Question

Orgo II Tutorial: Grignard Reagents

Answer 1

\({\bf{Synthesis~of~Grignards:}}\)
RX + Mg + Et2O --> RMgX (basically the Mg "sandwiches" itself between the alkyl and the halide). also works w/ aryl compounds. uses radical mechanism.

\({\bf{Reactions~of~Grignards:}}\)
> with acidic hydrogens: grignard acts as base/carbanion
RMgX + H2O --> RH + OH- + Mg + X
> with 1-alkynes: reacts with the terminal hydrogen

> with epoxides: react as nucleophile, attacks the least substituted end to open the eposide

Answer 2

> grignards with carbonyls (also act as nucleophiles)

Answer 3

reactions w/ aldehydes + ketones: generally the RMgX will attack the carbonyl center, attach the R group, and then you will add H3O+ to protonate the electronegative O

the end result depends on the configuration of the aldehyde/ketone/ester.
formaldehyde (only has H attached, no R groups) --> primary alcohol
other aldehydes (1 R group) --> secondary alcohol
ketones (2 R groups) --> tertiary alcohol

with esters, the first product will be a ketone and will react w/ a second molar equivalent to make a tertiary alcohol as indicated above.

Answer 4

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is Organic Chemistry 12th edition by Solomons, et. al.