Question

5. Compound C is insoluble in water and is soluble in 5M HCl solution. Identify the structure of C from the following options. i) Aniline ii) Benzoic acid iii) Phenol iv) Toluene 6. Compound D is insoluble in water/ 5M HCI / 5M NaOH / 5MNaHCO3 solutions. It forms a silver mirror when treated with Ammonical silver nitrate solution (Tollen's reagent). Identify the functional group in D. i) An alkyne ii) Phenol iii) An alkene iv) An aldehyde 7. Compound E is insoluble in water and 5M Sodium bicarbonate solution but, reacts with strong bases like NaOH to release Hydrogen gas. It also turns neutral FeCl3 solution to green. Identify the structure of E. i) Aniline ii) Benzoic acid iii) Phenol iv) Toluene 8. Compound F is insoluble in water / 5M HCI / 5MNOH/ 5M NaHCO3 solutions. It gives a positive lodoform test, but does not undergo oxidation with Alkaline Potassium permanganate solution. Identify the structure of F. i) Benzoic acid ii) t-Butyl amine iii) Acetaldehyde iv) Acetone v) acetophenone 9. Compound G is insoluble in water / 5M HCI / 5M NaOH / 5M NaHCO3 solutions. The IR spectrum of G shows a signal at 1600 cm-1. It doesn't decolorize Bromine solution or alkaline Potassium permanganate solution. Identify its structure. i. Acetone ii) Benzene iii) 2-Butene iv) Acetaldehyde 10. Compound H is insoluble in water and forms bubbles when treated with 5 M NaHCO3 solution. Identify the possible structure of A. i) Benzoic acid ii) Acetic acid iii) Acetone iv) Benzaldehyde

Answer 1

5. Aniline

Aniline does not undergo hydrogen bonding because of the presence of the benzene which is highly hydrophobic,therefore aniline is insoluble in water. Aniline (or phenylamine) is soluble in hydrochloric acid because it reacts with HCl to form phenylammonium chloride(PhNH3+Cl-), like so: A salt solution of phenylammonium chloride is formed.

6. An Aldehyde

aldehyde gives positve when treated with Tollen's reagent.Tollen's reagent can be used to distinguish between aldehyde and ketone.The test is positive for aldehydes and rests on the premise that aldehyde are more readily oxidised compared with ketone this is due to carbonyl containing carbon in aldehyde having an attached hydrogen.

7. Phenol

Phenol reacts with neutral FeCl3 to form an iron-phenol complex giving green colouration.This reaction can be used as a test for phenol groups.

8. Acetone

Acetone gives positive Iodoform test as it contains CH3CO group and it does not undergo oxidation with alkaline KMnO4 solution.

9. Benzene

Bromine water is an orange solution of bromine. It becomes colourless when it is shaken with an alkene. Alkenes can decolourise bromine water.Benzene molecule is unsaturated but it does not undergo electrophillic addition reaction because saturating the carbon-carbon bonds destroys the delocalized pi-cloud and as we know that this delocalized pi-structure is very stable. So due to this benzene does not decolourises bromine water

10. Benzoic acid

BBoth Benzoic acid and acetic acid form bubbles when treated with 5M NaHCO3 Solution but acetic acid is extremely soluble in water .

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