Write reasonable mechanisms for the reaction of ketene with alcohols and amines. Would you expect these reactions to be facilitated by acids and/or bases?

Ketene has the molecular formula C2H2O and a linear structure with a carbon-carbon double bond and a carbon-oxygen double bond. The structure of ketene is: H2C=C=O Now, let's analyze the reaction of ketene with alcohols and amines separately.

The general mechanism for the reaction of ketene with alcohols can be outlined as follows: Step 1: Nucleophilic attack by the oxygen atom of the alcohol on the electrophilic carbon atom of ketene, resulting in the addition of the alcohol to ketene and the formation of a tetrahedral intermediate. Step 2: Proton transfer from the alcohol oxygen to the ketene oxygen, converting the double bond between C and O back into a single bond and yielding an ester product. So, the overall reaction can be represented as: H2C=C=O + ROH -> RCOOCH2

The general mechanism for the reaction of ketene with amines can be outlined as follows: Step 1: Nucleophilic attack by the nitrogen atom of the amine on the electrophilic carbon atom of ketene, resulting in the addition of the amine to ketene and the formation of a tetrahedral intermediate. Step 2: Proton transfer from the amine nitrogen to the ketene oxygen, converting the double bond between C and O back into a single bond and yielding an amide product. So, the overall reaction can be represented as: H2C=C=O + RNH2 -> RCONHCH2

The nucleophilic centers in alcohols and amines (oxygen in alcohols and nitrogen in amines) are present in their free form, making them capable of attacking the electrophilic carbon in ketene without the need for any extra activation. However, the presence of a base may further increase the nucleophilicity of the oxygen or nitrogen atoms, thus facilitating the reaction. On the other hand, the presence of an acid may not have a significant effect on the reactivity of ketene because it already has an electrophilic carbon, and protonation of the carbonyl oxygen would not provide any benefit in these cases. In conclusion, these reactions are expected to be facilitated by the presence of bases while the presence of acids is not expected to have a significant effect on the reactivity of ketene with alcohols and amines.