Organic Reaction Mechanisms-I Exercises

Organic Reaction Mechanisms-I  Marked questions are recommended for Revision. PART - I : SUBJECTIVE QUESTIONS Section (A): Electrophile, Nucleophile, Nucleophilicity, Leaving group ability & Solvent A-1. A-2. Which of the followings are electrophile ? (a) CN– (b) H+ (c) Br+ (d) AlCl3 (e) BH3 (g) NH3 (h) & & (d) (CH3)3 N (e) :CH2 (f) Which of the followings are nucleophile ? (a) HS– (b) BF3 (c) C2H5–OH A-3. Arrange the given species in decreasing order of their nucleophilicity : (a) H2O (b) A-4. Define ambident nucleophile with an example : A-5. In nucleophilic substitution reactions the leaving ability order for the following species is (when attached to the sp3 hybridised carbon.) A-6. Label each of the following solvent as Protic or Aprotic (a) (b) Acetonitrile (c) Acetic acid O (Tetrahydrofuran) O (d) (e) (f) H C NH2 (Formamide) (DMSO) (g) (h) Cyclohexane (i) Amonia Section (B) : Types of organic reactions and reactions of acidic hydrogen B-1. Which of the following reactions are substitution reaction ? Ni / H2 → CH3–CH3 (a) CH2=CH2 ⎯⎯⎯ (b) NH3 ⎯⎯⎯ →   (c) CH3–I + OH ⎯⎯→ CH3 OH + I H KC N ⎯ ⎯ ⎯ → CH3 – C –OH (d) CH3–CHO  H CN Organic Reaction Mechanisms-I B-2. Which of the following reaction are addition reaction ? H KC N (a) CH3 – CHO ⎯⎯⎯→ CH3 – C –OH H CN HCl → (b) CH3–CH=CH2 ⎯⎯⎯ Alc. KOH ⎯⎯⎯⎯ → (c) CH3 OH ⎯⎯⎯⎯ → (d) B-3. Which of the following reaction is an elimination reaction ? PCl5 → CH3–CH2–CH2–Cl (a) CH3–CH2–CH2–OH ⎯⎯⎯ (b) Alc. KOH ⎯⎯⎯⎯ → CH3–CH=CH2 (c) B-4. Zn ⎯⎯→ CH2 = CH2 + ZnBr2 CH3 OH ⎯⎯⎯⎯ → (d) An organic compound which have molecular formula C 4H4O3, gives 3 moles of gas on treatment with methyl magnesium bromide. Give structure of the compound. B-5. Predict the product of the following reactions (a) Methylmagnesium iodide + D2O ⎯⎯→ ? (b) Isobutylmagnesium iodide + Phenylacetylene ⎯⎯→ ? MgBr + DOCH3 ⎯⎯→ (c) Section (C) : Nucleophilic addition reactions of carbonyl compounds C-1. Arrange the following compounds in decreasing order of reactivity for Nucleophilic addition reaction: C-2. Cyclohexanone forms cyanohydrin in good yield but 2,2,6-trimethylcyclohexanone does not. Explain why ? C-3. Complete the following reactions. NaCN (a) Ph–C–CH3 HCl 1. PhMgBr → (b) CH3–CH2–CHO ⎯⎯⎯⎯⎯ 2. H O 2 O CHO (c) O NaCN ⎯⎯⎯ → H SO 2 4 C-4. Bring about the following conversions (i) Acetone to 2-Methylpropan-2-ol. (d) NaCN ⎯⎯⎯ → H SO 2 4 (ii) Ethyl magnesium chloride to propan-1-ol. C-5. What is the product of each reaction when acetophenone treated with (a) LiAlD4 followed by H2O (b) LiAlH4 followed by D2O (c) NaBD4 followed by EtOH (d) NaBD4 followed by EtOD Organic Reaction Mechanisms-I Section (D) : Bimolecular nucleophilic substitution reaction with tetrahedral intermediate (SN2Th) D-1. How many reactions given below are proceed through SN2Th mechanism ? + NaOH ⎯→ (a) (b) CH3– –NH2 + NaI ⎯→ (d) CH3– – OC2H5 + NaNH2⎯→ (c) CH3– – OH + C2H5ONa⎯→ D-2. What will be the major products of the following reactions ? D-3. + + CH3OH ⎯→ (a) H (b) CH3– –OC2H5 + H2O ⎯⎯→ Predict the products of the