Chem 252 chapter 17
all the statements that correctly describe the mechanism for the LiAlH4 reduction of an aldehyde or ketone
The pi bond of the C=O group is cleaved in the first step of the reaction The oxygen atom of the C=O group is protonated in Step 2, after the nucleophile attacks. LiAlH4 serves as a source of hydride ions; i.e., there are no free hydride ions present.
What are the reagents that will oxidize an aldehyde to a carboxylic acid
Ag2O, NH4OH, CrO3, H2SO4, H2O
benzyl
CH2 + benzene ring
Which of the following compounds could be used to convert 1-octyne to the corresponding acetylide anion?
CH3MgBr NaH
10 carbon alkene
Dectene
Organomagnesium reagents are called __________ reagents.
Grignard
can go forward or backward with
Grignard
list the oxidizing agents:
Harsh CrO3/H2So4/H2O Na2Cr2O7/H2SO4/H2O Mild PCC,CH2Cl2
structural description of Acid Chloride
Has a chlorine atom bonded to the carbonyl group
structural description of amide
Has a nitrogen bonded to the carbonyl group
structural description of ester
Has an oygeng atom bonded to the carbonyl group
structural description of aldehyde
Has one or more hydrogens bonded to the carbonyl group
structural description of Ketone
Has two alkyl or aryl groups bonded to the carbonyl group
6 carbon alkene
Hexene
Metal Hydride Reducing Agents Milder reagents NaBH4 name the 2 aldehyde aka starting material and there products aka primary alcohol
RCHO RCH2OH R2CO R2CHOH
Metal Hydride Reducing Agents Strong reagent is LiAlH4 name the 3 aldehyde aka starting material and there product aka Primary alcohol
RCHO RCH2OH R2CO R2CHOH RCOOH RCH2OH
Ph3P
Replace the oxygen with what ever is attached to the double bond
BC
Select the reagents that will produce the desired product shown.
Why cant Aldehydes and ketones undergo sub?
They don't have a good leaving group
A C D
Which of the following structures are α,β-unsaturated carbonyl compounds?
What are the three main oxidation and reduction reactions of carbonyl starting materials?
[1] reduction of aldehydes and ketones to alcohols [2] Reduction of carboxylic acids and their derivatives [3] Oxidation of aldehydes to carboxylic acids.
A mixture of CrO3/H2SO4/H2O may be used to convert a(n) _____ into a(n) _____
aldehyde; carboxylic acid
In the carbonyl Group the carbon is _______ and the oxygen is ________. (a) electron-deficient (b) Electron Rich
carbon is electron-deficient and the oxygen is electron rich
Grignard reagents are usually prepared in ___________ _________ as solvent.
diethyl ether (CH3 CH2 OCH2 CH3)
tetra alcohols don't (do) oxidize
dont
Since both Li and Mg are very __________ metals, organolithium (RLi) and organomagnesium (RMgX) reagents contain very polar carbon-metal bonds and are therefore very reactive __________
electropositive reagents
9 carbon alkene
nonene
5 carbon alkene
pentene
Organocopper reagents (R2CuLi), also called organocuprates, have a less ________________ and are therefore less reactive.
polar carbon-metal bond
Carbonyl carbons are ____ hybridized, _____ planar, bond angle of _____
sp2, trigonal, 120
functional groups
the components of organic molecules that are most commonly involved in chemical reactions
Reduction of carboxylic acids and their derivatives: depends on the identity of ____ and ______ _______ usual gives aldehydes or 1 alcohols
z reducing agent
What is a good leaving group?
Increase in size better leaving group,
2 carbon alkene
ethene
a halogen is
fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At)
enzymes end in
-ase
Aldehyde reduce into ___ alcohol
1
During the reduction of aldehydes and ketones to alcohols, The aldehydes and ketones are reduced to ____ and _____ respectively
1 and 2 alcohols
Reaction of Grignard and organolithium reagents with α,β-unsaturated carbonyl compounds usually results in _____-addition.
1,2
What are the two broad classes of compounds containing the carbonyl Group
1. Compounds that have only carbon and hydrogen atoms bonded to the carbonyl 2. compounds that contain an electronegative atom bonded to the carbonyl (ketone)
Ketones reduce into ___ alchol
2
Reaction of a Grignard reagent with a ketone followed by hydrolysis results in the formation of a ______ alcohol.
3
Butyl
4 carbon chain as a substituent
Grignard (R-Mg-X) is
A Grignard reagent or Grignard compound is a chemical compound with the generic formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl.
explain why ketones are less reactive than aldehydes
An aldehyde is less sterically crowded, allowing nucleophilic attack to occur more easily. The two alkyl groups of a ketone stabilize the partial charge on the carbonyl C, making it less reactive.
