12 Chemistry - Aldehydes, Ketones and Carboxylic Acids

12 Chemistry – Aldehydes, Ketones and Carboxylic Acids

The number of attempts remaining is 3

This change occurs when the pi-bond breaks and the nucleophile attacks, changing the geometry.

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1. In the mechanism of nucleophilic addition to the carbonyl group, the hybridization of the carbon atom changes from sp² to sp³.

1. d²sp³

2. sp³

3. dsp²

4. sp

This reaction specifically targets the CH₃CO group.

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2. The Haloform reaction (oxidation of methyl ketones) requires the presence of which structural unit in the reactant?

1. A tertiary alkyl group

2. A primary alcohol group

3. A carboxyl group

4. A methyl ketone (CH₃CO) group

Check the list of important nucleophilic addition examples.

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3. Which reagent, when added to aldehydes, forms an addition product (often crystalline) that is useful for separating and purifying the aldehyde?

1. Grignard reagent

2. HCN

3. CrO₂Cl₂

4. NaHSO₃

It replaces the ‘-e’ of the corresponding alkane.

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4. According to IUPAC nomenclature, what suffix is used to denote ketones?

1. -ol

2. -one

3. -oic acid

4. -al

This is the primary requirement for base-catalyzed condensation reactions.

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5. Which reaction requires the presence of at least one α-hydrogen atom in the aldehyde or ketone molecule?

1. Aldol condensation

2. Cannizzaro reaction

3. Tollens’ test

4. Reduction to hydrocarbons

Polarity means electron density shifts towards the most electronegative atom.

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6. In the structure of the carbonyl group, the partial positive charge resides on which atom?

1. Alkyl group

2. Carbon

3. Oxygen

4. Hydrogen

This results in a mixture of up to four products.

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7. When two different aldehydes, both possessing α-hydrogen atoms, react in the presence of a dilute base, the reaction is classified as:

1. Wurtz reaction

2. Cross aldol condensation

3. Friedel-Crafts reaction

4. Cannizzaro reaction

This is a mild oxidation test for aldehydes.

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8. Which test is specifically used to distinguish aldehydes from ketones based on the reduction of an ammoniacal silver nitrate solution (Ag(NH₃)₂⁺) to metallic silver?

1. Cannizzaro reaction

2. Fehling's test

3. Tollens’ test

4. Haloform reaction

This reaction introduces an acyl group (-COR) to the aromatic ring.

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9. The preparation of aromatic ketones from benzene and an acyl chloride using a Lewis acid catalyst is an example of which reaction?

1. Etard reaction

2. Gattermann-Koch reaction

3. Cannizzaro reaction

4. Friedel-Crafts acylation

The resulting product is an alcohol.

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10. The catalytic reduction of aldehydes yields primary alcohols, while catalytic reduction of ketones yields secondary alcohols. This reaction is classified under:

1. Nucleophilic addition

2. Reduction to hydrocarbons

3. Oxidation

4. Reduction to alcohols

The interaction must involve water’s strong polarity.

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11. Despite being polar, haloalkanes are only slightly soluble in water. Similarly, lower members of aldehydes and ketones are miscible with water primarily due to their ability to form:

1. Metallic bonds

2. Covalent bonds

3. Ionic bonds

4. Hydrogen bonds

This reaction introduces a formyl group to the benzene ring.

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12. The specific reaction used is the Gattermann–Koch reaction, which prepares aromatic aldehydes by treating benzene with carbon monoxide (CO) and hydrogen chloride (HCl) in the presence of anhydrous AlCl₃/CuCl.

1. Gattermann-Koch reaction

2. Tollen's test

3. Wolff-Kishner reduction

4. Friedel-Crafts acylation

Reactivity is governed by both electronic and steric factors.

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13. Why are aldehydes generally more reactive than ketones towards nucleophilic addition reactions?

1. Aldehydes have higher boiling points

2. Aldehydes experience less steric hindrance

3. Ketones are less polar

4. Ketones form more stable carbocations

This is a specific reduction method listed under preparation of aldehydes.

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14. Aldehydes can be prepared from acyl chlorides(RCOCl) using hydrogen gas over a palladium catalyst poisoned by BaSO₄. This specific named reaction is known as:

1. Rosenmund reduction

2. Etard reaction

3. Clemmensen reduction

4. Wolff-Kishner reduction

Contrast this with the requirement for Aldol condensation.

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15. The Cannizzaro reaction is a disproportionation reaction exhibited by aldehydes that lack which characteristic structural feature?

