Ch 28 Introduction to Organometallic Compounds Flashcards
Organo metallic compounds
compounds containing a bond between a carbon atom and a metal (C-M)
Methyllithium
methyllithium is a very strong base and a very strong nucleophile.
Explan why methylllithium is a strong base and good nucleophile.
carbon is more electronegative than the metal to which it is attached, as a result the cabon atom is electron rich. the carbon atom is electron rich because inductive effects withdraw electron density from the metal.
The magnitude of the partial charge (-) on the carbon atom is dependent on ________.
the magnitude of the partial charge (-) on the carbon atom is dependent on the idenity of the metal.
acid halides react with two equivalents of organomagnesium (grignard) reagent to produce
alchols with to new alkyl groups.
acids halides react with one equivalent of and organocopper reagent to produce a
ketone
organocopper reagents are effective ______donors, while organomagnesium reagents are not
oranocopper reagent are effective micheal donors ,while organomafnesium reagents are not.
Carbonanions are
A structure with a negative formal charge on carbon.
are strong bases and nucleophiles
organolithium reagents can be prepared by treating an ________with two equivalent of Li
organohalide
a nonpolar solvent , such as hexane or diethyl ether is typically used.
iodides are the most reactive (I>Br>Cl), although bromides are used more commonly beacuse bromides are less expensive and less toxic than iodides
The formation of a Grignard reagent requires the use of a solvent that can________.
function as a lewis base and stabilize the grignard reagent as it is formed
Why must the formation of a Grignard be anhydrous. Draw a picture.
water will consume the Grignard reagent upon its formation.
the preparation of organolithium reagents must also be preformed with anhydrous solvents.
Grignard reagents(RMgX) and organolithium (RLi) are both very strong bases, and each of them react rapiidly with water to give a hydrocarbon(R-H)
Deuteration
a reation used to install a deuterium atom into a compound.
Grignard reagents will react with any functional group that exhibits ________.
a weakly acidic proton
therefore, none of these functonal groups can be present in the starting RX,
for example a grignard reagent cannot be prepared if an OH group is present in the compound.
preparation of Gilman Reagents
Gilman reagent (R21CuLi) react with organohalides(R2X) to give the product.
R1-R2
called he Corey-posner/Whiteside-House reaction
the R group on the organohalide (RX) can be methyl ,Primary,Vinyl or aryl
(RX) cannot be a tertiary alkyl halife as elimination products predominate.
Even secoundary alkyl halide are generally ineffective ,also because of competing elimination reactions, some secoundry ( cyclic) halides are observed to couple effectively with Gilman reagents.
