(c) 2,2,4-Trimethylpentane (d) 2,2,33-Tetramethylbutane. 2 HCl Cl. (d) CH3 CH = CH2. Because a give more stable carbocation.

Transcription

1 SM 1 Solved Problems bjective Problem 1: A hydrocarbon with formula 818 gives one monochloroderivative. The hydrocarbon is: (a) n-ctane (b) -Methylheptane (c),,4-trimethylpentane (d),,-tetramethylbutane All groups are equivalent in d. l l l (d) Problem : The addition of is fastest to the alkene (a) = (b) = (c) () = (d) = Because a give more stable carbocation. + carbocation (more stable) In (a) and (d), carbocation while (c) 1 carbocation is formed. (c) Problem : Which of the following is most suitable reagent to distinguish compound III from others? I. II. III. IV. = (a) omine in l 4 (b) Ammonical u l (c) Ammonical AgN (d) Both (a) and (c) nly terminal alkynes give white ppt. with ammonical AgN and give red ppt. with ammonical ul. (d) Problem 4: zonolysis of forms (a) eptanal (b) 5-Ketoheptanal

2 SM (c) 6-Ketoheptanal ozonolysis Ketoheptanal (d) Mixture of (a) and (b) 6 7 (c) Problem 5: Addition of I to -Methylbut--ene would form (a) -omo--iodobutane (b) -omo--iodobutane (c) -omo--iodo--methylbutane (d) -iodo--bromo--methylbutane (c) I Markownikov's addition I -bromo--iodo--methylbutane Problem 6: Which of following compounds give benzene on heating with (PhP)Rl? (a) 6 5 (b) 6 5 (c) 6 5 (d) 6 5 S 5 6 (b) Wilkinson 's catalyst (PhP) Rhl 5 6 Decarbonylation) Problem 7: When isobutylene reacts with diborane followed by reaction with, the product is (a) (b) (c) (d) In hydroboration oxidation (B6 followed by / ), the net result is addition of water which is anti-markownikoff s i) B6 ii) / (b)

3 SM Problem 8: An organic compound A (58) on hydrogenation gives compound B (51). ompound B on ozonolysis give methanal and -Ketopropanal. What is E? (a) (b) (c) (d) -Methyl-1,-butadiene (a) Problem 9: (a) In the dehydration of, the products formed are (b) (c) (d) All the three products are formed + + (A) + (d) alkyl shift ydride shift () (B) Problem 10: Free radical monochlorination of ter butyl bromide gives (a) 1-omo-1-chloro--methylpropane (b) -bromo-1-chloro--methylpropane

4 SM 4 (c) 1-omo--chloro--methylpropane (d) None l l Re arrangement l l l (c) 1 Free radical 1 Free radical (More stable) 1-bromo--chloro--met hylpropane Problem 11: Identify the end product ul A B (Main) N4l Pt / BaS4 (a) (b) (c) (d) ul / N4l Pt / BaS4 1,4-Addition (Main) 1,-Addition (Less) (a) Problem 1: When acetylene reacted with hydrochloric acid in presence of gl the product obtained is (a) Methyl chloride (b) Acetaldehyde (c) Vinyl chloride (d) Methanol. gl l l (c) Problem 1: When propyne is treated with aqueous S4 in presence of gs4, the major product is (a) Propanol (b) Propyl hydrogen sulphate (c) Acetone (d) Propanol. S 4/S 4 (c) Problem 14: Which one of the following does not dissolve in conc. S4?

5 SM 5 (a) (c) (b) (d) =. If is dissolved in S 4 a bisulphate salt of vinyl carbocation would be formed. The more s-character in the positively charged ` less stable is the carbocation and less likely to be formed. (c) Problem 15: Which one of the following compounds will give in the presence of peroxide a product different from that obtained in the absence of peroxide? (a) 1-butane l (b) 1-butene, (c) -butene, l (d) -butene,. Peroxide effect is observed when unsymmetrical alkene is treated with only (and not with l and l). (b) Problem 16: Which of the following compounds yields only one product on monobromination? (a) Neopentane (b) Toluene (c) Phenol (d) Aniline. has twelve equivalent 1. ence forms only one product on monobromination. (a) NaN Problem 17: `X ', What is X (a) = (b) (c) (d) ==. Isomerisation occurs, when -butyne is treated with NaN, it converts into terminal alkyne (1-butyne). (b) Problem 18: Identify the compound `Y in the following sequence of reaction i) Zn / X Y (a) (c) ii) / Zn Ac Ac (b) (d).

