OChem Chapter 17: Carbonyl Compounds, Chapter 17

Which of the following organometallic reagents will react with the acid chloride shown to give the desired reaction?

(CH3CH2)2CuLi

_____ are more reactive than _____ toward nucleophilic attack for both steric and electronic reasons.

Aldehydes, ketones

A Grignard reagent is prepared by reacting a(n) _________ with Mg metal in anhydrous ether.

Alkyl halide

What is the final product of the reaction shown?

D

Reaction of Grignard and organolithium reagents with α,β-unsaturated carbonyl compounds usually results in _____-addition.

1,2

Describe the mechanism of the reduction of acid chlorides and esters with a metal-hydride reducing agent

In step 2 the pi bond is re-formed An aldehyde is produced in step 2 of the mechanism In step 2 of ester reduction, an allkoxide leaving group is expelled from the tetrahedral intermediate

What reagents may be used to reduce aldehydes and ketones to alcohols?

NaBH4 LiAlH4

Reduction of a carboxylic acid with LiAlH4 results in the formation of a(n) _________.

Primary alcohol

Describe protecting groups

Protecting groups must be easily removed (deprotection) to regenerate the original functional group A reactive functional group is converted into another functional group that does not interfere with the desired product

Reaction of a Grignard reagent with a ketone followed by hydrolysis results in the formation of a ______ alcohol.

Tertiary

Describe an isolated carbonyl group

The C atom is sp2 hybridized The O atom is sp2 hybridized The O atom is electron rich

CrO3 in acid _____ aldehydes to _______

oxidized carboxylic acids

What is the product of the following reaction?

Structure B

Esters react with two equivalents of Grignard reagent to produce ______ alcohols.

Tertiary

Describe the bonding of the carbonyl group

The carbonyl C is trigonal planar The C=O bond is polarized and the C atom is electron deficient The C=O group can be represented by 2 resonace structures

Describe the mechanism for the LiAlH4 reduction of an aldehyde or ketone

The oxygen atom of the C=O group is protonated in Step 2, after the nucleophile attacks LiAlH4 serves as a source of hydride ion, H:- (there are no free H:- ions present) The pi bond of the C=O group is cleaved in the first step of the reaction

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. 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 the statements that correctly describe the mechanism of 1,4-addition of a nucleophile to an α,β-unsaturated carbonyl compound. A) In the first step a resonance-stabilized enolate if formed. B) Nucleophilic attack occurs at the alpha carbon of the carbonyl compound. C) The final product of the reaction is an allylic alcohol. D) Protonation of the enolate oxygen atom produces an enol. E) The 1,4-product is produced directly from protonation of the carbon end of the enolate, or by tautomerization of the enol.

A, D, E

Consider the synthetic scheme shown. Match each step (A-C) in the scheme to the appropriate reagents required to carry out the transformation

A- (i) BH3; (ii) H2O2, HO- B- pyridinium chlorochromate (PCC) C- (i) C2H5Li; (ii) H2O

The alcohol shown in the diagram may be synthesized in three different ways. Match the correct reagents required to produce the desired alcohol product.

A-D1 B- C E- D2

Describe the reactions of organometallic reagents

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

A mixture of CrO3/H2SO4/H2O may be used to convert a(n) _____ into a(n) _____.

Aldehyde, carboxylic acid

Match each carbonyl compound to the type of product that is formed when the carbonyl compound is reduced by either NaBH4 or LiAlH4

Aldehyde: 1° alcohol Ketone: 2° alcohol

Select all the compounds that undergo predominantly nucleophilic substitution rather than addition.

B,D

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 _________ groups, which is removed once the synthesis is complete.

Base, protecting

Select the structure for the product of the following reaction. (CH4 is also formed.)

C

Which one of the following statements does NOT correctly describe nucleophilic acyl substitution? A) A tetrahedral sp^3 hybridized intermediate is formed. B) The first step of the mechanism is identical to nucleophilic substitution. C) Two new sigma bounds are formed. D) The net result is that the nucleophile replaces the electronegative leaving group.

C

An alpha, beta- unsaturated carbonyl system has two electrophilic sites. Match each reaction site with the type of addition that occurs when the system reacts with a nucleophile

C=O carbon atom: 1,2 addition beta carbon atom: 1,4 addition

Grignard reagents react with _______ to give carboxylic acids after protonation of the resulting carboxylate anion

CO2 (carbon dioxide)

Grignard reagents react with _____ to give carboxylic acids after protonation of the resulting carboxylate anion.