following reactions : (a) + (b) + ⎯→ ⎯→ + CH3OH ⎯→ (c) D-4. A + B, find A and B. D-5. Write the structure of the hydroxy acid corresponding to each of the following lactones. O CH3 OH O (a) (b) O O PART - II : ONLY ONE OPTION CORRECT TYPE Section (A): Electrophile, Nucleophile, Nucleophilicity, Leaving group ability & Solvent A-1. A-2. A-3. Which of the following is an electrophilic reagent? (A) H2O (B) OH– (C) NO2+ (D) None Which of the following is not a nucleophile ? (A) AICI3 (B) (CH3)2 NH (D) H2O (C) C2H5OH Which one of the following has maximum nucleophilicity ? (A) CH3S (B) A-4. Out of the followings best leaving group is : (A) F– (B) Cl– (C) Et3N (D) (C) Br– (D) I– Organic Reaction Mechanisms-I A-5. The best leaving group is : (A) A-6. A-7. (B) (C) (D) Which of the following is protic solvent ? (A) Acetone (B) Ethanol (C) DMF (D) Ether Which of the following is aprotic solvent ? (A) DMSO (B) NH3 (C) H2O (D) CH3COOH Section (B) : Types of organic reactions and reactions of acidic hydrogen B-1. Which of the following reaction is an example of elimination reaction : H2 O NaOH → CH3 − CH − CH3 (A) CH3–CH=CH2 ⎯⎯⎯ (B) CH3–CH2–Br ⎯⎯⎯⎯ → CH3–CH2–OH | OH Fe + Br2 ⎯⎯→ Alc. KOH (C) CH3 − CH − CH3 ⎯⎯⎯⎯⎯ → CH3–CH=CH2 (D) | Br B-2. B-3. B-4. B-5. The following reaction is an example of : RCOOH + PCl5 ⎯→ RCOCl (A) Acid-base reaction (C) Addition reaction (B) Substitution reaction (D) Elimination reaction H2 O ⎯⎯⎯ →  The following reaction is an example of H (A) Acid-base reaction (C) Addition reaction (B) Substitution reaction (D) Elimination reaction C6H5COOH + CH3MgI ⎯→ ? (A) C6H5COOMgI (B) CH4 (C) Both A & B (D) none (CH3)3CMgCI on reaction with D2O produces : (A) (CH3)3CD (B) (CH3)3COD (C) (CD3)3CD (D) (CD3)3COD B-6. A compound X (C5H12O4) upon treatment with CH3MgX gives 4 mole of methane. Identify the structure of (X). (A) B-7. (B) (C) (D) How many functional group produced CH4 gas by the reaction of compound (I) with CH3MgBr. (A) 3 (I) (B) 4 (C) 5 (D) 6 Organic Reaction Mechanisms-I Section (C) : Nucleophilic addition reactions of carbonyl compounds C-1. The correct order of reactivity of following compounds with PhMgBr will be. (C6H5)2CO, CH3–CH=O, (CH3)2C=O (1) (2) (A) 1 > 2 > 3 (B) 2 > 3 > 1 (C) 3 > 2 > 1 (D) 1 > 3 > 2 (i) CH3MgBr ⎯⎯⎯⎯⎯ → Product is : C-2. (ii) H2 O (A) (B) (C) (D) H2 O PhMgBr → → ⎯⎯⎯ C-3. P ⎯⎯⎯⎯ P can be : (A) CH3COOH C-4. (3) (B) H–COOCH3 (C) CH3–COCl (D) CH3–CH=O Butan-2-ol is obtained by using carbonyl compound and Grignard reagent as : (i) CH3–CH2–MgBr (A) CH3–CH=O (B) CH3 (C) C-5. C-6. H 3C C=O (i) CH3–MgBr (D) CH2=O H 3C HCN reacts with fastest rate with : (A) Acetone (B) Ethanal (i) CH3–CH–MgBr (C) Benzophenone (D) Acetophenone LiAlD H3O 4 → is The product of the reaction Ph2C=O ⎯⎯⎯⎯  (A) Ph2CD(OH) (B) Ph2CH(OD) (C) Ph2CD(OD) (D) None Section (D) : Bimolecular nucleophilic substitution reaction with tetrahedral intermediate (SN2Th) D-1. The relative reactivity of acyl compounds towards nucleophilic substitution are in the order of : (A) Acid anhydride > Amide > Ester > Acyl chloride (B) Acyl chloride > Ester > Acid anhydride > Amide (C) Acyl chloride > Acid anhydride > Ester > Amide (D) Ester > Acyl chloride > Amide > Acid anhydride D-2. Consider the following compounds : (i) (ii) (iii) (iv) The correct order of reactivity towards hydrolysis is : (A) (i) > (ii) > (iii) > (iv) (B) (iv) > (ii) > (i) > (iii) (C) (ii) > (iv) > (i) > (iii) (D) (ii) > (iv) > (iii) > (i) D-3. Which of the following method is not used for the conversion of carboxylic acid into acid halide ? (A) RCOOH + SOCl2 ⎯→ (B) RCOOH + PCl5 ⎯→ (C) RCOOH + Cl2 ⎯→ (D) RCOOH + PCl3 ⎯→ Organic Reaction Mechanisms-I D-4. Predict the major product in the following reaction : C6H5CH2CO2CH3 (A) 1. CH3MgBr (excess) + 2. H (B) (C) (D) PART - III : MATCH THE COLUMN 1. Match List I (Reaction) with List II (Product) and select the correct answer using the code given below the lists : List-I List-II H2 O (P) (1) CH3–CH2–CH2–OH → CH3COCH3 + CH3MgBr ⎯⎯⎯ EtOH ⎯⎯⎯→ (Q) (2) H2 O ⎯⎯⎯ → (R) H2 O ⎯⎯⎯ → (S) Codes : P (A) 2 (C) 4 2. Q 4 2 R 3 1 Match the List-I with List-II : List-I (A) I CF3SO3 (B) (C) H2O (D) CH3CH2O (3) (4) S 1 3 (p) (q) (r) (s) (B) (D) P 4 2 Q 2 4 R 3 1 S 1 3 List-II Strong nucleophile Strong base Good leaving group Weak base  Marked questions are recommended for Revision. PART - I : ONLY ONE OPTION CORRECT TYPE 1. Addition reactions involves (A) Cleavage of a -bond and formation of a new -bond. (B) Cleavage of two -bonds and formation of a new -bond. (C) Cleavage of a -bond and formation of two new -bonds. (D) None of these. 2. Which one of the following has maximum nucleophilicity ? (A) (B) (C) (D) Organic Reaction Mechanisms-I NaCN ⎯⎯⎯ → 3. In the above reaction rate is fastest, when (X) is : (A) –OH (B)–NH2 O || (C) − S − O CH 3 || O O || (D) − O − S − CH 3 || O 4. Correct arrangement of the following nucleophiles in the order of their nucleophilic strength is : (A) C6H5O– < CH3O– < CH3COO– < OH– (B) CH3COO– < C6H5O– < CH3O– < OH– – – – – (C) C6H5O < CH3COO < CH3O < OH (D) CH3COO– < C6H5O– < OH– < CH3O– 5. Which of the following reactions is not feasible ? (A) PhSO3H + NaHCO3 ⎯→ (B) Ph–OH + NaNH2 ⎯→ (C) CH3–NH2 + NaOH ⎯→ (D) Ph–CCH + NaH ⎯→ 6. Give the decreasing order of nucleophilic addition reaction of the following : (i) HCHO (ii) PhCHO (iii) Chloral (Cl3C–CH=O) (iv) Acetophenone (A) iii > i > ii > iv (B) iv > ii > i > iii (C) i > iii > ii > iv (D) iii > i > iv > ii 7. Number of products formed in the following reaction(s) is/are  KCN/ H ⎯⎯⎯⎯ → (A) 1 8. (B) 2 (D) 4 Products Products obtained in the above reaction is(A) Diastereomers (C) Meso compound 9. (C) 3 (B) Enantiomers (D) Optically pure one product only Consider reduction of 2-butanone. B (A) (C) A, B and C are respectively. in all cases in all case (B) (D) , , , , Organic Reaction Mechanisms-I 10. Which of the following is correct order of esterification of following acids with CH 3OH : HCOOH, CH3COOH , CH3–CH2–COOH , I II (A) I = II = III = IV 11. III (B) I > II > III > IV IV (C) I < II < III < IV (D) I > IV > III > II Esterification of the acid (P) with the alcohol (Q) will gives. (P) ; (Q) : (R– configuration) (A) only