LEVEL I. 1. Electrolysis of concentrated solution of sodium propanate produces the hydrocarbon

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1 QUESTIN BANK--1 ydrocarbons LEVEL I 1. Electrolysis of concentrated solution of sodium propanate produces the hydrocarbon methane ethane propane butane. The reactivity of hydrogen atom in an alkane towards substitution by bromine atom is omination of an alkane as compared to chlorination proceeds at a slower rate at a faster rate with equal rates with equal or different rate depending upon the temperature 4. The product obtained on heating n-heptane with r3-al3 at 600 is cyclohexane cyclohexene benzene toluene 5. The major product obtained in the photobromination of -methylbutane is 1-bromo--methylbutane 1-bromo-3-methylbutane -bromo-3-methylbutane -bromo--methylbutane 6. Baeyer s reagent is alkaline potassium permanganate solution acidified potassium permanganate solution neutral potassium permanganate solution aqueous bromine solution 7. The ease of dehydrohalogenation of alkyl halide with alcoholic K is The order of stability of three alkenes R = R, R = R and R = R is R = R R = R R = R R = R R = R R = R R = R R = R R = R R = R R = R R = R 9. The addition of to an alkene in the presence of peroxide is the example of electrophilic addition reaction nucleophilic addition reaction free radical addition reaction the formation of carbocation as an intermediate

2 QUESTIN BANK The addition of to trans--butene produces (+)-,3-dibromobutane ( )-,3-dibromobutane rac-,3-dibromobutane meso-,3-dibromobutane 11. The treatment of ethene with cold alkaline potassium permanganate produces ethylene glycol formaldehyde formic acid carbon dioxide and water 1. The ozonolysis of an olefin gives only propanone. The olefin is propene but-1-ene but-1-ene,3-dimethylbut--ene 13. An alkene on oxidative ozonolysis gives adipic acid? The alkene is cyclohexene 1-methylcyclopentene 1,-dimethylcyclobutene 3-hexene 14. When propyne is treated with aqueous S4 in the presence of gs4, the major product is propanol propyl hydrogen sulphate acetone propanal 15. Acidic hydrogen is present is ethyne benzene ethene ethane 16. Propyne when passed through hot iron tube at 400 produces benzene toluene xylene mesitylene 17. Which of the following is strongest acid? A hydrocarbon on ozonolysis yields,3-butanedione and acetone as the products of ozonolysis. The hydrocarbon may be,3,4,5-tetramethyl-, 4-hexadiene,5-Dimethyl-, 4-hexadiene,4-Dimethyl-, 4-hexadiene,5-Dimethyl-1, 5-hexadiene 19. Benzene reacts with iso-butyl chloride in the presence of anhydrous All3 to give tert-butylbenzene iso-butylbenzene n-butylbenzene sec-butylbenzene 0. Na 3 Peroxide ether X Y The compound Y in the above sequence is Propane n-exane,3-dimethylbutane,4-exadiene 1. Which of the following has only one type of hybridized cabron

3 QUESTIN BANK Presence of electron-withdrawing substitutents stabilizes carbocations, carbanions as well as free radicals stabilizes carbocations and carbanions stabilizes carbocations and free radicals stabilizes carbanions 3. The correct IUPA name for 3 5-methyl-4-(1--dimethylpropyl)heptane 3-methyl-4-(1,-dimethylpropyl)heptane,35-trimethyl-4-propylheptane 4-propyl-,3,5-trimethylpeptane 4. Which of the following has maximum resonance energy? All equal 5. The number of stereoisomers formed by the catalytic hydrogenation of both double bonds in the following compound will be Answers

4 QUESTIN BANK LEVEL II 1. The reaction conditions leading to the best yield of 5l are uv light dark (excess) l l 6 uv light 6 l (excess) 6 room temperature l 6 uv light. The highest boiling point is expected for isooctane,,3,3-tetramethylbutane n-octane n-butane 3. Anti-Markovnikov addition of is not observed in propene butene -butene -pentene 4. i) S l X ii) NBS Y In both the cases, allylic substitution occur In (i), addition occurs while in (ii) allylic substitution occurs In (i), allylic substitution occurs while in(ii) addition takes place In both the cases, addition occur. 5. In 3, the bond that undergoes heterolytic cleavage most readily is