Carbon dioxide

Which of the following combinations will NOT produce 3-phenyl-3-pentanol (shown) after hydrolysis?

D

Which of the following statements are correct?

Organometallic reagents are strong nucleophiles, but they can be strong bases When using organometallic reagents, N-Hand O-H bonds must be protected

Match each definition to the appropriate term listed below: Oxidation: Reduction:

Oxidation: increase in the number of C-Z bonds (usually C-O) Reduction: Increase in the number of C-H bonds

For ketones having the general structure C6H5COR, the (S)-CBS reagent generally produces the ____ alcohol as the major product

R

Explain why ketones are less reactive than aldehydes

The two alkyl groups of a ketone stabilize the partial charge on the carbonyl C, making it less reactive An aldehdye is less sterically crowded, allowing nucleophilic attack to occur more easily

The reduction reaction of aldehydes and ketones results in the formation of

alcohols

A mixture of CrO3/H2SO4/H2O may be used to convert a(n) _____ into a(n) _____.

aldehyde; carboxylic acid

A nucleophile can react with an alpha, beta-unsaturated carbonyl compound at one of two sites. 1,2 addition involves reaction at the _______ C atom and the product formed is a(n) _________ alcohol. 1,4 addition involves reaction at the ______ C atom and the product formed is a(n) compound

carbonyl allylic beta carbonyl

In an enantioselective reaction, one ______ is formed predominately or exclusively

enantiomer

The reduction of 3-hexanone (shown below) with NaBH4 in CH3OH results in the formation of two products that are ______.

enantiomers formed in equal amounts

Reduction of carboxylic acid with LiAlH4 results in the formation of a(n)______ ______

primary alcohol

Select all the statements that correctly describe organometallic reagents. A) These reagents contain a polar carbon-metal bond. B) Organometallic reagents are good nucleophiles and strong bases. C) Organometallic reagents are ionic since they contain a bond between a metal and a nonmetal. D) Organometallic reagents are a source of electrophilic carbon.

A, B

Which of the following compounds could be used to convert 1-octyne to the corresponding acetylide anion? A) NaH B) CH3MgBr C) NaOCH2CH3 D) NaOH

A, B

Select all reagents that are capable of reducing aldehydes to 1° alcohols. A) NaBH4 B) K2Cr2O7, H2SO4, and H2O C) LiAlH4

A, C

Which of the following compounds could be used to deprotonate the hydrogen from a terminal alkyne? A) NaNH2 B) KOH C) CH3Li D) NaOCH3

A, C

Organometallic reagents are very strong bases and readily abstract a proton from which of the following? Select all that apply. A) Alcohols B) Alkanes C) Amines D) Water

A, C, D

Which of the following molecules can be reduced with LiAlH4 to form a primary alcohol?

A,C,D

Which of the following structures are α,β-unsaturated carbonyl compounds?

A,C,D

Consider the synthetic scheme shown. Match each step in the scheme (A-D) to the appropriate reagents required to carry out the transformation.

A- (i) (C2H5)2CuLi; (ii) H2O B- (i) C2H5MgCl; (ii) H2O C- H2, Pd on C D- (i) NaH; (ii) C2H5Br

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 work up.

Alcohol

The reduction reaction of aldehydes and ketones results in the formation of __________.

Alcohols

What functional group can be oxidized with Tollens reagent (Ag2O, NH4OH) to give a carboxylic acid

Aldehyde

Match the carbonyl compounds described with the type of reaction that each undergoes.

Aldehydes and ketones- Nucleophilic addition Carbonyl compounds that contain leaving groups (e.g., acid chlorides)- Nucleophilic substitution

After reduction with LiAlH4, followed by aqueous workup (protonation) the following starting materials will form what? Carboxylic acids Esters Amides

Carboxylic acids: alcohols Esters: alcohols Amides: amines

Place the following steps from the reduction of a 1° amide with LiAlH4 in their correct order (not all steps are shown)

Deprotonation of the 1° amide by LiAlH4 Formation of an imine after loss of (AlH3O)2- Delivery of "H:-" to an imine by LiAlH Protonation of the conjugate base of an amine by H2O

The polarized C=O bond results in a carbon that is _____ and therefore susceptible to attack by _____.

Electrophiles, nucleophiles

When acetaldehyde (shown) is reacted with CH3CH2MgBr, the nucleophile can attack the carbonyl group from either side of the trigonal planar carbonyl group. Since the starting materials are achiral, and a stereogenic center is formed, the products of the reaction will be ______.