one enantiomer (C) a mixture of enantiomer (1) excess PhMgBr (2) H2O ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ → 12. (A) (±) (B) a mixture of diastereomer (D) only one fraction on fractional distillation X , X is (B) (C) (D) PART - II : SINGLE AND DOUBLE VALUE INTEGER TYPE 1. How many reactions given below are examples of elimination reactions ? H2 O → CH3 − CH − CH3 (I) CH3–CH=CH2 ⎯⎯⎯ | OH NaOH (II) CH3–CH2–Br ⎯⎯⎯⎯ → CH3–CH2–OH Alc. KOH (III) CH3 − CH − CH3 ⎯⎯⎯⎯⎯ → CH3–CH=CH2 | Br CH3 EtOH/  (IV) CH3–CH–CH–CH3 ⎯⎯⎯⎯→ CH3–C=CH–CH3 CH3 Cl Br (V) Alc. KOH ⎯⎯⎯⎯⎯ → (VI) (VII) Ph–CH2–CH–CH3 Cl OH (VIII) Ph–CH–CH2–CH3 HI Organic Reaction Mechanisms-I 2. Among the following X is the number of electrophiles and Y is the number of nucleophiles. Report your answer as X Y .  (i) CH3 (ii) I (iii) NO2 & & (v) NH 3 (vi) Br (vii) Cl (viii) H+ (ix) AlCl3 (x) CH3OH (xi) (xii) BH3 (iv) CH3  3. Which is the strongest nucleophilic site in the following species ? 4. An alcohol (A), 0.22 g of this alcohol librates 56 ml of CH 4 at STP on reaction with CH3MgBr. Write the molecular weight of alcohol which satisfy these conditions. 5. How many carbonyl compounds will give secondary alcohol with molecular formula C 5H12O after reduction with LiAlH4? 6. How many compounds out of following will give secondary alcohol on treatment with Grignard reagent ? (a) Ph–CO–CH3 (b) Ph–CHO (c) HCHO (d) CH3CH2CHO (e) CH3CHO (f) Ph–CO–Ph (g) HCOCl (h) CH3COOC2H5 7. What is the maximum number of moles of CH3MgCl that can be consumed by one mole of phosgene ? 8. Find the moleculer weight of a sweet smelling compound which react with LAH to gives only ethanol. PART - III : ONE OR MORE THAN ONE OPTIONS CORRECT TYPE 1. 2. 3. Electrophiles are (A) Electron deficent species (C) Electron rich species (B) having atleast one pair of electron (D) Electron pair acceptor Which of the following is/are ambident nucleophile(s) ? (A) NO2– (B) CN (C) NaHSO3 (D) Cl The correct order of leaving group ability is/are : (A) (C) > > (B) (D) > > 4. Which of the following reactions yeild benzene ? (A) PhMgBr + CH3–Br (B) PhMgBr + H2O (C) PhBr + H2O (D) PhMgBr + CH3–CCH 5. Which of the following liberate hydrogen gas with NaH. (A) CH3–COOH (B) (C) CH3–CCH (D) CH3–CH2–OH Organic Reaction Mechanisms-I HCN ⎯⎯⎯ → Product 6. The correct statement about product is (A) The product is optical inactive (C) The product is mixture of two enantiomer (B) The product is meso compound (D) Products are in two diastereomeric forms 1. MeMgBr (1 eq.) ⎯⎯⎯⎯⎯⎯⎯⎯ → acetone as the sole organic product.  7. 2. H3O which is/are correctly matched with R and R. (A) R is –H (B) R’ is 8. (C) R’ is (D) R is –CH3 2-Phenylbutan-2-ol can be prepared by :  ether H ⎯⎯⎯ → ⎯⎯ ⎯ → (A) PhMgBr + O ether H → ⎯⎯ (B) CH3MgBr + Ph—C—C2H5 ⎯⎯⎯ ⎯ → O  ether H → ⎯⎯ (C) C2H5MgBr + Ph—C—CH3 ⎯⎯⎯ ⎯ →  ether H → ⎯⎯ (D) CH3CH2CH2MgBr + PhCHO ⎯⎯⎯ ⎯ → 9. The correct decreasing reactivity order of the given compound(s) towards hydrolysis under identical condition is/are : (A) CH3COCl > CH3CONH2 (B) CH3COCl > (CH3CO)2O (C) CH3COOCH3 > CH3COCl (D) (CH3CO)2O > CH3CONH2 10. (i)Grignard's reagent (Y) (execess) → product X (an ethyl ester) ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ (ii)H3O The product(s) may be : (A) (B) (C) (D) PART - IV : COMPREHENSION Read the following passage carefully and answer the questions. Comprehension # 1 Nucleophilic aliphatic substitution reaction is given by those compounds which have electron rich groups as leaving groups. Less is the basicity of the leaving group, more is its leaving power.   R – L + Nu R – Nu + L  In the given reaction, L is the leaving group which leaves as nucleophile. Nu is the incoming group which is always nucleophilic in character. The reaction is nucleophilic substitution reaction which can be unimolecular or bimolecular reaction. Organic Reaction Mechanisms-I 1. Leaving power of which group is maximum ?  ” (A) 2. (B) (D) –Cl (C) Which one of the following is strong base but poor nucleophile ?   (B) HO (A) CH3 (C) (D) Comprehension # 2 Observe the following experiment 3. 4. 5. If the reactant ‘P’ is ethyl chloride then the main product R can be (A) (B) CH3CH2 – O – CH2CH3 (C) (D) If the liquid Q is H − C − OC 2H5 then the product R can be (P can be any other halide) || O (A) (B) (C) (D) If R is (A) (C) CH3– then P and Q can be respectively. , CH3– –OC2H5 –CH3, (B) CH3–Cl, (D) , CH3Cl Organic Reaction Mechanisms-I Comprehension # 3 Q.6, Q.7 and Q.8 by appropriately matching the information given in the three columns of the following table. Columns 1, 2 and 3 contain reactions, type of reactions and lab test for reactants respectively. Column-1 Column-2 Column-3 H+ → (I) CH3–CH–CH2–CH2–C–OH ⎯⎯⎯ OH (II) O (III) C Ph−MgBr ⎯⎯ ⎯⎯ ⎯→ (P) 2,4-DNP test (ii) Nucleophilic addition reaction (Q) Carbylamine test (iii) Nucleophilic substitution reaction (R) Lucas test (iv) Fischer esterification (S) Neutral FeCl3 test CH3 NaBD4 ⎯⎯ ⎯ ⎯→ H2O CH3MgBr (IV) CH3–CH2–NH2 ⎯⎯ ⎯⎯ ⎯→ 6. (i) Acid base reaction O OH For the synthesis of hydrocarbon, the only correct combination is : (A) (II) (i) (R) (B) (III) (ii) (P) (C) (IV) (i) (Q) (D) (I) (iii) (S) 7. The only correct combination that gives two different stereoisomeric products is : (A) (II) (i) (S) (B) (III) (iii) (P) (C) (IV) (iii) (Q) (D) (I) (iv) (R) 8. The only correct combination in which the reaction product gives iodoform test. (A) (I) (iii) (R) (B) (III) (ii) (P) (C) (II) (i) (S) (D) (IV) (i) (Q) * Marked questions may have more than one correct option. PART - I : (ADVANCED) / PROBLEMS (PREVIOUS YEARS) 1. 2. A biologically active compound, Bombykol (C16H30O) is obtained from a natural source. The structure of the compound is determined by the following reactions. (i) On hydrogenation, Bombykol gives a compound (A), C 16H34O, which reacts with acetic anhydride to give an ester. (ii) Bombykol also reacts with acetic anhydride to give another ester (B), which on oxidative ozonolysis (O3 /H2O2) gives a mixture of butanoic acid, oxalic acid and 10-acetoxy decanoic acid. Determine the number of double bonds in bombykol. Write the structures of compound A and B. How many geometrical isomers are possible for Bombykol ? CH3MgBr → P. The product P will be Ethylester ⎯⎯⎯⎯⎯⎯ excess (A) (B) (C) (D) Organic Reaction Mechanisms-I 3. The order or reactivity of phenyl magnesium bromide with the following compounds is : (A) (II) > (III) > (I) (C) (II) > (I) > (III) 4. (B) (I) > (III) > (II) (D) all react with the same rate Phenyl magnesium bromide reacting with t-Butyl alcohol gives (A) Ph–OH (B) Ph–H (C) 5. 