Ch248 - Chemistry Past Papers University of Warwick 2016 series PDF

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Chemistry Past Papers University of Warwick 2016 series...

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CH2CHE

UNIVERSITY OF WARWICK SECOND YEAR EXAMINATIONS: SUMMER 2016 ORGANIC CHEMISTRY (CH2CHE)

You are required to answer ONE question in each section. You should NOT attempt more than this number of questions since only the first ONE will be marked in each section.

CHEMISTRY, CHEMISTRY WITH MEDICINAL CHEMISTRY, BIOMEDICAL CHEMISTRY Candidates should attempt ONE question from Section A, ONE question from Section B and ONE question from Section C. Time allowed: 3 hours Percentages in square brackets are intended as a guide to the time candidates should spend in answering the corresponding part of the question. Use a separate answer book for each question. Read carefully the instructions in the answer book and make sure the particulars required are entered on each answer book.

CHEMISTRY WITH MANAGEMENT Candidates should attempt ONE question from Section A and ONE question from Section B. Time allowed: 2 hours Percentages in square brackets are intended as a guide to the time candidates should spend in answering the corresponding part of the question. Use a separate answer book for each question. Read carefully the instructions in the answer book and make sure the particulars required are entered on each answer book.

1

CH2CHE

SECTION C 5 (a)

Answer ALL parts. Predict the structures of compounds 19 and 20 below, with full stereochemical details, and account for their formation.

[20%] (b)

Explain the term “chemoselectivity”.

[5%]

(c)

Predict the structures of compound 21 in the following scheme, and provide a mechanism for the transformation of 21 into 22.

(d)

[15%] Predict the structure of compound 23 and the mechanisms for the transformations shown below .

(e)

[20%] Give suitable reagents and conditions to perform the following four transformations. Each transformation will require more than one step.

[40%] (continued)

6

CH2CHE

6 (a)

Answer ALL parts. Predict the structures of compounds 19 and 20 below, with full stereochemical details, and account for their formation.

[20%] (b)

Explain the term “chemoselectivity”.

[5%]

(c)

Provide a mechanism for the transformation of 24 to 25, and predict the structure of product 26.

(d)

Provide a mechanism for the reaction shown below.

(e)

[10%] Suggest a suitable specific enol equivalent 29 in the transformation of 28 into 30 and give full mechanisms for both reaction steps.

[15%]

O

O

H

29

Ph 28

(f)

30

[15%] For each of the reactions below suggest two possible aldol condensation products, and then explain for each reaction which of the two products is more likely. O NaOH

H

NaOH

Ph

O

(g)

Ph

H

O Ph

Ph

H

[15%]

Give mechanisms and products for the following reactions, explaining any differences.

[20%] (END)

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