1. Aromatic ring

2. Low molecular weight

3. C=O bond

4. α-hydrogen

This method is listed under the preparation of aromatic aldehydes.

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16. The oxidation of methylbenzene to benzaldehyde using chromyl chloride (CrO₂Cl₂) is called the:

1. Etard reaction

2. Cannizzaro reaction

3. Gattermann-Koch reaction

4. Friedel-Crafts acylation

This determines the trigonal planar geometry.

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17. The typical hybridization state of the carbon atom in the carbonyl group (C=O) is sp².

1. dsp²

2. sp

3. sp³

4. sp²

The carbon atom is electrophilic and attracts these species.

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18. The carbonyl group (C=O) in both aldehydes and ketones typically undergoes nucleophilic addition reactions.

1. Nucleophilic addition reactions

2. Elimination reactions

3. Electrophilic addition reactions

4. Substitution reactions

This step converts the resulting halide into the hydroxyl/aldehyde group.

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19. The preparation of aromatic aldehydes by side chain chlorination of methylbenzene must be followed by which subsequent reaction step to yield the aldehyde?

1. Oxidation

2. Hydrolysis

3. Reduction

4. Dehydrogenation

This involves the formation of an imine intermediate.

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20. Ketones can be prepared from nitriles by reacting them with which class of metallic compounds, followed by hydrolysis?

1. Grignard reagent

2. Chromyl chloride

3. Dialkylcadmium

4. Hydrazine

Look for the section on specific ketone preparation.

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21. Ketones can be prepared from acyl chlorides by reaction with R₂Cd (Dialkylcadmium). Where does this specific preparation method fall in the sources?

1. From acyl chlorides (via Dialkylcadmium)

2. By ozonolysis of alkenes

3. By side chain chlorination

4. By oxidation of alcohols

This involves the removal of hydrogen gas.

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22. Which general preparation method involves the conversion of primary alcohols (RCH₂OH) to aldehydes by passing the vapour over a heated copper catalyst?

1. By ozonolysis of alkenes

2. By dehydrogenation of alcohols

3. By reduction of carboxylic acids

4. By hydrolysis of nitriles

This test is generally given by aliphatic aldehydes.

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23. Which test involves the oxidation of aldehydes using an alkaline solution of Cu²⁺ ions, leading to the formation of a red-brown precipitate of Cu₂O?

1. Fehling’s test

2. Haloform reaction

3. Tollens’ test

4. Aldol condensation

The simplest ketone has two methyl groups.

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24. Which common name is used for the simplest ketone, CH₃COCH₃?

1. Formaldehyde

2. Propionaldehyde

3. Acetaldehyde

4. Acetone

This is the second major reduction that yields hydrocarbons.

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25. The reduction of aldehydes and ketones to hydrocarbons using hydrazine (NH₂NH₂) and KOH in ethylene glycol is known as the:

1. Aldol condensation

2. Etard reaction

3. Clemmensen reduction

4. Wolff-Kishner reduction

Check the end of section 8.4.

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26. Which reaction type is listed as the last category under Chemical Reactions of Aldehydes and Ketones?

1. Oxidation reactions

2. Electrophilic substitution reaction

3. Nucleophilic addition

4. Reduction to alcohols

This involves reduction followed by hydrolysis.

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27. Which reagent combination is specifically used in the Stephen reaction to prepare aldehydes from nitriles?

1. LiAlH₄

2. CrO₂Cl₂

3. Zn–Hg / Conc. HCl

4. SnCl₂ / HCl

This is one of the two main reductions that yield hydrocarbons.

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28. Which specific reduction method is the Clemmensen reduction, which converts the carbonyl group (C=O) of aldehydes and ketones directly into a methylene group (CH₂) using zinc amalgam (Zn-Hg) and concentrated HCl.

1. Clemmensen reduction

2. Rosenmund reduction

3. Stephen reaction

4. Wolff-Kishner reduction

This method is an alternative to the Stephen reaction.

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29. DIBAL-H (Diisobutylaluminium hydride) is a specific reducing agent used to convert nitriles and esters into:

1. Aldehydes

2. Alkanes

3. Ketones

4. Carboxylic acids

This relates to the polarity of the C=O bond.

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30. Why do aldehydes and ketones exhibit higher boiling points than non-polar compounds of comparable molecular mass?

1. Due to strong intermolecular hydrogen bonding.

2. Due to low molecular weight.

3. Due to dipole-dipole interactions.

4. Due to their low polarity.

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12 Chemistry – Aldehydes, Ketones and Carboxylic Acids

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