FAD1018: Rapid-Fire Drill Pack — Carbonyl Compounds (Aldehydes & Ketones)

Objective: Achieve mechanical fluency in naming, reactions, identification tests, and synthesis of aldehydes and ketones.
Target: 45–90 seconds per problem. If you stall >3 minutes, skip and mark it.
Total problems: 56
Estimated time: 60–75 minutes

Cheat Sheet (Memorize First)

General Facts

  • General formula: $C_nH_{2n}O$
  • Carbonyl carbon is sp² hybridized; C=O is polar ($\delta^+$ on C, $\delta^-$ on O)
  • Aldehydes are more reactive than ketones in nucleophilic addition (less steric hindrance, less electron donation from alkyl groups)

Nomenclature Quick Rules

Feature Aldehydes Ketones
Suffix -al -one
Carbonyl locant Always C1 Lowest possible (acyclic); assumed C1 (cyclic)
Cyclic prefix carbaldehyde —
Lower-priority carbonyl oxo- or formyl- prefix oxo- prefix

Key Structures (SMILES)

C=O
CC=O
CC(=O)C
c1ccccc1C=O
O=C1CCCCC1
CC(=O)c1ccccc1

Core Reactions

Reaction Reagent / Condition Product Type
Cyanohydrin HCN (base-catalyzed) $\alpha$-hydroxynitrile
Grignard RMgBr, then H₃O⁺ 2° alcohol (from aldehyde); 3° alcohol (from ketone)
Bisulfite addition NaHSO₃ Crystalline addition compound
Acetal / Ketal R'OH, H⁺ Protecting group
Oxime NH₂OH R₂C=NOH
Hydrazone NH₂NH₂ R₂C=NNH₂
2,4-DNP 2,4-dinitrophenylhydrazine Orange/red precipitate
Imine (Schiff base) RNH₂ R₂C=NR

Oxidation & Reduction

Transformation Reagent
Aldehyde $\rightarrow$ Carboxylic acid Tollens', Fehling's, Benedict's, K₂Cr₂O₇/H⁺, KMnO₄/H⁺
Aldehyde $\rightarrow$ Primary alcohol NaBH₄, LiAlH₄, H₂/catalyst
Ketone $\rightarrow$ Secondary alcohol NaBH₄, LiAlH₄, H₂/catalyst
Carbonyl $\rightarrow$ Alkane (Clemmensen) Zn(Hg), HCl
Carbonyl $\rightarrow$ Alkane (Wolff-Kishner) NH₂NH₂, OH⁻, heat

Preparation

Target Starting Material Reagent
Aldehyde Primary alcohol PCC in CH₂Cl₂ (mild only!)
Ketone Secondary alcohol Any oxidant (PCC, K₂Cr₂O₇/H⁺, etc.)
Aldehyde / Ketone Alkene O₃, then H₂O/Zn (ozonolysis)
Aromatic ketone Benzene + RCOCl AlCl₃ (Friedel-Crafts acylation)

Identification Tests Summary

Test Aldehydes Ketones
Tollens' ($[\text{Ag}(\text{NH}_3)_2]^+$) Silver mirror Negative
Fehling's / Benedict's ($\text{Cu}^{2+}$) Brick-red $\text{Cu}_2\text{O}$ ppt Negative
2,4-DNP Orange/red ppt Orange/red ppt
Iodoform ($\text{I}_2$ / $\text{OH}^-$) Positive only if ethanal Positive if methyl ketone ($\text{CH}_3\text{CO}-$)
Schiff's reagent Pink color Negative

Special Reactions

  • Aldol condensation: $\alpha$-H + base $\rightarrow$ $\beta$-hydroxy carbonyl $\xrightarrow{\Delta}$ $\alpha$,$\beta$-unsaturated carbonyl
  • Cannizzaro: Non-enolizable aldehyde (no $\alpha$-H) + strong base $\rightarrow$ disproportionation (alcohol + carboxylate)
  • Haloform (Iodoform): $\text{CH}_3\text{CO}-$ or $\text{CH}_3\text{CH(OH)}-$ + $\text{I}_2$ / $\text{OH}^-$ $\rightarrow$ yellow $\text{CHI}_3$ precipitate

Part A: Nomenclature

Target: 30–45 seconds per problem.

Set A1 — IUPAC Naming (6 problems)

Write the systematic IUPAC name for each compound.

