[25.4] distribution and directing groups

Question 1

how does the OH in phenol ‘direct’ the substitution and where does it direct to?

Answer 1

• activates ther ing and reacts more readily with electrophiles
• direct substitutions to occur at positions 2, 4 and 6

Question 2

what are directing groups?

Answer 2

• substition of a 2nd group on a benzene ring
• 1st group directs the position of the 2nd substituted group

Question 3

what are the 2 types of directing groups?

Answer 3

• 2- and 4- directing groups activate the ring, reactivity increases
• 3- directing groups deactivate the ring, reactivity decreases

Question 4

2- and 4- directing groups

Answer 4

• -OH, NH₂
• group donates electrons onto ring
• reactivity increases
• 2nd substition at 2- or 4- positions

Question 5

3- directing groups

Answer 5

• -NO₂
• group withdraws electrons from ring
• reactivity decreases
• 2nd substitution at 3- position

Question 6

what are some examples of activating groups?

Answer 6

• -NH₂ or -NHR
• -OH
• -OR
• -R or -C₆H₅

Question 7

what are some examples of deactivating groups?

Answer 7

• RCOR
• -COOR
• -SO₃H
• -CHO
• -COOH
• -CN
• -NO₂
• NR₃⁺

Question 8

how do you use directing effects in organic synthesis?

Answer 8

when carrying out more than one ES on an aromatic compound, you may have to consider the order in which the reactions are carried out to ensure the correct substitution pattern and hence correct product