Select the structure of the product for the reaction shown. CH3CH2Li, THF H3o
B
An organometallic reagent cannot be used to react with a carbonyl compound that also contains an N-H or O-H group because the organometallic reagent is a strong _________ , which will deprotonate these groups instead of acting as a nucleophile. To prevent this interference, OH and NH groups must be "blocked" with a ________ group, which is removed once the synthesis is complete.
Base protecting
list of oxidizing agents for aldehydes
CrO3, Na2Cr2O7, K2Cr2O7 and KMnO4 silver oxide (Tollens's reagent)
Thus, 2-cyclohexenone, which contains both a C=C and a C=O, can be reduced into what? include the reagent used
Ketone Reagent: H2 Pd-C One equivalent of H2 reduces the C=C allylic alcohol NaBH4, CH3OH NaBH4 reduces the C=O
Wheat are the most common organometallic metals
Li, Mg, and Cu
Carboxylic acids are reduced to 1 degree alcohols with ________, LiAlH4 is too strong of a reducing agent to stop the reaction at the __________ , but milder reagents are not strong enough to initiate the reaction in the first place
LiAlH4, aldehyde
what is the synthesized from the vitamin niacin
NAD+
in cells, the reducing agent is _____
NADH
what reaction is enantioselectivity
NADH Reduction
what are the reducing agents for carbonyl ale compound
NaBH4 or LiAlH4
What are the reagents that may be used to reduce aldehydes and ketones to alcohols
NaBH4, LiAIH4
Which of the following compounds could be used to deprotonate the hydrogen from a terminal alkyne?
NaNH2 CH3Li
In the broad classes of carbonyl group what are Compounds that have only carbon and hydrogen atoms bonded to the carbonyl.
O=R-H (aldehyde) and O=R-R (ketone)
In the broad classes of carbonyl group what are Compounds that contain an electronegative atom bonded to the carbonyl.
O=R-OH (carboxylic acid) O=R-Cl (Acid Chloride) O=R-OR' (Ester) O=R-N (Amide)
8 carbon alkene
Octene
What are the general structures of common organometallic reagents
Organolithium reagents R-Li Organomagnesium reagents Grignard reagents R-Mg-X Organocopper reagents organocuprates R-R-Cu-Li
Which of the following statements are correct? Organometallic reagents will react with carbonyls before they deprotonate an O-H bond. Organometallic reagents are strong nucleophiles, but they can also be strong bases. When using organometallic reagents, N-H and O-H bonds must be protected.
Organometallic reagents are strong nucleophiles, but they can also be strong bases. When using organometallic reagents, N-H and O-H bonds must be protected.
Mechanism of NADH Reductions steps
The active site of the enzyme binds both the carbonyl substrate and NADH, keeping them in close proximity. NADH then donates H:− in much the same way as a hydride reducing agent.
Name the statements that correctly describe the mechanism of the reaction between an organometallic reagent and an aldehyde or ketone.
The intermediate of the reaction is a tetrahedral species. The final step of the reaction involves protonation of the alkoxide oxygen. The carbon group of the organometallic reagent acts as the nucleophile.
Select all statements that correctly describe the reactions of organometallic reagents. The polarity of the R-M bond determines the reactivity of the organometallic reagent. Organometallic reagents attack nucleophilic carbon atoms, especially the carbonyl group. After an organometallic reagent adds to a C=O group, the fate of the intermediate depends on the presence or absence of a leaving group.
The polarity of the R-M bond determines the reactivity of the organometallic reagent. After an organometallic reagent adds to a C=O group, the fate of the intermediate depends on the presence or absence of a leaving group.
Select all of the statements that correctly describe the structure and reactivity of α,β-unsaturated carbonyl compounds. The two π bonds in an α,β-unsaturated carbonyl compound are conjugated. An α,β-unsaturated carbonyl compound contains a double bond separated from a carbonyl group by a single bond. The α and β carbons in an α,β-unsaturated carbonyl compound are electrophilic.
The two π bonds in an α,β-unsaturated carbonyl compound are conjugated. An α,β-unsaturated carbonyl compound contains a double bond separated from a carbonyl group by a single bond.
c
What is the major product of the following reaction?
Protection groups What are the three steps of using a protection group to prevent poisonings of Grignard/alkyl lithium
[1] Convert the OH group into another functional group that does not interfere with the desired reaction. also referred to as the protecting group reaction that creates is called protection [2] Carry out the desired reaction [3] Remove the protecting group. aka deprotection
Metal Hydride Reduction of Carbonyls: The net result is
adding H:− (from NaBH4 or LiAlH4) and H+ (from H2O) is the addition of the elements of H2 to the carbonyl π bond.