  1. CH₃CH₂CHO
  2. CH₃COCH₃
  3. CH₃CH(Br)CH₂CHO
  4. O=CH–CH₂–CH₂–CO–CH₃
  5. c1ccccc1C=O
  6. CC(=O)c1ccccc1

Score: ___/6

Set A2 — Drawing Structures from Names (6 problems)

  1. 2-methylpropanal
  2. 3-hexanone
  3. 4-oxopentanal
  4. cyclohexanone
  5. butyrophenone
  6. trans-2-methylcyclohexanecarbaldehyde

Score: ___/6

Part B: Reactions and Mechanisms

Target: 60–90 seconds per problem.

Set B1 — Predict the Product (6 problems)

Give the major organic product for each reaction.

  1. Propanal + HCN $\rightarrow$
  2. Propanone + NaHSO₃ $\rightarrow$
  3. Benzaldehyde + CH₃MgBr $\xrightarrow{\text{1. Et₂O}}\xrightarrow{\text{2. H₃O⁺}}$
  4. Ethanal + 2,4-dinitrophenylhydrazine $\rightarrow$
  5. Cyclohexanone + NH₂NH₂ $\rightarrow$
  6. Propanal + LiAlH₄ $\xrightarrow{\text{1. Et₂O}}\xrightarrow{\text{2. H₃O⁺}}$

Score: ___/6

Set B2 — Fill in the Reagent / Condition (6 problems)

State the reagent(s) and conditions required.

  1. 1-Butanol $\rightarrow$ Butanal
  2. Butan-2-ol $\rightarrow$ Butan-2-one
  3. Benzene $\rightarrow$ Acetophenone
  4. Acetophenone $\rightarrow$ 1-Phenylethanol
  5. Butanal $\rightarrow$ Butanoic acid
  6. Propanone $\rightarrow$ Propane

Score: ___/6

Set B3 — Mechanism Concepts and Special Reactions (6 problems)

Provide a concise answer for each.

  1. Explain why aldehydes are generally more reactive than ketones toward nucleophilic addition.
  2. Arrange the following in order of increasing reactivity toward nucleophilic addition: formaldehyde, acetaldehyde, acetone, benzaldehyde, acetophenone.
  3. Which class of aldehydes undergoes the Cannizzaro reaction? Give one example.
  4. What is the final dehydration product when two molecules of ethanal undergo aldol condensation followed by heating?
  5. State the reagents and conditions for the Wolff-Kishner reduction.
  6. What is the product when benzaldehyde reacts with excess ethanol in the presence of an acid catalyst?

Score: ___/6

Part C: Identification Tests

Target: 45–60 seconds per problem.

Set C1 — Test Selection and Interpretation (6 problems)

  1. Name the test that gives a silver mirror with aldehydes but is negative with ketones.
  2. Which of the following give a positive iodoform test? Select all that apply: ethanol, propan-2-ol, propan-1-ol, acetophenone, benzophenone, ethanal.
  3. What colored precipitate is observed in a positive 2,4-DNP test?
  4. Why does benzaldehyde give a negative result with Fehling's solution?
  5. State the observation that indicates a positive Tollens' test.
  6. Compound X gives an orange/red precipitate with 2,4-DNP but does not reduce Tollens' reagent. What general class of compound is X?

Score: ___/6

Set C2 — Distinguishing Unknowns (4 problems)

Name one suitable chemical test to distinguish each pair. State the expected observation for each compound.

  1. Ethanal vs. propanone
  2. Benzaldehyde vs. acetaldehyde
  3. Propan-1-ol vs. propan-2-ol
  4. An aliphatic aldehyde vs. a methyl ketone (both give positive 2,4-DNP tests)

Score: ___/4

Part D: Synthesis Problems

Target: 90–120 seconds per problem.

Set D1 — One-Step and Multi-Step Routes (8 problems)

Give the reagents and key intermediate(s) for each transformation.

  1. Synthesize butanal from 1-butanol.
  2. Synthesize butan-2-ol from propanal.
  3. Synthesize acetophenone from benzene.
  4. Show how to prepare 3-methyl-3-pentanol from a carbonyl compound and a Grignard reagent.
  5. Starting from propene, outline a synthesis of propanone.
  6. Convert acetaldehyde to lactic acid (2-hydroxypropanoic acid) in two steps.
  7. Synthesize 2-phenyl-2-propanol from acetophenone.
  8. Starting from acetylene, show a synthesis of acetaldehyde.

