CHEM241 pKa Quiz

Which of the circled hydrogens is an alpha hydrogen?

• A

• B

• C

• D

How does the presence of electron-withdrawing groups affect the pKa of an alpha hydrogen?

• EWGs make them less acidic (lower pKa)

• EWGs make them more acidic (lower pKa)

• EWGs don't affect their pKa

• EWGs make them less acidic (higher pKa)

What is the pKa of an aldehyde?

• 20

• 25

• 17

• 15

What is the average pKa of a ketone?

• 15

• 20

• 5

• 25

Why are the pKas of aldehydes and ketones different?

What is the pKa of an ester?

• 9

• 25

• 17

• 20

What is the pKa of an amide?

• 15

• 17

• 20

• 25

What are the pKas of the following compounds?

• Left: 9

  Right: 11

• Left: 11

  Right: 9

• Left: 13

  Right: 9

• Left: 9

  Right: 15

Having more carbonyls increases a compounds acidity because they...

• don't

• Create a slight partial positive charge at the alpha carbon

• Make removing an H from the alpha carbon easier/more favorable

• Push electron density towards the alpha carbon