Isomerism Organic Halide

Transcription

1 Isomerism rganic alide r. Sangeeta Khanna Ph. 1 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

2 r. Sangeeta Khanna Ph. Test ate: Topic: rganic alide & Isomerism RE INSTRUTINS REFULLY 1. The test is of 2 hour duration. 2. The maximum marks are 80.. This test consists of 87 questions. 4. Keep your mobiles switched off during Test in the alls. (Single orrect hoice Type) Negative Marking [-1] This Section contains 45 multiple choice questions. Each question has four choices ), ), ) and ) out of which NLY NE is correct. Marks: 45 4 = In the given reaction PhMg + 2 (X); (X) will be: a. b. c. d. Mg 2. When the concentration of alkyl halide is triple and concentration of S N 2 Θ is reduced to half, the rate of a. times b. 1.5 times c. 2 times d. 6 times Rate = K[alide] [ ]. N 2 ompound is: 1. NaN , u N 2 N 2 N 2 a. b. c. d. [iazotisation & sandmeyer] 4. rder of stability of alkene is 2 (X) \ / (Y) 2 2 is: (Z) a. X > Y > Z b. Y > X > Z c. Z > X > Y d. Y > Z > X [Stability yperconjugation] r. Sangeeta Khanna Ph. 2 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

3 r. Sangeeta Khanna Ph. 5. Geometrical isomerism is possible in : a. b. c. d. 6. and are: 2 2 a. iastereomers b. Enantiomers c. Tautomers d. onformers 7. Which of the following is used as a purity test for chloroform? a. aq. K b. aq. K + gn c. gn solution d. xidation test 8. t-butyl bromide aq. K (X). The main product (X) is low temp. a. tertiary butyl alcohol b. 1-butoxy butane c. iso-butylene d. propene 9. When ethyl benzene is treated with one equivalent N-bromosuccinimide in 4, the major product obtained is 2 2 () 2 2 a. b. c. d. enzylic omination with NS 10. The decreasing reactivity order of halides towards dehydrohalogenation is a. RI > R > R > RF b. RI > R > R > RF c. RF > R > R > RI d. RF > RI > R > R K This reaction takes place mainly by a. S N 1 mechanism b. S N 2 mechanism c. free radical mechanism d. E1 mechanism 12. () (i) aq. Na white precipitate. () can be (ii) gn a. vinyl chloride b. benzyl chloride c. chlorobenzene d. o-chlorotoluene r. Sangeeta Khanna Ph. EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

4 r. Sangeeta Khanna Ph. 1. In an S N 1 reaction on chiral centres, there is: a. inversion more than retention leading to partial racemization b. 100% retention c. 100% inversion d. 100% racemization SN1 reaction gives racemic mixture with slight predominance of that isomer which corresponds to inversion because SN1 also depends upon the degree of 'shielding' of the front side of the reacting carbon. 14. I () () The product () is 2 2 Θ N 1mole 2 / a. 2 2 I b. 2 2 c. 2 2 d. 2 2 I Iodide is more reactive & -N gp on complete hydrolysis give acid. 15. What will be the order of reactivity for the nucleophilic substitution of chlorine in the following compounds? N 2 N 2 N 2 () () () () a. () > () > () > () b. () > () > () > () c. () > () > () > () d. () > () > () > () [e withdrawing gp increases Reactivity] 16. Which of the following alcohols will give a yellow coloured precipitate with iodine and sodium hydroxide? 2 a. b. c. d The correct order of S N 2 reactivity among the following is a. > > I b. > 2 > ( ) 2 c. 2 > 2 2 > d. ( ) > ( ) 2 > 2 2 r. Sangeeta Khanna Ph. 4 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc 2

