10.2 Functional Group Chemistry

Compounds W, X and Y are all carbohydrates with X and Y each containing five carbons. Compound W and a byproduct, compound Z, are formed from the reaction between compound X and Y. Compound X can be oxidised by the reaction with acidified potassium dichromate to give compound Y.

2.754 g of compound Y contains 0.027 moles.

Using the information given, state the name of compound Y and justify your answer.

Deduce the structural formula of compound W and explain how compound Z is formed in the reaction.

Compound X will oxidise to compound Y if allowed to fully oxidise. Explain how a student could stop the full oxidation of compound X. 

Deduce the formula of an isomer of compound X that will not react with acidified potassium dichromate, H⁺ / K₂Cr₂O₇.

Ester A is responsible for a raspberry scent and has the molecular formula C₅H₁₀O₂. Ester A can be produced by the reaction of an acid with a branched primary alcohol. Identify the acid and alcohol used to prepare ester A. 

State the IUPAC name and draw the structural formula of ester A.

The following scheme shows reactions of Compound A. 

Reaction 1 forms an alcohol when reacted with concentrated sulfuric acid, H₂SO₄ and steam. 

Butan-2-ol can also be directly formed from a halogenoalkane. 

Identify the structure of the repeating unit of poly(but-2-ene).

Compound A reacts with hydrogen bromide to form compound C. A student suggested a possible formula of compound C is CH₂(Br)CH₂CH₂CH₃.

State whether the student is correct and justify your answer. 

A student investigated two reactions of phenylethene, C₆H₅CHCH₂. First she reacted phenylethene with excess bromine at room temperature to form Compound A. She then added aluminium bromide, AlBr₃ to the reaction mixture to form Compound B.

Draw the structure of Compound A and identify one the isomers of C₈H₇Br₃ formed in the second reaction. 

2,4,6-trinitrotoluene (TNT) can be manufactured from benzene as shown below.

5.00 g of benzene was used in step 1. Use section 6 of the data booklet to determine the theoretical yield for step 1.

Step 2 involves the formation of a nitronium ion for the nitration of Toluene, as shown in the following equation:

HNO₃ + 2H₂SO₄ → NO₂⁺ + 2HSO₄^- + H₃O⁺

Explain why the product of step 2 is most likely to have the nitro group bonded to the second or fourth carbon atom. 

Phenylethene, C₆H₅CH=CH₂, is a substance that can be polymerized. Draw a section of the polymer showing three repeat units and name the resulting polymer.

A solution of bromine in hexane reacts with phenylethene.

Phenylethene can undergo catalytic hydrogenation. Draw the displayed structure of the product of the reaction, name the product, and state the reaction conditions.

2-phenylethanol, C₆H₅CH₂CH₂OH, is a colourless liquid with a pleasant floral smell widely found in nature. Under the right conditions, it can be made from phenylethene in a two-step reaction using sulfuric acid.

State the reaction conditions and write balanced equations for the two-step reactions.

Alkanes are generally unreactive and do not react with acids, bases, or with oxidising or reducing agents. However, they will react with halogens under suitable conditions, to form halogenoalkanes.

Methane reacts with chlorine in this way to form chloromethane.

The reaction described in part (a) consists of three steps. In the first step, the Cl-Cl bond is broken to form two chlorine free radicals.

Give the equations for each step of the reaction between methane and chlorine as described in part (a).

Label each equation with the name of the correct step. You only need to provide one equation for the final step.

Chlorofluorocarbons (CFCs) are organic compounds consisting of carbon, chlorine, and fluorine atoms. They are believed to destroy the ozone layer in a similar reaction to the one described in part (a).

Ozone can be broken down by radicals formed in the atmosphere. The ozone layer is important to protecting the Earth from harmful exposure to ultraviolet light.
Without this ozone layer, life on Earth would be very different.

An example of a CFC which can damage the ozone layer is CCl₃F.

Two isomeric compounds are shown below in Figure 1.

 Figure 1

Compound B, CH₃CH(CH₃)CH(OH)COOH, can be oxidized into compound C.

The same reaction in part (b) can be used to oxidize ethanol into ethanal or ethanoic acid, depending on the reaction conditions.

Outline how the reaction conditions can be changed to produce ethanal or ethanoic acid.

Under the right conditions, the two molecules of compound A can react together to produce a dimer.

Benzene, C₆H₆, typically undergoes electrophilic substitution

Benzene is a highly unsaturated molecule.

An aromatic organic compound with molecular formula C₇H₈ reacts with bromine in the presence of UV light to produce a compound with molecular formula C₇H₇

The same aromatic compound in part (c), C₇H₈, can be reacted with concentrated  nitric acid to produce a multiple substituted product, with molecular formula C₇H₅N₃O₆.