5 QUESTIN BANK hlorobutane on reaction with alcoholic potash gives 1-butene 1-butanol -butene -butanol 7. For the following reactions 3l l 3l l the correct order of enthalpies of ionization is (3)l (3) + + l 0 (3)3l (3)3 + + l The treatment of 3 3with NaI4 or boiling KMn4 produces only 9. The intermediate during the addition of l to propene in the presence of peroxide is 3l The reaction with gives The correct order of increasing stability of the given alkenes is 1-pentene cis-pentene trans-pentene -methyl--butene 1-pentene trans-pentene cis-pentene -methyl--butene 1-pentene cis-pentene trans-pentene -methyl--butene 1-pentene trans-pentene cis-pentene -methyl--butene 1. The treatment of trans--butene with baeyer s reagent produces (S, 3S)-,3-dihydroxybutane only (R, 3R)-,3-dihydroxybutane only (R, 3S)-,3-dihydroxybutane a mixture of (S, 3S) and (R, 3R)-,3-dihydroxybutane.

6 QUESTIN BANK An alkene on treating with hot acidified KMn4 gives 4-oxopentanoic acid. The alkene is pentene -pentene 1-methylcyclobutene 1,-dimethylcyclopropene 14. What is the decreasing order of strength of the bases, N, and 3? 3 N 3 N N 3 N 3 [1993] 15. The addition of water to propyne in the presence of gs4 S4 produces Which of the following orders regarding acid strength is correct? Which of the following orders regarding base strength is correct? From the following reactions LiN N3 Li Li Li predict which of the following facts regarding the base strength is correct? LiN Li Li LiN Li Li Li LiN Li Li Li LiN 19. When cyclohexane is poured on water, it floats, because yclohexane is in boat form yclohexane is in chair form yclohexane is in crown form yclohexane is less denser than water 0. The reaction of propene with l proceeds via the addition of + in the first step l + in the first step in the first step l + and in a single step 1. Which of the following reactions proceeds through carbocations as intermediate? Diffused Sunlight 3 l K 3 Peroxides Fel 3 l

7 QUESTIN BANK--7. Which of the following compounds would not yield glyoxal as one of the products of ozonolysis? Toluene Isoprene 1,3-Butadiene Ethyne 3. Which of the following compounds gives white precipitate on reaction with ammonical solution of AgN3? -Pentyne 3-Methyl-1-butyne 1-Pentene -Butyne 4. Which of the following compounds react with obeying Markovnikoff s rule? Propyne and propene can be distinguished by conc. S4 in l4 dil. KMn4 AgN3 in ammonia Answers

8 QUESTIN BANK LEVEL III 1. f the following compounds, which will have a zero dipole moment? 1,1-dichloroethylene cis-1,-dichloroethylene trans-1,-dichloroethylene none of these compounds. i) 3/ ii) heat A; A is () 3 3. n-propyl bromide on treating with ethanolic potassium hydroxide produces propane propene propyne propanol 4. The final product (D) formed in the following reaction sequence is: Naphthalene Benzene NBS alc.k Pd / AD D Tetralin Anthracene 5. For the following reactions catalyst catalyst 3 3 which of the following facts is expected to be correct? < Identify A and B /Pd AB and and and and 7. From the following reactions

9 QUESTIN BANK--9 LiN N3 Li 3 N R N R predict which of the following orders regarding base strength is correct R N R N R N R N 8. zonolysis of,3-dimethyl-1-butene followed by reduction with zinc and water gives Methanoic acid and 3-methyl--butanone Methanal and -methyl--butanone Methanal and 3-methyl--butanone Methanoic acid and -methyl--butanone 9. (3)3Mgl on reaction with D produces (3)3D (3)3D (D)3D (D)3D 10. Identify B i) NaN (3equivalent) [A] [B] 6 5 ii)3 I Identify final product in the reaction NaN (1equiv) Al 3, 3 3 Pd 400 A B D E Isoprene hloroprene Neoprene amphene 1. In presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti- Markovnikoff s addition to alkenes because both are highly ionic one is oxidizing and the other is reducing one of the steps is endothermic in both the cases all the steps are exothermic in both the case 13. Identify the end product ul A B (Main) N4l Pt / BaS4

