Anonymous asked in Science & MathematicsChemistry · 1 decade ago

Reaction of a Grignard reagent questions?

1) How would these compounds be arranged in order of increasing reactivity towards attack of the Grignard reagent at the carbonyl carbon atom: methyl benzoate, benzoic acid, benzaldehyde, acetophenone, benzoyl chloride. Explaining the basis for each.

2) What is/are the product(s) of reaction of each of the above carbonyl containing compounds with an excess of a Grignard reagent, RMgBr?

3) How might primary, secondary, and tertiary alcohols be prepared from a Grignard reagent, RMgBr, and a suitable carbonyl-containing compound? What would be the chemical equations, with stoichiometry, for these preparations?

2 Answers

  • Erebos
    Lv 6
    1 decade ago
    Favorite Answer

    benzoyl chloride's pretty good. no acidic hydrogens whatsoever

    methyl benzoate. a good ester, but some weakly acidic hydrogens

    benzaldehyde. hydrogen on the aldehyde is a poor acid,

    acetophenone, alpha hydrogen can be deprotonated instead

    benzoic acid. no question, the grignard will simply take the acid hydrogen and not attack the carbon at all

    respectively, in the above order

    lose the Cl, add the R

    lose the methoxide, add R to make ketone, then another R will attack the carbonyl, adding on, and making the ketone a tertiary alcohol

    add R, make aldehyde a secondary alcohol

    again, secondary alcochol, with an extra R

    you'd get benzoate(-) and MgBr(+), along with a full alkane R. ruined grignard

    primary, react with formladehyde

    secondary, react with aldehyde

    tertiary, react with ketone/ester derivative

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  • 4 years ago

    Break either the bond between C2 and C3 or C3 and C4. C2-C3 gives you ethylmagnesium bromide and 2-methylpentenal. C3-C4 gives you 2-pentylmagnesium bromide and pentanal.

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