R−O−R functional group.

The structures and names of two ethers are shown in Figure 1.

Figure 1

Ethers can be prepared by nucleophilic substitution of haloalkanes with alkoxide ions, RO⁻.

Alkoxide ions can be prepared by reacting sodium with an alcohol. A gas is also formed.

Write an equation for the formation of methoxide ions from sodium and an alcohol.

Methoxyethane, shown in part (a), can be prepared by reacting bromoethane, CH₃CH₂Br, with methoxide ions, CH₃O⁻.

Outline the mechanism for the nucleophilic substitution of CH₃CH₂Br with CH₃O⁻ using skeletal formulae.

Your answer should include relevant charges, dipoles and the products formed.

Cisplatin is an effective intravenous anti-cancer drug. It exists in two stereoisomers cisplatin and transplatin, only cisplatin is effective as a chemotherapy treatment. Cisplatin exists as a square planar molecule with a platinum (Pd²⁺) central metal ion surrounded by two NH₃ and two Cl^- ions which act as ligands. Each ligand forms a coordinate bond with the platinum ion.

State the limitation of the cis-trans naming rules when it comes to the molecule shown in Figure 1.

This question is about saturated hydrocarbons. Compound A is shown in Figure 2.

Figure 2 

The reaction of compound A with excess chlorine forms a compound D, which has a molar mass of 175.5 g mol⁻¹.

Draw a possible structure for compound D and write the equation for its formation from compound A. Use molecular formulae in the equation.

Butenedioic acid is HOOCCH=CHCOOH. It has two stereoisomers, commonly known as malic acid and fumaric acid. Both acids are responsible for the sour taste in fruit.

The hydrocarbon propane can be reacted with chlorine to prepare 2-chloropropane, CH₃CHClCH₃, by free radical substitution.

A student named the alcohol molecule shown in Figure 1 as Z-1,4-dichlorohex-2-ene-6-ol.

Figure 1

State the errors the student has made in naming the molecule and give the correct IUPAC name.

Aspirin is an ester of salicylic acid, HOC₆H₄CO₂. Aspirin is formed when an ester bond is created between the salicylic acids OH group and ethanoic anhydride, (CH₃CO)₂O, in the presence of an acid catalyst, as shown in Figure 2. Ethanoic acid is also formed as a product.

Figure 2

The organic compounds in Figure 3 below can be termed aliphatic, alicyclic or aromatic.

Figure 3 

Each response may contain more than one letter for the questions below.

Compounds with a carbon−carbon double bond are unsaturated. Figure 1 shows an unsaturated hydrocarbon.

Figure 1

Two structural isomers of C₁₀H₁₈O are linalool and geraniol. They are unsaturated alcohols with similar chemical properties and are both used in perfumes.

The IUPAC names for both linalool and geraniol are shown in Table 1.

Table 1

Draw the skeletal formulae for these two isomeric alcohols.

The organic compounds below in Figure 2 are all made by living organisms.

Figure 2

4.125 g of compound D (from part C) is reacted with an excess of hydrogen chloride. The mixture of products contains 95% by mass of one product and 5% by mass of the other product.

Calculate the mass of each product formed.

Crude oil consists of a mixture of hydrocarbons, which can be separated by fractional distillation. The shorter hydrocarbons are more useful as fuels such as gasoline and diesel fuel, so longer hydrocarbons are often converted into shorter ones in a       process called cracking. Cracking of hydrocarbons results in the formation of shorter alkanes and alkenes.

A hydrocarbon with molecular formula C₁₂H₂₄ is cracked to form oct-1-ene and one other alkene.

Figure 1 shows the reaction mechanism by which butene reacts with hydrogen bromide, to form compound X.

Figure 1

Compound X can also be formed from the reaction of butane with bromine.

CH₃CH₂CH₂CH₃ + Br₂ → CH₃CH₂CHBrCH₃ + HBr

Initiation step:                                                                 

Propagation step:                                        

Termination step: 

Once bromobutane has formed, further substitution can occur to form a compound with empirical formula C₂H₄Br.

Draw all the structural isomers of this compound.

A chemist is analysing a collection of organic compounds. The structural formulae of these compounds are shown in Table 1 below.

Table 1

Give the IUPAC name for the compounds to complete the table.

The scientist carried out some analytical research on his collection of compounds and found that some of these compounds display isomerism.

The scientist carries out a synthetic reaction to form compound D from compound A as shown in the reaction sequence in Figure 1 below.

Figure 1

Figure 2

Another compound in the scientist’s collection of organic compounds is shown in Figure 3 below.

Figure 3

This compound is the Z isomer. Which one of the labelled bonds leads to the prefix Z in the name? Explain your answer using CIP rules.

Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are widely used as solvents for dry cleaning, as refrigerants and as propellants for aerosols. 1,1,1,2,2-pentachloro-2-fluoroethane (CFC X) is an example of such CFCs.

Figure 1

State the IUPAC names of CFC Y and Z shown in Figure 1.

Unfortunately, CFCs are largely responsible for destroying the ozone layer. In the high atmosphere, the carbon-chlorine bonds break to give chlorine free radicals. It is these radicals which break down the O₃ and destroy the ozone layer. Figure 2 below shows the mechanism for this reaction.

Figure 2

CFCs are now being replaced by less environmentally harmful compounds such as hydrofluorocarbons (HFCs). These compounds only contain hydrogen, carbon and fluorine atoms. Since they don’t contain a chlorine atom, they have no effect on the ozone layer.

An example of a HFC is a compound with molecular formula C₃H₅F₃.

Draw all the possible structural isomers of this compound.

Amines are often used in making azo-dyes and nylon apart from medicines and drugs.

Draw the skeletal formula for 4-bromo-5,6-dimethylheptan-2-amine.

This question is about the structure of organic compounds.

Draw the skeletal formula of compound X formed in Figure 1.

Figure 2 shows the displayed formula of a type of fuel known as gasoline.

Pent-1-ene (C₅H₁₀) is a member of the homologous series of alkenes. Pent-1-ene has structural isomers but no stereoisomers.

The structure of an alcohol X is shown in Figure 3.

Figure 3