6 SM 6 (a) zonolysis Reduction Problem 19: Dehydration of 1-butanol gives -butene as a major product, by which of the following intermediate the compound -butene obtained. (a) (c) (b) + (d) (c) 1, hydride Shift 1 Problem 0: The principal-organic compound formed in the reaction Peroxide ( )... is (a) ( ) 8 (b) ( ) 8 ( ) 8 ( ) 7 (c) (d) Follows the peroxide effect ( ) ( ) 8 Peroxide 8 (c) Subjective Problem 1: -Butyne undergoes following reactions in steps as indicated. Identify A to. A B D /Pt NiB(P ) Na / Et D /Pt E F NiB(P ) G Ni D

7 SM 7 A is obtained by syn addition A = cis B is also obtained by syn addition B = is obtained by anti addition = D D meso D D is mix of d- and l- (reacemic mixture) D = E is obtained by syn addition E = as A D d- and l-(racemic) Addition of is anti F = G = = racemic as F Problem : Li, N(l) nbu Me A dil.kmn 4/ B Lindlar's catalyst / Identify A, B and with proper explanation.

8 SM 8 Li, n - Bu N n Bu Me Lindlar's catalyst n - Bu A-trans (by anti addition) B-cis (by syn addition) KMn 4 n-bu () - and its enantiomer (racemic) Problem : ne mole of a hydrocarbon (A) reacts with one mole of bromine giving a dibromo compound 510. Substance (A) on treatment with cold, dilute alkaline KMn 4 solution forms a compound 5 1. n ozonolysis (A) gives equimolar quantities of propanone and ethanal. Deduce the structural formula of (A). i) A Propanone + ethanal So, A is ii) -methylbut--ene -methylbut--ene -methylbut--ene alk. KMn 4,-dibromo--methylbutane -methylbutane-,-diol Problem 4: An unsaturated hydrocarbon A ( 6 10 ) readily gives B on treatment with NaN in liquid N. When B is allowed to react with 1-chloropropane a

9 SM 9 compound is obtained. n partial hydrogenation in the presence of Lindlar catalyst, compound gives D (9 10). n ozonolysis D gives, -dimethyl propanal and 1-butanal. With proper reasoning give the structures of A, B, and D. A = B = Na = D = Problem 5: A compound (X) when passed through dil S 4 containing gs 4 gives a compound (Y) which on reaction I and red phosphorous gives 6. The compound (X) is? The compound (X) is likely to be alkyne which reacts with water in presence of S 4 and gs 4 as catalyst to form a carbonyl compound. I and red phosphorous can reduce a carboxyl compound to alkane having same number of carbon atoms. Therefore (Y) is likely to be acetaldehyde which is the hydration product of ethyne S 4 [ ] X gs 4 (Y) 4I I red P Problem 6: What is the major product by the addition of l to,, -trichloropropene? l is a strongly electron withdrawing group. The addition of l to >=< double bond of,, -trichloropropene does not follows the Markownikoff s rule because intermediate secondary carbonium ion is destabilized by the 1 effect of l group. Less stable l l Instead the addition follows anti markownikoff s rule because primary carbonium ion becomes relatively more stable. l relatively more stables l l l l Problem 7: Write equation showing how the following compound can be converted to (a) an epoxide (b) a diol (c) a ketone.

10 SM old KMn4 [] Pdl /ul Problem 8: Identify (A), (B) and () in the following reactions (A) 1 eqv. r (B) in Ac () aq. KMn4 excess i) Peroxy formic acid hydroxylates double bond but not triple bond. Therefore, compound (A) is ii) xidation of triple bond is very much slower than that of double bond. Therefore, by using a suitable oxidizing agent it is possible to selectively oxidize double bond in presence of triple bond. r in presence of Ac is one such oxidizing agent, which oxidizes double bond and not triple bond. Thus, compound (B) is iii) Aqueous KMn 4 hydroxylates both the double bond as well as triple bond. The compound () is Problem 9: Write down the structures of close homolooguoes of heptane having in their molecule one quaternary carbon atom and the other having two tertiary carbon atom. omologuoes of heptane (716) are hexane (614) and octane (818).

