Q1/5L/11-13 Reg. No

St. Joseph’s College of Arts & Science (Autonomous) St. Joseph’s College Road, Cuddalore – 607001

Time : 3 hrs

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CH101S - ORGANIC CHEMISTRY - I Max Marks :75 SECTION A (20x1=20)

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Answer ALL the questions. I. Choose the correct answer 1. The IUPAC name of the compound CH2 CH3 CH CH3 Cl a) 2- chlorobutane b) 1- chlorobutane c) chloroethane d) propane

2. Dehydrohalogenation of Alkylhalides give a) Aldehydes

b) Ketones

c) Alkanes

d) Alkenes

3. The intermediate in the E1 elimination of an alkyl halide is a) Carbocation

b) Carbanion

c) Free radical

d) Alkene

4. The shape of Acetylene is ---------a) square planar b) tetrahedral c) planar

d) linear

5. Thermodynamically controlled product in an addition of hydrogen halide to a conjugated diene is a) 1,2-addition

b)1,3-addition

c)1,4-addition d) 1,1-addition 1

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6.1-butene can be prepared from 1-butanol by heating it with a) H 2 SO 4 R

R

R

R

b) NaNH 2 R

R

c) Acetone

d) Acetic acid

7. Which of the following orientations of two groups in a cyclohexane system is a cis conformer? a) 1,2-diaxial

b)1,2-axial equatorial

c) 1,4- diaxial

d)1,3-axial equatorial

8. The most stble alkene among the following is a)1-butene b) cis-2- butene c) trans 2- butane d) Ethylene 9. Which of the following is not a good source of electrons? a) Li in liquid ammonia

b) Na in liquid ammonia

c) K in liquid ammonia

d) Fe in liquid ammonia

10. Diels –Alder reaction is a / an a) cyclo addition b) elimination c) substitution d) Rearrangement II. Fill up the blanks with correct answers. 11. Hydrohalogenation of an alkene results in the formation of ---------. 12. The angular strain in cyclopropene is = ---------------. 13. The internuclear distance between two bonded atoms is called as -----14. Ethylene on treatment with Ozone followed by treatment with DMS gives -------. 2

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15. Treatment of formaldehyde with Grignard reagent followed by hydrolysis gives --------. III. Match the following 16. E 2 elimination

-

Cyclohexane

17. Kinetically controlled

-

Grignard reagent

18. Alkanes

-

Co-planarity

R

R

19. Boat form

–

20. Organometalic compound

sp 3 Hybridisation P

P

- 1,2- Addition in a Conjucated diene

SECTION B (10x2=20) Answer any TEN questions 21.a) Draw the structures of the following molecules i)

ethanol

ii) 2-iodooctane

22. Give the IUPAC names for the following compounds CH3 CH3 CH3 i)

ii) CH3

C

C

Br

Br

CH3

Br

23. Predict the product: O

+

O

100 C ?

O

3

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24.Write the organoborane obtained in the following reaction.

B2H6 3 H3C

CH

?

CH2 Et2O

.

25.Explain the shape of Ethylene molecule based on the hybridization involved in it’s formation. 26.Give the reason for the acidic nature of phenol. H2 / Ni

27.

HC

?

CH

28. Predict the products A and B of the following reaction . Br

H

C

C

H

Br

KOH H

H

NaNH2 A

B

Ethanol

29.Write the product and give the mechanism: H

H3C C H3C

C H

KMnO4 NaOH

30. Draw the chair and boat conformations of cyclohexane.

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31. Define the following terminologies : i) Bond angle

ii) Bond length

32. Predict the product for the following reaction. COOEt

C2H5ONa

COOEt

SECTION C (5x7=35) Answer any FIVE questions 33. a) Write the IUPAC names of the following compounds.

(4 + 3)

O i)

ii)

iii) CH CHO 3

iv) CH3OH

b) Explain the structure of Acetylene based on hybridization. 34. a) Predict the product of the following reaction and give the mechanism. H3C

C

C

H

+

HgSO4 OH2

H2SO4

(4 +3)

?

b) Give the reason for the acidic nature of terminal alkynes and write the reaction of Acetylene with Sodamide. 35. a)

CH3MgBr

+

OH2

?

(2+2+3)

b) How will you prepare ethane from methyl chloride? 5

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c) Write the Bayer strain theory and calculate the angular strain in cyclopropane . 36. a) Predict the major product of the following reaction and give the mechanism. (3+4)

H3C

CH2

CH

K

+

t - BuO

_

CH3

?

Cl

b) Find the products A and B. CH2

O3

CH2

CH2cl2

Zn / H2O A

B

37. Predict the products of the following reactions and give the mechanisms. No Peroxide

CH3

CH

CH2

+ HBr Peroxide

(3 +4)

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38. a. Label the hybridization involved in each carbon in the following molecules and draw the hybrid orbital diagram. (2.5+2.5) i)

HC

CH

ii) CH2

CH2

b. Assign E/z configuration to the following compounds. H

CH3 CH2Br

Br

H HO

(1+1)

CH2Br CH3

39. a. Predicts the product and explain with mechanism:

(2+2)

i) CH 3 Br + C 2 H 5 Br +2Na--------? R

R

R

R

R

R

ii) C 2 H 6 +Cl 2 ------light---- R

R

R

R

R

R

b. Mechanistically explain Kolb’s reaction.

(3)

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