5 r. Sangeeta Khanna Ph. 18. Which of the following is the correct order of dipole moment of methyl halides? a. F > > > I b. > F > > I c. I > > F > d. I > > > F ( ) K /( ) omopentane P The major product (P) formed in the above reaction is a. pent-1-ene b. cis pent-2-ene c. trans pent-2-ene d. 2 2 ( ) offmann s product with ulky base. 20. hloroform on boiling with Na solution gives a. sodium methoxide b. Methanal c. sodium methanoate d. dichloromethanol K K K 21. The organic compound formed in the following reaction is 6 5 g / ref lux product a. 6 5 b. 6 5 c. d. 22. The product formed when isopropyl alcohol is heated with a 2 + Na(aq.) is a. propyne b. 2-chloropropane c. chloroform d. carbon tetrachloride 2. The correct order of reactivity of the following alcohols with hydrobromic acid () is 1 phenylpropan 1 ol 1 phenylpropan 2 ol phenylpropan 1 ol (I) a. I > II > III b. I > III > II c. III > I > II d. III > II > I rder of Reactivity Pri. < Sec. < tert. 24. Which of the following statements is correct? a. 2 S is a stronger base, but weaker nucleophile than 2. b. 2 S is a weak base, but more nucleophilic than 2. c. 2 S is a stronger base and more nucleophile than 2. d. 2 S is a weak base and less nucleophilic than Identify the false statement among the following (II) a. The rate of hydrolysis of tert-butyl chloride does not change by increasing the concentration of [SN 1 ] b. 2-phenylethanol reacts with thionyl chloride to give a chloro compound with almost complete retention of configuration [SN i ] c. Polar solvents generally increase the rate of S N 1 reactions. d. S N 2 reaction of optically active substrate leads to racemization if the leaving group is attached to the chiral carbon. r. Sangeeta Khanna Ph. 5 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc (III)

6 r. Sangeeta Khanna Ph. 26. The configuration of the product in the following reaction NaI/acetone Product 2 2 a. b. c. d. None I I What is the relationship between the pair of compounds shown? I a. Identical: superimposable without bond rotations b. onformations c. Stereoisomers d. onstitutional isomers 28. orrect IUP name of following compound is a. 2-hlorocyclohexene b. -hlorocyclohexene c. yclohexenylchloride d. 1-hlorocyclohex-2-ene Fe X; X is a. b. c. d. None group is meta directing. 0. Which of the following reaction(s) can be used for the preparation of alkyl halides? anh. Zn 2 (I) (II) anh. Zn 2 (III) ( ) + (IV) ( ) a. (I) and (II) only b. (IV) only c. (III) and (IV) only d. (I), (III) and (IV) only (I) and (IV) can be used due to presence of anhydrous Zn 2 (III) gives alkyl halide due to formation of more stable carbocation. r. Sangeeta Khanna Ph. 6 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc 2

7 r. Sangeeta Khanna Ph. 1. Which of the following statements is not correct for a nucleophile? a. mmonia is a nucleophile b. Nucleophiles attack low e density sites c. Nucleophiles are not electron seeking d. Nucleophile is a Lewis acid Reason: Nucleophiles are electron rich species so act as Lewis base. 2. The number of structural isomers possible from the molecular formula 9 N is : a. 5 b. 2 c. d. 4. In the reaction with, an alkene reacts in accordance with the Markovnikov's rule, to give a product 1-chloro-1-methylcyclohexane. The possible alkene is 2 = 2 a. b. c. d., 2 + or 4. Na Product: a. b. c. d. No reaction and are not anti position. r. Sangeeta Khanna Ph. 7 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

8 r. Sangeeta Khanna Ph. 5. (II) (III) (IV) (I) Which omine is most reactive for SN 2 attack of ion a. I b. II c. III d. IV (III) (II) (IV) (I) [electron withdrawing group increases Reactivity in SN 2 ] 6. = Major product: a. b. 2 2 c d. = 2 (1 mol) () () 6 5 Fe The structure of (c) is NS / (i) Mg/ether (ii) (iii) + () a. b. c. d Mg NS Mg (i) (ii) r. Sangeeta Khanna Ph. 8 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

9 r. Sangeeta Khanna Ph. 8. To prepare 2-Methylbutane from ethyl chloride which of following will be the best reagent? a. Na (dryether) b. c. 2 2 Li + ux d. Li ux Na 2 (dryether) u LI 2 ux Li 2-Methylbutane 9. Which of the following alkyl bromides may be used for the synthesis of 2, -dimethyl butane by Wurtz reaction? a. b. c. Isobutyl bromide d. s-butyl bromide + 2Na + dry ether 40. Which among the following pairs are diastereomers: and and 2 2. and 4. I and I 2 2 Select the correct answer from the codes given below : F F a. only 2 b. only 1 c. 1 and 2 d. 1, 2 and Which of the following compounds are meso forms? a. 1 only b. only c. 1 and 2 d. 2 and r. Sangeeta Khanna Ph. 9 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