Score: ___/8

Part E: Mixed and Reverse Problems

Target: 90–150 seconds per problem.

Set E1 — Integrated Challenges (5 problems)

  1. Compound Y ($C_5H_{10}O$) gives a positive Tollens' test and a negative iodoform test. Draw its structure (SMILES) or give its name.
  2. Compound Z ($C_4H_8O$) gives a positive iodoform test but does not reduce Tollens' reagent. Identify Z.
  3. A ketone reacts with HCN. The resulting cyanohydrin upon hydrolysis yields 2-hydroxy-2-methylpropanoic acid. Identify the ketone.
  4. When two molecules of ethanal react in the presence of dilute NaOH followed by heating, what is the final product?
  5. Explain why fructose (a ketose) gives a positive Tollens' test even though it contains a ketone group.

Score: ___/5

Set E2 — Reverse Engineering (3 problems)

  1. Compound A ($C_4H_8O$) gives a positive iodoform test. Reduction of A with NaBH₄ gives B ($C_4H_{10}O$). Oxidation of B with PCC regenerates A. Identify A and B.
  2. A methyl ketone C ($C_6H_{12}O$) undergoes Clemmensen reduction to give 2-methylpentane. Identify C.
  3. Compound D reacts with 1 equivalent of CH₃MgBr to give 2-methyl-2-butanol. What is D?

Score: ___/3

Final Scorecard

Part Sets Problems Raw Score
A — Nomenclature A1, A2 12 ___/12
B — Reactions and Mechanisms B1, B2, B3 18 ___/18
C — Identification Tests C1, C2 10 ___/10
D — Synthesis D1 8 ___/8
E — Mixed and Reverse E1, E2 8 ___/8
TOTAL 56 ___/56

Proficiency Benchmarks

  • 40/56 (71%) — Proficient. You can handle standard exam problems.
  • 48/56 (86%) — Solid. Fast and accurate on most carbonyl chemistry.
  • 52/56 (93%) — Exam-ready. Any mistake is a careless slip.

Speed Benchmarks

  • <50 min: Excellent mechanical fluency.
  • 50–65 min: Good. Review missed patterns before the exam.
  • >65 min: Drill the specific sets you scored lowest on again tomorrow.

Error Log Template

After grading, list every wrong problem number with a one-word reason:

Problem Reason
e.g. 4 forgot oxo prefix

Re-solve all wrong problems immediately with notes, then again in 24 hours without notes.

Answer Key

Set A1

  1. propanal
  2. propanone
  3. 3-bromobutanal
  4. 4-oxopentanal
  5. benzenecarbaldehyde (benzaldehyde accepted)
  6. phenylethanone (1-phenylethanone or acetophenone accepted)

Set A2

   CC(C)C=O

CCC(=O)CCC

   O=CCCC(=O)C

O=C1CCCCC1

CCCC(=O)c1ccccc1

CC1CCCCC1C=O

Set B1

  1. 2-hydroxybutanenitrile ($\mathrm{CH_3CH_2CH(OH)CN}$)
  2. bisulfite addition compound (crystalline solid)
  3. 1-phenylethanol ($\mathrm{C_6H_5CH(OH)CH_3}$)
  4. ethanal 2,4-dinitrophenylhydrazone (orange/red precipitate)
  5. cyclohexanone hydrazone
  6. propan-1-ol ($\mathrm{CH_3CH_2CH_2OH}$)

Set B2

  1. PCC in $\mathrm{CH_2Cl_2}$
  2. $\mathrm{Na_2Cr_2O_7}$ / $\mathrm{H^+}$ (or $\mathrm{K_2Cr_2O_7/H_2SO_4}$, $\mathrm{CrO_3}$, PCC, etc.)
  3. $\mathrm{CH_3COCl}$ / $\mathrm{AlCl_3}$ (Friedel-Crafts acylation)
  4. $\mathrm{NaBH_4}$ (or $\mathrm{LiAlH_4}$, or $\mathrm{H_2}$ / Ni, Pt, Pd)
  5. $\mathrm{K_2Cr_2O_7}$ / $\mathrm{H_2SO_4}$ (or $\mathrm{KMnO_4/H^+}$, Tollens', Fehling's, Benedict's)
  6. $\mathrm{Zn(Hg)}$, HCl (Clemmensen) or $\mathrm{NH_2NH_2}$, $\mathrm{OH^-}$, heat (Wolff-Kishner)

