Aldehydes and Ketones – Carbonyl compounds – Preparation and Properties

Carbonyl compounds [Aldehydes and ketones]

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Aldehydes and ketones are the compounds containing carbonyl group, so are collectively called carbonyl compounds.

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Structure and nature of the carbonyl group

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In carbonyl group, there is carbon to oxygen double bond, which consist of a sigma (σ) bond and a pi (π) bond

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Both of the carbon and oxygen atoms are sp² hybridized. One sp² hybrid orbital of carbon forms σ-bond with oxygen atom and remaining two hybrid orbitals form σ-bond with hydrogen or carbon atom. π -bond is formed by the overlap of unhybridized orbitals of carbon and oxygen atom.

This carbonyl group is trigonal and planar with bond angle of 120⁰.

In carbonyl group, carbon atom is bonded with oxygen atom which is more electronegative than carbon. Thus, the bonded pair of electrons lie more closer to the oxygen atom than carbon atom which leads to the polarization in carbon-oxygen bond. There is charge separation, oxygen atom acquires slightly negative charge while the carbon atom acquires slightly positive charge.

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Nomenclature of aldehydes and ketones

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Isomerism in aldehydes and ketones

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1 . Chain Isomerism: Aldehydes having at least 4 carbon atoms and ketones having at least 5 carbon atoms show chain isomerism. Eg.

2. Position isomerism: Ketones having at least 5 carbon atoms and aromatic aldehydes show position isomerism.Eg.

3. Functional isomerism: Ketone and aldehyde having same molecular formula are functional isomers of one another.

4. Metamerism: Ketones exhibit metamerism due to difference in alkyl group present on either side of carbonyl group.

Q) Write the possible isomeric aldehydes and ketones that can be formed from C₄H₈O.

Ans.

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General methods of preparation of aldehydes and ketones

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1. From alcohol:

(i) By oxidation of alcohols:

• Alcohols on controlled oxidation give aldehydes and ketones.
• Acidified KMnO₄ or K₂Cr₂O₇ is used as oxidizing agent.
• 1⁰ alcohol gives aldehyde while 2⁰ alcohol gives ketone. Eg.

(ii) By dehydrogenation of alcohols:

When alcohol vapors are passed over heated copper at 300⁰C, different types of alcohols give different products.

1. Primary alcohols are dehydrogenated to aldehydes. Eg.

1. Secondary alcohols are dehydrogenated to ketones. Eg.

2. By ozonolysis of alkene:

Alkene reacts with ozone to give ozonide. On warming ozonide with Zn in water, it breaks down to give two molecules of carbonyl compounds (aldehyde or ketone). This process of formation of ozonide and it’s decomposition to give carbonyl compounds is called ozonolysis.

3. By catalytic hydration of alkynes :

Alkynes react with water in presence of mercuric sulphate and sulphuric acid to give vinyl alcohol which rearranges to give aldehyde or ketone.

For example, ethyne gives ethanal (i.e. aldehyde).

Propyne gives propanone (i.e. ketone).

4. From acid chlorides:

(i) By Rosenmund reduction: Aldehydes can be prepared by reducing acid chloride solution with hydrogen in the presence of Palladium(Pd) catalyst deposited on barium sulphate and partially poisoned with sulphur or quinoline. This reaction is called Rosenmund reduction.

(ii) Ketones can be prepared by treating acid chloride with dialkyl cadmium.

Q) How would you convert benzoic acid into benzaldehyde?

5. From gem-dihalides:

The alkaline hydrolysis of gem-dihalide gives aldehyde and ketone.

Aldehydes are formed when two halogen atoms are attached to terminal carbon atom.

Ketones are formed when two halogen atoms are attached to non-terminal carbon atom.

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Physical Properties of aldehydes and ketones

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1. Boiling point: Aldehydes and ketones have higher boiling point than hydrocarbon of comparable molecular masses. This is because aldehydes and ketones contain polar carbonyl group and therefore there exists strong dipole-dipole interaction between the opposite end of C=O dipoles.

However, aldehydes and ketones have lower boiling point than alcohols and carboxylic acid of comparable molecular masses. This is because dipole-dipole interaction is weaker than intermolecular H-bonding.