11 SM 11 Quaternary carbon,-dimethylbutane,-dimethylhexane t t t t,-dimethylbutane,-dimethylhexane Problem 10: Which alkane, having a molecular weight of 86, will form only two monobromo alkanes? General formula of alkane is nn+. Its molecular weight = 86 1n + n + = 86 n = 6 ence the given alkane is 614. Its isomer would give two products / UV light Problem 11: A hydrocarbon (A) was found to have a vapour density of 6. It forms only a single monochloro product. What is (A)? Molecular weight = VD = 6 = 7 nn+; 1n + n + = 7, n = 5 The alkane is 51; its isomer neopentane has all the four identical, hence will give only one monochloro product. Problem 1: Write balanced equations, naming all organic products, for the following reactions; a) isobutyl bromide + Mg/ether b) t-butyl bromide + Mg/ether c) product of (a) + d) product of (b) + a) b) Mg Mg ether ether Mg Mg

12 SM 1 c) d) Mg isobutane Mg isobutane Mg() Mg() Problem 1: hlorination of ethane ( ) to ethyl chloride is more practicable than the chlorination of n-pentane to 1-chloropentane. Why? It is because monochlorination of ethane gives only ethyl chloride, whereas monochlorination of n-pentane gives three isomeric monochloro h l l l l l h l l l Problem 14: What products are obtained when 1-bromo--methyl propane and -bromo-- methyl propane are allowed to react with metallic sodium in dry ether? Give their IUPA names and name the reaction involved.,,,-tetramethylbutane It is Wurtz reaction,,4-trimethylpentane,5-dimethylhexane Problem 15: A chloro derivative (A) on treatment with Zn-u couple gives ahydrocarbon of five carbon atoms. When (A) is dissolved in dry ether and reacted with Na, the product is,,5,5-tetramethyl hexane? What is (A)? Assignments (New Pattern) l l SETIN I Single hoice Questions 1. n heating Na with soda lime the gas evolved will be (a) (b) 4 (c) 6 (d) 4.. Which of the following will have least hindered rotation about carbon-carbon bond?

13 SM 1 (a) Ethane (c) Acetylene (b) Ethylene (d) hexachloro ethane. 1. A sample of 1.79 mg of a compound of molar mass 90 g mol when treated with Mgl releases 1.4 ml of a gas at STP. The number of active hydrogen in the molecule is (a) 1 (b) (c) (d) The addition of to trans--butene produces (a) (+), -dibromobutane (b) ( ), -dibromobutane (c) rac, -dibromobutane (d) meso-, -dibromobutane 5. The treatment of ()= with Nal 4 or boiling KMn 4 produces (a) (b) (c) (d). 6. What is the chief product obtained when n-butane is treated with bromine in the presence of light at 10? (a) (c) (b) (d) 7. The olefin, which on ozonolysis gives and. (a) But-1-ene (b) But--ene (c) Pent-1-ene (d) Pent--ene. 8. Addition of halogen acid (X) is least in (a) l (b) (c) (d) ( ). 9. Which of the following alkene will react fastest with under catalytic hydrogenation condition? (a) (c) R R R R R (b) (d) R R R R R R

14 SM Products of the reaction, D/D (a) D (b) D D D (c) (d) D D D D 11. Point out (A) in the given reaction sequence: / (A) (B) (a) (c) (b) (d) 1. End product of the following sequence is: eat g a (A) () () S 4 (a) Ethanol (c) Ethanal 1. ydrogenation of the compound (b) Ethyl hydrogen sulphate (d) Ethylene glycol. Me Me In the presence of poisoned palladium catalyst gives: (a) An optically active compound (b) An optically inactive compound (c) A racemic mixture (d) A diastereomeric mixture. 14. The treatment of 5Mgl with water produces (a) Methane (b) Ethane (c) Ethanal (d) Ethanol. 15. A. (predominant), A is

15 SM 15 (a) (c) (b) (d) None of these. 16. When isobutene is brominated, the percentage of (a) 0% (b) 8% (c) 10% (d) 100% would be 17. Which of the following is used for aromatization of n-hexane? (a) All (b) Na in liquid N (c) r/al with heat (d) Wilkinson s catalyst 18. Identify (B) in the following sequence of reactions. uln4l l (A) (B) (a) l (b) l l (c) (d) l 19. Propene can be converted into 1-propanol by oxidation. Which set of the reagents is used to effect the conversion? (a) s4 l (b) /Zn (c) Alkaline and cold KMn4 (d) B6 and alk.. 0. In the following sequence of reactions, identify the product (D). alk. K NaN (A) (B) () (D) (a) Ethanol (b) Ethyne (c) Ethanal (d) Ethene 1. Lindlar / B Na / N RR A A and B are geometrical isomers (R = R): (a) A is cis. B is trans (b) A is trans, B is cis (c) A and B both are cis (d) A and B both are trans. The products are NaI 4 / Kmn4 Pr oducts.