LiAIH4 can reduce an aldehyde to a primary __________
alcohol
Organolithium and Grignard reagents react with aldehydes and ketones forming a new carbon-carbon bond and resulting in the formation of a(n) ______ after aqueous workup (protonation)
alcohol
The reduction reaction of aldehydes and ketones results in the formation of
alcohol
Naming al
aldehydes
what is the most useful oxidation reaction of carbonyl compounds
aldehydes to carboxylic acids
(aldehydes/ ketones) are more reactive toward nucleophilic attack Because: aldehydes are (more/Less) crowded than ketones aldehydes are (more/Less) stable than ketones aldehydes are (more/Less) reactive than ketones
aldehydes: less less more
What is a coenzyme?
an organic molecule that can function only in the presence of the enzyme.
Phenyl
benzene as a substituent
4 carbon alkene
butene
CAN/NOT do catalytic hydrogenation of carbonyls
cannot
organometallic reagents contain a _____ atom bonded to a metal
carbon
Functional Group Transformations involving organometallic compounds [1] Reaction of R-M aldehydes and ketones to afford alcohols
carbon group attack's the postive end of O= electrons go out onto the oxygen added and R group and an O- Add H2O/CH3OH (solvent) The H attaches to negative O and makes it back to neutral R group is add
NADH is what type of enzyme
coenzyme
Reduction is the _________ of C-Z bonds (usually C-O) or an_________ in the number of C-H bonds (add H sub O)
decrease, increase
what is a halogen
fluorine, chlorine, bromine, iodine, and astatine,
7 carbon alkene
heptene
oxidation is the _______ in the number of C-Z bonds (usually C-O) or a _________ in the number of C-H bonds (add O sub H)
increase, decrease
When a Grignard reagent reacts with an unsymmetrical epoxide, nucleophilic attack occurs at the _____ substituted carbon to give a(n) _____.
least alcohol
When a Grignard reagent reacts with an unsymmetrical epoxide, nucleophilic attack occurs at the _____ substituted carbon to give a(n) _____.
least, alcohol
The _____ group determines the type of reaction the carbonyl will undergo
leaving group
R2CuLi is much________reactive than either RLi or RMgX toward _______ groups.
less carbonyl
The most useful reagents for reducing aldehydes and ketones are the _____ ______ _____ : Treating an aldehyde or ketone with______ and ______, followed by ______ or _______ affords an alcohol.
metal hydride reagents, NaBH4 or LiAlH4, H2O or some other proton source
1 carbon alkene
methene
Nucleophilic Addition (1) The________ attacks the electrophilic carbonyl. The pi bond is _______, moving an electron pair out on an _______ and forming an sp3 hybridized carbon (2) ________ of the negatively charged oxygen by ____ form the addition production Net result: 2 ____ bonds broke, Two new _____ bonds, H and Nu add to π
nucleophile, broken, oxygen , Protonation, H2O, π, σ, π
General Reactions of Carbonyl Compounds Aldehydes and ketones undergo ______ _______ which means ____ and ___ and added Carbonyl compounds with a leaving group undergo__________ _______ which means _______ replaces ______
nucleophilic addition H and Nu nucleophilic sub Nu z
Nucleophilic addiction is also known as
nucleophilic attack
The mechanism for the reaction of Grignard reagents with aldehydes and ketones proceeds by ________ attack at the carbonyl carbon to form a tetrahedral alkoxide intermediate followed by __________ of the alkoxide upon addition of water or aqueous acid.
nucleophilic protonation
The reaction of lithium metal with an alkyl halide gives a(n) _______ reagent
organolithium or alkyllithium
In the carbonyl group the electronegative oxygen means the bond is ______, thus, the carbonyl carbon is electron ______
polarized, deficient
3 carbon alkene
propane
N-H, O-H, water, alcohol amides carbocyclic acids, poison's the Grignard/alkyl lithium so to prevent this aka mask it we use _______ which means we do the reaction somewhere else
protection groups
Stereochemistry of Carbonyl Reduction Butan-2-one NaBH4/CH3OH --> sp2 into sp3 makes a _____ mixture which means there is a 50% chance attacking back or front. creating two enantiomers which are: because
racemic (S)-butan-2-ol and (R)-butan-2-ol
The more polar the carbon-metal bond, the more ____ the organometallic reagent
reactive
To determine what carbonyl and Grignard components are needed to prepare a given compound, follow these two steps:
step 1: find the carbon bonded to the OH group in the product step 2: break the molecule into two components: one alkyl group bonded to the carbon with the OH group comes from the organometallic reagent, the rest of the molecule comes form the carbonyl component
Addition of Organometallics to Aldehydes and Ketones to make _____ alcohols
tetra
Why is the product racemic
the carbonyl is planar, the hydride can approach the double bond with equal probability from both sides.
NADH is the reduced form of the coenzyme
true
to remove a alkyl halides let it react with water
water
Organometallic reagents are very strong bases and readily abstract a proton from which of the following?
water, alcohols amines
A Grignard reagent has a formula RMgX where X is a halogen, and R is an alkyl or aryl (based on a benzene ring) group
where X is a halogen, and R is an alkyl or aryl (based on a benzene ring) group