Electrophilicity And Hydration Of Aldehydes

To determine the correct answer, we need to analyze both statements regarding their veracity based on chemical principles:

1. Statement I: "In the case of formaldehyde, is about 2280, due to small substituents, hydration is faster."
   • Formaldehyde ( ) is a simple aldehyde where the carbonyl group ( ) is bound to one hydrogen atom and one aldehyde hydrogen. Because of its small size, there is less steric hindrance, which increases its reactivity towards nucleophilic attack by water, leading to faster hydration.
   • The hydration of aldehydes involves the addition of water across the carbonyl bond to form a geminal diol. This reaction is influenced by both steric factors and electronic factors.
   • The given hydration constant is a reflection of this high reactivity. Therefore, Statement I is true.
2. Statement II: "In the case of trichloroacetaldehyde, is about 2000 due to the -I effect of Cl."
   • Trichloroacetaldehyde, also known as chloral ( ), has three chlorine atoms attached to the carbon adjacent to the carbonyl group.
   • The chlorine atoms exert a strong electron-withdrawing inductive effect (denoted as the -I effect), which polarizes the carbonyl group, making the carbon more electrophilic.
   • This increased electrophilicity enhances the reaction with nucleophiles such as water, thus favoring the formation of the geminal diol.
   • The hydration constant being around 2000 supports this assertion. Therefore, Statement II is true.

Based on the analysis above, both Statement I and Statement II are true about the hydration constants and the effects impacting the reactivity of formaldehyde and trichloroacetaldehyde.