10 r. Sangeeta Khanna Ph. 42. onsider the following pair of compounds: Which among the following statements is correct? 1. oth are enantiomers 2. oth are in threo form. oth are diastereomers 4. oth are in erythro form a. 1 and 2 b. 1, 2 and c. 2 and d. and (1) 2 5 (2) 4. onsider the following reaction sequence In this and respectively are 2/Fe N / 2S 4 elow 0K N / 2S 4 2/Fe a. b. and N 2 and N 2 N 2 N 2 c. d. 44. hydrocarbon with molecular mass 84 gives a single monochloride but four dichlorides (only structural) on photochemical chlorination. The hydrocarbon is S and a. yclopentane b. yclohexane c. 2, -imethylbutane d. Methyl cyclopentane Single monochloro product Four dichloro products 45. Match the column I with column II olumn I NaN 2 in liq.n olumn II () hlorobenzene (p) meso-2, -ibromobutane () cis-2-utene 2 () trans-2-utene 2 () p-nitrochlorobenzene N 2 2. h 2. h 6 12 (mol. wt. 84) + + q. K () + (q) enzyne mechanism (r) imolecular mechanism (s) (±)-2, -ibromobutane r. Sangeeta Khanna Ph. 10 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc N 2 and N 2 N 2

11 r. Sangeeta Khanna Ph. a. p ; r; q ; - s b. q ; s ; p ; r c. p ; r; s ; q d. q ; r, s ; p (chlorobenzene) q(benzyne mechanism); (cis-2-butene)-s ((±)-2, -dibromobutane); (trans-2-butene)-p(meso-2, -dibromobutane); (p-nitrochlorobenzene)-r-(bimolecular /mechanism). rsn 2 SETIN (SSERTIN & RESN) This Section contains 10 multiple choice questions. Each question has four choices ), ), ) and ) out of which NLY NE is correct. (10 5 = 50 Marks) (a) Statement -1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1 (b) Statement- 1 is True, Statement-2 is True; Statement-2 is NT a correct explanation for Statement-1 (c) Statement-1 is True, Statement -2 is False (d) Statement 1 is False, Statement-2 is True 1. Statement 1: Nucleophilicity does not always match with basicity. Statement 2: While nucleophilcity is more related to size, polarizability and steric factors, the basicity is the ability to abstract a proton from a substrate & depend on stability of bond with hydrogen a. (a) b. (b) c. (c) d. (d) 2. Statement 1: 2 2 when treated with NaN gives mainly the corresponding cyanide or nitrile. Statement 2: Sodium cyanide have only one nucleophilic centre on carbon atom. a. (a) b. (b) c. (c) d. (d) N is ambident Nucleophile.. Statement 1: Fluorobenzene undergoes nucleophilic substitution much faster than chlorobenzene. Statement 2: Fluorine being more electronegative causes more decrease in electron density at the carbon leading to a faster attack by the nucleophile & it also stablise intermediate formed after nucleophilic attack. a. (a) b. (b) c. (c) d. (d) 4. Statement 1: In Reimer Tiemann reaction of phenol only one aldehyde group will be introduced at either ortho & para position Statement 2: ldehyde group introduced after first RTR, will deactivate the ring for further Reimer Tiemann s reaction a. (a) b. (b) c. (c) d. (d) 5. Statement 1: rder of acidic strength of trihalomethane is: > F > > I Statement 2: onjugate base of is resonance stabilized for, rest of the trihalide decrease in I effect will decrease the acidic strength. a. (a) b. (b) c. (c) d. (d) r. Sangeeta Khanna Ph. 11 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

