4.8.4d HW Organic Chemistry and Spectroscopy QUESTIONS (1)

7/25/2019 4.8.4d HW Organic Chemistry and Spectroscopy QUESTIONS (1)

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4.8.4d: HW Organic chemistry and spectroscopy (52 Marks)

1. Molecule Phas the molecular formula C3H6O3.

(a)What can be deduced by the structure of Pfrom the following information?

(i) Preacts with sodium hydrogencarbonate solution to produce effervescence.(ii) Preacts with acidified potassium dichromate(VI) to form a green solution and

product Rwith the molecular formula C3H4O3.

(iii) Pand Reach react with sodium hydroxide and iodine to form a yellow precipitate.

(iv) Pdoes not react with 2,4-dinitrophenylhydrazine but Rdoes.

(v) Preacts with lithium tetrahydridoaluminate to form a compound with the formula

C3H8O2.

[7]

Name: Hand in:


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(b)The proton nmr of Preveals the following data:

Chemical shift /ppm Split of the peak

11.9 singlet

4.0 quadruplet

3.4 singlet

1.2 doublet

Use the data and the inferences you made in part (a) to identify the structure of P.

Include a description of the proton environments responsible for the chemical shifts

and explain the splitting pattern of the peaks.

[6]

(c)Pcan form a polymer. Draw two repeatsof the polymer and name the linkage present

in the polymer.

[2][Total: 15]


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2. The following reaction scheme shows some of the reactions that

(a)State the reagents and conditions for the steps shown in the reaction scheme above.

Reaction step Reagents/reactants Conditions

1

2

3

4

5

6

7

[14]


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(b)Draw the structure of H.

[1]

(c)Draw the organic products J and K.

J K

[2]

(d)Name compound C.

[1]

(e)The product formed in step 2has no optical activity. Explain why not?

[3]

(f) Draw the curly arrow mechanism for the reaction in step 2. Include relevant dipoles.

[4][Total: 25]


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3 An unknown aldehyde T, C5H10O, was analysed using different techniques.

(a) (i) Describe a chemical test that could be used to confirm that compound Tis an aldehyde.

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.......................................................................................................................................[2]

(ii) Identify the functional group formed in this chemical test.

.......................................................................................................................................[1]

(b) Describe a chemical method that could be used to confirm the presence of the carbonylgroup in compound T.

Explain how you would use the product of this test to identify compound T.

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...............................................................................................................................................[3]

(c) In a mass spectrum of compound T, determine the m/evalue of the molecular ion peak.

...............................................................................................................................................[1]

(d) There are the four possible structural isomers for the aldehyde T, C5H10O. Two structures areshown below.

C

H

isomer1

H

H

C

H

H

C

H

H

C

H

H

O

H

C C

H

isomer2

H

H

C

H

H

C

CH3

H

O

H

C

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(i) Draw the skeletal formula for structural isomer 2.

[1]

(ii) Draw the two other possible structural isomers of the aldehyde T, C5H10O.

[2]

(e) The proton n.m.r. spectrum of aldehyde Tis shown below.

12 11 10 9 8 7 6 5

chemical shift /ppm

absorptionofenergy

4 3 2 1 0

Identify aldehydeT

. Explain your reasoning.

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...............................................................................................................................................[2]

[Total: 12]

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4.8.4d HW Organic Chemistry and Spectroscopy QUESTIONS (1)

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