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Roll No.
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Total No. of Questions : 11
Total No. of Pages : 02
M.Sc. (Chemistry) (2018 Batch) (Sem.-2)
REACTIVE INTERMEDIATES-II
Subject Code : CHL-412-18
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M.Code: 75982
Time: 3 Hrs.
Max. Marks : 70
INSTRUCTIONS TO CANDIDATES :
- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains EIGHT questions carrying FIVE marks each and students have to attempt any SIX questions.
- SECTION-C will comprise of two compulsory questions with internal choice in both these questions. Each question carries TEN marks.
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SECTION-A
- Answer Briefly :
- Addition of an electrophile to 2,4-hexadiene generates two intermediates. Write their structures and tell which one is more stable.
- Discuss the use of organozinc reagent for nucleophilic addition reaction.
- Write the mechanism of Wittig-Horner reaction.
- Selenium dioxide is quite often used in bringing about allylic oxidation. Presuming selenious acid or equivalent as the oxidant. Write steps involved in this process.
- What reagents are used for the oxidation of glycols and amines to aldehyde and ketones? Write their reactions only.
- What is the use of 9BBN reagent in organic chemistry?
- Write the reagents for hydrogenation of alkynes to cis and trans alkenes.
- Write a short note on Neber rearrangement.
- Discuss the use of Arndt-Eistert synthesis.
- Predict the products and name the following rearrangements :
(i) Cl C2H5O-
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Heat
(ii)
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SECTION-B
- Discuss the mechanistic and stereochemical outcome for the addition of bromine in electrophilic addition reactions.
- Explain briefly free radical addition reaction of hydrogen halides and thioles to carbon-carbon double bonds. Illustrate with examples for the possibility of these reactions.
- With suitable examples, illustrate the role of Pb(OAc)4 and O3 for the oxidation of olefinic double bond.
- How will you oxidize alcohols through Swern Oxidation and Pyridinium Chlorochromate (PCC)? Support your answer with suitable mechanism.
- Discuss with mechanism for the use of sodium triacetoxyborohydride and diisopinocamphenyl borane.
- What are the product(s) formed when (i) an aromatic hydrocarbon and (ii) an a,ß-unsaturated ketone is treated with sodium and liquid ammonia? Discuss the mechanism of formation of these products.
- Write a short note on oxymercuration and Sharpless asymmetric epoxidation reactions.
- With suitable example, illustrate the role of various reagents used for the oxidation of glycols, halides and amines.
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SECTION-C
- Write a short note on the following rearrangements :
- Pinacol-pinacolone rearrangement (5)
- Criegee rearrangement (5)
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OR
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- Discuss the mechanistic and stereochemical aspects of the reduction by lithium aluminium hydride. What is meant by steric approach control and product development control in such reactions? (6)
- With suitable examples, illustrate the oxidation of methylene and aryl methanes. (4)
- Discuss with mechanism for following rearrangements : (2.5×4)
- Isonitrile-Nitrile rearrangement
- Hofmann rearrangement
- Demanov rearrangement
- Wagner-Meerwein rearrangement
OR
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- What is Fries rearrangement and Baeyer-Villiger rearrangement? Illustrate their mechanism by a suitable example. (10)
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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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