Aldehydes, Ketones and Carboxylic Acids — MHT-CET Chemistry

Formulas (2)

• General Formula, Simple Ketones, and the Physical Facts · General formulas
  $$\text{aldehyde / ketone: } \text{C}_n\text{H}_{2n}\text{O};\qquad \text{acid: } \text{C}_n\text{H}_{2n}\text{O}_2$$
• IUPAC Priority: COOH Beats CHO Beats OH · Priority and prefixes
  $$\text{COOH (parent)} \to \text{CHO as 'formyl'};\quad \text{CHO (parent)} \to \text{OH as 'hydroxy'};\quad \text{C=O (parent)} \to \text{OH as 'hydroxy'}$$

Reference tables (1)

Watch out for (3)

• Hearing 'valeric' and 'glutaric' as the same kind of name
  → The Named Acids: Mono-, Di- and Tricarboxylic
• Calling acetophenone a simple ketone
  → General Formula, Simple Ketones, and the Physical Facts
• Naming the compound as a phenol because the OH is on the ring
  → IUPAC Priority: COOH Beats CHO Beats OH

Formulas (3)

• Rosenmund, Stephen and DIBAL-H: Three Ways to an Aldehyde · Three aldehyde routes
  $$\text{RCOCl} \xrightarrow{\text{H}_2/\text{Pd-BaSO}_4} \text{RCHO};\quad \text{RCN} \xrightarrow{\text{SnCl}_2/\text{HCl};\ \text{H}_3\text{O}^+} \text{RCHO};\quad \text{RCN} \xrightarrow{\text{DIBAL-H};\ \text{H}_3\text{O}^+} \text{RCHO}$$
• Grignard and Dialkylcadmium: Ketones and Alcohols · Cadmium route to ketones
  $$\text{R}_2\text{Cd} + 2\,\text{R'COCl} \to 2\,\text{R'COR} + \text{CdCl}_2$$
• Etard Reaction and Hydrolysis Routes · Etard reaction
  $$\text{C}_6\text{H}_5\text{CH}_3 \xrightarrow{\text{CrO}_2\text{Cl}_2/\text{CS}_2} \text{Etard complex} \xrightarrow{\text{H}_3\text{O}^+} \text{C}_6\text{H}_5\text{CHO}$$

Watch out for (3)

• Assigning DIBAL-H to Rosenmund
  → Rosenmund, Stephen and DIBAL-H: Three Ways to an Aldehyde
• Stopping at dimethylcadmium
  → Grignard and Dialkylcadmium: Ketones and Alcohols
• Reading the Etard intermediate as benzal chloride
  → Etard Reaction and Hydrolysis Routes

Formulas (2)

• Cyanohydrins, Hemiacetals and the Ammonia Derivatives · Addition then loss of water
  $$\text{>C=O} + \text{H}_2\text{N-Z} \to \text{>C(OH)-NH-Z} \xrightarrow{-\text{H}_2\text{O}} \text{>C=N-Z}$$
• Aldol Reaction and the Cannizzaro Reaction · Aldol and Cannizzaro
  $$2\,\text{RCH}_2\text{CHO} \xrightarrow{\text{OH}^-} \text{RCH}_2\text{CH(OH)CHR-CHO} \xrightarrow{\Delta} \text{RCH}_2\text{CH=CR-CHO};\qquad 2\,\text{ArCHO} \xrightarrow{\text{conc. OH}^-} \text{ArCOO}^- + \text{ArCH}_2\text{OH}$$

Watch out for (2)

• Confusing hydrazine with semicarbazide
  → Cyanohydrins, Hemiacetals and the Ammonia Derivatives
• Reducing the wrong aldehyde in the crossed Cannizzaro
  → Aldol Reaction and the Cannizzaro Reaction

Formulas (2)

• Clemmensen, Wolff–Kishner and Hydride Reductions · C=O to CH₂
  $$\text{Clemmensen: Zn-Hg / conc. HCl};\qquad \text{Wolff–Kishner: NH}_2\text{NH}_2 \text{ then KOH / ethylene glycol}$$
• Tollens, Fehling, Schiff and the Haloform Test · Tollens' reaction
  $$\text{RCHO} + 2[\text{Ag(NH}_3)_2]^+ + 3\text{OH}^- \to \text{RCOO}^- + 2\text{Ag}\downarrow + 4\text{NH}_3 + 2\text{H}_2\text{O}$$

Watch out for (2)

• Losing a carbon in Wolff–Kishner
  → Clemmensen, Wolff–Kishner and Hydride Reductions
• Expecting the haloform reaction from every carbonyl
  → Tollens, Fehling, Schiff and the Haloform Test

Formulas (2)

• Boiling Points of Acids, and Making Them · Grignard to acid
  $$\text{R-MgX} \xrightarrow{\text{(i) CO}_2\text{ (dry ice); (ii) H}_3\text{O}^+} \text{R-COOH} \quad (\text{one carbon more than R})$$
• Acid Chlorides, Anhydrides, Esters and Amides · Derivative ↔ acid
  $$\text{RCOOH} \xrightarrow{\text{PCl}_5} \text{RCOCl} \xrightarrow{\text{H}_2\text{O}} \text{RCOOH};\qquad \text{RCOOR'} \xrightarrow{\text{NaOH}} \text{RCOONa} \xrightarrow{\text{HCl}} \text{RCOOH}$$

Watch out for (2)

• Forgetting the carbon that CO₂ brings
  → Boiling Points of Acids, and Making Them
• Stopping at the sodium salt
  → Acid Chlorides, Anhydrides, Esters and Amides