2. Solubility: Lower aldehydes and ketones containing up to 4 carbon atoms are soluble in water due to formation of hydrogen bond between the polar carbonyl group and water molecule.

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Chemical Properties

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[A] Nucleophilic addition reaction

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Aldehydes and ketones undergo nucleophilic addition reaction due to presence of polar carbonyl group.

The positively charged carbon of carbonyl group is readily attacked by nucleophilic species for the initiation of reaction. This leads to the formation of intermediate anion which is then attacked by electrophile (eg.H⁺) to give the final addition product.

Q) Why does aldehydes easily undergoes nucleophilic addition reaction as compared to that of ketone?

Aldehydes and ketones contain polar carbonyl group and hence carbonyl carbonyl carbon is a suitable site for nucleophilic attack.

In aldehydes, one electron releasing alkyl group is attached to carbonyl carbon while in ketone two alkyl groups are attached to carbonyl carbon. Thus, aldehydic carbon is electron deficient than ketonic carbon and hence aldehyde is more easily attacked by nucleophilic species.

1. Addition of HCN: Aldehydes and ketones react with hydrogen cyanide to form addition product called cyanohydrins. Eg.

Cyanohydrin on acidic hydrolysis gives α-hydroxy acids which on heating loses a molecule of water to form α,β-unsaturated acid.

Q) Identify A, B , C and D.

Q) How would you obtain 2-hydroxy-2-methylpropanoic acid from propanone?

2. Addition of sodium bisulphite: Aldehydes and ketones react with saturated solution of sodium bisulphite to form crystalline bisulphite addition products. Eg.

3. Addition of Grignard reagent:

Aldehydes and ketones (i.e carbonyl compounds) when treated with Grignard reagent gives addition product, which on acidic hydrolysis give alcohols.

⊗ Formaldehyde gives primary alcohol. Eg.

⊗ Aldehydes other than formaldehyde give secondary alcohol. Eg.

⊗ Ketones give tertiary alcohol. Eg.

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[B] Addition followed by elimination of water molecule [Addition of ammonia derivatives]

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Aldehydes and ketones react with number of ammonia derivatives such as hydroxylamine(NH₂OH), hydrazine(NH₂-NH₂), phenylhydrazine(C₆H₅NHNH₂), etc. in weakly acidic medium to form compounds containing C=N group.

1. Reaction with hydroxylamine: Aldehydes and ketones react with hydroxylamine to form oximes. Eg.

2. Reaction with hydrazine: Aldehydes and ketones react with hydrazine to form hydrazone. Eg.

3. Reaction with phenyl hydrazine: Aldehydes and ketones react with phenyl hydrazine to form phenylhydrazones. Eg.

4. Reaction with 2,4-dinitrophenyl hydrazine : Aldehydes and ketones react with 2,4-dinitrophenyl hydrazine (2,4-DNP) to form yellow, orange or red ppt. of 2,4-dinitrophenyl hydrazone. Eg.

5. Reaction with semicarbazide: Aldehydes and ketones react with semicarbazide to form semicarbazone. Eg.

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2,4-DNP test

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Aldehydes and ketones react with 2,4-dinitrophenyl hydrazine (2,4-DNP) to form yellow, orange or red ppt. of 2,4-dinitrophenyl hydrazone. Eg.

Q) Write a chemical test to distinguish ethanal from ethanol?

Ethanal and ethanol can be distinguished by 2,4-DNP test. Ethanal (i.e aldehyde) reacts with 2,4-dinitrophenyl hydrazine (2,4-DNP) to form orange ppt. of ethanal 2,4-dinitrophenyl hydrazone. But ethanol does not give this test.

Note : 2,4-DNP = Brady’s reagent.

≠ Action with PCl₅:

Aldehydes and ketones react with PCl₅ to give gem-dichloroalkane (gem-dihalide).

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[C] Oxidation reactions of aldehydes

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Aldehydes are oxidized not only by strong oxidizing agents like KMnO₄ or K₂Cr₂O₇ but also by weak oxidizing agents like Br₂ water, Ag⁺, Cu⁺⁺, etc. So, aldehydes are strong reducing agents.

