Grignard

Question 1

organometallic reagents

Answer 1

metal-carbon bonds

carbon becomes Nu/base

carbanion

Question 2

to make Grignard reagents

Answer 2

alkyl halide + magnesium —> R-Mg-X

free radical rxn

Question 3

best halides for Grignards

Answer 3

I > Br > Cl > F

good L.G, can stabilize Mg+ ———- bad L.G

Question 4

R groups for Grignards

Answer 4

CH3, 1°, 2°, 3°, alkenyl (C=C w/ X), aryl

Question 5

rxn conditions for making Grignard

Answer 5

polar aprotic solvent

ether, 35°C OR THF, 60°C

Question 6

alkyl halide limitations

Answer 6

no acidic f.g. ( ROH, RNH, RSH, terminal alkynes)

no reactive E+ (ketone, aldehyde, epoxy)

Question 7

alkyl halide possibilities

Answer 7

R-X w/ c=c, internal alkyne, ether, NR3

Question 8

what does a Grignard extend?

Answer 8

carbon chains

Question 9

rxns w/ epoxies

Answer 9

if R = H —-> 1° ROH

if R = R —-> 2° ROH

if R = R+R’ —-> 3° ROH

Question 10

epoxy rxn addition type

Answer 10

anti-addition: R- attacks from opp. side of oxygen in epoxy

regiospecific, if chiral you get only 1 enantiomer

Question 11

do you get E2 with Grignard rxns?

Answer 11

very little; Grignard formation has a lower E pathway