Guru Nanak Dev University 2005 B.Sc Chemistry ORGANIC OF FUNCTIONAL GROUPS - I (Chem - 102) - 2k5 - Question Paper

B.Sc. (H.S.) In Chemistry first Semester
2125
PAPER - Chem - 102
Organic Chemistry Of Functional Groups - I

Time Allowed : three hours

Maximum Marks : 75

part - A ( 1(1/2) every )

Note : Attempt All ques.

1. provide the relative order of strength of van der Waals interactions in fluorocarbons and hydrocarbons of approximately identical molecular weight. Mention the resulting effect on boiling points of compounds of these 2 classes.

2. Mention the improper combinations :
(i) Half headed and full headed arrows or (ii) Half headed and double headed arrows ;
(iii) Single headed and double headed arrows. discuss the objective of arrows by writing 3 simple organic reactions mechanisms.

3. Can you refute or argue in favour of the subsequent statement with examples; "There is a relationship ranging from D, L and R, S system of nomenclature".

4. provide an unambiguous method for naming the geometrical isomers. provide examples.

5. Write 2 chemical reactions in which cyclopropane undergoes unlike other alkanes (cyclic or otherwise). discuss.

6. Write an formula for the Hofmann elimination to form alkene. discuss the stability of product.

7. How is the addition of water at carbon-carbon triple bond in presence of Hg (II) salt and sulphuric acid an example of electrophillic addition reaction ?

8. What is Wurtz reaction ? How would you find 2,5-dimethyl hexane by using this reaction ?

9. Draw the MO diagram of benzene molecule. How can the carbon-carbon bond length and electron density be understood by this diagram ?

10. Outline the reactions on side chain of benzene. How do they differ ? provide Examples.

part - B ( 4(1/2) every )

Note : Attempt any 8 ques..

11. explain the interactions which take place in the inclusion compounds. Highlight their uses in organic chemistry. provide examples

12. describe inductive effect. explain its effect on acidity of acetic acid, phenols and carbonyl compounds. What role does it play in the reactivity of aliphatic and aromatic halides ?

13. elaborate arynes ? explain their structure bonding and aromaticity. How does cycloaddition reaction occur in these compounds ?

14. Indicate the number of chiral carbons in 2,3-dichloropentane. compute the number of enentiomers/stereo isomers. Draw the structure formulae of all isomers using flying wedge formulae. explain the relationship ranging from pairs of structure formulae such as enantiomers and stereo isomers.

15. elaborate the intermediates in the reaction of chlorine with methane in the presence of light ? explain the role of energy of activation and transition state with reaction progress. Depict it with the help of diagram.

16. Write the chair conformers of 1,2-dimethyl, 1,3-dimethyl and 1,4-dimethyl cyclohexanes. every compound should have 2 isomers, assign them in terms of trans and cis isomerism. explain the stability of every pair in terms of 1,3-diaxial interaction.

17. How do alkenes form from the dehydration of 3,3-dimethyl-2-butanol in presence of 85% H3PO4 ? Write their names and justify their formation using improper mechanisms.

18. Write th formula for the hydration of 3,3-dimethyl-1-butane in presence of sulphuric acis=d. Name the major products. Giva an improper mechanism for the formation of major products. discuss the intermediacy of reactive intermediates with its stability.

19. What is the relative order of acidity of C-H bond in methane, ethyne and ethylene ? discuss the order. provide a few chemical reactions of ethyne, where its acidity has been detected.

20. elaborate the important classes of dienes ? provide a few examples, with the structure formulae, methods of formation. explain the polymerisation for various classes.

21. elaborate the activating and deactivating substituents in the reactions of Aromatic compounds ? By taking examples of every class, explain the orientation and formation of products with mechanism.

22. explain Friedal-Crafts acylation reaction. Mention different steps, catalyst, limitations of reactions and uses in industrial applications.

part - C

Note : Attempt any 2 ques..

23. (a) explain the structure formulae of the subsequent compoubds (Use the hybridization theory).
(i) methane
(ii) benzene
(iii) ethyne
(b) How would you compute formal charge on organic compounds. Mention formal chargs on carbocation and carbene.
(c) describe a reaction mechanism. elaborate the methods of determination of reaction mechanism ? define 2 methods. (6,3,3)

24. (a) Write equations and the absolute configurations of isomeric products in the asymmetric reduction of 2-butanone. Can you suggest 2 various paths for their formation ?
(b) How does hydroxilation of (E)-2-butene take place with potassium permanganate ? What is the relationship betweeen the isomers formed ? Assign the absolute configurations and IUPAC names of the products. provide mechanisms.
(c) Bromocyclohexane can be represented by 2 structural formulae in chair form. Which is more stable ? discuss. (4,5,3)

25. refer to attachment (12 Marks)

26. (a) provide sequence rules (of R and S system) of determination of absolute configuration.
(b) Show all tartaric acid structural formulae by Newman's projection, Sawhorse, Fisher and Flying wedge representation. Which isomer is which stereo isomer ? provide their IUPAC names.
(c) Draw a potential for a rotation about C-C bond in ethane. Name conformers with their relative energy. (4 each)

Earning:   Approval pending.