Set B3

  1. Less steric hindrance at the carbonyl carbon; fewer electron-donating alkyl groups stabilize the partial positive charge, making the carbonyl carbon more electrophilic.
  2. Acetophenone < Benzaldehyde < Acetone < Acetaldehyde < Formaldehyde
  3. Non-enolizable aldehydes (no $\alpha$-hydrogen). Example: benzaldehyde, formaldehyde, or trimethylacetaldehyde.
  4. but-2-enal (crotonaldehyde, $\mathrm{CH_3CH=CHCHO}$)
  5. Hydrazine ($\mathrm{NH_2NH_2}$), strong base ($\mathrm{OH^-}$ / KOH), heat (high-boiling solvent such as ethylene glycol)
  6. benzaldehyde diethyl acetal ($\mathrm{C_6H_5CH(OC_2H_5)_2}$)

Set C1

  1. Tollens' test
  2. Ethanol, propan-2-ol, acetophenone, ethanal
  3. Orange/red precipitate
  4. Fehling's solution is too weak an oxidizing agent to oxidize aromatic aldehydes; it only oxidizes aliphatic aldehydes.
  5. Formation of a silver mirror on the inner wall of the test tube
  6. Ketone (non-methyl ketone)

Set C2

  1. Tollens' test: ethanal gives a silver mirror; propanone does not. (Fehling's or Schiff's also acceptable.)
  2. Fehling's test: acetaldehyde gives a brick-red $\mathrm{Cu_2O}$ precipitate; benzaldehyde does not. (Iodoform test also acceptable: acetaldehyde gives yellow $\mathrm{CHI_3}$ precipitate; benzaldehyde does not.)
  3. Iodoform test: propan-2-ol gives a positive test (yellow $\mathrm{CHI_3}$ precipitate); propan-1-ol does not.
  4. Tollens' test: the aldehyde gives a silver mirror; the methyl ketone does not. (Fehling's, Benedict's, or Schiff's also acceptable.)

Set D1

  1. PCC in $\mathrm{CH_2Cl_2}$
  2. Propanal + $\mathrm{CH_3MgBr}$ (1. Et₂O, 2. $\mathrm{H_3O^+}$)
  3. Benzene + $\mathrm{CH_3COCl}$ $\xrightarrow{\mathrm{AlCl_3}}$ acetophenone + HCl
  4. Pentan-3-one + $\mathrm{CH_3MgBr}$ (1. Et₂O, 2. $\mathrm{H_3O^+}$) — or equivalent valid combination
  5. Propene $\xrightarrow{\mathrm{H_2O, H^+}}$ propan-2-ol $\xrightarrow{\mathrm{Na_2Cr_2O_7/H^+}}$ propanone
  6. Ethanal + HCN $\rightarrow$ 2-hydroxypropanenitrile; then $\mathrm{H_3O^+}$ / heat $\rightarrow$ lactic acid (2-hydroxypropanoic acid)
  7. Acetophenone + $\mathrm{CH_3MgBr}$ (1. Et₂O, 2. $\mathrm{H_3O^+}$)
  8. Acetylene + $\mathrm{H_2O}$ $\xrightarrow{\mathrm{HgSO_4, H_2SO_4}}$ acetaldehyde

Set E1

  1. Pentanal ($\mathrm{CH_3CH_2CH_2CH_2CHO}$) or any other $C_5$ aldehyde lacking the methyl ketone / iodoform-positive structure
  2. Butan-2-one ($\mathrm{CH_3COCH_2CH_3}$)
  3. Propanone (acetone, $\mathrm{CH_3COCH_3}$)
  4. but-2-enal (crotonaldehyde, $\mathrm{CH_3CH=CHCHO}$)
  5. Under the alkaline conditions of Tollens' / Benedict's test, fructose isomerizes to glucose (and mannose) via an enediol intermediate, exposing a free aldehyde group that is oxidized.

Set E2

  1. A = butan-2-one ($\mathrm{CH_3COCH_2CH_3}$); B = butan-2-ol ($\mathrm{CH_3CH(OH)CH_2CH_3}$)
  2. 4-methyl-2-pentanone ($\mathrm{CH_3COCH_2CH(CH_3)_2}$)
  3. Butan-2-one ($\mathrm{CH_3COCH_2CH_3}$)

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