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BSc (VI Semester) Examination
CHEMISTRY
Paper : CHEM–363
( Organic Chemistry )
Full Marks : 80
Pass Marks : 35%
Time : Three Hours
Note : 1. Answer all questions.
2. The figures in the margin indicate full marks for the questions.
1. Answer any five questions : 2×5=10
(a) What is active methylene compound? Give one example.
(b) What are azo dyes? How are they classified?
(c) Why are amino acids called amphoteric compounds?
(d) What is meant by antarafacial overlapping? Give an example.
(e) What are the differences between fluorescence and phosphorescence?
(f) What are meant by singlet and triplet states?
(g) What is quantum yield?
2. Answer any four questions : 5×4=20
(a) Give the preparation of diethylmalonate. Write two reactions in support of active methylene group of diethylmalonate. 1+(2+2)=5
(b) Write the synthetic route of indigo.
(c) How will you synthesize peptide from amino acids by protecting amino group?
(d) Describe sigmatropic reactions by taking example of [1, 5 ] and [1, 7 ] H-shift.
(e) Describe Norrish type-II reactions. Explain with example.
(f) Write the selection rules for electrocyclic reactions. Predict the mechanism of the following reaction using the selection rule : 2+3=5
3. Answer any five questions : 10×5=50
(a) Starting from ethyl acetoacetate, how will you prepare the following? 3+3+4=10
(i) Butane-1,4-dioic acid
(ii) 3-Methyl-butan-2-one
(iii) n-Valeric acid
(b) (i) How can dyes be classified on the basis of application to fibre? 3
(ii) Explain the colour change of phenolphthalein in alkaline medium giving chemical reactions. 3
(iii) Give the synthesis of methyl orange. 4
(c) Write short notes on : 5×2=10
(i) Secondary structure of protein
(ii) Protein denaturation
(d) (i) What are Diels-Alder reactions? Explain the [2+2] and [4+2] cycloaddition reactions. 1+(2+2)=5
(ii) What is Claisen rearrangement reaction? Explain with mechanism. 5
(e) (i) Explain Franck-Condon principle in the context of photochemistry. 6
(ii) How can you perform the photoreduction of benzophenone? 4
(f) Draw Jablonski diagram and explain all the possible photophysical processes. 10
(g) Write notes on : 5×2=10
(i) Cope rearrangement
(ii) HVZ reaction of phenylalanine
(h) (i) Discuss keto-enol tautomerism in diethylmalonate. 2
(ii) Discuss Woodward-Hoffmann selection rule for electrocyclic reaction. Write down the products of the following reactions with correct stereochemistry : 4+4=8
