07a4bs03-organicchemistry

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Code No: 07A4BS03 R07 Set No. 2

II B.Tech II Semester Supplementary Examinations,May 2010

ORGANIC CHEMISTRY

Chemical Engineering

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

1. (a) Draw the structure of Bismark-Brown -Y.

(b) How can this compound be prepared in the laboratory?

(c) What are the chief uses of this compound? [4+8+4]

2. (a) How are free radicals detected ?

(b) Describe a simple method to terminate chain reactions proceeding by Free-radical pathway.

(c) Describe the reaction between HCl and 1-propene. [6+6+4]

3. (a) Write briefly on the following reactions of pyrrole :-

i. Sulphonation and

ii. Friedel-Crafts reactions.

(b) Explain the importance of quinoline ring system.(c) State and explain the Bishler-Napieralski method for synthesis of isoquino-

lines. [4+4+8]

4. (a) What do you understand by configuration of an optically active organiccompound and a compound exhibiting geometrical isomerism? Explain youranswer with examples.

(b) Indicate which of the following compounds will exhibit optically isomerism orgeometrical isomerism?

i. 2- Chloroacetic acid

ii. 2- Pentene

iii. 2- Bromobutane

iv. Cinnamic acid. [8+8]

5. (a) Differentiate between hyperconjugative effect and inductive effect givingexamples.

(b) Write down the resonance structures of following compounds and explainthem.

i. Phenol

ii. Nitrobenzene [8+8]

6. (a) Discuss the formation of Charge Transfer Complex and Wheland intermediatein the electrophilic substitution reactions of benzene.

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II B.TECH II SEMREGULAR/SUPPLEMENTARY EXAMINATIONS MAY - 2010


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(b) What happens when p-fluorophenol is refluxed with chloroform in the presenceof sodium methoxide in methanol ? [8+8]

7. (a) Discuss the process and function of various ingredients used in compoundingof rubber.

(b) What is meant by fabrication of plastics? Discuss any two methods used inthe moulding of plastics. [8+8]

8. (a) Describe the reaction between acetophenone and propanaldehyde in the pres-ence of aq.ethanolic KOH.

(b) Describe a laboratory method for the preparation of-phenylacrylic acid usingPerkin condensation reaction. [8+8]

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ORGANIC CHEMISTRY





1. Explain the preparation, properties and uses of:

(a) Polyester and

(b) Silicone resins. [8+8]2. (a) State and explain Perkin reaction?

(b) Discuss the scope and limitations of this reaction. [4+12]

3. (a) What are dyes? How are they classified?

(b) Write a note on colour and constitution of dyes. [6+10]

4. (a) Compare the reactivity order towards electrophilic substitution of the followingtwo Derivatives:-

i. N, N-Dimethylaniline

ii. 2,6-Dimethyl, N,N-Dimethylaniline.

(b) Which of the following is a more stable carbocation and why ?

i. Ph CH+ CH3ii. Ph CH2 CH

+

2[8+8]

5. (a) Explain how would you prepare pure ethylbenzene from benzene and acetylchloride using Friedel-Crafts reaction?

(b) What happens when phenol is refluxed with chloroform in the presence ofpotassium t-butoxide in t-butanol? Formulate the reaction and mechanism

for product formation. [8+8]

6. (a) Draw the resonance structures of pyrrole and explain its reactivity towardselectrophiles.

(b) What happens when thiophene is treated with cold Conc.H2SO4? [8+8]

7. (a) Predict the product obtained when 1-hexene is treated with NBS using CCl4as solvent.

(b) What happens when the reaction of 2-pentene is carried out with HBr in thepresence of diphenyl peroxide? [8+8]

8. (a) Indicate which of the following compounds can exhibit geometrical isomerismand give justification for your answer :-

i. 1-Propene

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ii. Acetaldehyde

iii. Acetophenoneiv. 2-Butene.