1. Reaction with Tollen’s reagent: [Silver mirror test]

Tollen’s reagent is an ammonical solution of silver nitrate. It is prepared by adding dilute solution of NH₄OH to AgNO₃ solution till the precipitate of Ag₂O once formed gets dissolved.

Aldehydes on heating with Tollen’s reagent reduces the reagent to metallic silver.

The silver deposits on the inner wall of test tube forming a shining layer like mirror. Hence, this test is known as silver mirror test.

• Both aliphatic and aromatic aldehydes give this test but ketones do not give this test.

Q) Write the functional isomer of C₃H₆O and give a chemical test to distinguish them.

The functional isomers of C₃H₆O are:

These two isomers can be distinguished by silver mirror test (i.e. Tollen’s reagent). Propanal (i.e. aldehyde) gives positive silver mirror test but propanone (i.e. ketone) does not give this test.

2. Reaction with Fehling’s solution: [Fehling’s test]

Fehling’s solution is an alkaline solution of CuSO₄ containing some Rochelle salt (i.e. sodium potassium tartarate. It is prepared by adding alkaline solution of Rochelle salt [Fehling solution B] to CuSO₄ solution [Fehling solution A]. When an aliphatic aldehyde is heated with Fehling’s solution, a brick red ppt. of cuprous oxide is formed. This reaction is known as Fehling’s test.

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[D] Haloform reaction

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Aldehydes and ketones containing CH₃CO- group on reaction with excess halogen in presence of NaOH gives haloform (chloroform’ bromoform, iodoform). Eg.

Iodoform test :

Note:

• This reaction occurs in same way as lab preparation of chloroform. Eg.

• This reaction is used to distinguish some of the pairs of compounds. Eg.

1. Ethanol and methanol
2. Ethanal and methanal
3. 2-pentanone and 3-pentanone, etc.

Q) How can you distinguish 2-pentanone and 3-pentanone.

2-pentanone and 3-pentanone can be distinguished by iodoform test as 2-pentanone gives iodoform reaction but 3-pentanone doesn’t give iodoform reaction. Eg.

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[E] Reduction reaction

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1. Reduction to alcohols: Aldehydes and ketones are reduced to primary and secondary alcohols respectively using H₂ in presence of Ni, Pt, Pd or LiAlH₄. Eg.

2 . Clemmensen’s reduction: The reduction of aldehydes and ketones to alkane using zinc amalgam and conc. HCl is Clemmensen’s reduction. In this reaction, carbonyl group (-CO-) is reduced to methylene group (-CH₂-). Eg.

3 . Wolff-Kishner reduction : In this method aldehyde and ketone is treated with hydrazine to form hydrazone which is then heated with KOH in presence of glycol to give alkane. Eg.

4 . Reduction with HI in presence of red P : Aldehydes and ketones can be reduced into corresponding hydrocarbon when heated with HI in presence of red phosphorus at 150⁰C.

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[F] Special reactions of methanal (formaldehyde)

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1. Reaction with ammonia: Formaldehyde reacts with ammonia to form hexamethylene tetramine which is commonly known as ‘urotropine’. It is used as medicine to treat urinary infections.

2. Reaction with phenol:

Phenol condenses with formaldehyde in the presence of an acid or basic catalyst to form a polymer called Bakelite.

Formation of linear polymer:

Formation of cross-linked polymers:

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Aldol condensation reaction

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Condensation between two molecules of aldehydes or ketones having at least one α – hydrogen atom in presence of dilute alkali to form β-hydroxy aldehyde or β-hydroxy ketone is known as aldol condensation reaction. Examples:

Aldehydes and ketones which do not contain any α – hydrogen atom such as HCHO, (CH₃)₃CCHO, C₆H₅CHO, etc. do not undergo aldol condensation reaction.

Note : Dehydration of aldol product gives α, β-unsaturated aldehyde or ketone.