Enantiomers in equal amounts

Match the structure of the reactant aldehyde/ketone to the identity of the alcohol produced by reaction of the adehyde/ketone with a Grignard reagent

HCHO: 1° alcohol CH3CH2CHO: 2° alcohol (CH3)2CO: 3° alcohol

When a Grignard reagent reacts with an unsymmetrical epoxide, nucleophilic attack occurs at the _____ substituted carbon to give a(n) _____.

Least, alcohol

Reduction of acid chlorides and esters with _____ results in the formation of 1° alcohols

LiAlH4

Which of the following reagents will reduce acid chlorides and esters to primary alcohols?

LiAlH4

Reduction of an amide with ____ results in the formation of a(n) _________

LiAlH4 amine

Match the correct description of each reagent.

LiAlH4- Strong reducing agent that reacts with all carboxylic acid derivatives DIBAL-H- Contains two bulky isobutyl groups and is a milder reducing agent LiAlH[OC(CH3)3]3- Has three electronegative atoms bonded to aluminum making reagent less nucleophilic

Select all statements that correctly describe the reducing agents given below.

LiAlH[OC(CH3)3]3is less nucleophilic than LiAlH4. DIBAL-H has two bulky isobutyl groups, which make this reagent less reactive than LiAlH4.

Describe the role of NADH in biological reduction

NADH is a coenzyme that donates H:- to the carbonyl group Biological reduction with NADH proceed with 100% enentioselectivity Pyruvic acid is reduced to lactic acid by NADH when there is insufficient O2 to metabolize pyruvic acid to CO2

Consider the reactant shown. Select all statements that correctly describe the reduction of this compound.

NaBH4 would reduce the C=O group. Excess H2/Pd-C would reduce both the C=O and C=C groups. 1 equivalent of H2/Pd-C would reduce only the C=C group.

What compounds could be used to convert 1-octyne to the corresponding acetylide anion?

NaH CH3MgBr

What compounds could be used to deprotonate the hydrogen from a terminal alkyne?

NaNH2 CH3Li

Describe the steps for the mechanism of the reaction of Grignard and organolithium reagents with acid chlorides and esters

Nucleophilic attack at the carbonyl carbon atom of the carboxylic acid derivative to form a tetrahedral intermediate Elimination of a leaving group resulting in the formation of a carbonyl group Nucleophilic attack at the carbonyl carbon of a resulting aldehyde or ketone Protonation of an alkoxide oxygen after addition of a proton source

The mechanism for 1,4-addition to an α,β-unsaturated carbonyl compound involves _____ attack at the _____ carbon resulting in an enolate, which is then protonated.

Nucleophilic, beta

The mechanism for reaction of Grignard reagents with aldehydes and ketone proceeds by _________ attack at the carbonyl to form a tetrahedral alkoxide intermediate followed by _______ of the alkoxide upon addition of water or aqueous acid.

Nucleophilic, protonation

The mechanism of the reaction of Grignard reagents with aldehydes and ketones proceeds by ________ attack at the carbonyl carbon to form a tetrahedral alkoxide intermediated followed by ________ of the alkoxide upon adding of water or aqueous acid.

Nucleophilic, protonation

Describe organometallic reagents

Organometallic reagents are good nucelophiles and strong bases These reagents contain a polar carbon-metal bond

correctly Describe organometallic reagents

Organometallic reagents react with acids such as H2O The more polar the carbon-metal bond, the more reactive the organometallic reagent Organometallic reagents react with electrophilic carbon atoms to form new C-C bonds

Describe the mechanism of 1,4 addition of a nucleophile to an alpha, beta-unsaturated carbonyl compound

Protonation of the enolate oxygen atom produces an enol In the first step a resonance-stabilized enolate is formed The 1,4-product is produced directly from protonation of the carbon end of the enolate, or by tautomerization of the enol

Select all the statements that correctly describe the mechanism of the reaction between an organometallic reagent and an aldehyde or ketone.

The carbon group of the organometallic reagent acts as the nucleophile. The intermediate of the reaction is a tetrahedral species. The final step of the reaction involves protonation of the alkoxide oxygen.

Select all of the statements that correctly describe the process of nucleophilic acyl substitution.

The carbonyl group is preserved in this reaction. The electronegative atom attached to the carbonyl group acts as a leaving group. This reaction does not require protonation as the final step.