16 SM 16 (a) (c),(), ( ) (b) (d) None is correct, ( ). Al hydrocarbon (X). X is (a) (b) (c) (d) None is correct 4. The reaction of with gives (a) (b) (c) (d) None of these 5. A sample of diesel has the same knocking characteristic as a 60 ml mixture of centane and -methyl naphthalene mixed in : 1ratio (V/V). What is the cetane number of the diesel sample? (a) 56.6 (b) 66.6 (c) 76.6 (d) 86.6 SETIN II May be more than one choice 1. R / l 4 PQ R 1

17 SM 17. Where P and Q are (a) enantiomers if R R (b) diastereomers if R R (c) Both are meso and hence the same compound if R = R (d) An equimolecular mixture of P and Q is a racemic mixture if R R per acid per acid A + / + / B D Which of the following statements is/are true : (a) B is a single compound and optically inactive (b) D is a single compound and optically inactive (c) B is an equimolar mixture of two enantiomeric compounds (d) D is an equimolar mixture of two enantiomeric compounds. gs 4 / S 4 A B /TF / g(a), B NaB 4 B is identical when A is (a) (c) (b) (d) 4. Which of the following statements are correct: (a) ydrogenation of -butyne in presence of Na and liquid ammonia yields trans-- butene (b) ydrogenation of -butyne in presence of Lindlar s catalyst yields cis--butane (c) ydrogenation of -butyne in presence of own s catalyst gives cis--butane (d) None of these 5. Which of the following statements are correct on the basis of heat of combustion: (a) Trans--hexene has less heat of combustion than -methyl--pentene (b) is--pentene has higher heat of combustion than trans--pentene (c) 1-hexene has higher heat of combustion than trans--hexene (d), 5-dimethyl hexane has higher heat of combustion than octane 6. This change can be carried out using:

18 SM 18 (a) N N, glycol/ (c) P/I (b) Zn.g/conc. l (d) None of these 7. ydroboration oxidation and acid hydration will yield the same product in case of: (a) (b) (c) = (d) = 8. gs 4 / S4 A B B / TF / g(a), NaB4 B is identical when A is: (a) (c) (b) (d) 9. A + -bromo-, -dimethyl butane. ence A can be: (a) (c) (b) (d) / 10. /Ni (A) (B) ence A and B are: (a), = (b) ==, = (c), = (d) None of these 11. Ammonical silver nitrate reacts with (a) ethyne (c) butyne-1 (b) ethylene (d) butyne- 1. When nitrobenzene is treated with in the presence of Fe, the major product formed is m-bromonitrobenzene. Statements whichare related to obtain the m-isomer are (a) the electron density on meta carbon is more than that on ortho and para positions (b) the intermediate carbonium ion formed after initial attack of + at the meta position is least destabilized. (c) loss of aromaticity when + attacks at theortho and para positions and not at meta position

19 SM 19 (c) easier loss of + to regain aromaticity from the meta position than fromortho and para position 1. Which of the following compounds will show cis-trans isomerism? (a) () = (b) = l (c) 65() = (d) = () 14. When toluene was treated with l in presence of light which one of the product/s is formed. (a) (b) 65 (c) l6 (d) l 15. Which one of the following has the smallest heat of hydrogenation per mole? (a) 1-butene (b) trans--butene (c) cis--butene (d) 1, -butadinene 16. Benzyl chloride (65l) can be prepared from toluene by chlorination with (a) Sl (b) Sl (c) l (d) Nal 17. Toluene, when treated with /Fe, gives p-bromotoluene as the major product because group (a) is para directing (b) is meta directing (c) activates the ring by hyperconjugation (d) deactivates the ring 18. Which is/are true statements/reactions? (a) Al4 + 4 (b) a + (c) Mg + (d) olme signal uses mixture of ap and a 19. Following are used as anaesthetics in surgical operations: (a) 4 (b) N (c) l (d) solid 0. This change can be carried out using: (a) NN, glycol/ (c) P/I 1. 4 gas is also called/content of : (a) NG (c) water gas gs 4 / S4 B / TF. A B / B is identical when A is: (a) (c) (b) Sn(g)/conc. l (d) N/LiAl4 (b) Marsh gas (d) producer gas (b) (d)