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Cannizzaro’s reaction

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Aldehydes which do not contain α-hydrogen like HCHO, C₆H₅CHO,etc. undergo self oxidation and reduction on treatment with conc. alkali. In this reaction one molecule is oxidized to carboxylic acid and other molecule is reduced to alcohol. Thus, a mixture of an alcohol and a salt of carboxylic acid is formed by Cannizzaro’s reaction

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Formalin and its Uses

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A 37-40% solution of formaldehyde in water is called formalin. Its molecular formula is HCHO (i.e. formaldehyde).

Uses of Formalin:

1. It is used in preservation of biological specimens.
2. It is used as an antiseptic and disinfectant.
3. It is used to manufacture urinary antiseptic i.e. Urotropin.
4. It is used to manufacture polymers like Bakelite, resins, etc.
5. It is used in the manufacture of dyes like indigo, pararosaniline, etc.

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EXERCISE

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1. Write isomers of C₄H₈O with their IUPAC names. Which one of them gives iodoform test?

2. An organic compound is represented by the formula, C₃H₆O. Give one chemical test to show that compound is an aldehyde but not a ketone. Why does this compound not give Cannizzaro’s reaction?

3. A carbonyl compound ,A, having molecular formula C₃H₆O is found to decolorize acidified KMnO4 and responds to 2,4-DNP test. The compound does not give iodoform test. Identify A, write the related reactions. How can the compound A be converted into ethanal?

4. What is formalin solution? Give its two uses.

5. An alkene ‘A’ (Mol. formula C₅H₁₀) on ozonolysis gives a mixture of two compounds, ‘B’ and ‘C’. Compound B’ gives positive Fehling’s test and forms iodoform on treatment with I₂ and NaOH. Compound C’ does not give Fehling’s test but forms iodoform. Identify the compounds A, B, and C. Write the reaction for ozonolysis and formation of iodoform from B and C.

6. When liquid ′A′ is treated with a freshly prepared ammonical silver nitrate solution, it gives a bright silver mirror. The liquid forms a white crystalline solid on treatment with sodium hydrogen sulphite. Liquid ′B′ also forms a white crystalline solid with sodium hydrogen sulphite, but it does not give a test with ammoniacal silver nitrate. Which of the two liquids is aldehyde? Write the chemical equations of these reactions also.

7. An alcohol A (C₄H₁₀O) on oxidation with acidified potassium dichromate gives carboxylic acid B(C₄H₈O₂). Compound A when dehydrated with conc. H₂SO₄ at 443K gives compound C. Treatment of C with aqueous H₂SO₄ gives compound D(C₄H₁₀O) which is an isomer of A. Compound D is resistant to oxidation but compound A can be easily oxidised. Identify A,B, C and D and write their structures.

8. A compound X (C₂H₄O) on oxidation gives Y (C₂H₄O₂). X undergoes haloform reaction. On treatment with HCN, X forms a product Z which on hydrolysis gives 2-hydroxypropanoic acid. Write down the structures of X and Y.

9. An alkene (A) with molecular formula (C₇H₁₄) on ozonolysis yields acetone and an aldehyde. The aldehyde is easily oxidized to an acid (B). When B is treated with bromine in presence of phosphorous it yields a compound (C) which on hydrolysis gives a hydroxyl acid (D). This acid can also be obtained from acetone by the reaction with hydrogen cyanide followed by hydrolysis. Identify A, B, C and D and write the chemical equations for the reactions involved.

10. Compound ‘A’ of molecular formula C₅H₁₁Br yields a compound ‘B’ of molecular formula C₅H₁₂O when treated with aqueous NaOH. On oxidation, the compound ‘B’ yields a ketone ‘C’. Vigorously oxidation of ketone yields a mixture of ethanoic and propanoic acids. Deduce the structures of ‘A’, ‘B’ and ‘C’.

11. A compound ‘A’ with molecular formula C₅H₁₂O, on oxidation forms compound ‘B’ with molecular formula C₅H₁₀O. the compound ‘B’ on reduction with amalgamated zinc and HCl gives compound ‘C’ with molecular formula C₅H₁₂. Identify A, B and C. Write down the chemical reactions involved.