12 r. Sangeeta Khanna Ph. 6. Statement 1: liphatic pri-amine are less reactive than aromatic pri.amine on reaction with & alc. K Statement 2: oth give foul smelling isocyanide on reacting with & alc. K a. (a) b. (b) c. (c) d. (d) 7. Statement 1: 2 Ph 2 2 N 2 2 on heating in presence of g 2 give vinylbenzene as major product Statement 2: Least acidic -hydrogen will be attacked by. a. (a) b. (b) c. (c) d. (d) 8. ssertion. = exhibits geometrical isomerism but 2 2 does not. Reason. Geometrical isomerism arises due to restricted rotation about = double bond a. () b () c. () d. () 9. ssertion. Twist boat conformation of cyclohexane is more stable than boat formation. Reason. Flagpole-flagpole interactions are less severe in boat conformation than in twist boat conformation. a. () b.() c. () d. () 10. ssertion. Stereoisomers which are not mirror images are called diastereomers. Reason. iastereomers may or may not be optically active. a. () b. () c. () d. () SETIN (Paragraph Type) This Section contains 2 paragraph. Each of these questions has four choices ), ), ) and ) out of which NLY NE is correct. 9 4 = 6 Marks omprehension 1 Since Grignard reagents resemble carbanion so they are strong nucleophile and strong base. Their most useful nucleophilic reaction is addition to carbonyl group. Θ \ RMgX / Θ X / R MgX R Mg \ 1. Which of the following compounds will not give acid-base reaction with RMgX? a. 2 b. c. N d. 2 S 2 give substitution reaction. r. Sangeeta Khanna Ph. 12 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

13 r. Sangeeta Khanna Ph. 2. Which of the following compounds give racemic mixture on reaction with Mg? a. b. c. Ph d. Ph Θ \ Mg Racemic Product /. What will be the final product in the following: (1) Mg dry ether (2) (5) KN (6) a. 2 b. 2 2 c. d N Mg Mg () (4) P (1) P 5 (2) KN 2 2N Which of the following will give sec. alcohol with excess of grignard Reagent a. b. 2 5 c. d. 25 R RMgX R - MgX R R sec. alcohol 5. Which of the following is the final product of given reaction Mg 2. Product a. b. c. d r. Sangeeta Khanna Ph. 1 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc 2 2

14 r. Sangeeta Khanna Ph Mg Passage 2 Under common reaction conditions, a carbocation rearranges to another carbocation of equal or greater stability. For example, secondary carbocation will rearrange to a tertiary carbocation. It will not rearrange to a less stable primary carbocation. This generalization is not absolute, and because there is not a high energy barrier to the rearrangement of carbocations, rearrangement to a less stable cation can occur if it offers the chance to form a more stable product. 6. In which of the following cations rearrangement takes place? a. b. c. d In which of the following cations rearrangement takes place most rapidly? a. 2 b. 2 c. d. 2 2 Ph 2 8. In the following cation, / that is most likely to migrate to the positively charged carbon is: a. at 4 b. at 4 c. at 2 d. at ,-imethyl-2-butene can be prepared by heating which of the following compounds with a strong acid? a. ( ) = 2 b. ( ) 2 = 2 c. ( ) 2 2 = 2 d. ( ) 2 2 r. Sangeeta Khanna Ph. 14 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

15 r. Sangeeta Khanna Ph. + = 2 shift - + = SETIN (More than ne nswer Type) No Negative Marking This Section contains 10 multiple choice questions. Each question has four choices ), ), ) and ) out of which ne or More than one answer may be correct = 50 Marks 1. Which of the following are correct order of nucleophilicity? a. N N2 N2 b. Θ Θ Θ 2 Θ Θ Θ Θ c. F I d.,, 2. Which of the following are electrophiles? > a. F b. 2 c. 4, N omplete octet, not electrophilic.. Which of the following have asymmetric carbon atom? N d. I Θ a. 2-2 b. - 2 c. - d. 2 --, 4. Which structure/s has (R) configuration? a. b. c. 2 5 d. Et 2 7, 5. Which of the following will not give addition reaction with RMgX? a. 2 b. 2 c. S 2 d., (b,d) (b) gives substitution reaction while (d) gives acid base reaction. r. Sangeeta Khanna Ph. 15 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

