General Reactions of Carbonyl Compounds
______________ results in a decrease ini the number of C-Z bonds ( usually C-O bonds) or an increase in the number of C-H bonds.
Reduction
Aldehydes are oxidized selectively in the presence of other functional groups using________ reagent;Silver(I) oxide in aqueous ammonium hydroxide (Ag2O in NH4OH). Oxidation with this reagent provides a distinct color change, because the Ag+ reagent is reduced to solver metal (Ag), which precipitates out of solution.
Tollens
__________ are organometallic compounds prepared by an acid-base reaction of an alkyne with a base such as NaNH2 or NAH. We can think of these compounds as organosodium reagents. These are considered ionic rather than polar covalent because sodium is even more electropositive than lithium. An acid-base reaction can also be used to prepared sp hybridized Organolithium compounds, Treatment of a terminal alkyne with CH3Li affords a lithium acetylide
Acetylide Anions
carbonyl compounds that also contain N-H or O-H bond undergo an __________ reaction with organometallic reagents, not nucleophilic addition. Hence the need for protecting groups.
Acid-base
Oxidation of aldehydes to ____________.
Carboxylic acids
What are the selective reducing agents:
DIBAL,LiALH[OC(CH3)3]3
R-X+Mg---> R-Mg-X. With magenesium , the metal inserts in the carbon-halogen bond, forming the Grignard reagent. Grignard reagents are usually prepared in Ch3CH2OCH2CH3 or diethyl ether solvent. This is preperation of an ____________ reagent.
Grignard
Nucleophilic addition with aldehydes and ketones occurs with two different nucleophiles: carbanions, and __________.
Hydrides
Carboxylic acids are reduced to alcohols with what strong reducing agent?
LiAlH4
Hydride reduction of an achiral ketone with LiAlH4 or _______ gives a racemic mixture of two alcohols when a new stereogenic center is formed
NaBH4
Aldehydes and ketones undergo_____________ addition reactions.
Nucleophilic
Organocuprates are prepared from____________ reagents by reaction with a Cu+ salt, often CuI. 2R-Li+CuI-->R2Cu-Li+LiI
Organolithium
___________ results in an increase in the number of C-Z bonds; Z being the electronegative atom (usually C-O bonds) or a decrease in the number of C-H bond.
Oxidation
A common O-H protecting group is _____
TBDMS
Reduction of carboxylic acid derivatives
The reduction of carboxylic acids and their derivatives gives a variety of products, depending on the identity of Z and the nature of the reducing agent. The usual products are aldehydes or primary alcohols.
LiAlH4 reduction of amide forms__________. Both C-O bonds are reduced to C-H bonds. Amide reduction proceeds with formation of an intermediate __________, a compound containing a C-N double bond, which is then further reduced to an amine.
amines,imine
organometallic reagents are strong __________ that readily abstract a proton from water to form hydrocarbons.
bases
alpha-beta unsaturated carbonyl compounds: Organolithium and Grignard reagents afford 1,2 addition products meaning they add to the _________ thus forming an allylic alcohol .while organocuperates produce 1,4 addition products or conjugate addition where the nucleophile attacks the beta carbon ( where the double bond is located) forming a carbonyl compound
carbonyl group
aldehydes can be oxidized to____________using a variety of oxidizing agents such as CrO3,Na2Cr2O7,K2Cr2O7,KMnO4,Cr6+. Because ketones have no H on the carbonyl carbon they do not undergo this oxidation reaction
carboxylic acids
Grignards react with CO2 to afford__________. this reaction is called carboxylation,
carboxylic acids.
Organometallic reagents are also strong________ that react with electrophilic carbon atoms to form new carbon-carbon bonds.
nucleophiles
Organometallic reagents react as if they wwere free carbonaninons; carbon bears a partial negative charge; so the reagents react as bases _______
nucleophiles
Aldehydes and ketones react with______ to form addition products by the two-step process : Nucleophilic attack followed by___________. The elements of H and Nu are added across the pi bond.
nucleophiles,protonation
Organocuperates have less polar carbon-metal bonds than Grignard (organomagenesium) and organolithium reagents( these two metals; Mg and Li are more electropositive) and therefore Organocuperates are less reactive. Although organocuperates contain two alkyl groups bonded to copper, only______ R group is utilized in reaction.