12. An organic compound A having the molecular formula C₃H₈O on treatment with copper at 573K gives B, B does not reduce Fehling solution, but gives positive iodoform test. Write down the structural formulae of A and B.

13. A ketone A, which undergoes haloform reaction gives compound B on reduction. B on heating with conc. H₂SO₄ gives compound C, which forms mono-ozonide D. D on hydrolysis in the presence of Zn dust gives only acetaldehyde. Identify A, B, and C. Write the reactions involved.

14. An alkene A on ozonolysis yield acetone and an aldehyde. The aldehyde is easily oxidized to an acid B. when B is treated with bromine in the presence of phosphorus, it yield compound C, which on hydrolysis gives a hydroxyl acid D. This acid can also be obtained from acetone by the hydrogen cyanide followed by hydrolysis. Identify the compound A,B,C and D.

15. Compound A(C₅H₁₀O) forms phenyl hydrazone, gives negative Tollen’s and iodoforms tests, and is reduced to pentane. What is the structure of the compound A?

[Ans. CH₃CH₂.COCH₂CH₃, Pentan-3-one]

16. A ketone ‘A’ gives iodoform on reacting with iodine, and sodium hydroxide. ‘A’ on reduction gives B which on heating with sulphuric acid gives C. C on ozonolysis gives acetaldehyde and acetone . Identify A,B and C.

17. Compound ‘A’ C₅H₁₂O reacts with K₂Cr₂O₇/H⁺ to form ‘B’ C₅H₁₀O. Compound ‘B’ reacts with 2,4-dinitrophenylhydrazine to form a yellow solid but does not give a silver mirror when treated with Tollen’s reagent or a precipitate of iodoform when heated with basic solution of I₂ . Draw the structures of ‘A’ and ‘B’. Show the reactions involved.

18. Compound (A), C₆H₁₂O, gives the following results:

(a) (A) gives positive test with hydroxylamine.

(b) (A) does not react with Tollen’s reagent.

(c) (A) on catalytic hydrogenation gives (B), C₆H₁₄O.

(d) (B) on treatment with conc. H₂SO₄ gives (C), C₆H₁₂.

(e) (C) on ozonolysis gives two compounds, (D)C₃H₆O and (E) C₃H₆O.

(f) (D) gives a negative Tollens’ test and +ve iodoform test.

(g) (E) gives a negative iodoform test and +ve Tollens’ test.

What are the structure of (A) to (E)? Explain the reactions.

19. An organic compound (A) when reacts with alc. KOH gives (B) which on ozonolysis gives (C). This compound on Clemmensen reduction gives propane. The compound (C) also give iodoform test. Compound (D) is obtained when (C) undergoes Aldol condensation. On reaction of (C) with 2,4 -DNP reagent gives compound (E). Identify (A), (B), (C), (D) and (E).

20. An organic compound (A) reacts with HCN to give (B). On hydrolysis of (B) in acidic medium gives (C). Compound (A) also produces propane when treated with zinc-amalgam and HCI. Identify (A), (B) and (C) with reaction and give their IUPAC names. What product would you expect when (A) is treated with trichloromethane in alkaline medium?

21. Compound (A), C₅H₁₀O gives the following results:

(a) Treatment with 2,4-DNP gives a coloured precipitate.

(b) It gives negative Tollen’s test.

(c) It gives positive iodoform test.

Suggest two structures for (A) that are consistent with these facts.

22. An alkene, C₆H₁₂, after ozonolysis yielded two products. One of them gave a positive iodoform test but negative Tollen’s test. The other gave a positive Tollen’s test but negative iodoform test. What is the structure and IUPAC name of the alkene?

23. An alkene ‘A’ on ozonolysis gives twoaldehydes ‘B’ and ‘C’. compound ‘B’ gives Fehlings test and on Clemmensen reduction gives propane while the compound ‘C’ on treatment with HCN followed by acid hydrolysis gives 2-hydroxypropanoic acid. Identify A, B and C writing related reactions.

24. An organic compound ‘A’ on oxidation using CrO₃/pyridine gives compound ‘B’. both the compounds ‘A’ and ‘B’ respond to iodoform test. The compound ‘A’ is a primary alcohol. Identify ‘A’ and ‘B’ writing related reactions. How can the compound ‘A’ be converted into benzene?

