OCR A LEVEL CHEMISTRY alcohol ALL QUESTIONS

1(a) Three alcohols, A, B and C, are structural isomers with the molecular formula C5H12O.


A, B and C take part in combustion reactions.


Complete the equation for the complete combustion of C5H12O.


C5H12O + ..................................................................................................................................... [2]
(b) Alcohols A, B and C are each refluxed with acidified dichromate(VI), H+/Cr2O72–.
The organic products are shown in the table below.


Complete the table to show the structures of alcohols A, B and C.



Alcohol Structure of alcohol Organic product after refluxing with H+/Cr2O72–
A




B




C No reaction




[3]




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, 2 This question is about the analysis of organic compounds.


Compounds F, G, H and I are structural isomers.


A student carries out test-tube tests on the compounds.
The student records the observations after carrying out each test.
These are shown in Table 5.1.


In Table 5.1, 2,4-dintrophenylhydrazine has been abbreviated to 2,4–DNP.


Table 5.1



Compound Test
2,4-DNP Acidified Bromine water Tollens' reagent
dichromate(VI)
reflux
F Orange solution Green solution Colourless solution Colourless solution
G Orange solution Green solution Orange solution Colourless solution
H Orange precipitate Orange solution Orange solution Colourless solution
I Orange precipitate Green solution Orange solution Silver mirror



i. Write the formula of the species causing the colours after refluxing with acidified dichromate(VI).


Green solution


Orange solution [2]




ii. The student is provided with further information about compounds F–I.


• They all have the molecular formula C5H10O.
• One of the compounds is alicyclic.
• The other compounds are unbranched.


Use this further information and the student’s observations in Table 5.1 to answer the following.


• How do the observations provide evidence for the possible functional groups in compounds F–I?
• Suggest a possible structure for each of the compounds F–I.
Show your reasoning.




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, Extra answer space if required.




[6]




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, 3(a) This question is about reactions of alcohols.


There are 4 structural isomers of C4H10O that are alcohols:
CH3CH2CH2CH2OH
CH3CH2CHOHCH3
(CH3)2CHCH2OH
(CH3)3COH


Alcohols take part in many different types of reaction, including


• elimination
• oxidation
• substitution
• esterification.


For each type of reaction, choose appropriate reagent(s) and/or catalyst, and show the organic product formed.


Elimination reaction of CH3CH2CH2CH2OH


Reagent(s) and/or catalyst




organic product


[2]




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