Organometallic Nucleophiles: Grignard and Organolithium Reagents · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Carbon that attacks

Science · Chemistry · ages 20-21
Name ______________________   Date ____________

  1. Formaldehyde meets a Grignard reagent. What class of alcohol forms?

    • Primary
    • Secondary
    • Tertiary

  2. Why is the carbon of a Grignard reagent nucleophilic?

    • Because magnesium is far less electronegative than carbon
    • Because carbon always attacks everything
    • Because the ether solvent donates the nucleophile directly

  3. Water protonates the Grignard reagent and kills it as a nucleophile.

    Circle one:   True   False

  4. The same reagent meets a non-formaldehyde aldehyde and a ketone in separate flasks. What differs?

    • The aldehyde gives a secondary alcohol, the ketone a tertiary one
    • Both give primary alcohols
    • The ketone gives no product at all

  5. A non-formate ester meets excess Grignard reagent, then a protonating workup. What forms?

    • A primary alcohol after one addition
    • A ketone that refuses further attack
    • A tertiary alcohol with two identical reagent groups

  6. Which conditions keep a Grignard reagent alive?

    • Aqueous acid in an open beaker
    • Dry ether with no protic sources, often under inert gas
    • Boiling water with dissolved oxygen

  7. You must build a tertiary alcohol with two identical methyl groups. Which statement about the routes is true?

    • Only an ester route can land two identical methyl groups here
    • A ketone route works as well as the ester route
    • An aldehyde plus one methyl Grignard does the job

  8. Your target needs a Grignard step on a molecule that also carries an alcohol group. What is the plan?

    • Run the Grignard first and hope the alcohol keeps quiet
    • Mask the alcohol, run the Grignard, then deprotect
    • Add extra water to protect the alcohol
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Answer key

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

Carbon that attacks W1-mt_0X06qlyafO-s1

  1. Primary · One new carbon bond on formaldehyde leaves one carbon neighbour.
  2. Because magnesium is far less electronegative than carbon · The electronegativity gap piles partial negative charge on carbon.
  3. True · The reagent becomes a plain alkane on contact with acid.
  4. The aldehyde gives a secondary alcohol, the ketone a tertiary one · Count carbon neighbours: one for aldehydes, two for ketones.
  5. A tertiary alcohol with two identical reagent groups · Non-formate esters take two copies of the reagent, and workup protonates the alkoxide.
  6. Dry ether with no protic sources, often under inert gas · Ether solvates the reagent while dryness starves the killing reaction.
  7. A ketone route works as well as the ester route · A ketone already carrying both methyl groups adds once, so the ester route is not the only way.
  8. Mask the alcohol, run the Grignard, then deprotect · An unmasked proton would destroy the reagent before any attack.
Worksheet · LightMySky