Organic chemistry conversion questions for practice
1. Compound A (C5H10O) forms a derivative with hydrazine, gives a yellow ppt with iodine and sodium hydroxide solution. Compound A does not react with Tollen’s reagent. What is the structure of A?
2. A liquid of molecular formula C7H6O forms an oxime, reduces Tollen’s reagent and undergoes Clemmensen reduction to give toluene. Explain the reaction involved and write the structural formula of this liquid.
3. Compound A (C6H6) undergoes Friedel-Crafts alkylation and then oxidation to form B (C7H6O). B on reduction yields a neutral compound C (C7H8O). C reacts with sodium metal to produce hydrogen gas. B gives Perkin reaction to give D (C9H8O2). This decolourises bromine water. B reacts with aqueous ethanolic potassium cyanide to give compound E (C14H12O2). Identify A to E and explain the reactions.
4. Compound A (C5H12O) reacts with K2Cr2O7/H+ to form B (C5H10O). B reacts with 2,4-DNP to form a yellow solid, but does not give a silver mirror or iodoform. Identify A and B showing reactions.
5. Identify A from the following result.
- It gives a positive Tollen’s test.
- It reacts with 2,4-DNP to give a yellow-orange product with the formula C9H10N4O4.
6. Compound A, C7H8O, does not react with sodium metal. When A is treated with HI, two compounds, B and C, are formed. Compound B reacts with sodium to produce hydrogen and also forms a salt with NaOH. Compound B can be brominated, and the major product contains three bromine atoms. Compound C contains iodine. Compound C react with magnesium in dry ether to form a Grignard’s reagent. The Grignard reagent reacts with CO2, followed by acid hydrolysis to form acetic acid. Identify A, B and C with reactions.
7. A hydrocarbon A gives a positive Baeyer’s test. When A is treated with conc. sulphuric acid and water, 2-butanol is produced. Ozonolysis of A gives propanal and methanal. What is the structure of A? Write all reactions.
8. A compound C6H12 reacts with aq. Br2 to give a dibromide C6H12Br2. On ozonolysis, the original compound yields an aldehyde and a ketone, both of formula C3H6O. Give the structure of the original compound with all reactions.
9. An ether A (C6H14O), when heated with excess HI, produces two alkyl halides which, on hydrolysis, form compounds B and C. Oxidation of B give acid D, whereas oxidation of C gives ketone E. Identify A to E with all reactions.
10. Compound A, C6H6O, is soluble in NaOH. When treated with CHCl3 and NaOH, it forms B. B on oxidation gives C, which reacts with acetic anhydride in the presence of H2SO4 to form D, C9H8O4. Deduce the structural formula of A, B, C and D with reactions.
11. Compound A, C3H7Cl, reacts with alcoholic KOH to form B, C3H6. Compound B decolourises Br2/CCl4 solution. Reaction of A with Mg in ether and subsequent treatment with CO2 and dilute acid gives a compound C whose molecular formula is C4H8O2. When we add compound C to an aqueous NaHCO3 solution, bubbles are evolved. Give the structural formula of A, B and C with reactions.
12. Compound A (C6H12) decolourises bromine but gives no reaction with sodium metal or phenyl hydrazine. Ozonolysis of A gives two compounds, B and C, and both react with phenyl hydrazine. Compound B gives positive Tollen’s test and Iodoform test. Compound C has a molecular weight of 72. Suggest structures for A, B and C with reactions.
13. Compound A, C5H10, on ozonolysis gives acetaldehyde and acetone. What is A?
14. An organic compound A (C3H5N) undergoes reduction with lithium aluminium hydride to give B, C3H9N. B reacts with chloroform and KOH to give an unpleasant smell. B reacts with sodium nitrite and hydrochloric acid to give C, C3H8O, which on treatment with conc. H2SO4 gives D, C3H6. D on reaction with conc. H2SO4 and hydrolysis yield an isomer of C. Identify A, B, C and D with reactions.
15. Compound A, which contains C, H, O and N, is treated with bromine and sodium hydroxide to give compound B. B reacts with nitrous acid to give ethanol and N2. Write the structure of A and B with reactions.
16. Hydrocarbon A, C8H10 on oxidation with acidic KMnO4 gives monobasic acid B, C7H6O2. On treatment with soda lime, B gives benzene. What are A and B?
17. A compound of formula C8H8O forms an oxime but does not reduce Tollen’s reagent. What is the compound?
18. A neutral compound A of molecular formula C7H8O is converted to methyl iodide and alkali soluble compound on heating with HI. Write the structure of A.
19. Compound A, C6H12O, gives the following results:
- A gives a positive test with hydroxylamine.
- A does not react with Tollen’s reagent.
- A on catalytic hydrogenation gives B, C6H14O.
- B on treatment with conc. H2SO4 gives C, C6H12.
- C on ozonolysis gives D (C3H6O) and E (C3H6O).
- D gives a negative Tollen’s test and a positive iodoform test.
- E gives a negative iodoform test and a positive Tollen’s test.
What are the structure of A to E? Give reactions.
20. The compound A, C3H8O, acts as a Lewis base in its reaction with conc. HBr to give B, C3H7Br. On treatment with conc.H2SO4, A undergoes an elimination reaction to give hydrocarbon C, C3H6. When C is reacted with conc. HBr, the resultant product D, C3H7Br is formed in accordance with Markovnikov’s rule and is isomeric with B. Deduce the structures of A to D with reactions.