25. A pathological report of a patient shows high blood sugar level.

(a) Suggest a probable test that has to be carried out by pathologist to detect the blood sugar level.

(b) What would be the possible compound present in his blood sugar?

(c) Is there any possible isomer of this compound?

(d) The physician has advised the patient not to take more rice, potatoes, sweet, etc., why?

(e) One component of a sugar shows positive Fehling solution test with the formation of a compound of formula C₆H₁₂O₇. Identify this compound.

26. Compound A on treatment with PCl₅ gives compound B which on reduction with H₂/Pd in presence of BaSO₄, gives compound C. the compound C gives Tollen’s test, Fehling’s solution test and iodoform test. When C is treated with dilute NaOH, compound D is obtained, which on heating gives crotonaldehyde (CH₃-CH=CH-CHO). Identify A, B, C and D, and complete the sequence of reaction.

27. An organic compound ‘A’ C₂H₄O gives a red precipitate with Fehling’s solution. It also undergoes aldol condensation in the presence of dilute alkali.

(a) Write IUPAC name of the compound and give the reaction involved.

(b) Prepare iodoform from ‘A’.

(c) How can you distinguish ‘A’ from formaldehyde?

(d) What product would you expect when ‘A’ is heated with 2,4-DNP?

28. An organic compound A(C₃H₆O) is resistant to oxidation but forms compound B(C₃H₈O) on reduction which reacts with HBr to form the bromide(C). C forms a Grignard reagent which reacts with A to give D (C₆H₁₄O). Give the structures of A, B, C and D and explain the reactions involved.

29. An organic compound (A) which has characteristic odour, on treatment with NaOH forms two compounds (B) and (C). Compound (B) has the molecular formula C₇H₈O which on oxidation with CrO3 gives back compound (A). Compound (C) is sodium salt of the acid. Compound (C) when heated with soda lime yields an aromatic hydrocarbon (D). Deduce the structures of (A), (B), (C) and (D). Write chemical equations for all reactions taking place.

30. Two moles of organic compound ‘A’ on treatment with a strong base gives two compounds “B” and “C”. Compound “B” on dehydrogenation with Cu gives “A” while acidification of “C” yields carboxylic acid “D” with molecular formula of CH₂O₂. Identify the compounds A, B, C and D and write all chemical reactions involved.

31. A compound ‘A’ has the molecular formula C₂H₂O₂. ‘A’ reacts with HCN to give compound ‘B’ C₄H₄O₂N₂. ‘A’ is readily oxidized by acidified K₂Cr₂O₇ to compound ‘C’, C₂H₂O₄. When 0.5gm of ‘C’ is dissolved in water and titrated with 0.5M NaOH solution, 15.9ml of sodium hydroxide is required for neutralization. Suggest structural formulas of A, B and C and explain the above reaction.

32. Compound ‘A’ C₅H₁₂O does not react with phenyl hydrazine. Oxidation of ‘A’ with K₂Cr₂O₇/H+ gives ‘B’ (C₅H₁₀O). compound ‘B’ reacts with phenyl hydrazine but does not give Tollen’s test and iodoform test. The original compound ‘A’ can be dehydrated with H₂SO₄ to give a hydrocarbon ‘C’ (C₅H₁₀).  Identify compounds A, B and C.

33. The thermosetting plastic used in the given figure is first synthetic plastic formed by condensation polymerization process.

• Name the monomers involved in this polymer.
•  Write the reaction involved.
• Write the oxidation products of both monomers.
• Starting from one of the monomers, write the reaction to prepare phenolphthalein.
• Starting from one of the monomers, write the reaction to prepare urotropin.

34. A carbonyl compound ‘A’ reduce Tollen’s reagent and itself reduced with metal hydride to give compound ‘B’. Similarly another carbonyl compound ‘C’ does not reduce Tollen’s reagent and itself reduced with metal hydride to give compound ‘D’. The compound A and C can be obtained by the ozonolysis of compound ‘E’. The compound B and D both response positive iodoform test. The compound ‘C’ can also be obtained by catalytic hydration of propyne.

