Functionalising a Carbon-Hydrogen Bond Without a Handle · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Teaching a metal to pick one bond

Science · Chemistry · ages 23-24
Name ______________________   Date ____________

  1. A ring carries an amide directing group. Which position reacts?

    • The farthest position from the amide
    • The neighbour the amide holds the metal beside
    • Every position in equal measure

  2. Why is working straight on a carbon hydrogen bond difficult?

    • Every position looks alike, so choosing one is hard
    • The bonds never react with any metal
    • The molecule falls apart before reacting

  3. Classical routes need a leaving group or halide already in place.

    Circle one:   True   False

  4. Two plans give the same product. Which one wastes less?

    • The directed plan, because it skips installing a handle
    • The halide-first plan, because extra steps are free
    • Both plans always waste exactly the same

  5. What is the metallacycle in a directed reaction?

    • The solvent shell around the metal
    • A chain left after the metal falls off
    • A ring joining the metal, the directing group, and the chosen carbon

  6. A halide-first route needs 5 steps and a directed route needs 3 steps for the same product. How many steps does the directed route save?

    Answer: ______________

  7. How do you test that the amide group caused the selectivity?

    • Add extra metal until every position reacts
    • Run it without the amide and see if the preference vanishes
    • Measure the finished product twice for accuracy

  8. A bulky group beside the directing group blocks the near positions. Where does the reaction go?

    • It stops entirely and nothing reacts
    • It squeezes into the blocked near position anyway
    • It moves to a farther open site
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Teaching a metal to pick one bond W1-mt_j0LaIeS2VP-s1

  1. The neighbour the amide holds the metal beside · The amide holds the metal close to one neighbour. Closeness chooses the site.
  2. Every position looks alike, so choosing one is hard · Many similar bonds compete. The puzzle is selectivity, not reactivity.
  3. True · The handle comes first in the old way. Direct work skips it.
  4. The directed plan, because it skips installing a handle · Fewer steps mean less material thrown away. Skipping the handle saves both.
  5. A ring joining the metal, the directing group, and the chosen carbon · The metal closes a ring with its holder and its target. That ring explains the choice.
  6. 2 · Subtract the shorter count from the longer one. Saved steps are the gap.
  7. Run it without the amide and see if the preference vanishes · Remove the suspected cause. If the effect goes with it, the cause is confirmed.
  8. It moves to a farther open site · Blocked means blocked. The metal takes the open site that remains.
Worksheet · LightMySky