20 SM 0. Which gases are poisonous? (a) Lewisite (c) Phosgene (b) Mustard (d) MI SETIN III omprehension Type Questions Write-up I hlorination of methane involves three steps: chain-initiating, chain-propagating and chain-terminating. eat or light l l hain initiating 4 l l hain propagating l l l When oxygen is passed through the reaction mixture, chlorination of methaneslows down temporarily 1. hain-propagating steps (a) consume reactive species and form another reactive species (b) do not produce reactive species (c) absorb energy and produce reactive species (d) are not always the part of chain-reaction mechanism. hain-terminating step may involve the formation of (a) hlorine (b) Methyl chloride (c) Ethane (d) All the three. Although chlorination of methane is an exothermic, the reaction requires high temperature because (a) Activation energy is low (b) heat of reaction is negative (c) hain-initiating step is endothermic (d) hain-terminating step is endothermic 4. Temporary slow down of chlorination of methane in presence of oxygen in due to the formation of (a) which is highly unstable and decomposes easily (b) which is less reactive than (c) l which is highly reactive (d) a diradical l Write-up I B / TF = B NBS, Alc. D E F K 5. In the reaction B is (a) ethyl alcohol (c) Allyl alcohol (b) propyl alcohol (d) None of these

21 SM 1 6. In this D is (a) Allyl omide (c) 1, dibromo propane 7. F is (a) 1, -diomo-1-propene (c) 1, 1-diomo-1-propene 8. E is (a) 1,, -Tri omo propane (c) 1,, -Tri omo Propane (b) Vinyl omide (d) None of these (b) 1, -di-omo-1-propene (d), -di omo-1-propene (b) 1, 1, -Tri omo Propane (d) None of these Write-up II A/B 1 butene I Go through above reaction sequence and answer the following question 9. The compound A/B is (a) (c) I/ 10. The name of the reaction is (second step) (a) Wurtz reaction (c) offmann elimation (b) /RR (d) I (b) annizaro reaction (d) Finkelstein reaction Write-up V By virtue of its shape s orbitals can attract electron density more than p orbitals. More the s character more is the electronegativity of the hybrid orbitals. rder of electronegativity of hybrid orbitals is sp sp sp. 11. Which is acidic? (a) (c) (b) = (d) 6 1. Acetylene reacts with sodium hypochlorite to form (a) vinyl chloride (b) dichloro acetylene (c) sodium acetylide (d) chloro ethane 1. Acetylene reacts with sodium and methyl iodide and produces (a) -butyne (b) 1-butyne (c) 1-pentyne (d) -pentyne buyne and -butyne can be distinguished by (a) in l4 (b) Tollen s reagent (c) Schiff s reagent (d), 4-DNP Write-up VI

22 SM A B l4 Alo. K Na liq. NaN ne mole l D E B 6 /TF Al(Et) / 15. B with excess amount of NaN followed by treatment with methyl chloride produces (a) butyne-1 (b) butyne- (c) propyne-1 (d) 1, butadiene 16. ydroboration and oxidation is (a) cis addition (c) cis and anti addition (b) Anti addition (d) cis addition and elimination 17. hydride ion migration take place in the following (a) Tischenko reaction (b) Aldol ondensation (c) annizaro reaction (d) a and c 18. Vicinal dihalide of ethane on treatment with aqueous K followed by lead tetra acetate produces. (a) + (b) (c) (d) + SETIN IV Subjective Questions LEVEL I 1. An organic compound (A) 610 on reduction, first give (B) 6 1 and finally (c) (A) on reaction with ozone followed by hydrolysis in presence of Zn gives two aldehydes (E). xidation of (B) with acidified KMn4 gives acid (F) 6. Determine structures of (A) to (F) with proper reasoning.. Identify (a) the chiral compound, 10 14, that is oxidized with alk. KMn 4 to Ph, and (b) the achiral compound D, 10 14, inert to oxidation under the same condition.. An alkyl halide, (X), of formula 61l on treatment with potassium tertiary butoxide gives two isomeric alkenes Y and Z (6 1). Both alkenes on hydrogenation gives, - dimethylbutane. Predict the structures of X, Y and Z. 4. a) Ph (A) /peroxide (B) Identify A and B b) Write the product(s) of the following reactions: Peroxide l?

