A carbon atom double-bonded to an oxygen atom (>C=O)
Explication
The carbonyl functional group is characterized by a carbon atom double-bonded to an oxygen atom (>C=O), which is fundamental in aldehydes, ketones, and other related compounds.
Gatterman and Koch, 1904
Explication
The Gatterman-Koch reaction, used for synthesizing aromatic aldehydes like benzaldehyde, was developed by Gatterman and Koch in 1904. This is a well-documented historical fact in organic chemistry.
To produce aldehydes selectively without further oxidation to acids
Explication
Oxidizing primary alcohols with mild oxidants like PCC is specifically used to produce aldehydes selectively, stopping oxidation at the aldehyde stage without further oxidation to acids. This controlled oxidation is essential for synthesizing aldehydes in laboratory and industrial settings.
Methanal as a gas, ethanal as a liquid, higher aldehydes and ketones as solids
Explication
Methanal (formaldehyde) is gaseous at room temperature due to its small size and low molecular weight. Ethanal (acetaldehyde) is a volatile liquid, and higher aldehydes and ketones have larger molecular weights, making them liquids or solids at room temperature. This sequence reflects the typical physical states of aldehydes and ketones as their molecular size increases.
Aldehydes have a carbonyl group bonded to a hydrogen, making them more reactive than ketones, which have two alkyl groups attached to the carbonyl carbon.
Explication
Aldehydes have a carbonyl group bonded to a hydrogen atom and a carbon chain, which makes them more electrophilic and generally more reactive than ketones, which have two alkyl groups attached to the carbonyl carbon, providing steric hindrance and electron donation that reduce reactivity.
Gatterman and Koch
Explication
The Gatterman-Koch reaction was proposed by Gatterman and Koch in 1904 as a method to synthesize aromatic aldehydes, especially benzaldehyde, from benzene derivatives using carbon monoxide and hydrogen chloride in the presence of catalysts.
It increases acidity by stabilizing the conjugate base.
Explication
Resonance stabilization of the conjugate base disperses the negative charge over two oxygen atoms, making the conjugate base more stable and thus increasing the acidity of the carboxylic acid.
Pyridinium chlorochromate (PCC)
Explication
PCC is a mild oxidizing agent that selectively oxidizes primary alcohols to aldehydes without further oxidation to acids. Potassium dichromate and potassium permanganate are stronger oxidants that tend to oxidize aldehydes further to carboxylic acids. Sodium borohydride is a reducing agent, not an oxidant, so it would not oxidize alcohols.
Carbonyl group (>C=O)
Explication
The carbonyl group (>C=O) is the key structural component in aldehydes and ketones that determines their reactivity and makes them useful in various industrial applications. Its polarity and resonance stabilization influence their chemical behavior, enabling reactions such as nucleophilic addition.
Mémorisez les réponses avec 18 flashcards sur Carbonyl Chemistry Masterclass.
Carbonyl group — structure?
C=O double bond, sp2 hybridized carbon.
Aldehydes — nomenclature?
Named with -al suffix, chain numbered from aldehyde carbon.
Ketones — nomenclature?
Named with -one suffix, numbered from nearest carbonyl.
Consultez la fiche de révision complète sur Carbonyl Chemistry Masterclass.
Voir la fiche →Importe ton cours et l'IA génère des QCM avec corrections en 30 secondes.
Générateur de QCM