The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions. - Both compounds react with sodium metal, and both decolorise bromine water. - Compound V forms a yellow precipitate with alkaline aqueous iodine, whereas compound W does not. - When reacted with cold KMnO4(aq), both V and W produce the same neutral compound X, C4H8O3. - Both V and W exist as pairs of stereoisomers. (a) Suggest which functional groups are responsible for the reactions with (i) sodium (ii) bromine water (iii) alkaline aqueous iodine. (b) Suggest structures for V and W. (c) State the type of stereoisomerism shown by compound V and draw the structures of the stereoisomers. type of stereoisomerism structures of stereoisomers (d) Suggest the structure of the neutral compound X.

A-Level CIE Chemistry 7.9 Organic Mechanisms (A Level only): The two compounds V and W are is

The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions - CIE - A-Level Chemistry - Question 5 - 2014 - Paper 1

Question 5

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The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions. - Both compounds react with sodium metal, a... show full transcript

Worked Solution & Example Answer:The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions - CIE - A-Level Chemistry - Question 5 - 2014 - Paper 1

Step 1

Suggest which functional groups are responsible for the reactions with sodium (i)

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Answer

The functional group responsible for the reaction with sodium is the hydroxyl group, -OH. This group allows for the formation of alkoxides when sodium reacts.

Step 2

Suggest which functional groups are responsible for the reactions with bromine water (ii)

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Answer

The functional group responsible for the reaction with bromine water is the alkene functional group. The presence of double bonds allows for the addition reaction with bromine, which leads to decolorization.

Step 3

Suggest which functional groups are responsible for the reactions with alkaline aqueous iodine (iii)

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Answer

The functional groups involved in the reaction with alkaline aqueous iodine are the -CHO (aldehyde) or -C=O (ketone) groups. These groups can react to form a yellow precipitate.

Step 4

Suggest structures for V and W.

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Answer

The structure for compound V is CH3CH(OH)CH=CH2. The structure for compound W is CH3CH=CHCHO.

Step 5

State the type of stereoisomerism shown by compound V and draw the structures of the stereoisomers.

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Answer

Compound V shows optical isomerism.

Structure 1:

   CH3
    | 
H2C=CH 
    | 
   OH

Structure 2:

   CH3
    | 
H2C=CH 
    | 
   H

Step 6

Suggest the structure of the neutral compound X.

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Answer

The structure of the neutral compound X can be represented as:

   HO      O
    |    // 
H2C-C-CH2
    |  \
   OH  H

Or alternatively,

   CH3
    | 
H2C-C-CHO
    | 
   OH

The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions - CIE - A-Level Chemistry - Question 5 - 2014 - Paper 1

Worked Solution & Example Answer:The two compounds V and W are isomers with the molecular formula C4H8O, and show the following properties and reactions - CIE - A-Level Chemistry - Question 5 - 2014 - Paper 1

Suggest which functional groups are responsible for the reactions with sodium (i)

Suggest which functional groups are responsible for the reactions with bromine water (ii)

Suggest which functional groups are responsible for the reactions with alkaline aqueous iodine (iii)

Suggest structures for V and W.

State the type of stereoisomerism shown by compound V and draw the structures of the stereoisomers.

Suggest the structure of the neutral compound X.

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