one
R--X+2Li---> R--Li+LiX with lithium, the halogen and metal exchange to form the organolithium reagent. This is preperation of an ______________ reagent
organolithium
___________________ reagents contain a carbon atom bonded to a metal. The more polar the carbon-metal bond, the more reactive this kind of reagent is.
organometallic
acid chlorides and ester can be reduced to either aldehydes or alcohols depending on the ___________ agent
reducing
Carbonyl compounds that contain leavings groups undergo nucleophilic ______________.
substitution
Carbonyl compounds with leaving groups react with nucleophiles to form ( substitution/addition) products?
substitution
Both esters and acid chlorides form ________ alcohols when treated with two equivalents of either Grignard or Organolithiumm reagents. in the mechanism the first equivalent converts the ester or acid chloride to a ____ and then the second equivalent to the final product.
tertiary, ketone. Organolithiumm and Grignard reagents always afford tertiary alcohols when they react with esters andd acid chlorides .
A C=C is reduced faster than a C=O with H2(Pd-C) A C=O is readily reduced with NaBH4 and LiAlH4, but a C=C is inert.
true
The better the leaving group Z, the more reactive RCOZ is in nucleophilic acyl substitution. Acid chlorides have the best leaving group--Cl- (True/ False) Amides have the worst leaving group( True/False)
true,true Cl is electronegative and have weak electron withdrawing inductive effect while NH2, the N has a pair of lone pair of electrons that it can donate and therefore is more basic thus making it a weak leaving group. The best leaving group is the weakest base; base donates electrons however you want leaving groups to hold onto electrons to leave.
One enantiomer can be formed selectively from the reduction of a carbonyl group provided a chiral reducing agent such as oxazaborolidine (CBS) it has one stereogenic center and thus two eneatintiomers. R-CBS and S-CBS and attack with R-CBS forms S-alcohol and attack with S-CBS forms R-alcohol .
....
NaBH4 selectively reduced aldehydes and ketones in the presence of most other functional groups. LiAlH4 is a stronger reducing agent because the Al--H bonds are more polar. Reduction with NaBH4 are typically carried out in_________ as solvent. LiAlH4 reduces aldehydes and ketones and many other functional groups.
CH3OH
The net result of nucleophilic substitution is Nu replaces Z-- a nucleophilic substitution reaction. This reaction is often called nucleophilic_____- substitution to distinguish it from the nucleophilic substitution reactions at sp3 hybridized carbons. Carboanions and Hydrides are also used as nucleophiles in this reaction.
acyl
Treatment of an aldehyde or ketone with either a Organolithium or Grignard reagent followed by water forms an ________ with a new carbon-carbon bond. This is an addition reaction because the elements of R'' and H are added across the pi bond. This reaction is used to prepare primary, secondary and tertiary alcohols depending on the number of alkyl groups bonded to the carbonyl carbon of the aldehyde or ketone.
alcohol
LiAlH4 converts acid chlorides and esters to ________
alcohols.
Organometallic reagents (RLi,RMgX,R2CuLi) open epoxide rings to form______
alcohols.
Reduction of aldehydes and ketones to ____________.
alcohols. Aldehydes and ketones are reduced to primary and secondary alcohols, respectively.
Reduction of Aldehydes and Ketones Treating a _________ with a metal hydride reagent results in a primary alcohol. Treating a ___________ with a metal hydride reagent results in a secondary alcohol. catalytic ________________ also reduces aldehydes and ketones to primary and secondary alcohols.
aldehyde, ketone,catalytic
DIBAL or LiALH[OC(CH3)3]3 converts acid chlorides and esters to_______________. These are milder reducing agents while LiAlH4 are strong reducing agents.
aldehydes
siethyl ether is typically removed with a ______ salt such as tetrabutylammoniumfluoride.
fluoride
Reaction of R2CuLi with acid chlorides: Organocuperates react with acid chlorides to afford________. Acid chlorides have the best leaving group and Organocuperates are less reactive than Grignard and Organolithium,
ketones
Carbonyl compounds with leaving groups react with nucleophiles to form substitution products by the two- step process: Nucleophilic attack followed by the loss of the ________________.
leaving group
aldehydes are (more/less) reactive than ketones towards nucleophilic attacks for both steric and electronic reasons?
more