(a) Identify A, B, C, D and E with suitable chemical reaction.

(b) Write a suitable chemical test to distinguish A from C.

35. An organic compound used in the figure to preserve museum specimens and also to prepare urinary antiseptics.

• Write the chemical reaction when the given preservative is treated with phenol in acidic medium.
• How would you obtain the preservative from methanol?
• Write the reaction when the compound is heated with concentrated sodium hydroxide.
• Draw the structure of urinary antiseptic.

Write short note on:

1. Aldol condensation
2. Cannizzaro’s reaction
3. Perkin’s condensation
4. Benzoin condensation
5. Silver mirror test
6. Fehling’s test
7. DNP test
8. Wolff-Kishner reduction
9. Rosenmund reduction
10. Clemmenson’s reduction

What happens when:

1. Ethanal is warmed with semi carbazide.
2. Ethanal is warmed with iodine and aqueous NaOH
3. Ammonia is treated with methanol
4. Propanone is heated with hydrazine in presence of glycerol.
5. Acetylene is passed through H₂SO₄ in the presence of HgSO₄.
6. Benzaldehyde is warmed with conc. NaOH.
7. Benzaldehyde is heated with ethanoic anhydride in presence of sodium ethanoate.
8. Acetophenone is treated with Zn-Hg and HCl.
9. Methanal reacts with ammonia.
10. Methanol reacts with conc. NaOH.
11. Name a carbonyl compound which do not produce crystalline products with sodium bisulphate.
12. Ethanol is treated with CrO₃ and pyridine.

[Hint: CrO₃/pyridine converts 1⁰ alcohol to aldehyde]

13. Acetylene is passed through H₂SO₄ in the presence of HgSO₄.

14. But-2-ene is ozonized.

Give reason:

1. CH₃CHO is more reactive than CH₃COCH₃ towards HCN.
2. Aldehydes are more reactive than ketones towards nucleophilic addition reaction.
3. Di-tert-butyl ketone does not give a NaHSO₃ adduct but acetone does.
4. Aromatic carbonyl compounds are less reactive than those of aliphatic ones.
5. Boiling points of aldehydes and ketones are lower than the alcohols and carboxylic acids having nearly same molecular mass.
6. Acetone is highly soluble in water but acetophenone is not.
7. CH₃-CHO is more reactive than CH₃COCH₃ towards HCN.
8. Lower members of aldehydes and ketones are soluble in water.

Convert:

1. Acetylene to acetic acid
2. Toluene to m-nitrobenzoic acid
3. Ethanol to acetone
4. Acetaldehyde to acetone
5. Phenol to benzaldehyde
6. Acetaldehyde to acetone and vice-versa
7. Methanol to ethanal
8. Ethanal to methanol
9. Propanone into 2-hydroxy-2-methyl propanoic acid
10. Acetylene to acetic acid
11. Peopanone to methanol
12. Propanone to 4-hydroxy-4-methyl pentan-2-one
13. Acetaldehyde to lactic acid

How would you distinguish:

1. Pentan-2-one to pentan-3-one
2. Acetaldehyde and acetone
3. Benzaldehyde and ethanal
4. Methanal and ethanal
5. Propanal and propanone
6. Methanol and ethanol

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REFERENCES

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• Bahl, B.S., A., Advanced Organic Chemistry, S. Chand and company Ltd, New Delhi, 1992.
• Finar, I. L., Organic Chemistry, Vol. I and Vol. II, Prentice Hall, London, 1995.
• Ghosh, S.K., Advanced General Organic Chemistry, Second Edition, New Central Book Agency Pvt. Ltd., Kolkatta, 2007.
• Morrison, R.T. , Boyd, R.N., Organic Chemistry, Sixth edition, Prentice-Hall of India Pvt. Ltd., 2008.
• March, j., Advanced Organic Chemistry, Fourth edition, Wiley Eastern Ltd. India, 2005.
• https://chemicalnote.com/category/organic-chemistry/name-reactions/
• https://www.dailymotion.com/video/x3nq0aj
• https://www.rxlist.com/formalin/definition.htm