MUNISH KAKAR s INSTITUTE OF CHEMISTRY

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1 REACTONS & PREPARATON OF HALOGENATED COMPDS. WS#3 Q1. Reagent for preparing a chloroalkane from an alcohol is (a) SOCl 2 (b) HCl/ZnCl 2 (c) PCl 3 (d) All of these Q2. n the addition of H to propene in the absence of peroxides, the first step involves the addition of (a) H + (b) - (c) H (d) Q3. When propene is heated at 800 o C in the presence of chlorine, it gives the following compound: (a) Polyvinyl chloride (b) No reaction (c) 1,2-Dichloropropane (d) Allyl chloride Q4. Toluene reacts with chlorine in the presence of light to give (a) Benzyl chloride (b) Benzoyl chloride (c) p-chlorotoluene (d) o-chlorotoluene Q5. The compound which reacts with H obeying Markownikov s rule is (a) 2 = 2 (b) cis-2-butene (c) trans-2-butene (d) () 2C = 2 Q6. Alcoholic solution of KOH is a specific reagent for (a) dehydration (b) dehalogenation (c) dehydrohalogenation (d) dehydrogenation Q7. The most reactive among the given compounds is: (a) 2 = Cl (b) 2 = 2Cl (c) 2Cl (d) C 6H 5Cl Q8. Anti-Markownikov addition of H is not observed in (a) Propene (b) 1-Butene (c) 2-Butene (d) 2-Pentene Q9. Alkyl halides can be converted to alkenes by (a) substitution (b) addition (c) elimination (d) rearrangement Q10. When hydrochloric acid gas is treated with propene in presence of benzoyl peroxide, it gives (a) 2-Chloropropane (b) Allyl chloride (c) no reaction (d) n-propyl chloride Q11. S N2 mechanism proceeds through the intervention of (a) carbocation (b) transition state (c) free radical (d) carbanion Q12. Silver benzoate reacts with bromine to (a) C 6H 6 (b) C 6H 5COO (c) m--c 6H 4-COOAg (d) C 6H 5 Q13. n the following groups: -OAc() -OMe() -OSO 2Me() -OSO 2CF 3(V) the order of leaving group ability is (a) > > > V (b) V > > > (c) > > > V (d) > > V > Q14. The intermediate during the addition of HCl to propene in presence of peroxide is

2 (a) C H 2Cl (b) C H (c) 2 C H 3 (d) 2 C H 2 Q15. 2-omopentane is heated with potassium hydroxide in ethanol. The major product obtained is ; (a) 2-Ethoxypentane (c) cis-pent-2-ene (b) Pent-1-ene (d) trans-pent-2-ene Q16. The reaction, COOAg + 2 CCl + CO 2 + Ag is known as 4 a) Finkelsteijn reaction b) Frankland reaction c) Hunsdiecker reaction d) Sandmeyer reaction Q17. Which among the following halogen can be easily displaced as halide by an added nucleophile in 1-omo-4-chloro-2-iodo-3,5-dinitrobenzene? a) odine b)omine c)chlorine d) all of these Q18. The addition of H is easiest with (a) 2 = Cl (b) Cl = Cl (c) -= 2 (d) () 2C= 2 Q19. S N1 reaction of alkyl halides leads to (a) retention of configuration (c) inversion of configuration (b) racemisation (d) none of these Q20. Which of the following has the highest nucleophilicity? (a) F - (b) OH - (c) 3 (d) NH 2 Q21. dentify the set of reagent/reaction conditions X and Y in the following set of transformations: Product X Y (a) X = dilute aqueous NaOH, 20 o C Y = H/acetic acid, 20 o C (b) X = concentrated alcoholic NaOH, 80 o C (c) X = dilute aqueous NaOH, 20 o C (d) X = concentrated alcoholic NaOH, 80 o C Y = H/acetic acid, 20 o C Y = 2/Cl 3, 0 o C Y = 2/Cl 3, 0 o C Q22. The order of reactivity of alkyl halides towards elimination reaction is (a) 3 o > 2 o > 1 o (b) 2 o > 1 o > 3 o (c) 3 o > 1 o > 2 o (d) 1 o > 2 o > 3 o Q23. Which of the following is least reactive in a nucleophilic substitution reaction? (a) 2 = Cl (b) 2Cl (c) 2 = 2Cl (d) () 3C-Cl Q24. Among the following the most reactive towards alcoholic KOH is