Describe the mechanism of nucelophilic addition to an aldehyde or ketone

The electrophilic carbon of an aldehyde changes its hybridization state upon nucleophilic attack As the nucleophile attacks, the electron pair of the pi bond moves onto the O atom

What, if anything, is wrong with mechanism shown for reduction of acetone with NaBH4?

The final product should be protonated on oxygen.

Which one of the following statements does NOT correctly describe nucleophilic acyl substitution?

Two new sigma bonds are formed

A Grignard reagent is prepared by reacting a(n) _____ with Mg metal in anhydrous ether

alkyl halide

Select the reagents that will produce the desired product shown. (d= 2ch3mgbr)

b,c

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 nucelophile. To prevent this interference, OH and NH groups must be "blocked" with a ______ group, which is removed once the synthesis is complete

base protecting

Reduction results in a(n0 ______ in the number of C-O bonds or a(n) ____ in the number of C-H bonds

decrease increase

Hydride reduction of the ketone shown will result in the formation of products that are (pent with double bonded o)

diastereomers formed in unequal amounts

LiAlH4 contains a _____ polar metal-hydrogen bond the NaBH4 and therefore is _____ reactive in reduction reactions

more, more

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

nucelophilic protonation

A(n) _____ reagent is prepared from the reaction of an organolithium reagent with a Cu(I) salt

organocuprate

The reaction of lithium metal with an alkyl halide gives a(n) _____ reagent

organolithium

lithium tri-tertbutoxyaluminum hydride has three electronegative ________ atoms bonded to aluminum, which makes this reagent _______ reactive that LiAlH4

oxygen less

A C-Cu bond is less _____ that either a C-Li or C-Mg bond, and so the organocuprate reagent is ______ reactive than organolithium or Grignard reagents

polar less

Since the carbonyl carbon is _____ hybridized and the geometry of the carbonyl group is ______, attack by hydride occurs from both faces of the carbonyl group. If the compound contains no other stereogenic centers and a stereogenic center is produced by the reduction, the resulting products will be _______

sp2 trigonal planar enantiomers

LiAlH4 is a _____ reducing agent and is _______ in that it reduces most polar functional groups

strong nonselective

Organometallic reagents are ______ bases that easily abstract a ______ from water to form hydrocarbons

strong proton

When a Grignard reagent reacts with an unsymmetrical epoxide, the Gignard group attacks _______

the least substituted carbon from the back side

Organometallic reagents are very strong bases and readily abstract a proton from which of the following?

water amines alcohols

Alcohols can be reacted with tert-butyldimethylsilyl chloride (TBDMSCl) and imidazole to form TBDMS _______.

ethers

Reaction of Grignard and organolithium reagents with α,β-unsaturated carbonyl compounds usually results in _____-addition.

1, 2

Reaction of organocuprate reagents with alpha, beta-unsaturated carbonyl compounds usually results in ________

1,4-addition

During reduction of an acid chloride _____ equivalent(s) of H:- is/are delivered by LiAlH4. The leaving group Z is _____ and a _____ alochol is formed

2 chloride primary

Reaction of a Grignard reagent with a ketone followed by hydrolysis results in the formation of a ______ alcohol.

3o tert

What is the product of the following reaction? (CuLi)

A

Which of the following reagents will reduce acid chlorides and esters to primary alcohols? A) LiAlH4 B) DIBAL-H C) LiAlH[OC(CH3)3]3 D) NaBH4

A

Match the type of carbonyl compound listed to its appropriate structural description.

Amide matches Choice, Has a nitrogen atom bonded to the carbonyl group Has a nitrogen atom bonded to the carbonyl group Ester matches Choice, Has an oxygen atom bonded to the carbonyl group Has an oxygen atom bonded to the carbonyl group Aldehyde matches Choice, Has one or more hydrogen atoms bonded to the carbonyl group Has one or more hydrogen atoms bonded to the carbonyl group Ketone matches Choice, Has two alkyl or aryl groups bonded to the carbonyl group Has two alkyl or aryl groups bonded to the carbonyl group Acid chloride matches Choice, Has a chlorine atom bonded to the carbonyl group Has a chlorine atom bonded to the carbonyl group

Describe the structure and reactivity of alpha, beta-unsaturated carbonyl compounds

An alpha, beta-unsaturated carbonyl compound contains a double bond separated from a carbonyl group by a single bond The two pi bonds in an alpha, beta-unsaturated carbonyl compound are conjugated

Select all of the statements that correctly describe the structure and reactivity of α,β-unsaturated carbonyl compounds.