6. (D) Match the compounds/ions in Column I with their properties/reactions in Column II. Column-I Column-II (A) C6H5CHO (p) gives precipitate with 2,4 dinitrophenylhydrazine. (B) (q) gives precipitate with AgNO3. CH3CCH (C) CN– (r) is a nucleophile. (D) (s) is involved in cyanohydrin formation. – In the reaction shown below, the major product(s) formed is/are NH2 NH2 O H N acetic anhydride ⎯⎯⎯⎯⎯⎯ → product(s) CH Cl 2 2 NH2 CH3 O (A) NH2 + CH3COOH O O H N H N (B) O H N O O NH3CH3COO CH3 (C) CH3 + CH3COOH CH3 O + H2O H N (D) O CH3 O PART - II : (MAIN) / PROBLEMS (PREVIOUS YEARS) (MAIN) OFFLINE PROBLEMS 1. Acetyl bromide reacts with excess of CH3MgI followed by treatment with a saturated solution of NH 4Cl gives (1) Acetone (2) Acetamide (3) 2-Methyl-2-propanol (4) Acetyl iodide Organic Reaction Mechanisms-I 2. Rate of the reaction is fastest when Z is : O O R––C R––C + Nu Z Nu (1) Cl 3. +Z (2) OCOCH3 (3) OC2H5 (4) NH2 On mixing ethyl acetate with aqueous sodium chloride, the composition of the resultant solution is : (1) CH3COOC2H5 + NaCl (3) CH3COCl + C2H5OH + NaOH (2) CH3Cl + C2H5COONa (4) CH3COONa + C2H5OH 4. The decreasing order of the ratio of HCN addition to compounds A to D is (a) HCHO (b) CH3COCH3 (c) PhCOCH3 (d) PhCOPh (1) d > b > c > a (2) d > c > b > a (3) c > d > b > a (4) a > b > c > d 5. Phenyl magnesium bromide reacts with methanol to give (1) a mixture of anisole and Mg(OH)Br (2) a mixture of benzene and Mg(OMe)Br (3) a mixture of toluene and Mg(OMe)Br (4) a mixture of phenol and Mg(Me)Br 6. The treatment of CH3MgX with CH3CC–H produces (1) CH3CC–CH3 (2) (4) CH3–CH=CH2 (3) CH4 7. A liquid was mixed with ethanol and a drop of concentrated H 2SO4 was added. A compound with a fruity smell was formed. The liquid was : (1) HCHO (2) CH3COCH3 (3) CH3COOH (4) CH3OH 8. Sodium ethoxide has reacted with ethanoyl chloride. The compound that is produced in the above reaction is : (1) Diethyl ether (2) 2-Butanone (3) Ethyl chloride (4) Ethyl ethanoate 9. A compound with molecular mass 180 is acylated with CH 3COCl to get a compound with molecular mass 390. The number of amino groups present per molecule of the former compound is : (1) 2 (2) 5 (3) 4 (4) 6 (MAIN) ONLINE PROBLEMS 1. The major product expected from the following reaction is : CH2OH O HO2C NH2 HCl(g)/CCl 4 ⎯⎯⎯⎯⎯→ OH O HO2C O O O O (1) NH2 (2) OH CH2OH O HO2C OH O NH2 (3) Cl HO2C O (4) Cl Organic Reaction Mechanisms-I 2. The major product obtained in the following reaction is : OH (CH3CO)2O/Pyridine (1 eqv.) NH2 room temperature COCH3 OH OCOCH3 (1) (3) 3. (2) NH2 NH2 OH (4) NHCOCH3 NHCOCH3 The decreasing order of ease of alkaline hydrolysis for the