3 (a) 2 = (b) CO 2 2 (c) 2 (d) 2 2 Q25. Elimination of bromine from 2-bromobutane results in the formation of (a) predominantly 2-butyne (c) predominantly 2-butene (b) predominantly 1-butene (d) equimolar mixture of 1 and 2-butene Q26. Which of the following undergoes nucleophilic substitution exclusively by S N1 mechanism? (a) Ethyl chloride (b) sopropyl chloride (c) Chlorobenzene (d) Benzyl chloride Q27. The structure of the major product formed in the following reaction 2 Cl NaCN DMF is 2 CN 2 Cl 2 Cl 2 CN NC (a) CN (b) (c) CN (d) H 3 C 2 + H A Q28. A (predominantly) is ; (a) (b) 2 2 C 2 (c) (d) Q29. The organic chlorocompound, which shows complete stereochemical inversion during of S N 2 reaction, is: (a) Cl (b) (C 2H 5) 2Cl (c) () 3CCl (d) () 2Cl Q30. The major product of the following reaction is

Ans : (a) Q31. Which of the following halides would undergo nucleophilic substitution most readily? a) 1-Chloro-1-butene b)2-chloro- 1-butene c) 3-Chloro-1-butene d)4-chloro-1-butene. Q32.

4 Ans : (a) Q31. Which of the following halides would undergo nucleophilic substitution most readily? a) 1-Chloro-1-butene b)2-chloro- 1-butene c) 3-Chloro-1-butene d)4-chloro-1-butene. Q32. When tert-butyl bromide is treated with sodium methoxide in methanol, the major product obtained is ; a) 2-Methoxy-2-methylpropane b) 1-Methoxy-2- methylpropane c) 2-Methylpropene d) Dimethyl ether. Q33. Which is more reactive towards the reactions specified below? a) Chloro cyclohexane or Chlorobenzene ( nucleophilc substitution ) Chloro cyclohexane 1 b) tert. butyl bromide or iso- butyl bromide ( SN mechanism.) tert. butyl bromide 2 c) 2 omobutane or 1 omobutane ( SN mechanism ) 1 omobutane 1 d) 2 omo 2 methylbutane or 2 omobuatne ( E mechanism ) 2 omo 2 methylbutane Q34. Complete the following reactions ; P3 a C OH b) Bu tan 2 ol? conc. HCl ) ( 3) 3? c Methylbu ol SOCl2 ) 3 tan 1? Pyridine Ans : (a) ( 3) 3C Cl (b) 3 ( ) 2 3 (c) 1-Chloro-3-methylbutane Q35. Why an alkyl halide forms different products on reacting with KCN and AgCN separately?

5 CN is an ambident nucelophile. As KCN is ionic hence, CN shows nucelophilic action through carbon. As AgCN is covalent hence CN shows nucleophilic action through nitrogen Q36. Explain the following: (a) Alkyl iodides become darken on standing in presence of light. n Alkyl iodide, C - bond is very weak hence it is easily broken to liberate 2. (b) Vinyl halide is less reactive while allyl halide is more reactive than alkyl halides. n vinyl halide halogen is attached to sp 2 hybridized carbon while in alkyl halide halogen is attached to sp 3 carbon. Due to this reason carbon halogen bond in vinyl halide is stronger than in alkyl halide. (c) 2-Chloro-3-methylbutane on treatment with alcoholic potash gives 2-methylbut-2-ene as the major product. Alc. KOH behaves as base and has chance of rearrangement. Due to this reason2- Methylbut-2-ene is obtained as major product

Indian School Muscat. Chemistry IIT - JEE

Indian School Muscat. Chemistry IIT - JEE Indian School Muscat Chemistry IIT - JEE HALOALKANES AND HALOARENES 1. Which one of the following is not formed when a mixture of methyl bromide and bromobenzene is heated with sodium metal in the presence