10 QUESTIN BANK onsider the following reaction, 3 + X D Identify the structure of the major product X 3 3 D D 3 3 D 15. Which of the following is used for the conversion of -hexyne into trans--hexene? /Pd/BaS4, Pt NaB4 LiN3/5 16. A compound X (58) reacts with ammonical AgN3 solution to give a white precipitate, and on oxidation with hot alkaline KMn4 gives the acid (3). ompound X may be 3-Methyl-1-butyne 3-Methyl-1-butene -Methyl-1,3-butadiene 1-Pentyne 17. A hydrocarbon X decolourises bromine water. It reacts with one mole of to give another saturated hydrocarbon. X reacts with acidified KMn4 to give two moles to propanoic acid. X could be NBS alc. K 3 X Y The compound Y is But-3-en--ol But-3-en-ol 1,3-Butadiene 1,-Butadiene

11 QUESTIN BANK Which of the following is obtained as the product when excess benzene reacts with l in the presence of anhydrous All3. l l l l l 0. Identify the end product (Z) in the following sequence: r 3/ 3 Se/ Zn dust/ (W) (X) (Y) (Z) 1. In the reaction sequence? A is /S 4 g A S 3 None of these. Which of the following hydrocarbon can react with maleic anhydride? (I) (II) (III) (IV) only (i) (i), (iii) and (iv) (i) and (iv) all the four

12 QUESTIN BANK The ease of nitration of the following three hydrocarbons follows the order (I) (II) (III) II = III I III II I II III I I = III I 4. The following alcohol is treated with conc. S4 the major product obtained is 5 6 conc. S4 ( ) Mgl (i) B6 X. The compound X is - (ii), Both and Answers

13 QUESTIN BANK ints & Solutions YDRARBN INTS AND SLUTINS LEVEL I 1. Electrolysis of 3Na will produce 33 (butane).. The reactivity of hydrogen atom is omination proceeds with much slower rate as compared to chlorination. 4. r3al 3 33

14 QUESTIN BANK Methylbutane is 3. The major product in the photobromination is 3 () 6. Baeyer s reagent is an alkaline potassium permanganate solution. 7. The more stable intermediate 3 carbocation is formed more easily than and is formed faster than 1. ence, the ease of dehydrohalogenation follows the order According to Saytzeff rule, more substitute alkene is more stable. ence, the order of stability is R = R R = R R = R 9. The addition of across a double bond in the presence of peroxide involves free radical addition. 10. The addition of to trans--butene produces meso-, 3-dibromobutane. 11. The treatment of ethene with cold alkaline potassium permanganate produces ethylene glycol ,3-dimethylbut--ene S 4/gS Ethyne ( ) contains acidic hydrogen. 16. Fe tube mesitylene 17. The acidic character is in the order:

15 QUESTIN BANK ,3,4,5-tetramethylhexa-,4-diene l All , ydride shift All tert-butyl carbocation tert-butyl carbocation on reaction with benzene gives tert-butyl benzene = 1. Do yourself ( ) Peroxide Na 3 ether 3 4 a nexane. Electron-withdrawing substituents disperse the electrons or negative charge, hence they stabilize carbanions, and destabilize carbocations. 3. In case two or more chains are of equal length, then the chain with greater number of side chains is selected as the principal chain ,3,5-trimethyl-4-propylheptane 4. Resonance energy = Theoretical heat of hydrogenation Experimental heat of hydrogenation Benzene has 3 double bonds, so its theoretical heat of hydrogenation will be more than that of cyclobutadiene having double bonds. Further, since all the double bonds in benzene form a delocalized orbital over the complete ring, the molecule is quite stable with less experimental heat of hydrogenation however, it is not in cycloheptatriene which has one sp 3 carbon, hence the 6 electrons are not delocalized over the complete ring with the result the difference between theoretical and experimental heat of hydrogenation (resonance energy) will be quite low. 5. ydrogen may add to both double bonds from the same face to form meso compound B. If adds to the two double bonds from opposite faces, the two enantiomers ( and D) are formed in equal amounts.