An α,β-unsaturated carbonyl compound contains a double bond separated from a carbonyl group by a single bond. The two π bonds in an α,β-unsaturated carbonyl compound are conjugated.

Select the structure of the product for the reaction shown. (THF)

B

What is the product of the reaction shown? (h2 1 equiv))

B

Which of the following statements are correct? A) Organometallic reagents will react with carbonyls before they deprotonate an O-H bond. B) When using organometallic reagents, N-H and O-H must be protected. C) Organometallic reagents are strong nucleophiles, but they can also be strong bases.

B, C

Select all statements that correctly describe organometallic reagents. A) The carbon atom bonded to the metal bears a partial positive charge. B) The more polar the carbon metal bond, the more reactive the organometallic product. C) Organometallic reagents react with acids such as H2O. D) Organometallic reagents react with electrophilic carbon atoms to form new carbon-carbon bonds.

B, C, D

Select all of the statements that correctly explain why ketones are less reactive than aldehydes. A) The hydrogen atom attached to the aldehyde carbonyl is easily lost, making aldehydes more reactive. B) The two alkyl groups of a ketone stabilize the partial change on the carbonyl C, making it less reactive. C) The carbonyl group of an aldehyde is less polarized, making it more reactive, D) An aldehyde is less sterically crowded, allowing nucleophilic attack to occur more easily.

B, D

Select the reagents that will oxidize an aldehyde to a carboxylic acid. A) PCC B) CrO3, H2SO4, H2O C) NaBH4, CH3OH D) Ag2O, NH4OH

B, DSelect the reagents that will oxidize a 1o alcohol to a carboxylic acid. Multiple choice question. Ag2O, NH4OH Reason: Ag2O/NH4OH oxidizes an aldehyde to a carboxylic acid. It does not oxidize alcohols. CrO3, H2SO4, H2O NaBH4, CH3OH Reason: NaBH4 is a reducing agent. Pyridinium Chlorochromate (PCC) Reason: PCC is used to selectively oxidize 1° alcohols to aldehydes. Correct Answer CrO3, H2SO4, H2O.

Which one of the following statements does NOT correctly describe nucleophilic acyl substitution? A) The net result is that the nucleophile replaces the electronegative leaving group. B) A tetrahedral sp^3 hybridized intermediate is formed. C) Two new sigma bonds are formed. D) The first step of the mechanism is identical to nucleophilic substitution.

C

From the list below, select the reagent that will reduce an ester to an aldehyde, and select the reagent that will reduce an acid chloride to an aldehyde. A) LiAlH4 B) NaBH4 C) DIBAL-H D) LiAlH[OC(CH3)3]3

C, D

A C=O bond will react differently than a C=C double bond. Match each bond with the manner in which it will react

C=C bond: The pi bond reacts as a nucleophile C=O bond: C atom reacts as an electrophile

Aldehydes undergo nucelophilic ________ reactions. Carboxylic acid derivatives have a group containing a heteroatom attached to the carbonyl carbon. This group acts as a _____ group, allowing these compounds to undergo nucleophilic _____ reactions instead

addition leaving substitution

Organolithium and Grignard reagents react with aldehydes and ketones forming a new C-C bond and resulting in the formation of a(n) ______ after aqueous workup (protonation)

alcohol

When the OH group of an ______ is reacted with TBDMSCl/imidazole, the resulting TBDMS ether is known as a _____ group

alcohol protecting

Match each carbonyl compound to the type of product that is formed when the carbonyl compound is reduced by either sodium borohydride or lithium aluminum hydride.

aldehyde- 1 alcohol Ketone- 2 alcohol

When acetaldehyde (shown) is reacted with CH3CH2MgBr, the nucleophile can attack the carbonyl group from either side of the trigonal planar carbonyl group. Since the starting materials are achiral, and a stereogenic center is formed, the products of the reaction will be ______.

enantiomers in equal amounts

In cells, NADH donates a ______ to a carbonyl and acts as a ______ agent.

hydride, reducing

An aldehyde always has at least one ______ atom bonded to the carbonyl group, whereas a(n) _____ has two alkyl or aryl groups bonded to the carbonyl carbon

hydrogen ketone

When a Grignard reagent reacts with an unsymmetrical epoxide, nucleophilic attack occurs at the ______ substituted carbon to give a(n) ________

least alcohol

R2CuLi is much ______ reactive than either RLi or RMgX toward _____ groups

less carbonyl