following esters is COOC2H5 Cl COOC2H5 () () O2N COOC2H5 CH3O COOC2H5 () (1) III > II > IV > I 4. (V) (2) II > III > I > IV (3) IV > II > III > I (4) III > II > I > IV Which of the following compounds reacts with ethyl magnesium bromide and also decolourizes bromine water solution : (1) (2) (3) (4) OH 5. CH3CH2–C–CH3 cannot be prepared by : Ph (1) HCHO + PhCH(CH3)CH2Mg (3) PhCOCH3 + CH3CH3MgX 6. The increasing order of the reactivity of the following with LiAlH 4 is: O O (A) NH2 C2H5 (1) (A) < (B) < (C) < (D) (3) (B) < (A) < (D) < (C) 7. (2) PhCOCH2CH3 + CH3MgX (4) CH3CH2COCH3 + PhMgX (B) C2H5 O OCH3 O (C) Cl C2H5 (2) (A) < (B) < (D) < (C) (4) (B) < (A) < (C) < (D) (D) C2H5 O O C2H5 The aldehydes which will not form Grignard product with the equivalent Grignard reagents are: CHO CHO (A) (B) (C) HO2C (1) (B), (D) CHO (2) (B), (C) CHO (D) H3CO (3) (C), (D) HOH2C (4) (B), (C), (D) Organic Reaction Mechanisms-I EXERCISE – 1 PART – I A-1. b, c, d, e, f, h A-3. (a) A-4. Ambident nucleophile: The species which have more than one nucleophilic site for reaction are called ambident nucleophiles. For example, cyanide ion : > A-2. > a, c, d > H2O (b) > > > – :C  N: :C = N:¯ CH3Br + AgCN ⎯→ CH3NC + AgBr CH3Br + KCN ⎯→ CH3CN + KBr A-5. I > II > IV > III A-6. B-2. Protic solvent (c, f, i) ; Aprotic solvent (a, b, d, e, g, h) (a), (b) B-3. (b), (c) B-4. O OH || | HO − C − C − C  CH | H B-1. (b), (c) B-5. (a) CH3 – D + C-1. III > II > I > IV C-2. Cyanohydrin is formed by nucleophilic attack on carbonyl group (C=O), 2,2,6-trimethylcyclohexanone has more steric crowding due to three methyl groups. (b) CH3 − CH − CH3 + | CH3 (c) CN OH C-3. (a) Ph–C–CH3 CH–OH (b) CH3–CH2–CH–Ph CN C-4. H2 O ⎯⎯⎯ → H2 O ⎯⎯⎯ → ⎯⎯ → (ii) D C-5. (d) OH ⎯⎯ → (i) (c) (a) Ph—C—CH3 OH H (b) Ph—C—CH3 OD D (c) Ph—C—CH3 OH + CH3CH2CH2OH + D (d) Ph—C—CH3 OD Organic Reaction Mechanisms-I D-1. 2 (a, d) D-2. D-3. (a) (b) D-4. (A) = PhCOOH, (B) = O || (a) CH3–C–OCH3 + HCl O || (b) CH3– C –OH + CH3CH2 OH (c) CH3 D-5. (a) CH3–CH–CH2–CH2–C–OH OH (b) CH2–CH2–C–CH2–COOH OH O OH PART - II A-1. (C) A-2. (A) A-3. (A) A-4. (D) A-5. (A) A-6. (B) A-7. (A) B-1. (C) B-2. (B) B-3. (C) B-4. (C) B-5. (A) B-6. (C) B-7. (B) C-1. (B) C-2. (A) C-3. (D) C-4. (A) C-5. (B) C-6. (A) D-1. (C) D-2. (C) D-3. (C) D-4. (B) PART - III 1. (B) 2. (A) - p, r, s ; (B) - r, s ; (C) - r, s ; (D) - p, q EXERCISE - 2 PART - I 1. (C) 2. (A) 3. (D) 4. (D) 5. (C) 6. (C) 7. (B) 8. (A) 9. (B) 10. (B) 11. (B) 12. (C) 4. 88 gm. 5. 3 (ABCD) PART - II 1. 4 (III, IV, V, VI) 2. 75 3. 4 6. 4 (b, d, e, g) 3 8. 88 7. PART - III 1. (AD) 2. (ABC) 3. (AB) 4. (BD) 5. 6. (AD) 7. (BD) 8. (ABC) 9. (ABD) 10. (ABC) 4. (A) 5. (B) PART - IV 1. (B) 2. (D) 3. (C) 6. (C) 7. (D) 8. (B) Organic Reaction Mechanisms-I EXERCISE - 3 PART - I 1. Structure of Bombykol is CH3–CH2–CH2–CH=CH–CH=CH(CH2)8CH2OH 2. (A) 5. (A) – (p, q, s) ; (B) – (q) ; (C) – (q, r, s) ; (D) – (q, r) 3. (C) 4. (B) 6. (A) PART - II (MAIN) OFFLINE PROBLEMS 1. (3) 2. (1) 3. (1) 4. (4) 6. (3) 7. (3) 8. (4) 9. (2) 4. (3) 5. (2) 5. (1) (MAIN) ONLINE PROBLEMS 1. (2) 2. (4) 6. (2) 7. (1) 3. (4)