16 QUESTIN BANK--16 meso (B) Racemic mixture ( and D) LEVEL - II 1. Excess quantity of 6 will yield mono chlorinated product (i.e. 5l). n-ctane is expected to have the highest boiling point. 3. -Butene is 3=3. The addition of gives the same product whether it occurs via Markovnikov or anti-markovnikov rule. 4. i) S l Sulphuryl chloride l NBS Wohl Ziegler bromination In both cases, allylic substitution take place. 5. will show heterolytic cleavage. 6. 3l ethanolic 3= K 7. The more stable carbocation, the lesser the value of. ence, the order is NaI The addition of l proceeds via the formation of carbocation 3 3. The peroxide is not able to produce radicals from l as the bond l cannot be broken into radicals Saytzeff s rule dictates -methyl--butene to be more stable than pentenes. Trans-pentene is more stable than cis-pentene due to less crowding of bulky groups. 1-pentene will be

17 QUESTIN BANK--17 least stable. ence, the correct order of stability is 1-pentene cis-pentene transpentene -methylbutene. 1. The product is a mixture of (S, 3S) and (R, 3R)-, 3-dihydroxybutane for trans-- butene. 13. KMn4 1-methylcyclobutene 4-oxopentanoic acid 14. The strength of conjugate acids follows the order 33 N3 The strength of given bases follows the order 3 N The product is which rearranges to arboxylic acid is stronger than alcohol which, in turn, is tronger than acetylene. 17. Base strength follows the reverse order of their conjugate acid. ence, the order is From the given reaction,s the order of base strengths is : LiN Li and Li Li. ence, the corret order of base strength is LiN Li Li 19. yclohexane is ligher than water. 0. l ionizes of and l +. The attacking electrophile is, therefore, l Electrophilic substitution reactions of benzene take place via reasonance stabilized carbocation as intermediate.. Isoprene would yield methanal and methyl glyoxal Methyl-1-butyne is a terminal alkyne. 4. contains unsymmetrical double bond. 5. Propyne gives white ppt. with ammoniacal AgN3 while propene does not react. LEVEL III 1. trans-1, -dichloroethene will have zero dipole moment.., 3 () heat 3

18 QUESTIN BANK ethanolic 3=. K Dielsalder reaction NBS (A) (B) alc. K K, - Pd Tetralin () naphthalene (D) 5. The value of s of hydrogenation are kj mol 1 and kj mol 1 for triple to double and double to single bonds, respectively. Most of alkyne is hydrogenated before alkene starts hydrogenated. 6 /Pd 7. We have LiN Li and R N. ence, the correct order is R N (i) 3 (ii) /Zn 3 9. (3)3Mgl + D (3)3D + Mg(D)l (A) NaN Na + 3I NaI NaN 1/ 5 6 (B)

19 QUESTIN BANK Na Na 3 Tautomerise 3 NaN N3 3 addition 3 3 (A) (B) 3 3 Al 3,400, Pd 3 (E) isoprene (D) () 13 4 ul/ N l Pt / BaS4 1,4-Addition (Main) 1,-Addition (Less) 14. The free radical formed in this case is 3 and hence most stable. 15. The partial reduction of alkynes by active metals, such as Li and Na, in liquid ammonia produces trans alkene. 16. Formation of (3) indicates the presence of (3) group in the compound whereas formation of white ppt. with ammonical AgN3 indicates the presence of terminal triple bond. KMn 4 / = 3 + [] NBS brings about allylic bromination. NBS 3 3 alc. K 19. Factual question.

20 QUESTIN BANK--0 0 r 3/ 3 (W) (X) Se/ Zn dust / (Y) (Z) 1 / S4 g Ketoenol tautomerism. It is an example of Diel s-alder reaction in which a dienophile (maleic anhydride, here) reacts with a conjugated diene to form cyclic adduct. ere although structure (i), (iii) and (iv) have conjugated system of double bonds, hence theoretically all the three can undergo Diel s-alder reaction, but strucvture (iii) does not undergo this reaction becaue this will lead to larger ring (9-membered) which is unstable All the three compound have same electron-releasing groups, but the presence of two such groups in II and III make them more reactive than I. Further note that in m-xylene (II), the two methyl groups cooperate each other at two positions, while in III no position is activated by both the groups rearranges 6 5 Benzyl carbocatron is more stable trans-(more stable due to steric relief) cis-(less stable due to bulky gps. lying on same side)

21 QUESTIN BANK ydroboration-oxidation reaction of alkenes leads to anti-markovnikov s hydration. Further addition of water adds in syn-manner, i.e., and are added to the same face of the double bond leading trans-product. In short, hydroboration-oxiadtion of alkenes is regioselective as well as stereoselective. 3