16 r. Sangeeta Khanna Ph. 6. For an S N 2 reaction, which of the following statements are true? a. The rate of reaction is independent of the concentration of the nucleophile. b. The nucleophile attacks the -atom on the side of the molecule opposite to the group being displaced c. The reaction proceeds with simultaneous bond formation and rupture. d. More than one transition states are formed, 7. Which of the following are chiral? a. 25 P b. \ S Ph / c. 25 N d. \ S / 65 65,, 8. Which of the following is the correct order as indicated a. F < 2 2 < 2 2 (oiling point) b. < 2 2 < < 4 (density) c. < F < < I (density) d. 4 < < < 2 2 (dipole-moment), 9. mong the following pair of reactions in which pair second reaction is more reactive than first for S N 1 reaction? a. Me + 2 and Me + 2 b. Me + and Me + c. Me 2 and Me 2 d. Me + S and Me F + S (1M) (2M), 10. Predict the pair in which 2 nd will undergo solvolysis (in aqueous ethanol) more rapidly. (I) II I II a. b. 2 c. d.,, r. Sangeeta Khanna Ph. 16 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

17 r. Sangeeta Khanna Ph. SETIN E (Matrix Type) No Negative Marking This Section contains questions. Each question has four choices (,, and ) given in olumn I and five statements (p, q, r, and s) in olumn II. ny given statement in olumn I can have correct matching with one or more statement(s) given in olumn II. 8 = 24 Marks 1. Match List I with List II (Single Match) olumn I (Statement) olumn II (Reason) () 2 S is weaker nucleophile than S Θ (p) ulky group present on nucleophilic centre decreases nucleophilicity () Θ Θ (q) Nucleophilicity decreases on going from left is stronger nucleophile than N 2 to right in the period of periodic table () (r) species with negative charge is a stronger R P is stronger nucleophile than R N nucleophile than a similar species without a () Θ is weaker nucleophile than Θ r; q; s; p 2. Match the olumn I with olumn II. olumn I (s) negative charge Nucleophilicity increases on going down in the group of the periodic table olumn II () ( 2 ) N and ( ) N (p) Position isomers () 2 2 and 2 2 (q) hain isomers () and 2 2 (r) Functional isomers () 2 = and (s) Metamers (q); (s) or (q); (p), (s) ; (r). Match olumn (I) with olumn (II) (a) 2 Ph l + Ph 2 (p) Nucleophilic substitution (b) + Ph l Ph (q) Electrophilic substitution (c) K (aq.) (r) ation intermediate (d) 2, hv 2 (s) Free radical substitution (q), (r); (q), (r) ; (p), (r); (s) r. Sangeeta Khanna Ph. 17 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

18 r. Sangeeta Khanna Ph. SETIN F (Integer Type) No Negative Marking This Section contains 10 questions. The answer to each question is a single digit integer ranging from 0 to = The total number of methyl groups in the major product of reaction Na ry ether 2 Tertiary alkyl halide gives alkene in Wurtz reaction. Na ry ether 2 2. Total number of alkenes structure which will show geometrical isomerism of molecular formula (i) = 2 2 (ii) (iii) 2 (iv) 2 = 2 [1-hexene; 2,-dimethylbut-2-ene; 2,-dimethylbut-1-ene; 2,2-dimethylbut-1-ene do not show geometrical isomer]. ow many chiral carbons are there in Reserpine (in antipsychotic drug)? 8 N 4. The number of possible enantiomeric pairs that can be produced during monochlorination of 2- methylbutane is 2 2; 2 ; N N N r. Sangeeta Khanna Ph. 18 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc

19 r. Sangeeta Khanna Ph. 5. ow many optical isomers are possible for the compound? F 2 (single chiral) 6. ow many meso isomers of will be formed? nly one meso possible 7. ow many of the following are good substrate for oth SN 1 & SN 2 () 2 () () 2 () 2 = 2 (E) (F) (G) (F ) () ; (); (); () 8. ow many of the following give yellow ppt. with gn + aq.k () 2 = () 2 = 2 () 2 2 I 2 () ( ) (E) (F) = (G) 2 I 4; (b); (c); (d), (g) 9. ow many dimethyl cyclobutane will be possible (including stereoisomers)? 6 cis(meso) Trans (d, ) () cis-trans (2) (1) 10. ow many Mg molecules are required for the given molecule 2 4 acidic 2 electrophilic centre acidic cidic r. Sangeeta Khanna Ph. 19 EMISTRY ING IRLE :\Important ata\2016\+2\rg\test\grand Test\+2 Grand Test-5\+2 Grand Test-V.doc