23 SM 5. Write the major products of the hydroboration and oxidation of: a) 1-Ethyl cyclopentene b) Methylene cyclopentene. 6. Give the missing compounds in the following: a) B.TF?? b) B.TF?? B c).tf?? d) (i) B.TF? (ii) 7. omplete the following equation: (A) a) Pt Pt Na 5 b) (B) Na5 8. a) Starting with any alkyne, prepare ethyl cyclohexyl ethyne. b) Starting with cyclohexyl ethyne, prepare acetyl cyclohexane. 9. a) omplete the following reactions: NaN (1 equiv) Al, A B D E Pd 400 b) omplete the following reactions: i) NaN I A B ii) Lindlar's catalyst Zn(u) 10 X KMn 4, Y, Z (mix) Identify X, Y and Z LEVEL II 1. Predict the product of the following a) conc. S 4/ A l B b) / A B (i) B6 (ii) ( ) (i) g(ac) (ii) NaB4 c) R J

24 SM 4. a) Give reasons for the following: When 1-penten -4-yne is treated with in equimolecular proportion, the addition takes place on double bond and not on triple bond yielding thereby the product (). b) Provide a suitable mechanism for the following reaction.. Three isomeric alkenes A, B and, ( 5 10) are hydrogenated to yield -methylbutane A and B gave the same R on oxymercuration demercuration B and give different 1 R s on hydroboration oxidation supply the structures of A, B and. 4., -dimethyl-1-butene and l react to give two products, 61l. n reaction with alc. K one isomer, (I) gives back, -dimethyl-1-butene the other (J) gives an alkene that is reductively ozonized to Me. Give the structures of (l) and (J) and explain the formation of the latter. 5. a) Identify X, Y and Z in the following sequence of reactions giving stereo chemical structures wherever possible. (X) (Y) (Z) b) omplete the following sequences i) (i) Na (i) (i) (ii) PdBaS 4 (ii) / l All ii) i) NaN (equi.) A B 6 5 ii) I 6. ydrocarbon (A) 610 on treatment with /Ni, /Pd BaS4 and Na/liquid N forms three different reaction products (B), () and (D) respectively. (A) does not form any salt with ammoniacal AgN solution but forms a salt (E) on heating with NaN in an inert solvent. ompound E reacts with I to give (F). ompound (D) on oxidative oznolysis gives n-butanoic acid along with another product. Give structures of (A) to (F) with proper reasoning. 7. A hydrocarbon (A) containing 90% carbon reacts with dil. S4 in presence of gs4 to give (B). ompound (B) is reduced by LiAl4 to () which on heating with S4 gives (D) directly by hydrogenation in presence of deactivated Pd-a catalyst. utline the reactions. 8. Identify the missing compound in the following sequence of reaction: i) K (alc.) NaN a (A) (B) () (D) (E) Lindlar 's catalyst ii) 4 /g LiAl 4 onc. S4 Mg (A) (B) () (D) NaN (E) (F) / h / l4 KMn4 iii) alcoholic K alcoholic K 1 mol A B D E

25 SM 5 9. An hydrocarbon (A), 814, decolourises /l4 and cold dil. neutral KMn4 solution, but does not react with ammonical AgN and ul solutions. It on ozonolysis produced two molecules of the same acid (B), 48, which on heating with sodalime gave propane. What are (A) and (B)? 10. A hydrocarbon (A) is treated with excess of l to give a dihalogen compound (B), which on treatment with alc. K and aq. K separately gives (A) and () respectively. () can also be obtained by heating calcium salt of -methyl propanoic acid with calcium acetate. What are (A), (B) and ()? LEVEL III (Judge yourself at JEE level) 1. When gas (A) is passed through dry K at low temperature, a deep red coloured compound, (B) and a gas () are obtained. The gas (A), on reaction with but--ene, followed by treatment with Zn/ yields acetaldehyde. Identify (A), (B) and ().. 1,4-pentadiene reacts with excess of l in the presence of benzoyl peroxide to give compound (X) which upon reaction with excess of Mg in dry ether forms (Y). ompound (Y) on treatment with ethyl acetate followed by dilute acid yields (Z). Identify the structures of compounds (X), (Y) and (Z).. An organic compound E (58) on hydrogenation gives compound F(51). ompound (E) on ozonolysis gives formaldehyde and -ketopropanal. Deduce the structures of compound (E). 4. A hydrocarbon (A) of the formula 810, on ozonolysis gives compound (B) (46) only. The compound (B) can also be obtained from the alkyl bromide () (5) upon treatment with magnesium in dry ether, followed by carbon dioxide and acidification. Identify (A), (B) and () and also give equations for the reactions. 5. The hydrocarbon (A), adds one mole of hydrogen in the presence of a platinum catalyst to form n-hexane. When (A) is oxidized vigorously with KMn4, a single carboxylic acid, containing three carbon atoms, is isolated. Give the structure of A and explain. 6. A hydrocarbon (A) of molecular weight 54 reacts with an excess of in l4 to give a compound (B) whose molecular weight is 59% more than of (A). owever, on catalytic hydrogenation with excess of hydrogen, (A) forms () whose molecular weight is only 7.4% more than that of (A). (A) reacts with in the presence of NaN to give another hydrocarbon (D) which on ozonolysis yields diketone (E). (E) on oxidation gives propanoic acid. Give structures of (A) to (E) with reasons 7. omplete the following reaction. i) 1 ii) Major product Lindlar catalyst iii) Major product 5