(b) Indicate which of the following compounds can exhibit optical isomerism andgive justification for your answer : -

i. -Chloroacetic acid

ii. Benzyl chloride

iii. Propionic acid

iv. 2-Chlorobutanoic acid. [8+8]

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ORGANIC CHEMISTRY





1. (a) Write the correct structure of the following heterocyclic compounds and givetheir systematic names : -

i. Furoic acid

ii. Piperidineiii. Furfuraldehyde

iv. Quinaldine.

(b) Describe the electrophilic aromatic substitution and nucleophilic aromatic sub-stitutution reactions undergone by quinolines. [8+8]

2. (a) What are nucleophilic additions reactions ? How are they important?

(b) Discuss the reaction between acetone and benzaldehyde in the presence ofaq.ethanolic KOH. [6+10]

3. (a) Explain why guanidine (NH2C(= NH)NH2) ) is a stronger base than

urea (NH2 CO NH2) ?

(b) Differentiate between the concepts of polarity and polarisability giving suitableexamples. [8+8]

4. (a) Discuss the reaction between methane and chlorine gas in the presence ofmonochromatic light of wavelength 300 nm.

(b) Formulate and give mechanism for the reaction of 2-pentene with NBS. [8+8]

5. (a) If a compound does not show absorption in the UV region of electromagnetic

spectrum, can it exhibit the property of colour?

(b) Draw the resonance structures of Bismark - Brown - R. [4+12]

6. (a) What is the composition of polyester?

(b) How is polyester manufactured?

(c) Describe its conversion to fibers. [4+8+4]

7. Reaction of p-bromoacetophenone with hydroxylamine hydrochloride in aq.ethanolicsodium carbonate yields a mixture of oximes which on heating with p- toluenesul-fonic acid in benzene result in the formation of mixture of amides. Formulate

the reaction and explain the mechanism involved. Indicate the major and minorproducts in this reaction. [16]

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8. (a) Explain why geometrical isomers are not readily interconvertable at roomtemperature.

(b) In a chemical reaction, acetaldehyde was treated with HCN to yield a cyanohy-drin which on hydrolysis resulted in an a- hydroxy acid. Formulate the reactionsequence and explain whether the final products will be optically active or not?

[6+10]

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ORGANIC CHEMISTRY





1. (a) What are and complexes and how are they formed? Explain your answerby taking the case of benzene reacting with electrophiles.

(b) Write a note on Beckmann rearrangement reaction. [8+8]

2. (a) What is the full structure of Bismark-Brown - R?(b) Summaries the important steps in its synthesis.

(c) What are the applications of Bismark-brown-R? [4+8+4]

3. (a) What are the different types of polyethylenes manufactured? Explain theirdifferences & properties.

(b) Describe the properties, preparation and applications of polyurethane resins.[8+8]

4. (a) Differentiate between conformation and configuration of an organic com-

pound using examples.(b) Draw the chair, boat and twist boat forms of Cyclohexane and comment on

their stability. [8+8]

5. (a) Write the reactivity sequence for the reaction between bromine vapour andtoluene using Hg vapour lamp with a wavelength of 250 nm.

(b) Describe a simple laboratory preparation of NBS from readily available start-ing materials. [8+8]

6. (a) Discuss any three reactions of furan in which it acts as a -excessive system.

(b) Using simple qualitative experiments in the laboratory, how can you differen-

tiate between:

i. Thiophene and benzene

ii. Pyrrole and pyridine. [8+8]

7. (a) Differentiate between inductive effect and resonance effects giving examples.

(b) Explain why ammonia is a weaker base than diethylamine. [8+8]

8. (a) Describe the reaction between formaldehyde and 3,4-dimethylbenzaldehyde inthe presence of aq. NaOH at RT.

(b) What happens when m-methoxybenzaldehyde reacts with acetic anhydride in

the presence of anhydrous sodium acetate under reflux. [8+8]

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07a4bs03-organicchemistry

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