21. An alcohol A, C4H10O, on oxidation with acidic sodium dichromate gives a carboxylic acid B, C4H8O2. Treatment of A with hot conc. H2SO4 brings about dehydration and gives compound C, C4H8. Treatment of C with warm aqueous sulphuric acid gives D, C4H10O, a new alcoholic isomer with A. Compound D is resistant to oxidation. What are the structure of A to D? Give reactions.
22. An alkene, C6H12, after ozonolysis yielded two products. One of these gives a positive iodoform but a negative Tollen’s test. Others give a positive Tollen’s test but a negative iodoform test. Write the structure and IUPAC name of the alkene.
23. A ketone A undergoes haloform reaction and gives B on reduction. B on heating with conc. H2SO4 gives C, which forms an ozonide D. D on hydrolysis in the presence of zinc gives only acetaldehyde. Identify A to C with reactions.
24. An organic compound A, C8H6, on catalytic hydration in the presence of dil. Sulphuric acid and mercuric sulphate give B, which can also be obtained from a reaction of benzene with acid chloride in the presence of anhydrous aluminium chloride. The compound B, when reacted with iodine in aq. KOH yields C, and a yellow compound D. Identify A to D with reactions.
25. An organic compound A reacts with sodium metal to form hydrogen gas. The compound A, on treatment with alkaline iodine, forms a yellow crystalline substance, and on oxidation with acidified dichromate forms an aldehyde with molecular formula C2H4O. Identify A with reactions.
26. An unknown ester C5H12O2 was hydrolysed with water and acid to give carboxylic acid A and alcohol B. Treatment of B with PBr3 gave an alkyl bromide C. When C was treated with KCN, a product D was formed, which on acid hydrolysis gave the carboxylic acid A. Give the structure and name of the original ester. Identify A to D with reactions.
27. Compound A, C3H7Cl, reacts with alcoholic KOH to form B, C3H6. Compound B decolourises Br2/CCl4 solution. Reaction of A with Mg in ether and subsequent treatment with CO2 and dilute acid gives a compound C whose molecular formula is C4H8O2. Bubbles are evolved when compound C is treated with aqueous NaHCO3. Give the structural formulas of A to C with reactions.
28. An organic compound A having molecular formula CH4O on treatment with red phosphorus and iodine gives a compound B. B on treatment with KCN followed by reduction gives a compound C. C on treatment with nitrous acid at cold conditions gives D, which gives a positive iodoform test. Identify A to D with reactions.
29. Compound A, C5H10O, gives phenyl hydrazone. It gives the iodoform test but not the Fehling’s solution test. Clemmensen reduction of A gives n-pentane. Write the structure of A with the required reactions.
30. An organic halide A, C5H11Br, on treatment with aq. NaOH gives a compound B, C5H12O. On oxidation, compound B gives ketone C. Oxidation of C under drastic conditions gives a mixture of ethanoic and propanoic acids. What are A, B and C? Also, give the reactions.
31. An amine A has formula C3H9N. When A is treated with nitrous acid, a reaction takes place, and an oily yellow layer separates from the reaction mixture. Identify A with the reaction.
32. An ester A, C5H10O2, undergoes acid hydrolysis to give an acid B and an alcohol C. Treatment of C with PBr3 gives alkyl bromide D. When D was treated with KCN, a product E was formed, which on acid hydrolysis gave B. Identify A to E with reactions.
33. An organic compound A on reduction gives B. B on treating with sodium nitrite and hydrochloric acid gives an alcohol with two carbon atoms. B, when warmed with alcoholic KOH and CHCl3, gives an offensive odour D. D on reduction gives 2° amine (E). Identify A to E with explanations.
34. An organic compound A having molecular formula C6H6O gives a characteristic colour with aq. FeCl3 solution. A on treatment with CO2 and NaOH at 400K under pressure gives B, which on acidification gives C. C reacts with acetyl chloride to give D, which is a proper pain killer. Deduce the structures of A to D with explanations.
35. A mixture of two aromatic compounds, A and B, was separated by dissolving in chloroform, followed by extraction with aqueous KOH solution. The organic layer containing compound A, when heated with an alcoholic solution of KOH, produced a compound C (C7H5N) associated with an unpleasant odour. The alkaline aqueous layer, on the other hand, when heated with chloroform and then acidified, gave a mixture of isomeric compounds D and E having formula C7H6O2. Identify A to E with reactions.
36. An organic compound A having molecular formula C6H7N undergoes diazotization to give the product B, which undergoes Sandmeyer reaction with Cu2Cl2 and HCl to give a compound C. C, when heated with caustic soda solution at 623 K and 300 atm, gives D. D is also obtained by boiling B with water. Identify A to D with reactions.
37. An aromatic hydrocarbon A, on heating with methyl chloride in the presence of AlCl3, gave another hydrocarbon B (mol. wt. 92). B on oxidation gave a monobasic acid C. C gave back A on heating with sodalime. What are A, B and C?
38. A compound A with molecular formula C5H10 decolourized bromine water. A on reduction forms 2-methyl butane, and A on ozonolysis produces ethanal and propanone. Deduce the structure of A.