26 SM 6 8. yclobutyl bromide on treatment with magnesium in dry ether forms an organometallic (A). The organometallic reacts with ethanal to give an alcohol (B) after mild acidification. Prolonged treatment of alcohol (B) with an equivalent amount of gives 1-bromo-1- methylcyclopentane (). Write the structures of (A), (B) and explain how () is obtained from (B). 9. An alkene (A) 1616 on ozonolysis gives only one product (B) 88. ompound (B) on reaction with Na/I yields sodium benzoate. ompound (B) reacts with K/NN yielding a hydrocarbon () 810. Write the structures of compounds (B) and (). Based on this information, two isomeric structures can be proposed for alkene (A). Write their structures and identify the isomer which one catalytic hydrogenation (/Pd ) gives a racemic mixture. 10. Write down the heterogeneous catalyst involved in the polymerization of ethylene. 11. Draw Newmann projection of relatively less stable staggered form of n-butane. The reason of low stability of this form is vander Waal s repulsion, torsional strain, or both. 1. Write the structures of ()N and (mesi) N. Are they isostructural? Justify your answer. SETIN V Miscellaneous Questions The following questions (to) consists of two statements, one labelled as ASSERTIN (A) and REASN (R). Use the following key to chose the correct appropriate answer. (a) If both (A) and (R) are correct, and (R) is the correct explanation of (A). (b) If both (A) and (R) are correct, but (R) is not the correct explanation of (A). (c) If (A) is correct, but (R) is incorrect. (d) If (A) is incorrect, but (R) is correct. ASSERTIN (A) REASN (R) 1. Addition of to 1-butene gives two optical isomers. 1-Butene on reaction with in the presence of a peroxide produces 1- bromobutane. Additino of bromine to trans--butene yields meso-, -dibromobutane 4. Addition of to = gives and not = = 5. But--yne or reduction with Na/N(l) gives trans--butene Butene on reation with in the presence of a peroxide produces 1- The product contains one asymmetric carbon. It involves the formation of a primary radical. omine addition to an alkene is an electrophilic addition. A triple bond is less reactive than a double bond. To minimize interelectronic repulsions the addition of electrons occur on the opposite faces of the triple bond. It involves the formation of a primary radical.

27 SM 7 bromobutane Answers to Assignments SETIN - I 1. (b). (d). (c) 4. (c) 5. (c) 6. (b) 7. (d) 8. (b) 9. (d) 10. (b) 11. (c) 1. (c) 1. (b) 14. (b) 15. (c) 16. (d) 17. (c) 18. (d) 19. (d) 0. (b) 1. (b). (a). (b) 4. (b) 5. (b) SETIN - II 1. (a), (c), (d). (b), (c). (a), (c) 4. (a), (b), (c) 5. (a), (b), (c) 6. (a), (b), (c) 7. (b), (c), (d) 8. (a), (c) 1. (a). (d). (c) 4. (b) 5. (b) 6. (a) 9. (a), (b), d) 10. (a), (b) 11. (a), (c) 1. (a), (d) 1. (c), (d) 14. (b), (c), (d) 15. (b) 16. (c) SETIN - III 7. (a) 8. (a) 9. (b) 10. (d) 11. (c) 1. (b) SETIN - IV LEVEL I 17. (a), (c) 18. (a), (b), (c), (d) 19. (a), (b), (c) 0. (a), (b), (c) 1. (a), (b). (a), (c). (a), (b), (c), (d) 1. (a) 14. (b) 15. (b) 16. (a) 17. (d) 18. (c) 1. Reduction Reduction (A) (B) () As (A) on ozonolysis yielding two aldehydes its formula suggest that it has two double bonds. As (D) and (E) So A (hexa,4diene)

