Practice Questions

Justify why carboxylic acids have significantly higher boiling points than aldehydes and alcohols of comparable molecular mass.

Apply your understanding of reaction requirements to examine whether 2,2-Dimethylpropanal can undergo an Aldol condensation reaction. Justify your answer.

Name the product formed when a ketone reacts with a semicarbazide ($H_2N-NH-CO-NH_2$).

Identify the reagent commonly known as 'Tollens' reagent' and state its chemical composition.

Name the reaction used to prepare aldehydes from acyl chlorides using a palladium on barium sulphate catalyst.

Recall the IUPAC names for the following compounds: (i) $CH_3COCH_3$ (Acetone), (ii) $HCHO$ (Formaldehyde), (iii) $CH_3CH_2CHO$ (Propionaldehyde).

Critique the use of sodium borohydride ($NaBH_4$) for the reduction of a carboxyl group to a primary alcohol.

Define the term 'carbonyl group' and list the functional groups where it is present.

Explain the term 'esterification' and write a general chemical equation for the reaction.

Compare the electrophilicity of the carbonyl carbon in ethanal ($CH_3CHO$) versus propanone ($CH_3COCH_3$).

Compare the boiling point of propanal ($CH_3CH_2CHO$) and propan-1-ol ($CH_3CH_2CH_2OH$), which have comparable molecular masses, and analyze the reason for the difference.

Demonstrate the mechanism for the nucleophilic addition of hydrogen cyanide ($HCN$) to propanone ($CH_3COCH_3$) in the presence of a basic catalyst ($OH^-$) to form a cyanohydrin.

Compare and contrast the chemical principles and observations of Tollens' test and Fehling's test.

Solve for the final organic product when butanoic acid ($CH_3CH_2CH_2COOH$) is subjected to the Hell-Volhard-Zelinsky reaction using bromine ($Br_2$) and red phosphorus, followed by hydrolysis.

Justify why p-nitrobenzoic acid ($pK_a = 3.41$) is a stronger acid than benzoic acid ($pK_a = 4.19$), which in turn is stronger than p-methoxybenzoic acid ($pK_a = 4.46$).

Propose a reason why the Hell-Volhard-Zelinsky reaction specifically halogenates the $\alpha$-carbon of a carboxylic acid and not other positions.

Justify why ketones are generally less reactive than aldehydes towards nucleophilic addition reactions, considering both steric and electronic factors.

Evaluate the statement: 'The Cannizzaro reaction is a disproportionation reaction.' Provide a suitable example and explain the oxidation and reduction processes.

Examine the acid-catalyzed esterification reaction. Explain why the reaction is reversible and apply Le Chatelier's principle to suggest two distinct methods for increasing the yield of the ester.

Analyze the acidity of fluoroacetic acid ($FCH_2COOH$) and chloroacetic acid ($ClCH_2COOH$). Which one is the stronger acid and why?

Design a multi-step synthesis to prepare benzene-1,4-dicarboxylic acid (terephthalic acid) starting from p-xylene.

A student attempts to prepare an ester by reacting a carboxylic acid with an alcohol in a neutral medium and observes a very low yield. Critique this approach and propose a modification to improve the reaction's efficiency, explaining the role of the proposed reagent.

Identify the products formed when ethanal ($CH_3CHO$) undergoes Aldol condensation.

Name the two reduction methods used to convert the carbonyl group of aldehydes and ketones into a methylene ($CH_2$) group.

Define the Cannizzaro reaction and state the necessary condition for an aldehyde to undergo this reaction.

List two electron-withdrawing groups and two electron-donating groups, and explain their effect on the acidity of carboxylic acids.

Apply IUPAC nomenclature rules to provide the systematic name for the compound with the structure $CH_3CH(Br)CH_2COCH(CH_3)_2$.

Solve for the major organic product when benzoyl chloride ($C_6H_5COCl$) is treated with hydrogen gas over a palladium catalyst supported on barium sulphate ($Pd/BaSO_4$). Also, identify this named reaction.

Explain why the boiling points of aldehydes and ketones are higher than those of nonpolar hydrocarbons of similar molecular mass.

Describe the chemical test used to distinguish between aldehydes and ketones that involves ammoniacal silver nitrate solution.

Explain why carboxylic acids are more acidic than alcohols.

Design a chemical test to distinguish between pentan-2-one and pentan-3-one. Write the chemical equations for the positive test.

Evaluate the synthetic utility of the cross-aldol condensation between benzaldehyde and acetone. Predict the major product and justify why it is formed preferentially.

Propose why Friedel-Crafts acylation is preferred over Friedel-Crafts alkylation for preparing aryl ketones like acetophenone.

Apply your knowledge of electrophilic aromatic substitution to devise a two-step synthesis for converting benzene into m-Nitroacetophenone.

An unknown organic compound (A) with molecular formula $C_8H_8O$ forms an orange-red precipitate with 2,4-DNP reagent and gives a yellow precipitate on heating with iodine and NaOH. It does not reduce Tollens' reagent. On drastic oxidation, it gives a carboxylic acid (B) with molecular formula $C_7H_6O_2$. Create a reaction scheme to identify compounds (A) and (B) and justify each inference.

An organic compound (A) with the molecular formula $C_8H_8O$ gives a positive 2,4-DNP test. It does not react with Tollens' reagent but gives a yellow precipitate with iodine and sodium hydroxide. Upon vigorous oxidation, it produces benzoic acid ($C_6H_5COOH$). Solve for the structure of compound (A) and demonstrate the key reactions.

Design a synthetic pathway to convert toluene into 3-phenylpropan-1-ol in not more than four steps. Justify the choice of reagents for each step.

Justify the meta-directing nature of the carbonyl group in benzaldehyde during electrophilic aromatic substitution, such as nitration. Draw resonance intermediates for ortho, meta, and para attack to support your reasoning.

Solve for the structures of the four possible aldol addition products formed when a mixture of ethanal ($CH_3CHO$) and propanal ($CH_3CH_2CHO$) is treated with dilute $NaOH$.

Summarize the key steps in the preparation of a carboxylic acid from a Grignard reagent.

Analyze why formaldehyde ($HCHO$) undergoes the Cannizzaro reaction in the presence of concentrated alkali, whereas ethanal ($CH_3CHO$) undergoes the Aldol condensation. Demonstrate the products formed when formaldehyde undergoes this reaction.

Formulate a plausible mechanism for the acid-catalyzed formation of an acetal from ethanal and excess ethanol.

Analyze the following compounds and arrange them in increasing order of their reactivity towards nucleophilic addition reactions: Propanone, Ethanal, Benzaldehyde, Acetophenone. Provide a detailed justification for your arrangement.

Describe the Hell-Volhard-Zelinsky (HVZ) reaction.