28 SM 8 /Zn (A) (D) (E) 1,4addition [] KMn / (F). Given alk. KMn 4 chiral () (D) achiral Inert to oxidation Since benzoilic acid is the product ` should be monosubstituted benzene Achiral and resistant to oxidaztion () (D). An alkyl halide X (61l) gives two isomeric alkenes Y and Z. Since it is forming two isomeric alkane on dehydrohalogenation reaction, l should not be at the terminal alkyl group. The reaction are l Potassium tertbutoride (Y) (Z) ydrogenation Y&Z (Z)

29 SM 9 4. a) (Trans Addition) Ph (A) (B) b) l 5. a) 5 (i) B, TF 5 (ii), (Trans and racemic) b) 6. a) ( ) B, b) ( ) B, c) [ ] B, d) 7. a) b) 8. a) NaN Na b) /g 9. a) A = Na B = Na = D = E = isoprene

30 SM 0 b) A = B = = 10. X = triple bond is not affected by Y = KMn 4 hydroxylates = bond and bond Z = ; =, and bonds are affected due to ozonolysis LEVEL II 1. a) l b) (A) (B) ( ) (B),dimethylbu tanol1 c). a) Electrophilic addition of on carbon - carbon double leads to the formation of carbocation while that on carbon - carbon triple bond leads to the formation of vinylic carbocation as the intermediate. Vinylic carbocation being most unstable whereas -carbocation being relatively more stable, addition is favoured on ethylenic linkage more stable, addition is favoured on ethylenic linkage rather than on acetylenic. Addition on carbon - carbon double bond:

31 SM 1 = + - carbocation (Actual product) Addition on carbon - carbon triple bond. = + = = (Vinylic carbocation) = = b). A = B = = ( ) 4. I = J = I I 5. a) X = B = b) i) Z = l l All

32 SM ii) Na NaN / Phenyl ethene Phenyl1, dibromo ethane I Phenyl prop-1-yne 6. A = = E = B = cis D = trans Na F = 7. LiAl4 /g onc. S 4 (A) (B) () (D) (D) can also be obtained from (A) as follows: Pda (A) 8. i) (A) (B) () (D) (E) ii) (A) (B) () (D) (E) (F) iii) A = B = = D = E = ( mol)

33 SM 9. (A) (B) 10. l (A) (B) () l LEVEL III 1. (A) is ozone as it reacts with butene- to show ozonolysis. Zn / The deep red coloured compound is K and gas is 5 K K 5 (A) (B) () l l l Mg / ether Mgl Mgl Mgl (Y) 5 Mgl Mgl 5 Mgl (Intermediate) (Z) (Z) can also be ( ). (i) ompound (E) gives (F) on hydrogenation. Also (E) on ozonolysis gives & - ketopropanal. Thus (E) (5 8) having two double bonds may be

34 SM 4 E is The reactions are ydrogenation zonolysis 4. The formula and reactions suggest that: (A) (dicyclopropyl ethyne) ozonolysis (B) Mg Mg (cyclopropyl bromide) 5. i) It should be an alkene as it adds one mole of ii) Alkene should be symmetrical of six carbon atoms [] KMn4 6. i) Mol. wt. of (a) suggests is to be 4 6 i.e.,mol.wt. = 54 ii) 4 8 has terminal triple bond as it reacts with in presence of NaN iii) (A) (B) Mol. wt. = 54 Mol. wt. = Thus, Mol. wt. of B iv) () Mol. wt. = Thus Mol. wt. of NaN v) (D) zonolysis [] (D) (F) (E)

35 SM 5 7. i) ii) LiAl4 Lindlar catalyst S 4 5 iii) ( ) ( ) 8. A B Mg cyclobutylmagnesium bromide 1-cyclo butyl ethanol 1-bromo-1-methyl cyclopentane A B Ziggler Natta catalyst (R Al + Til 4 )

36 SM I (Less stable) II (Most stable) 1. SiMe N N SiMe SiMe They are not iso-structural SETIN - V 1. (a). (c). (b) 4. (a) 5. (a) 6. (c)